text:
Determination of Section 404
Permit and Habitat Mitigation
Final Report 589
September 2012
Arizona Department of Transportaon
Research Center
Final Report 589
September 2012
Prepared by:
Greg Martinsen, Timothy Wade, and Tricia Balluff
EcoPlan Associates, Inc.
701 West Southern Avenue, Suite 203
Mesa, Arizona 85210
Prepared for:
Arizona Department of Transportation
in cooperation with
U.S. Department of Transportation
Federal Highway Administration
This report was funded in part through grants from the Federal Highway Administration,
U.S. Department of Transportation. The contents of this report reflect the views of the
authors, who are responsible for the facts and the accuracy of the data, and for the use
or adaptation of previously published material, presented herein. The contents do not
necessarily reflect the official views or policies of the Arizona Department of
Transportation or the Federal Highway Administration, U.S. Department of
Transportation. This report does not constitute a standard, specification, or regulation.
Trade or manufacturers' names that may appear herein are cited only because they are
considered essential to the objectives of the report. The U.S. government and the State
of Arizona do not endorse products or manufacturers.
Technical Report Documentation Page
1. Report No.
2. Government Accession No. 3. Recipient's Catalog No.
4. Title and Subtitle 5. Report Date
September 2012
6. Performing Organization Code
7. Author
Greg Martinsen, Ph.D., Timothy Wade, and
Tricia Balluff
8. Performing Organization Report No.
9. Performing Organization Name and Address
EcoPlan Associates, Inc.
10. Work Unit No.
701 West Southern Avenue, Suite 203
Mesa, Arizona 85210
11. Contract or Grant No.
12. Sponsoring Agency Name and Address
Arizona Department Of Transportation
206 South 17th Avenue
13.Type of Report & Period Covered
May 2007 – December 2011
Phoenix, Arizona 85007
ADOT Project Manager: Estomih (Tom) Kombe, Ph.D., P.E.
14. Sponsoring Agency Code
15. Supplementary Notes
Prepared in cooperation with the US Department of Transportation, Federal Highway Administration
16. Abstract
The Arizona Department of Transportation (ADOT) is committed to developing habitat, mitigation,
monitoring, and maintenance plans that replace the loss of the functions and values of an area and
are self-sustaining, thereby providing long-term compensation for habitat adversely affected by ADOT
construction activities. This study focuses on identifying administrative and biological criteria that are
important to the success or failure of mitigation and/or restoration projects and developing
recommendations from these criteria. Files on ADOT and non-ADOT riparian habitat restoration and
mitigation projects were obtained from several sources and were reviewed for project applicability to
the study goals. Thirty-four sites were selected for further analysis. In addition, employees from the
Corps and ADOT were interviewed to gain a realistic perspective. A review of project files, associated
site data sheets, and analysis of the interview results yielded mitigation practices and a variety of
administrative and biological problems commonly associated with restoration projects in Arizona.
More specifically, the problems are associated with ADOT mitigation projects for which Clean Water
Act Section 404 permits are involved. Recommendations based on analysis of these problems, review
of applicable peer-reviewed literature, and research team expertise, are offered in this report to aid
future ADOT projects and all future restoration projects in Arizona, regardless of the agency or
organization undertaking the restoration of riparian areas.
17. Key Words
Riparian, restoration, mitigation, Section 404,
Arizona, ADOT
18. Distribution Statement
Document is available to the
US public through the National
Technical Information Service,
Springfield, Virginia 22161
23. Registrant's Seal
19. Security Classification
20. Security Classification
21. No. of Pages
22. Price
Symbol When You Know Multiply By To Find Symbol
in inches 25.4 millimeters mm
ft feet 0.305 meters m
yd yards 0.914 meters m
mi miles 1.61 kilometers km
in2 square inches 645.2 square millimeters mm2
ft2 square feet 0.093 square meters m2
yd2 square yard 0.836 square meters m2
ac acres 0.405 hectares ha
mi2 square miles 2.59 square kilometers km2
fl oz fluid ounces 29.57 milliliters mL
gal gallons 3.785 liters L
ft3 cubic feet 0.028 cubic meters m3
yd3 cubic yards 0.765 cubic meters m3
NOTE: volumes greater than 1000 L shall be shown in m3
oz ounces 28.35 grams g
lb pounds 0.454 kilograms kg
T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t")
TEMPERATURE (exact degrees)
oF Fahrenheit 5 (F-32)/9 Celsius oC
or (F-32)/1.8
fc foot-candles 10.76 lux lx
fl foot-Lamberts 3.426 candela/m2 cd/m2
FORCE and PRESSURE or STRESS
lbf poundforce 4.45 newtons N
lbf/in2 poundforce per square inch 6.89 kilopascals kPa
Symbol When You Know Multiply By To Find Symbol
mm millimeters 0.039 inches in
m meters 3.28 feet ft
m meters 1.09 yards yd
km kilometers 0.621 miles mi
mm2 square millimeters 0.0016 square inches in2
m2 square meters 10.764 square feet ft2
m2 square meters 1.195 square yards yd2
ha hectares 2.47 acres ac
km2 square kilometers 0.386 square miles mi2
mL milliliters 0.034 fluid ounces fl oz
L liters 0.264 gallons gal
m3 cubic meters 35.314 cubic feet ft3
m3 cubic meters 1.307 cubic yards yd3
g grams 0.035 ounces oz
kg kilograms 2.202 pounds lb
Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T
TEMPERATURE (exact degrees)
oC Celsius 1.8C+32 Fahrenheit oF
lx lux 0.0929 foot-candles fc
cd/m2 candela/m2 0.2919 foot-Lamberts fl
FORCE and PRESSURE or STRESS
N newtons 0.225 poundforce lbf
kPa kilopascals 0.145 poundforce per square inch lbf/in2
*SI is the symbol for th International System of Units. Appropriate rounding should be made to e comply with Section 4 of ASTM E380.
(Revised March 2003)
Executive Summary .......................................................................................................... 1
Chapter 1. Introduction.................................................................................................... 7
Chapter 2. Methods .......................................................................................................... 9
Site Visits ....................................................................................................................... 9
Interviews ....................................................................................................................... 9
Chapter 3. Results ........................................................................................................... 11
Project File Review and Site Visits .............................................................................. 11
Mitigation Practices ................................................................................................. 11
Tall-Pot Plantings............................................................................................... 11
Planting Stock Collected On-Site ...................................................................... 13
Nursery Stock Planted........................................................................................ 13
Preplanting Soil Testing ..................................................................................... 14
Replacement of Dead or Unhealthy Trees ......................................................... 14
Salvaged/Transplanted Saguaros ....................................................................... 15
Seeding/Hydroseeding ....................................................................................... 15
Administrative Process Mitigation Problems .......................................................... 16
Failure to Monitor Mitigation Plantings ............................................................ 16
Failure to Inspect Irrigation or Irrigation Removed Prematurely ...................... 18
Mitigation Not Completed ................................................................................. 19
Mitigation Monitor Not Qualified ..................................................................... 19
Staff Turnover .................................................................................................... 20
Overplanting ...................................................................................................... 20
No Irrigation....................................................................................................... 21
No Reference Plot .............................................................................................. 21
Revised Mitigation ............................................................................................. 21
Biological Mitigation Problems ............................................................................... 22
Animal Damage ................................................................................................. 22
Flooding ............................................................................................................. 22
Animal Damage to Irrigation Lines ................................................................... 24
Transplant Shock ............................................................................................... 24
Drought Stress .................................................................................................... 25
Insects and Pests ................................................................................................ 25
Tamarisk ............................................................................................................ 25
Invasive Species ................................................................................................. 26
Root-Bound Nursery Plants ............................................................................... 27
Mistletoe ............................................................................................................ 27
Heat-Damaged Roots in Tall-Pot Plantings ....................................................... 27
Fire ..................................................................................................................... 28
Interviews ..................................................................................................................... 28
ADOT Interviews .................................................................................................... 32
Administrative Processes ................................................................................... 32
Biological Factors .............................................................................................. 35
Corps Interviews ...................................................................................................... 37
Administrative Processes ................................................................................... 37
Chapter 4. Discussion ..................................................................................................... 41
Chapter 5. Recommendations ........................................................................................ 45
Administrative Processes ............................................................................................. 45
Biological Factors ......................................................................................................... 48
References ........................................................................................................................ 53
Appendix: Case Studies .................................................................................................. 55
Case Study 1: 'Ahakhav Tribal Preserve ..................................................................... 56
Case Study 2: Covered Wells, Why–Tucson Highway (SR 86) .................................. 59
Case Study 3: SR 89A, Cornville Road to Sedona, Arizona ........................................ 61
Case Study 4: SR 75, Gila River Bridge #311 ............................................................. 65
Case Study 5: Peck Canyon Bridges ............................................................................ 67
Figure 1. Mitigation Practices ........................................................................................... 12
Figure 2. Administrative Process Mitigation Problems .................................................... 17
Figure 3. Biological Mitigation Problems. ....................................................................... 23
Figure 4. Evenly Spaced Plantings at the Northern End of the
'Ahakhav Tribal Preserve Project Site ............................................................... 58
Figure 5. Dense Cover Behind the 'Ahakhav Tribal Preserve Nursery ............................ 58
Figure 6. Relocated Saguaros at the Western End of the Covered Wells,
Why–Tucson Highway (SR 86) Project Site. .................................................... 60
Figure 7. An Actively Growing Saguaro Near the Irrigation Tube at the
Covered Wells Why–Tucson Highway (SR 86) Project Site ............................ 60
Figure 8. Revegetated Area Adjacent to and West of the SR 89A,
Cornville Road to Sedona Project Site (Facing North) ...................................... 63
Figure 9. Revegetated Area Adjacent to and West of the SR 89A,
Cornville Road to Sedona Project Site (Facing South). ..................................... 64
Figure 10. The 40-Foot-Wide Mitigation Strip Along the West Side of the
SR 75, Gila River Bridge #311 Project Site ................................................... 66
Figure 11. Dense, Naturally Recruited Riparian Trees Along the West Side of the
SR 75, Gila River Bridge #311 Project Site ................................................... 66
Figure 12. Pole Planting Knocked Down by Flooding at Peck Canyon Bridges
Project Site, Between the Frontage Road and the I-19 Bridges. ..................... 69
Figure 13. Growing and Dead Pole Plantings Downstream at the Peck
Canyon Bridges Project Site ........................................................................... 69
Table 1. Comments from ADOT Interviews .................................................................... 28
ADOT Arizona Department of Transportation
ADWR Arizona Department of Water Resources
AGFD Arizona Game and Fish Department
DEC district environmental coordinator
EPA Environmental Protection Agency
EPG Environmental Planning Group
FHWA Federal Highway Administration
FCDMC Flood Control District of Maricopa County
MP milepost
NEPA National Environmental Policy Act
NGO non-governmental organization
NWP nationwide permit
PVC polyvinyl chloride
SR state route
TI traffic interchange
The authors would like to express appreciation to members of the Arizona Transportation
Research Center Technical Advisory Committee for sharing expertise and providing
input on this final report. We also appreciate the many employees of federal, state, and
county agencies; nonprofit organizations; and private entities who gave of their time and
shared their expertise in the interviews and on-site visits. We thank The Flood Control
District of Maricopa County for its aid in locating tall-pot planting sites and the Arizona
Department of Water Resources for allowing access to its files on riparian mitigation
Using current U.S. Army Corps of Engineers (Corps) guidelines as the backdrop, this
study focuses on determining administrative processes and biological factors that are
important to the success or failure of land restoration and disturbance mitigation projects.
Data were collected by identifying past or ongoing projects of the Arizona Department of
Transportation (ADOT) and other agencies that have habitat restoration or disturbance
mitigation components, conducting site visits as needed, and interviewing Corps project
managers and ADOT employees who work with mitigation projects. The data were used
to assess the condition of mitigation plantings at these projects and from this analysis, to
identify factors important to the success or failure of such projects.
ADOT and the Federal Highway Administration (FHWA) are committed to mitigating
the ecological impact of ADOT construction on an area. They do this by executing plans
that provide for the replacement of lost habitat with plants that will be self-sustaining in
the long run. ADOT has concluded that its projects too often fail to meet the planting
success criteria contained in the mitigation requirements of Corps' Clean Water Act,
Section 404, permits. When these requirements are not initially met, the replantings and
extension of monitoring periods needed to do so create time and cost burdens for ADOT,
the FHWA, and Arizona taxpayers. ADOT and the FHWA have concluded that research
is needed to ensure that mitigation developed for future ADOT projects meets the criteria
required by the Corps.
Files on ADOT and non-ADOT habitat restoration and land disturbance mitigation
projects were obtained from the Corps; internal EcoPlan Associates, Inc. (EcoPlan)
project files; the University of Arizona Water Resources Research Center; and the
Arizona Department of Water Resources (ADWR). The files were reviewed to determine
project goals, the level of available detail such as planting plans and follow-up
monitoring reports, and overall file completeness. Researchers selected 34 projects for
detailed study: 19 ADOT projects, four projects from the Flood Control District of
Maricopa County (Flood Control District), and 11 restoration projects undertaken by
private entities or non-governmental organizations (NGOs). Of these 34 projects, 23 were
selected for further evaluation through site visits by EcoPlan biologists. Eleven of the
sites visited were ADOT project sites, four were Flood Control District sites, and eight
were private or NGO sites. Researchers used information in the file and field
observations to make an overall determination of each project's success.
One-on-one interviews with select Corps and ADOT employees provided important
insights into the causes of success or failure of mitigation projects. Researchers obtained
firsthand knowledge from individuals who are, or should be, involved in the mitigation
process. ADOT employees were interviewed using a standardized set of questions to
facilitate comparison and analysis of responses.
A review of project files, site visit observations, and associated site visit data sheets and
photo logs yielded seven common mitigation practices:
Planting stock collected at the site.
Planting nursery stock.
Planting stock raised in tall pots.
Testing the soil before planting.
Replacing dead trees on a regular basis.
Salvaging and transplanting saguaros.
Seeding or hydroseeding.
These practices have varying levels of success.
The project file review and associated site visits also yielded a list of problems that
occurred during the mitigation projects, although these did not always lead to failure.
Many of the projects had multiple problems, which increased their potential to fail. The
problems were divided into two main categories: administrative processes and biological
factors. Some problems, such as unmaintained irrigation, were classified as both.
Administrative process problems were:
Failure to monitor mitigation plantings.
Failure to inspect the irrigation system.
Premature removal of irrigation systems.
Not initiating or not completing the planned mitigation work.
Mitigation monitors who lacked monitoring experience.
Disconnects in project knowledge and follow-through caused by staff turnover.
Not irrigating.
Not using a reference plot to create mitigation or planting plans.
Revising mitigation plans due to an unsuccessful original plan.
Biological factor problems were:
Direct damage to the planted vegetation from wildlife, cattle, or both.
Wildlife damage to irrigation lines.
Transplant shock.
Drought stress.
Insect and pest damage.
Invasion of the project site by tamarisk or other invasive plants.
Root-bound nursery plants.
Parasitic infestation by mistletoe.
Improper handling of tall-pot container trees prior to planting.
Natural events such as flooding and fire.
Results of the interviews with Corps and ADOT employees were subjective and variable,
so those data were analyzed in a slightly different manner from the other data. Comments
were categorized as either administrative process or biological factor, with the following
subcategories added to clarify the results:
Administrative processes:
In-lieu fees and other off-site mitigation.
Responsible parties.
Staffing and training.
Other agency involvement.
Mitigation plans and monitoring.
Biological factors:
ADOT employees were split between opposition and support for in-lieu fees: Five
respondents opposed and eight favored use of in-lieu fees as a mitigation method. Most
interviewees agreed that ADOT should designate a staff position responsible for
developing mitigation plans and monitoring their completion from project beginning
through final acceptance by the Corps. Employees most commonly suggested the ADOT
district environmental coordinator (DEC) as the responsible position.
The issue of staffing and training came up tangentially during some of the interviews,
where it was noted that there is an overall need for dedicated, local personnel who are
involved with each project and for increased cross-training among all employees so
everyone understands all of the components of a project, including mitigation work.
Interviewees indicated that mitigation and planting plans should be developed by
someone with experience in desert ecology, not by someone whose experience is limited
to urban landscaping only.
According to interviewees, working with multiple agencies on one project can be difficult
because of differing goals and priorities, making mitigation less likely to succeed. Three
interviewees suggested that the Corps be involved in the process from the beginning to
ensure everyone agrees on a mitigation plan's goals and success criteria.
Five ADOT employees indicated that mitigation plans and monitoring need to have
specific success criteria; three said plans should be site-specific. Five ADOT employees
said that monitoring should be conducted by consultants; three said these consultants
should have a minimum of two or three years of experience.
Biological factors were fairly wide ranging, but the most commonly stated problems were
issues with irrigation, seasonality, and animal damage to plantings. Many ADOT
interviewees were unfamiliar with using tall-pot plantings to minimize irrigation needs.
Time of planting was another concern because mitigation plans are often based on the
construction schedule rather than the biological schedule of plants.
The interviews with Corps employees only covered administrative process issues and
yielded many of the same responses as the ADOT employee interviews. However, the
Corps project managers in general favored the use of in-lieu fees. Five project managers
mentioned problems obtaining permittee compliance with mitigation requirements of
Section 404 permits, including monitoring and reporting. Mitigation plans often lack
required information. One project manager saw insufficient monitoring and compliance
as one of the biggest problems. Another said that ADOT's chain of responsibility is not
strong enough and does not hold contractors sufficiently responsible for their actions or
Though many problems were identified, inefficiency was frequently noted by ADOT and
Corps interviewees. For example, mitigation plans that are not based on desert ecology
and local conditions ultimately fail and require replanting and extended monitoring. This
causes additional expense for ADOT, the contractor, or both.
Another problem they noted was inadequate planning, monitoring, and maintenance of
the irrigation system, and seasonal adjustment of the frequency and duration of
supplemental water. Failure of the irrigation system or application of insufficient depth
and frequency of supplemental water most often results in failure of the mitigation
In some cases, disconnects occur when projects transition between employees or
departments, making it difficult to follow the progress of mitigation and maintain
oversight of the contractor.
Clear objectives, specific measures of success, and a clearly defined monitoring plan
detailed in the mitigation plan are key to project success. Replacement ratios should be
based on site-specific characteristics and the use of multiple reference plots. Cooperation
with the Corps and other agencies in the early phases of the project will ensure that all
agencies understand the objectives and success criteria of a mitigation project. A
qualified ADOT employee or consultant should develop mitigation plans; plan
implementation should include biological timing considerations.
If no viable on-site or nearby off-site opportunities exist for compensatory mitigation, in-lieu
fees should be considered. The Corps rule regarding mitigation, "Compensatory
Mitigation for Losses of Aquatic Resources," which became effective June 9, 2008,
encourages the use of in-lieu fees over permittee-responsible mitigation. According to
Corps managers, in-lieu fees may especially be appropriate for linear projects where the
impacts are small and occur within the right of way.
A partial list of recommendations that were developed based on the data analysis is given
below. A complete list of recommendations is given in Chapter 5.
Administrative processes:
Enlist an ADOT employee or consultant with a clear understanding of natural
environments and a background in landscape ecological design, landscape
ecological restoration, plant biology, or restoration ecology to develop and
monitor land disturbance mitigation plans.
Create mitigation plans that outline clear performance objectives with specific
success criteria and a monitoring plan that defines the quantitative data needed to
determine success.
Designate an ADOT staff position responsible for following all mitigation
projects—from initial development through implementation, monitoring, and final
acceptance by the Corps—to ensure that each project has met success criteria. All
employees in that position should have a similar understanding of their
responsibilities and receive training, if warranted.
Biological factors:
Provide exclusionary fencing or other plant protection around each planting or
planting site in areas prone to wildlife or cattle damage.
Ensure irrigation lines are regularly monitored and maintained.
Irrigate plantings for at least two years to ensure adequate root system
Monitor plantings for at least five years, as required by the Corps—two years
during irrigation and three years after irrigation ceases.
Turn off irrigation only if the site is meeting or exceeding the required success
ADOT's mission is to provide products and services for a safe, efficient, cost-effective
transportation system that links Arizona to the global economy, promotes economic
prosperity, and demonstrates respect for Arizona's environment and quality of life.
Fulfilling this mission sometimes entails unavoidable impacts to jurisdictional Waters of
the United States (Waters). In keeping with the Clean Water Act, these impacts must be
mitigated according to direction from the Corps and the Environmental Protection
Agency (EPA).
ADOT is committed to developing and implementing mitigation plans that provide long-term
compensation for habitat adversely affected by its construction activities. The
mitigation must be self-sustaining in perpetuity. To ensure that mitigation strategies
developed for future ADOT projects meet these goals, research and subsequent analysis
are needed. Any mitigation plan ADOT develops and adopts must further the Corps' goal
of no net loss of Waters while remaining cost-effective.
ADOT has concluded that its projects too often fail to meet the planting success criteria
of the mitigation requirements of the Corps' Clean Water Act, Section 404, permits.
These permits typically require replacing plants (usually trees) that are damaged or
removed as a result of a construction project at a 3:1 ratio. The permits usually require
that the planted trees have an 80 percent success rate five years after being planted and a
minimum of two years after supplemental watering sources have been removed. When
these criteria are not met, the consequent replantings and extensions of mandated
monitoring periods create substantial time and cost burdens for both ADOT and Arizona
Plantings can fail for many reasons. Site conditions may be inappropriate, a site may not
be properly prepared, or planting stock may have been improperly handled before
planting. The supplemental water required to establish plantings may not be provided in
the quantity, frequency, or length of time needed for plants to establish adequate root
systems that enable long-term survival without irrigation. Also, typical planting success
criteria required by the Corps permit may be unattainable. The planting densities and
survival percentage required in many Corps permits at the end of a typical three- to five-year
monitoring period frequently cannot be met because the required plant densities are
too high to be sustainable without long-term irrigation. Even with favorable rainfall
conditions, a substantial number of plants die when supplemental watering is stopped and
success criteria may not be met. In the current long-term drought, the required survival
rate for excessively dense plantings is even more difficult to achieve.
The April 19, 2004, Corps' Los Angeles District mitigation guidelines are an example of
provisions that do not specify mitigation requirements, but instead direct applicants to
propose realistic success criteria. To date, ADOT has not successfully proposed criteria
different from the Corps' typical guidelines because adequate documentation to support
different, more locally based benchmarks is unavailable. Research and subsequent
analysis are needed. Realistic success criteria developed from permit history of Arizona
projects, local experience and knowledge, and published literature would benefit the
Corps as well as ADOT.
The requirements for compensatory mitigation are contained in Corps guidance memos
and federal rules. Final rule "Compensatory Mitigation for Losses of Aquatic Resources,"
as published in the Federal Register April 10, 2008, became effective June 9, 2008 (EPA
2008). The rule revises and consolidates existing Corps regulations and guidance to
establish equivalent standards for all types of compensatory mitigation, including
permittee-responsible on-site and off-site mitigation, in-lieu fees, and mitigation banks.
The rule encourages using mitigation banks and in-lieu fee programs instead of
permittee-responsible mitigation in which the permittee retains direct responsibility for
implementing, monitoring, and ensuring the success of mitigation. The Corps now prefers
mitigation bank credits for compensatory mitigation; in-lieu fee program credits are
second; and permittee-responsible mitigation is the least-preferred choice.
The rule sets a minimum monitoring period of five years for all types of mitigation. The
content and level of detail for monitoring reports are to match a project's scope. Reports
for projects with small impacts to Waters will presumably require less detail.
Restoration projects have increased in the Southwest over the past 20 years in an attempt
to mitigate the effects of human activity (Follstad Shah et al. 2007). This study reviews
restoration projects as well as Section 404 mitigation projects. According to Follstad
Shah et al. (2007), the greatest number of restoration projects in the National River
Restoration Science Synthesis database for the Southwest was in Arizona. This finding
and the associated amount of data on restoration practices that was collected suggest that
it is important for all restoration practitioners to have studies that focus on improving the
success of such projects in Arizona.
ADOT hired EcoPlan to research mitigation practices and develop recommendations for
future mitigation and restoration projects. To identify mitigation practices that are
successful and those that need improvement, this study focuses on the following areas:
Identification of projects over the past three to 10 years that involved, or ongoing
projects that will involve, a habitat restoration or Section 404 mitigation
Opinions of Corps project managers and ADOT employees who work most
closely with mitigation projects.
Assessment of the conditions of any mitigation plantings associated with the
projects that were required to meet the Section 404 permit habitat restoration
mitigation requirements.
Determination of administrative processes and biological factors that are
important to the success or failure of mitigation or restoration plantings.
The Corps, EcoPlan, the University of Arizona Water Resources Research Center, and
the ADWR provided files about ADOT and non-ADOT habitat restoration and land
disturbance mitigation projects. The files were reviewed to determine project goals; the
level of available data such as mitigation plans, planting plans, and monitoring reports;
and overall file completeness. Thirty-four projects were selected for detailed study: 19
ADOT projects, four Flood Control District projects, and 11 restoration projects
undertaken by private entities or NGOs. Twenty-three projects with goals and actions that
were determined to be valuable to this assessment but had insufficient postplanting
information to determine project failure or success were selected for site visits: 11 ADOT
projects, four Flood Control District projects, and eight private or NGO projects. The four
Flood Control District sites were specifically selected to further determine the level of
success or failure of tall-pot plantings. The remaining 19 sites used seeding, container
plants, or a combination of seeding, container plants, and tall-pot plants.
EcoPlan biologists conducted the site visits. Before visiting a project site, they reviewed
details of restoration activities and any preliminary results or observations available in the
project file. At each site (with the exception of the tall-pot sites), they made general
observations about the area, noting the overall level of ground, understory, and overstory
cover, and identifying plant species, focusing specifically on the species that were planted
or seeded, if known. For each species, they observed the relative dominance, health, and
presence of planted individuals compared with natural recruitment. The biologists noted
any signs of erosion, flood activity, or damage to the site from animals or recreational use
to identify potential outside sources of plant failure or stress. After the site visits, the
biologists determined the overall project success based on the information available in the
file and field observations.
Because the tall-pot sites did not lend themselves to gathering the same types of data as
other sites, EcoPlan limited its observations to the overall success of the site, site photos,
and possible reasons for success or failure of mitigation.
EcoPlan interviewed employees from the Corps and ADOT to obtain firsthand
knowledge of the success or failure of practical mitigation practices and overall agency
processes. An effort was made to interview employees involved at every stage of the
ADOT project process, including project managers in the Corps' Arizona office and
ADOT Environmental Planning Group (EPG) senior reviewers and biologists, DECs,
development engineers, resident engineers, Natural Resource Management Group project
managers, maintenance engineers, and maintenance superintendents.
EcoPlan interviewed the Corps project managers in January and February 2008. One
Corps project manager was the ADOT liaison, who normally handled all ADOT projects;
another had primary responsibility for managing the Corps in-lieu fee program in
Arizona. The other project managers had experience with many projects that are quite
different from ADOT projects, such as dams and master-planned communities, which
involve private developers as well as public agencies. However, all Corps project
managers administered projects that include linear features, such as roads and sewer
lines, which cross Waters in a manner similar to many ADOT projects. The managers'
comments therefore reflected experience with different kinds of projects and applicants,
including linear projects.
With the exception of the ADOT liaison, project managers in the Corps' Arizona office
had approximately five to 22 years of experience, with an average of about 15 years.
Individual ADOT liaisons had stayed in the position for years. Project managers were
asked to describe key components of successful and unsuccessful project mitigation
efforts based on their experience. Preferences for types of mitigation (for example, on-site
replacement vs. in-lieu fee) were also discussed.
EcoPlan researchers asked ADOT employees a standard set of questions organized under
two main categories that influence project success: administrative processes and
biological factors. Interviewees were queried regarding the success or failure of specific
on-the-ground practices, their experience with and assessment of the practice of using in-lieu
fees, their experience with current ADOT processes and suggestions for
improvement based on these experiences, and the success or failure of specific planting
types and practices. Employees were also asked to cite specific project examples to
support their responses.
Thirty-five of the 52 people selected for interviewing were actually interviewed.
Interview questions were answered based on interviewee experience. Not every
interviewee answered every question; instead, many interviewees only answered
questions dealing with topics with which they had experience. An additional four
employees declined to be interviewed because they had only recently been hired by
ADOT and were inexperienced in the subject matter. The remaining 13 employees did
not respond to attempts to contact them. However, at least one person was interviewed
from each key area.
This section presents the mitigation practices along with the administrative and biological
problems that were noted during the data collection portion of this study. The majority of
the projects had multiple problems and may be referenced in more than one subsection.
To illustrate specific mitigation practices and/or problems, a select number of case
studies have been included at the end of this report. Because each case study may
illustrate more than one mitigation practice or problem, it may be referred to in more than
one subsection.
Mitigation Practices
Thirty-four habitat restoration and/or mitigation projects were selected for detailed study;
EcoPlan biologists visited 23 sites. Figure 1 shows the number of projects that used
various common mitigation practices. The total number of projects and successful
projects are depicted for each mitigation practice. For example, five projects used
planting stock that was collected on-site, but only two succeeded. It is important to
emphasize that the data reported in Figure 1 are conservative because there was no
standard reporting form for the projects reviewed, and many of the practices may have
been employed but not reported. Seven mitigation practices are discussed.
Tall-Pot Plantings
Most desert plants have a deep taproot. Traditional planting containers cannot
accommodate this taproot, which requires uninterrupted development when growing,
making the plants difficult to propagate. The tall-pot method uses a 30-inch section of 6-
inch-diameter PVC pipe. Plants are grown in tall pots for approximately one year, then
transplanted into holes (dug with a power auger) that correspond to the depth and
diameter of the pots. If the water table is shallow, the tall-pot plants may not require
supplemental irrigation; otherwise, supplemental irrigation may be needed.
The tall-pot method has been successfully used in various locations in the deserts of
California, such as in the Joshua Tree National Monument; however, it is a relatively new
method of planting in Arizona, where it has had varying degrees of success. Only one of
the six projects analyzed could be verified as being successful to date. However, on three
of the sites—the Red Mountain Freeway, State Route (SR) 87 to US 60 site; the Flood
Control District North Inlet Channel site; and the Chicken Ranch site—the tall-pot plants
were planted too recently to draw any conclusions.
In Riparian Restoration on the San Xavier Indian Reservation, the tall-pot plants were left
in the pots in direct sunlight for an extended period before planting. Excessive heat
buildup in the planting tube killed many of the trees (see the Biological Mitigation
Problems section in this chapter).
Figure 1. Mitigation Practices. Total number of projects and number of successful projects that
incorporated each mitigation practice. Projects may be listed in multiple categories.
Planting Stock
Soil Testing
of Dead Trees
Mitigation Practice
Number of Projects
Total Proje cts Success ful Projects
Invasive species have negatively affected several of the tall-pot planting sites. Invasive
species took over the Flood Control District Chandler Heights site and it failed. Tall-pot
planting sites, like other types of sites, should receive routine maintenance, including
removing invasive weeds within the drip line of the planted trees and replacing unhealthy
or dead trees as soon as they are detected.
Planting Stock Collected On-Site
Many growers involved in revegetation have noted—and it was observed in this study—
that volunteer plants do better than nursery-grown plants at the same site even though
they do not get supplemental watering. Possible reasons for this are nursery plants may
be genetically different from volunteers that are locally adapted to the planting site;
nursery plants may be conditioned to a potted existence and may not acclimate well to the
barren soil and other extreme conditions of a mitigation site; and nursery plants,
especially larger ones, may be root-bound and never overcome that condition.
To take advantage of local adaptation and avoid problems associated with nursery stock
that might have been obtained from hundreds of miles away, several projects have
collected seed or cuttings and later used them for mitigation or revegetation (Paschke,
Redente, and Brown 2003; Anderson, Russell, and Ohmart 2004). In this study, only two
of five projects that used planting stock grown on-site were successful. There are many
reasons such projects might not be successful, as discussed in the Administrative Process
Mitigation Problems section and the Biological Mitigation Problems section in this
chapter. Case Study 1 is a synopsis of a restoration project that collected and propagated
planting stock on-site.
Nursery Stock Planted
Many of the project files reviewed did not specify the origin of the plantings used. In all
cases where tall-pot plantings, seeding, or on-site propagation was not specified, it was
assumed that nursery stock was used.
Over half (10 of 16) of the projects that used nursery stock resulted in successful
mitigation and restoration. SR 51, Bell Road to Pima Loop 101 Freeway planted more
than 2000 nursery trees (1672 mesquite [Prosopis velutina]; 209 paloverde [Cercidium
microphyllum]; and 209 ironwood [Olneya tesota]). Despite a number of problems in the
first year following planting, after three years the overall survival rate was almost
94 percent.
Several problems have been associated with using nursery stock: Nursery plants are not
as well-adapted to local conditions as plants collected or propagated on-site; nursery
plants are often root-bound; and nursery plants taken directly from the greenhouse and
planted in the field may experience transplant shock (see the Transplant Shock section in
this chapter).
SR 87, MP 201–MP 202.5 is an example of an unsuccessful project that used nursery
stock. The project's failure may not be completely associated with the use of nursery
stock because it had a number of other problems, including overplanting, lack of
monitoring, and failure to maintain the irrigation system (see the Administrative Process
Mitigation Problems section in this chapter).
Preplanting Soil Testing
Soil testing before planting is not commonly done—it was reported in only two
projects—but it may be a valuable tool for mitigation and revegetation (Amezketa and de
Valle de Lersundi 2008). Researchers at the Glen-Grand Canyon Riparian Restoration
Project planned to measure soil type, electroconductivity, and water table depth, and then
use these data to determine where to plant. This project largely failed because
supplemental water was discontinued; but survival was good near the perennial Colorado
River, presumably an area with a high water table.
The 'Ahakhav Tribal Preserve (Case Study 1) measured soil type, pH, salinity, and water
table depth to determine anticipated success at each site. Soil testing before planting,
especially measurement of water table depth, probably contributed to the success of this
restoration project.
Murder Camp Wash is an ADOT mitigation project located on State Route (SR) 78 near
the New Mexico border. Project construction resulted in the loss of suitable planting
soils. Essentially, most of the topsoil at the project site was removed during the
construction of a low water crossing, leaving behind rocky soils that probably contributed
to the failure of the early mitigation plantings. However, once the replacement plantings
received sufficient water (by hand watering), survival increased dramatically.
Replacement of Dead or Unhealthy Trees
ADOT's Standard Specifications for Road and Bridge Construction states that "all dead
or unhealthy plant stock shall be removed and replaced ..." (ADOT 2008, 807). Based on
this specification, the replacement of dead or unhealthy trees or shrubs during a
mitigation and revegetation project is probably more common than is indicated by the
data (only five cases in more than 30 projects). In the Partnership for Riparian
Restoration in NE Pima County revegetation project, many of the original plantings,
which were obtained from a nursery, were root-bound and eventually had to be replaced.
The replacement trees were grown from seeds collected on-site, which was an
opportunity afforded by the long-term nature of this project. The replacement plantings
were much more successful than the original plantings.
The original mitigation plan for Murder Camp Wash was unsuccessful for a variety of
reasons, including trees being planted in dry, shallow, and rocky soil, and problematic
and unreliable irrigation. Planted trees included 50 sycamore (Platanus wrightii), 40
velvet ash (Fraxinus pennsylvanica spp. velutina), and 12 netleaf hackberry (Celtis
reticulata). An additional 25 trees were planted after one year. To accommodate poor
survival, the Corps agreed to several modifications to the mitigation plan, including
reducing the survival rate to less than 50 percent of the original number of trees planted
and counting all volunteer trees toward the success criteria. Ultimately, while the overall
number of surviving trees is sufficient, the number of sycamores is far below the
mitigation plan success criteria.
Salvaged/Transplanted Saguaros
The Arizona Department of Agriculture has declared the saguaro (Carnegiea gigantea) a
Highly Safeguarded Protected Native Plant. Saguaros are valuable in terms of aesthetics
because they are symbolic of the desert Southwest and they are important wildlife habitat.
They are commonly salvaged and transplanted when they are associated with
development projects such as road construction, as illustrated in Case Study 2. As long as
sufficient supplemental water is provided and support is provided to prevent leaning,
these transplants are usually successful.
For most ADOT construction projects, seeding is required postconstruction for mitigation
and erosion control. This seeding may be done in combination with landscape or
mitigation plantings. Hydroseeding uses a slurry of seed and mulch that is sprayed over
prepared ground in a uniform layer. The mulch helps maintain the moisture in the seed
and seedlings and is thought to result in faster germination and better erosion control.
Certain tree seeds may be too large for use with a hydroseeder without damaging the
seed. In these cases, it may be necessary to spread tree seed by hand.
Ligurta Wash is a seeding-only project on Interstate 8 (I-8) near Yuma; no supplemental
plantings were included. A native herb, shrub, and tree seed mixture was applied without
any supplemental irrigation. Shrub germination and survival either from the seed mix or
from nearby seed sources were fairly successful given the area. However, most of the
shrubs showed signs of drought stress at the site visit. No trees that might have
germinated as a result of this seeding application were observed.
SR 89A, Cornville Road to Sedona (Case Study 3) used hydroseeding to propagate
mesquite and acacia. Supplemental irrigation was provided but was discontinued within
the first year, and most seedlings died.
SR 87 North of Rye was a successful seeding project. The site, in the median of SR 87,
was hydroseeded approximately 15 years ago with mesquite, shrubs, and forbs. The site
is unique because the original plan had been to waste excess material, but instead the
excess was used for contouring. The ground was ripped 12 inches deep, which is much
deeper than usual but perhaps should be considered as a requirement when ripping areas
to be hydroseeded. Survival, even among the mesquite, was good.
Administrative Process Mitigation Problems
Figure 2 shows the number of projects that experienced various common administrative
process problems. Some of these problems (for example, failure to monitor) can be
classified as both administrative process and biological problems. The total number of
projects and successful projects are depicted for each mitigation problem. For example,
unmaintained irrigation occurred in four projects, and only one of these projects was
successful. It is important to emphasize that the data reported in Figure 2 are
conservative. Because there was no standard reporting form for the projects reviewed,
many of the mitigation problems may have occurred but were not reported.
Ten administrative process problems are discussed in the following sections: failure to
monitor mitigation plantings, failure to inspect irrigation, irrigation removed prematurely,
mitigation not completed, mitigation monitor not qualified, staff turnover, overplanting,
no irrigation, no reference plot, and revised mitigation.
Failure to Monitor Mitigation Plantings
SR 87, MP 201–MP 202.5 is an example of a project with insufficient monitoring. The
original mitigation plan called for 350 trees to be planted in three wash corridors. When
EcoPlan visited the site, most of these plants were dead, stressed, or could not be located,
partly as a result of a lack of monitoring. Subsequent versions of the mitigation plan
called for a more realistic number of trees to be planted and included trees and cacti
planted in upland areas. Eventually, the survival criteria for the plan were achieved.
One way to ensure that the required level of monitoring is performed would be to
designate a job position (probably at the ADOT district level) that would be in charge of
following all projects through the mitigation and monitoring stages. To be effective, all
employees in this position would need to have a similar understanding of their
responsibilities and receive the necessary training, if warranted. This individual would
coordinate with the biological monitor conducting the on-site monitoring, if applicable.
The irrigation monitoring should be done by the irrigation contractor as frequently as is
needed to avoid problems. This monitoring would be in addition to the quarterly or
monthly monitoring performed by the biological monitor. Biological monitors should, as
part of their scope of work during site visits, ensure that the plants are receiving adequate
water and that the system is in good repair. Any deficiencies should be noted in the
monitoring report to ADOT.
* The number of projects in this category is likely underestimated. Many project files did not have sufficient information to determine if a reference plot was used.
Figure 2. Administrative Process Mitigation Problems. Total number of projects and number of successful projects
experiencing each type of administrative process mitigation problem. Projects may be listed in multiple categories.
Failure to Monitor
Irrigation Not Inspected
Irrigation Removed Prematurely
Mitigation Not Completed
Monitor Not Qualified
Staff Disconnect
No Irrigation
No Reference Plot*
Revised Mitigation
Mitigation Problems
Number of Projects
Total Projects Successful Projects
Failure to Inspect Irrigation or Irrigation Removed Prematurely
One common mitigation problem is the failure to inspect the irrigation system frequently
enough. Irrigation systems should be tested every 60 to 90 days and should include stress
flushing, checking emitter ends, and ensuring that the PVC piping remains covered. For
example, irrigation lines placed above ground in times of drought and/or in areas where
wildlife have access tend to be chewed on to obtain water. Frequent maintenance of these
lines is required to ensure water is delivered to the plants. If possible, irrigation lines
should be buried to prevent this problem, and individual emitters should not be placed on
the ends of drip lines. If individual emitters are used and chewed off, the line is
completely open. If buried emitter hubs are used and the drip line is chewed, it will
continue to drip.
Unreliable irrigation was found at four projects, only one of which was successful. As
mentioned previously, problematic and unreliable irrigation resulted in a lack of water
and contributed to the failure of mitigation plantings at Murder Camp Wash. In another
project, Riparian Restoration on the San Xavier Indian Reservation, an irrigation
malfunction that lasted only two weeks resulted in more than 10 percent mortality of the
affected trees.
Another project where the failure to monitor the irrigation system likely contributed
greatly to the initial failure of the mitigation plantings is SR 87, MP 201–MP 202.5. In
this case, an EcoPlan biologist found damaged and disconnected irrigation lines. Many of
the plantings had therefore not received water for a while.
One possible solution to ensure that the irrigation system remains in good repair, is
adequately inspected, and that the planted material remains healthy would be to require a
separate bond for the mitigation component of the construction project. The primary
contractor's bond would be returned once construction was completed and approved by
ADOT. However, ADOT would retain the mitigation bond until the survivorship
requirements were met and the project was accepted by the Corps.
In two projects, the irrigation system was removed before the mitigation plants had
become established, resulting in widespread mortality and failure of the original
plantings. I-10 (Fort Grant TI) had recurring problems with its irrigation system over the
two-year monitoring period. Nevertheless, the mitigation was largely successful, most
likely because dead plants were replaced as they were discovered. The other project, SR
89A, Cornville Road to Sedona (Case Study 3), used hydroseeding and mitigation
plantings in two locations: Dry Creek and Spring Creek. At the Spring Creek location,
irrigation water was terminated and the irrigation system was removed in the first year by
the landscape/irrigation contractor before a dedicated biological monitor was contracted
to monitor the sites. As a result, the hydroseeding and plantings failed. The project was
eventually successful, but only after the irrigation system was reinstalled, irrigation was
resumed, and new trees were planted.
To prevent this problem, ADOT, the landscape/irrigation contractor, and the biological
monitor should coordinate to ensure that the irrigation system remains in place and in
good repair for the required period. The landscape/irrigation contractor should also
completely understand the requirements of the mitigation plan. The landscape/irrigation
contractor should be required to monitor the irrigation system frequently enough to detect
any problems with the system before any plant mortality occurs. During the summer
months in desert areas, this should be at least weekly. ADOT should retain the services of
a biological monitor or an ADOT employee should monitor at the required intervals (at
least quarterly) once the plantings are in place. Along with assessing the health and
growth rates of the planted vegetation during site visits, the monitor should note whether
the irrigation system is in place and working properly. ADOT could require that the
irrigation system remain in place and in working order until it authorizes in writing the
irrigation contractor to end irrigation and remove the system. It is important that all
parties realize that early removal of the irrigation system puts the success of the
mitigation plantings at risk.
Mitigation Not Completed
Construction occurred and a mitigation plan was developed but not implemented at three
projects. Because of natural recruitment, these areas revegetated, but only because there
was perennial or intermittent water on-site, as illustrated in SR 75, Gila River Bridge
#311 (Case Study 4). If the mitigation plan had been implemented, a much larger area
would have been restored to preconstruction functions and values.
To ensure that mitigation is completed, a district-level staff position should be charged
with following all projects through mitigation, monitoring, and ultimate acceptance by
the Corps. All employees in that position should have a similar understanding of their
responsibilities and should receive adequate training, if warranted.
In summary, ADOT must take a stronger oversight role in the preparation and
implementation of the required mitigation plans and supervision of subcontractors
responsible for them.
The first monitoring report should document as-built conditions, including a thorough
assessment of mitigation that actually occurred, the limits of the mitigation area, species
and number of individuals planted compared with plantings required in the mitigation
plan, and irrigation information.
Mitigation Monitor Not Qualified
Monitoring is often performed by someone other than a qualified biologist, resulting in
improper, inconsistent data collection that is not useful to the Corps or other agencies and
that could contribute to project failure. For example, in SR 89A, Cornville Road to
Sedona (Case Study 3), the irrigation system was prematurely removed, resulting in the
loss of most of the initial plantings and seedlings. The landscape contractor for the
construction project was initially tasked with monitoring the mitigation sites. However,
the contractor was not familiar with the mitigation requirements and the monitoring
requirements of the mitigation plan. As a result, the contractor did not obtain the
appropriate information required in the monitoring reports. A qualified biologist was
eventually contracted to conduct the monitoring, but the site was already failing by that
Monitoring should be performed only by a qualified biologist with at least two years of
experience who thoroughly understands the mitigation plan and Corps guidance and rules
regarding mitigation. The monitor can be an ADOT employee or a qualified consultant.
Monitoring techniques should be quantitative, repeatable, and clearly defined in the
mitigation plan. Site monitoring should be conducted at least quarterly and for at least
five years as required by the Corps.
Staff Turnover
Mitigation projects may fail because turnover among ADOT staff or consultant staff
results in a lack of project knowledge or follow-through on key project components. In
Riparian Restoration on the San Xavier Indian Reservation, turnover in the
groundskeeper position caused a disconnect in knowledge. The current groundskeeper
was not in place when plantings occurred and was unaware of the locations of all the
Another practical problem with monitoring occurred when the tags that identified the
monitored trees were lost. The tags were attached to the wire baskets around the plant and
not to the plant itself. The baskets were removed as the plants matured, and the tags were
lost. (Monitoring tags, if used, should be placed on a conspicuous location on the tree that
will still be able to be located as the tree density and height increases. Tree tags should
not be attached with wire around a trunk or main branch of the tree. If tree tags are lost,
they should be promptly replaced.)
To preserve project knowledge, all project information, including the mitigation plans,
planting plans, and monitoring reports, should be kept in at least one location with the
original Corps permit that includes any special conditions of the permit. The ADOT
employee responsible for following through on mitigation plans should keep these
Mitigation plans often call for planting more trees than the area can support in the long
term without supplemental irrigation, resulting in mortality and ultimately the failure of
the mitigation plan. This scenario occurred in SR 87, MP 201–MP 202.5, where the
mitigation plan was revised several times to accommodate low survival and to include
plantings in upland areas outside the washes that were originally included in the plan. In
this case, replacement ratios seemed to be higher than would ideally be demanded,
instead of being based on naturally occurring tree densities. Several relatively small sites
received mitigation plantings. The numbers of plants required in these areas greatly
exceeded what was found naturally. Overplanting can also result when too many trees are
planted near stands of naturally occurring trees, as was the case in Peck Canyon Bridges
(Case Study 5).
To avoid the negative effects of overplanting, the percentage of intentional overplanting
to meet survivorship requirements must be determined on a site-by-site basis. One way to
accomplish this is by using reference plots—areas adjacent to the planting site that are
surveyed to obtain natural species' composition and density—to assist in creating the
mitigation plan (see the Revised Mitigation section in this chapter). As dead or severely
stressed trees are detected during the monitoring site visits, they should be replaced
immediately so that at the end of the irrigation period, 100 percent of the trees will be
alive. This assists in ensuring that after three years without water, the required
survivorship percentage (usually 80 percent) will be met.
No Irrigation
Sometimes seeding-only projects are planted without supplemental irrigation, such as at
Ligurta Wash. The seed mix included herbaceous vegetation, shrubs, and trees. At the
site visit, there was no evidence of tree survival, and though herb and shrub survival was
relatively good, surviving shrubs appeared drought-stressed.
In the desert Southwest, seeding without irrigation is only successful if it is timed to
occur with natural precipitation, either prior to the sometimes rainy winter season or in
the summer monsoon season. Given the unpredictable nature of precipitation in Arizona,
it would be best to provide any mitigation plantings with supplemental irrigation at least
until the plants are well-established.
No Reference Plot
SR 87, MP 201–MP 202.5 did not use reference plots, which contributed to overplanting
and led to several revisions of the mitigation plan. This scenario is probably much more
common than reported here because many projects did not report whether a reference plot
was used. Reference plots are vital to developing a mitigation plan, to determining
appropriate replacement ratios for the site, and to justifying those ratios to the Corps and
other agencies.
Revised Mitigation
When mitigation plans are unsuccessful, they are often revised (with Corps approval) to
make success achievable, such as in Case Study 3. Required survivorship percentages
may be reduced, additional plantings are most often done, and sometimes natural
recruitment is counted toward survival of the plantings (for example, Murder Camp
Wash). Revised mitigation plans allow many projects that would otherwise be
unsuccessful to move forward and eventually achieve at least some measure of success,
though at a high cost temporally and economically.
Biological Mitigation Problems
Figure 3 shows the number of projects that experienced some common biological
problems. The total number of projects and the number of successful projects are
depicted for each mitigation problem. For example, animal damage occurred on eight
projects, and only four of these projects were successful. It is important to emphasize that
the data reported in Figure 3 are conservative. Because there was no standard reporting
form for the projects reviewed, many of the mitigation problems may have occurred at
these sites but were not reported.
Twelve biological problems are discussed in this section: animal damage, flooding,
animal damage to irrigation lines, transplant shock, drought stress, insects and pests,
tamarisk, invasive species, root-bound nursery plants, mistletoe, heat-damaged roots in
tall-pot plantings, and fire. The following biological problems are also considered
administrative process problems and were discussed previously: overplanting, failure to
monitor, unmaintained irrigation, no irrigation, no reference plot, and revised mitigation.
Animal Damage
Animal damage to mitigation plantings is common and was reported in eight of the 34
projects. Browsing by domestic herbivores, such as cattle, and native herbivores, such as
deer and elk, can damage mitigation plantings. Beavers and other small rodents that chew
on the trunks and main branches of planted trees can also damage them. Planted trees are
particularly vulnerable to animal damage because of their vigorous new growth and
because they are often planted at high densities. Animal damage on these trees is more
pronounced because of their small size. Small trees planted at high densities are also
susceptible to trampling by large mammals.
Several methods can be used to prevent animal damage to mitigation plantings, including
placing plastic tree sleeves over small trees; placing wire cages around the trunks of
larger trees to prevent beavers from cutting them down or other rodents from girdling
them; fencing the planting areas to exclude large mammals; trapping and removing small
mammals, such as gophers and voles, from the planting area; and implementing various
biological controls. In some cases, a combination of these techniques is necessary for the
same project.
To take advantage of favorable groundwater conditions, plantings are often placed in
floodplains and sometimes even in floodways. Unfortunately, flooding often negatively
impacts small trees, as illustrated in Case Study 5, Peck Canyon Bridges. Many trees are
uprooted and removed by floodwaters, and many other trees are buried by debris carried
by the flood. Inundation also causes tree mortality, which may occur when plantings are
grown in artificial basins associated with development projects such as with SR 51, Bell
* The number of projects in this category is likely underestimated. Many project files did not have sufficient information to determine if a reference plot was used.
Figure 3. Biological Mitigation Problems. Total number of projects and number of successful projects
experiencing each type of biological mitigation problem. Projects may be listed in multiple categories.
Animal Damage
Failed to Monitor
Unmaintained Irrigation
No Irrigation
Animal Damage to Irrigation Lines
No Reference Plot*
Revised Mitigation
Transplant Shock
Drought Stress/Chlorosis
Invasive Species
Nursery Trees Rootbound
Tall Pots Heat-Damaged
Fire Mitigation Problems
Number of Projects
Total Projects Successful Projects
Road to Pima Loop 101 Freeway. At this site, 85 trees (25 mesquite, 25 paloverde, and
35 ironwood) were killed by flooding or had suffered significant damage because of the
amount of water retained in the basin during an unseasonably wet winter.
To avoid damage by floods, plants should not be placed in the floodway of a stream,
river, or wash. If possible, plantings should be restricted to the overbank and upland areas
of a site. Also, riparian species that have a relatively low resistance coefficient, such as
coyote willow (Salix exigua), cottonwood, and Goodding's willow (Salix gooddingii),
should be used for areas that may be prone to flooding but should not be planted in areas
prone to scour.
Animal Damage to Irrigation Lines
Irrigation pipe is commonly placed above ground to make it accessible for maintenance
and repairs. Unfortunately, this makes the irrigation line more accessible to animals that
chew through the pipe to obtain water. Damage to main lines can prevent the irrigation of
hundreds of trees, resulting in considerable mortality, especially if the leaks go
undetected during hot, dry periods. Animal damage to irrigation lines was reported in
three projects and likely occurred in others. To control animal-chewing damage on the
North Simpson Site Riparian Restoration project, dead snags were erected at several
locations to attract raptors that hunted the rodents, which achieved some success.
Animal-chewing damage can become a serious problem when plants and irrigation
systems aren't monitored frequently enough for the conditions. These systems should be
frequently maintained or placed underground to ensure that water is delivered to the
plants. In areas where limited supplies of water are available to wildlife, a simple
watering guzzler could be constructed away from the irrigation lines to provide water and
possibly discourage wildlife from chewing on irrigation lines.
Transplant Shock
Transplant shock occurs when plants are taken from a controlled environment and
planted in a natural environment, often resulting in nutrient or water stress. It can also
occur when the established root system within a planting pot is disturbed during
transplanting. Transplant shock is common in mitigation plantings and was noted in SR
51, Bell Road to Pima Loop 101 Freeway, where more than 2000 trees were planted in a
basin created by freeway construction.
The adverse effects of transplant shock may be lessened if potted plants are brought to a
protected area of the planting site for a few weeks and allowed to acclimate to site
conditions before being planted. Planting should occur during the cooler times of the day
and not during the stressful summer months in desert areas of the state. The irrigation
system should be operational before planting begins, and supplemental water should be
provided to transplants as soon as possible after planting.
Drought Stress
Drought stress occurs when plants receive insufficient water because the irrigation
system is set improperly and does not run often enough or long enough, or the irrigation
system fails. In severe cases of drought stress, plants' leaves turn yellow and are shed.
This condition, which can be mistaken for chlorosis (which is caused by nutrient
deficiency), was noted in SR 51, Bell Road to Pima Loop 101 Freeway and Rio Salado
Habitat Restoration Project. When given supplemental irrigation, most of the plants
recovered from drought stress.
Drought stress can be avoided by providing sufficient water, watering at an appropriate
rate for long durations to ensure deep watering, and regular maintenance of the irrigation
Insects and Pests
Insects may become a problem in mitigation plantings because the trees are often
genetically similar, increasing the chances that susceptible trees may be colonized by the
same species of insect herbivore. In fact, if the plants were propagated from cuttings, they
may be genetically identical. Insect infestations are often associated with plant water or
nutrient stress, both of which can be found in mitigation plantings. Insect damage was
noted in SR 51, Bell Road to Pima Loop 101 Freeway and 'Ahakhav Tribal Preserve
(Case Study 1). In both cases, the plants were doing well despite the insect infestations.
In general, the presence of insects in plantings in normal densities is probably not a
concern. However, an infestation of insects such as spider mites or tent caterpillars on
young plants in high densities is a cause for concern, especially during high-stress
months. If infestations are detected, an aggressive eradication program should start. The
presence of insects on older, established plants is usually not a reason for concern in and
of itself. Insect damage may, however, indicate that the plants are stressed or in otherwise
poor health.
Tamarisk, also known as saltcedar (Tamarix spp.), was introduced to the southwestern
United States in the early 1900s to stabilize irrigation canals and control erosion on
elevated railroad lines. It quickly escaped cultivation and today occupies thousands of
acres of land, especially riparian habitats. Tamarisk is both drought- and salt-tolerant, is
able to outcompete native cottonwoods and willows in disturbed habitats, and is thought
to use more water than native vegetation (Briggs 1996, 39-42).
Generally, tamarisk is removed from mitigation or restoration sites before planting,
though several projects reported that tamarisk had recolonized planting sites. For
example, workers at the Glen and Grand Canyon Riparian Restoration Project attempted
to improve bird habitat by replacing tamarisk with native vegetation. However, the
tamarisk re-established itself within the mitigation area, undoubtedly due to the presence
of nearby tamarisk stands that acted as a seed source. Also, in SR 75, Gila River Bridge
#311 (Case Study 3), natural colonization of the mitigation area included numerous large
tamarisk shrubs.
Tamarisk is difficult to eradicate. Burning a site is initially somewhat effective, but this
method also kills the mitigation plants. Tamarisk seems to thrive and come back in even
higher densities after a fire. Prolonged inundation kills tamarisk, but prolonged flooding
would also kill many of the native mitigation plants. The best method is mechanical
clearing and grubbing, followed by treating the stumps with a systemic herbicide to
prevent resprouting and to kill the entire root system.
Simply removing tamarisk does not usually ensure that native species will become
established or that they can even be grown in those areas. If tamarisk has been present for
any amount of time, the soil in those areas may be too saline to allow native trees, which
have a relatively low tolerance to salt, to become established. If native riparian or upland
species are to be planted in locations that formerly supported stands of tamarisk, the
soil's salinity should be tested. If the salinity is outside the tolerances of the desired
species, soil amendments may have to be applied, the salt may have to be flushed out of
the soil by natural or man-made flooding, or the soil may have to be replaced with soil
whose salinity is within the level of tolerance of the desired species.
Tamarisk removal may not always be desirable. Increased water yield may not always
result, and the potential for successful revegetation is not assured (Shafroth et al. 2005).
Because many riparian birds use tamarisk as habitat, projects that remove tamarisk but do
not replace it with high-quality native riparian habitat may ultimately reduce net riparian
habitat value, especially for birds (Sogge, Sferra, and Paxton 2008). However, even if the
tamarisk is replaced with native habitat, the temporal losses experienced until the new
vegetation can support the local species needs to be considered.
Invasive Species
Several non-native plants besides tamarisk are a problem for mitigation and restoration
plantings. Competition with these fast-growing weeds is a particular problem when the
planted trees are small and just becoming established. Invasive species were a problem on
at least five of the 34 projects that were reviewed. In Partnership for Riparian Restoration
in NE Pima County, the entire floodplain where most of the plantings occurred was
dominated by carelessweed (Amaranthus palmeri) and prickly Russian thistle (Salsola
tragus). Only the tops of the planted trees were visible above the weeds. These two
species and others have created serious problems at another southern Arizona site,
Bingham Cienega Natural Preserve Restoration. Other common invasive species at the
North Simpson Site Riparian Restoration project include Johnsongrass (Sorghum
halepense), Bermudagrass (Cynodon dactylon), and giant reed (Arundo donax).
Control of invasive species is notoriously difficult. Systemic herbicides are sometimes
used, but these can damage mitigation and restoration plants. The field of carelessweed at
the Partnership for Riparian Restoration in NE Pima County site is regularly mowed, but
this technique puts the restoration plantings at risk. The best technique may be to
mechanically remove invasive species, either by hand or with tools such as hoes and
shovels, or with mechanized equipment in an open area. But all of these methods are
Root-Bound Nursery Plants
Many greenhouse or nursery plants are grown too long in pots without being transplanted
or planted in the field. This results in their roots encircling the inside of the pot—a
condition known as being root bound. Many root-bound plants never recover—their roots
continue to grow in a circle, and they are unable to obtain sufficient water to survive.
This condition is undoubtedly common in plants grown for mitigation planting, but it was
reported in only one project, Partnership for Riparian Conservation in NE Pima County.
Here, the project manager began growing his own trees from the seed of trees in the area
as replacements for the dead and underperforming trees.
Taking on the role of tree propagation is probably the best solution to the problem of
root-bound plants. However, if this is not feasible, the appropriate ADOT employee or
consultant should be on-site when mitigation vegetation is planted to inspect each plant
as it is removed from the pot and either reject any that appear to be root-bound or, at the
very least, require that the root balls be sliced to free up the roots. The landscape
contractor should be made aware of this possibility before bidding on the project.
Mistletoe in mitigation and restoration plantings was noted in one project, 'Ahakhav
Tribal Preserve (Case Study 1). Though mistletoe is a plant parasite that is sometimes
associated with plant stress, the observer noted that the infested mesquite trees in this
study did not appear stressed.
Heat-Damaged Roots in Tall-Pot Plantings
Tall pots are an increasingly popular method of propagating plants for mitigation and
restoration projects (see the Planting Stock Collected On-Site section in this chapter). A
potential downside to the tall-pot method was noted in Riparian Restoration on the San
Xavier Indian Reservation. Planting was conducted from June to September. The black
containers heated up considerably during this time, even though the plants were placed
under shade. According to notes from the ADWR files, the roots in long, narrow tall-pot
containers were particularly prone to heat damage; this heating had the potential to
"cook" the roots of the plant before it was planted, thus effectively killing the plant
before it was put in the ground. Mortality from this heating effect was observed in several
tall-pot plants during the planting period.
One project, Bingham Cienega Natural Preserve Restoration, has experienced periodic
fire since its inception in 1998. The fires have not affected most of the wetland vegetation
except Fremont cottonwood (Populus fremontii) and Goodding's willow (Salix
gooddingii) along the edges of marsh areas; these plantings have been unsuccessful
because of the fires. In general, riparian vegetation is not fire-adapted, and fire should be
avoided in most mitigation and restoration projects.
This section presents the results of interviews with Corps project managers and ADOT
employees in August and September 2008. The information obtained during these
interviews is based on the experience and knowledge of these staff members and provide
valuable, realistic perspective. The comments and suggestions offered during the
interviews were carefully considered and contributed to the recommendations given in
Chapter 5.
These interviews yielded generally similar comments, although more topics were
investigated during the ADOT interviews than the Corps interviews. Comments are
presented according to the two main categories (administrative process and biological
factors) and the following subcategories: in-lieu fees, responsible parties, staffing and
training, other agency involvement, mitigation plans and monitoring, planting, and
seeding. The Corps interviews section does not include the planting and seeding
subcategories. Table 1 summarizes the key points of these interviews.
Table 1. Comments from ADOT Interviews.
Key Points Number of
Administrative Process
In-Lieu Fees and Other Off-Site Mitigation
In-lieu fees should not be used because benefits don't stay in
the same watershed as impacts. 5
In-lieu fees should be used as close to the location of impact
as possible. 5
ADOT should initiate mitigation banks as a replacement for
in-lieu fees. 1
In-lieu fees encourage developers to just pay the money
because it's easier than doing the restoration work. 1
In-lieu fees are practical, efficient, and provide habitat in the
most effective areas by individuals with knowledge of
restoration techniques.
On-site mitigation rather than in-lieu fees should be used in
unique waters or on federal lands. 2
Table 1. Comments from ADOT Interviews.
Key Points Number of
Responsible Parties
The DECs should be involved in project implementation
because they are with a project from the beginning. 12
The resident engineer should be responsible for mitigation
success. 8
Mitigation and monitoring are successful because the Corps
requires them to be successful. 1
The contractor should be held economically responsible for
mitigation failure. 6
The DECs should be given more authority to ensure that
mitigation is addressed by the resident engineer. 5
An ADOT team should be responsible for the success of
mitigation. 3
There has been inadequate ADOT oversight and no clear
chain of command. The contractors were left in charge of
mitigation, and it has not been clear who at ADOT is
responsible for mitigation.
If ADOT enforces contractor obligations, then the current
system works. 3
Staffing and Training
ADOT should have several environmental engineers on staff. 1
Local, dedicated personnel is the key for successful
mitigation and survivorship. 2
Knowledgeable National Environmental Policy Act (NEPA)
planners are needed to carry restoration needs to the
engineers, who don't always understand practical issues such
as temporal plant losses, and ensure planting needs are
ADOT has sufficient personnel, but training and awareness
are needed, specifically regarding mitigation and monitoring. 6
Landscape architects need to be willing to listen to different
ideas on species and irrigation issues. 1
ADOT should have restoration ecologists develop and/or
review restoration plans. Landscape architects do not always
have the proper background to understand desert ecology.
Sometimes ADOT [employees] do not pay attention to
smaller projects because they believe that in the big scheme
of things, smaller projects don't matter.
The contractor should have someone local to do regular
irrigation checks and for rapid maintenance response. 1
The EPG needs to focus on a teamwork approach. Personnel
should be cross-trained so there is a broad understanding of
the issues and areas of concern.
Table 1. Comments from ADOT Interviews.
Key Points Number of
Other Agency Involvement
Upfront negotiations are needed with the Corps regarding
replacement ratios based on local conditions. 1
The state wildlife agency should be involved because of its
experience and vested interest in successful mitigation and
restoration projects.
Working with multiple agencies can be difficult because of
differing goals and expectations; competing goals lead to a
low assurance of success.
Nationwide permits (NWPs) are not written for the Southwest
or dry washes; projects should meet intent rather than the
letter of the NWP.
The Corps should provide flexibility and understanding about
the unique situation in the Southwest. 1
The Corps should monitor projects regularly because it can
enforce [them]. 1
For local government projects, responsibility should not pass
to the local jurisdiction too early. 1
Mitigation Plans and Monitoring
Current plans are based on straight lines; plans should try to
simulate the natural environment and avoid straight lines. 1
ADOT should contract mitigation monitoring through a
consultant. 5
Restoration plans, planting, and monitoring should be site-specific.
Arizona has 14 biozones, and there should be a
general plan for each that can be tweaked as necessary for
specific projects within each biozone. [Note: Arizona has 12
Mitigation and planting plans should be more specific, with
clearer success criteria. 5
A centralized clearinghouse is needed for all project
information, especially mitigation, that contains information
from beginning to end.
Mitigation, monitoring, and reporting should be better tracked
(permit). 2
Monitoring consultants should have at least two or three years
of experience and biologically sound methodologies. 3
Monitoring reports should be more detailed and include more
background information; reports get lost, and having key
information on each report would be useful.
Monitoring should include more quantitative data gathering;
visual assessment/"eyeballing it" is not sufficient. 1
Table 1. Comments from ADOT Interviews.
Key Points Number of
Topsoil should be saved and replaced in ADOT projects,
except areas with invasive species issues. 2
Currently, there is inadequate control over contractor choice;
contractors with the lowest bid are awarded the contracts; a
request for proposal system would allow contractors to be
selected based on qualifications and past performance rather
than lowest bid.
A better handoff system is needed between construction and
maintenance. 5
A tall-pot nursery pilot program to test cost-effectiveness
would be good. 1
Biological Comments
Browsing from cattle and animal damage causes problems;
exclusionary fencing is needed around the entire area, not just
individual trees.
Implementation of mitigation and/or plantings should be
based on biology, not the construction schedule; planting
should not be performed during the dry season.
There is inadequate follow-up on mitigation projects. 2
Reports are not always completed, or if completed, they are
not read and followed up on by appropriate individuals; need
better follow-through.
Consultants are not tagging plants as required, so success
monitoring is hard. 1
Plantings should be in place so that they are not destroyed in
a large rainfall event; consideration needs to be given in the
planting plans to the anticipated flows in a planting area.
Contractors should perform frequent and timely inspections
of irrigation lines. 5
Tall-pot plantings should not be used statewide; they would
not work in certain areas. 1
Tall pots without irrigation is a good idea as long as you
know depth to groundwater. 2
ADOT should partner with entities (such as cities) to carry
out replanting responsibilities. 1
Including seeding with native tree species could offset
planting casualties. 2
Salvaged plants should be used more often; they tend to be
successful if a plan is in place prior to salvaging. 1
We need guidelines for monitoring salvaged plants. 1
Table 1. Comments from ADOT Interviews.
Key Points Number of
Pole plantings work if done at the right time and get into the
water table. 2
Irrigation systems should be computerized so they can send
an alert when line or pump problems occur. 1
Irrigation of plantings should be a more formal program. 1
Lack of irrigation is not a problem; animal damage and
drought are bigger problems; irrigation will get done because
it is part of the mitigation plan.
Seeding should be based on seasonality. 4
Millings are dumped and compacted on shoulders, and then
these areas have to be seeded even though there's little to no
growth after this process. Compacted millings are not a
planting medium conducive to plant growth.
There is inadequate follow-up after hydroseeding. 1
Seeding with native trees is a good option; recommend
including native tree species for seeding projects in all areas
of the state.
Monitoring methods to determine success should be
transparent and available upon request. 1
Focus should be on the growth success of desirable
vegetation, not weeds. 1
The ADOT Roadside Development section should be sure to
include native species for the specific area when seeding. 2
ADOT Interviews
Administrative Processes
In-Lieu Fees and Other Off-Site Mitigation. ADOT employees had differing opinions
about in-lieu fees. Five respondents did not support in-lieu fees because mitigation often
does not remain in the impacted watershed. Eight respondents supported the in-lieu fee
process because it is more efficient, mitigation is more likely to occur in suitable areas,
and mitigation is more likely to be implemented by individuals with knowledge of
restoration techniques. For example, an ADOT project in the Yuma District affected the
endangered flat-tailed horned lizard (Phrynosoma mcallii). Rather than mitigate for the
effects on-site where there was little to no suitable habitat, the project used in-lieu fees to
preserve or enhance habitat for that lizard at a more suitable site in southern California.
The benefit to the overall lizard population was greater than would have occurred with
on-site mitigation.
Five ADOT employees said that if on-site mitigation is not practical, in-lieu fees should
be distributed to benefit an area close to the project area, preferably within the same
watershed. One ADOT employee suggested that a mitigation bank system would be
effective for ADOT projects.
When asked if there were any circumstances in which in-lieu fees would not be
appropriate, most interviewees could not think of any. However, two ADOT employees
said that projects in unique waters or on federal land should mitigate impacts on-site
whenever possible.
Responsible Parties. Two ADOT responders noted that historically, ADOT oversight of
contractors has been inadequate. ADOT employees also said that ADOT needs to hold
contractors more accountable for their actions or lack thereof. Three ADOT interviewees
reported that when ADOT enforces contractor responsibilities such as irrigation checks,
the current system of management works. Contractor neglect extends the monitoring
period or replanting mitigation, which is both inefficient and a waste of economic
resources. Therefore, a better system for contractor oversight is needed. The most
common solution, suggested by six ADOT interviewees, was to change the contractor
bond system so that the contractor is held financially responsible for mitigation failure
over a longer term. Another suggestion from two of the respondents was to change how
contractors are awarded a contract. Currently, contractors with the lowest bid are awarded
the contracts. A system that chooses contractors based on qualifications and past
successes rather than solely on the lowest bid would likely improve mitigation success.
Along with the oversight issue, ADOT employees noted that no clear chain of command
was in place to determine who in the district office would be in charge of mitigation.
When asked who should be responsible for ensuring that mitigation and monitoring occur
as planned, 12 ADOT interviewees said that the recently created DEC position is the
appropriate choice. Most ADOT personnel said the DEC position, which is perceived to
be involved with a project from its inception through completion of monitoring, should
be responsible for ensuring mitigation and monitoring success. The second most frequent
choice (eight respondents) was the resident engineer. A third idea suggested by three
ADOT interviewees was a team of ADOT personnel, including the DEC and employees
from the Natural Resource Management Group.
Staffing and Training. This topic was not a direct interview question but the issue arose
in a few interviews. Because this subject was not discussed with all interviewees, the
number of responses will not be presented; instead, a review of the problems and
solutions recommended by ADOT interviewees follows.
The availability and training of ADOT staff was raised tangentially when employees
were discussing responsible parties, mitigation and planting plan development, and
project follow-through and monitoring. ADOT interviewees suggested that although
ADOT has sufficient personnel for adequate follow-through on projects, training and
awareness are needed, especially in mitigation and monitoring practices. The EPG needs
to focus on a teamwork approach. Personnel should be cross-trained so all employees
understand the broader picture of a project, recognize valid concerns and issues, and can
recognize how all the pieces fit together. ADOT employees also said that project follow-through
seems to break down when a project switches from Construction Division to
Maintenance, and they suggested a better handoff system between the two divisions.
ADOT employees also said that knowledgeable NEPA planners are needed to transmit
the restoration needs to the engineers. Mitigation and restoration issues and needs should
be supported throughout the development process, but engineers don't always have the
background to understand this aspect of design and development or to understand
concepts such as temporal plant losses. Planting designs are often developed by
landscape architects who do not necessarily have the proper background to understand
desert ecology and what is sustainable in a natural system. Employees suggested ADOT
use restoration ecologists to develop planting plans because they have the background
and training to develop a sustainable plan that is more likely to succeed. One interviewee
also commented that current planting plans are often based on straight lines, which do not
look natural. A restoration ecologist would be more likely to simulate the natural
environment and avoid straight lines. Another suggestion was to have environmental
engineers on staff during the development stage.
The likelihood for long-term success of mitigation efforts is increased if ADOT and/or its
contractors have dedicated personnel locally. The presence of someone in the area who
can easily check irrigation lines and plant survivorship, or respond quickly to a crisis that
threatens mitigation success is important. Whether ADOT personnel or contractors are
checking on the mitigation site frequently, ADOT personnel need to follow through on
the project to the end regardless of project size. Some respondents said that smaller
projects get ignored in favor of big projects because the small projects "don't matter" in
the larger scheme of things.
Other Agency Involvement. One ADOT interviewee mentioned that working with
multiple agencies on one project can be difficult due to differing goals and priorities.
When so many interests are competing, mitigation success is less likely. No example was
given, though a conversation with a private party currently in the midst of a large
mitigation project yielded the same comment. One ADOT interviewee recommended that
ADOT involve the state wildlife agency in mitigation planning because of its years of
experience and vested interest in the success of mitigation and restoration projects.
Three ADOT respondents discussed the responsibilities of the Corps in the mitigation
process. One interviewee said that ADOT should have upfront negotiations with the
Corps to determine appropriate replacement ratios on a site-by-site basis. A one-size-fits-all
replacement ratio will not work because individual site conditions vary greatly across
the state. One ADOT respondent noted that NWPs were not written with the Southwest
or ephemeral washes in mind; therefore, the Corps should be flexible and understanding
about meeting the conditions of a NWP and focus on meeting the intent rather than the
letter of the NWP. The final comment regarding Corps involvement was a suggestion that
the Corps become more involved in monitoring each project because it, as the regulatory
agency, has the power to enforce the Section 404 permit.
Mitigation Plans and Monitoring. Five ADOT respondents said that mitigation and
planting plans need to have specific success criteria, which many plans currently lack.
Three ADOT interviewees emphasized that restoration and monitoring plans should be
site-specific because Arizona has 12 biozones. Two associated problems were raised.
First, one general plan will not work for Arizona. For example, a mitigation plan for
Yuma will not work in Payson, and vice versa. Therefore, restoration plans should be
developed on a more specific level. Second, developing restoration plans takes time,
which most projects cannot afford. ADOT interviewees suggested a general mitigation
plan be created for each biozone in Arizona that can then be quickly adjusted for specific
projects. Having a base plan will reduce the time required to develop a restoration and
mitigation plan.
Five ADOT respondents also said that ADOT should hire consultants to perform the
mitigation monitoring. Three interviewees said these consultants should have a minimum
of two or three years of restoration mitigation field experience, and monitoring should be
biologically sound. One respondent said monitoring should be more quantitatively based,
using accepted data-gathering practices, and such methods should be transparent.
As mentioned earlier in the Staffing and Training section, follow-through is sometimes
an issue with mitigation projects, partly because of employee turnover but also because
reports are not always read by the appropriate person. One employee suggested that
monitoring reports have more detail and include more background information. Reports
get lost or do not get passed on during project transfers; therefore, all monitoring reports
should repeat the key information. Three interviewees said project and mitigation
information needs better organization. For example, a centralized clearinghouse for all
project information, including mitigation, should be maintained so the information can be
easily accessed even if responsibility for the project changes before the project is
completed. Employees also suggested better tracking of mitigation, monitoring, and
Biological Factors
Planting. Issues discussed about planting were fairly wide-ranging—from irrigation to
planting areas to browsing damage. The most common topics were water and seasonality.
Nine respondents discussed the importance of seasonality when planning plantings. Often
planting timing is based on the construction schedule rather than plant biology, leading to
mitigation failure. For example, if a project ends in a dry time, such as May or June, the
plantings, already stressed by the transplanting process, are unlikely to survive. These
interviewees emphasized that the implementation of mitigation plantings should be based
on biology, not the construction schedule.
Water is almost always a major limiting factor when establishing plants in Arizona. Ten
of the comments in this section addressed water availability—either naturally or through
irrigation. Only two of the 40 total comments in this section stated that the lack of
irrigation is not a main problem, and that because it is part of the mitigation plan, it will
get done. The majority of the interviewees said a lack of irrigation line monitoring or
other failures in the irrigation system are frequent problems. Five ADOT respondents
said that the contractor needs to perform frequent and appropriately timed inspections of
irrigation lines. As discussed in the Staffing and Training section of this chapter,
mitigation is more likely to succeed if the contractor has someone locally who can inspect
project sites regularly and quickly repair irrigation systems.
Planting methods exist that theoretically need minimal to no irrigation. Two methods—
pole plantings, which are generally used for trees such as cottonwoods and willows, and
tall-pot plantings, which are propagated in narrow tubes to increase the length of the
taproot at planting—were discussed during the ADOT interviews. Two interviewees said
pole plantings work if they are done in the right season and are placed so that they are at
the water table from the very beginning. Two ADOT interviewees agreed that tall-pot
plantings can be used without irrigation as long as the depth to groundwater is known and
the taproot can reach it. However, one interviewee acknowledged that tall-pot plantings
would not work universally across the state but should be used on a site-specific basis.
One interviewee said that although irrigation would be needed, salvaged plants should be
used more often on mitigation sites. Because they are local stock and proven to be
adapted to conditions at the project site, they tend to be successful if a specific mitigation
and monitoring plan is in place before salvaging. However, the interviewee said
guidelines are needed for monitoring salvaged plants.
Other general planting recommendations were to seed with native tree species in addition
to planting trees to offset planting casualties, and to design planting plans so plantings
would not be destroyed during a heavy rainfall. Planting plans should consider the
anticipated flows within a planting area, keep the plantings out of the active flow channel,
and consider exclusionary fencing around an entire mitigation area to prevent browsing
or other animal damage. Finally, employees recommended that ADOT partner more
frequently with other entities such as city governments to replant areas as it did with the
Red Mountain Park site in Mesa.
Seeding. While the focus of the interviews was on physical plantings, many of the
interviewees had more experience with seeding. Recommendations regarding seeding are
included in this report because many of the comments apply to plantings as well.
The most common comment regarding seeding was seasonality: Four ADOT
interviewees said seeding should be based on seasonality rather than on the construction
schedule. Seeding immediately following construction is usually done for erosion control,
but many interviewees said there is no benefit to laying seed that is either eaten by birds
or sits for months before conditions are right for growth. Millings that are dumped and
compacted on the shoulders of a road are required to be seeded even though there is little
to no germination of seeds on this type of compacted substrate.
As has been previously discussed with plantings and mitigation plans, the seeding mix
should include plants that are native to the area and are likely to successfully establish
cover, including native tree species. The focus of seeding establishment, even for erosion
control, should be the germination and survival of desirable native vegetation, not weeds.
Monitoring of establishment success should be transparent, and monitoring methods
should be available upon request.
Corps Interviews
Administrative Processes
In-Lieu Fees and Other Off-Site Mitigation. Of the five project managers who
commented on in-lieu fees, three advocated the use of in-lieu fees or mitigation banks to
satisfy compensatory mitigation requirements for projects, particularly projects with
small impacts to jurisdictional Waters. A fourth project manager indicated that he had
become more willing to accept in-lieu fees in the last few years after the program was
revised to tighten legal requirements so that true compensation was more likely to occur;
however, in his opinion, the full effect of in-lieu fee programs in Arizona was not yet
known because these programs were still relatively new. Two project managers noted
that permittees seem to prefer using in-lieu fees to satisfy mitigation requirements
because of the certainty of being done with permit requirements upfront, including the
need to hire consultants to monitor a site for years.
When discussing compensatory mitigation for linear projects, one project manager said
that the 2004 Corps mitigation guidance was designed to address relatively large
mitigation sites and was not suitable for the typical linear ADOT project that involves a
number of small impacts at different sites. This same project manager said that road right
of way was not the appropriate place to try to compensate for habitat lost within right of
way. Instead, it made more sense to limit on-site mitigation within the right of way to site
stabilization, including seeding but not planting, and provide compensatory mitigation for
habitat impacts off-site through in-lieu fees or a mitigation bank. This project manager
suggested that ADOT could create several mitigation banks in different parts of the state
to be used to diminish the impacts of ADOT projects anticipated to impact relatively
large amounts of Waters.
Responsible Parties. Five project managers said there are problems with obtaining
permittee compliance with compensatory mitigation requirements of Corps permits,
including monitoring and reporting requirements. One project manager said that the key
to monitoring success was to have a conscientious permittee who actively tracked
mitigation progress and took action when changes were needed. Another said
noncompliance was not as common with "repeat permit customers" such as public
agencies and municipalities as it was with one-time permittees.
One project manager noted that ADOT does not have a strong enough chain of
responsibility because there is no evidence of follow-through from the time the permit is
issued to the time the project is constructed and completed. ADOT hires one consultant
firm during the design phase to assist in the permitting process, including preparation of
the mitigation plan. When the project enters the construction phase—sometimes years
later—the same consultant is not hired to follow through with mitigation installation and
monitoring. No one at ADOT seems to be responsible for ensuring that compensatory
mitigation is done and done properly, particularly in projects with a long time between
permit issuance and project construction.
The project manager said that if design changes in the field during construction affected
design or implementation of the mitigation plan authorized in the Corps permit, the Corps
was not being notified to obtain authorization for a modified plan. The manager also said
that ADOT does not seem to hold its contractors sufficiently responsible for their actions
or lack of actions. In one example, contractor neglect apparently caused plants to die. The
area had to be replanted and the monitoring period extended, yet ADOT apparently did
not fine or penalize the contractor for these avoidable project costs.
Staffing and Training. Two project managers noted that the Corps does not have
sufficient staff to inspect construction or mitigation sites on a semiregular basis and
therefore relies on permittees and their consultants for site inspections and reporting.
Three project managers said mitigation plans have included plants that are not native to
the area or are unsuitable for site conditions. One project manager said that sometimes
the plant material is too large—24-inch pots are fine for landscaping purposes, but
smaller plants are more likely to survive long term without irrigation.
Other Agency Involvement. When asked if there was a constructive role that ADOT
could take if there were no existing in-lieu fee projects in an area where ADOT
construction projects were proposed, the project manager primarily responsible for the in-lieu
fees program in the Corps' Arizona office said the Arizona Game and Fish
Department (AGFD) has an existing memorandum of agreement with the Corps that
covers the entire state, so project locations are limited only by the locations that the
AGFD proposes for suitable projects. If ADOT had a need for an in-lieu fee project in
areas where the AGFD did not already have projects, ADOT might encourage AGFD
field managers to develop proposals for in-lieu fee projects in those areas.
Mitigation Plans and Monitoring. One project manager said mitigation plans are often
incomplete, leading to repeated requests by the Corps for the missing information. As
mentioned earlier, another project manager said the 2004 Corps mitigation guidance was
designed to address large mitigation projects and may be unsuitable for the typical linear
ADOT project that involves a number of small impacts at a given site. A third project
manager said that in addition to providing compensatory mitigation for impacts,
mitigation plans require avoiding and minimizing impacts to jurisdictional Waters as
much as possible.
One project manager saw insufficient monitoring and compliance as one of the biggest
problems and said that some permittees take advantage of the Corps' lack of staffing for
monitoring compliance. On-site mitigation adjacent to residential areas is another
concern. According to two Corps project managers, residents do not always want to abide
by the requirements of the Corps permit or restrictive covenants. Problems with
compliance result when residents prune trees that block their views, cut down vegetation
they feel is a fire hazard, allow unleashed dogs to run through the site, or set fires.
The Corps also noted that design changes in the field during construction are not always
passed on to the Corps.
This section presents the results of the project file review and site visits. It also includes
comments and suggestions from the interviews that, in association with a review of the
literature and knowledge of the research team, seem most relevant and have the potential
to increase the success of future projects.
Inefficiency in the administrative process and biological categories was observed in the
projects reviewed for site visits and noted by ADOT and Corps interviewees. The
complexity of mitigation and revegetation projects along with the size and complexity of
the agencies involved contributes to this inefficiency. Strategic changes can improve the
efficiency temporally and economically.
Irrigation issues created one area of inefficiency—because of incorrect placement, early
withdrawal, maintenance issues resulting from lack of contractor follow-up, or a lack of
ADOT oversight of the contractor. In arid Southwest riparian areas, water is the limiting
factor that controls species composition (National Research Council 2002; Anderson,
Russell, and Ohmart 2004). Stromberg, Tiller, and Richter (1996) show that species
distribution in southern Arizona is associated with depth to groundwater. Irrigation to
planted species, especially in areas where depth to groundwater has not been determined
or in areas with a low water table, is critical until they are able to gather sufficient water
on their own. In many cases, the contractor uses a manual irrigation system, which may
not operate on a regular, timely basis or for the necessary length of time, leading to plant
failure. Using automatic irrigation timing systems would reduce the concerns associated
with manual watering and would ensure that irrigation occurred on a regulated basis.
Solar-powered emitter controllers can be used in areas where power sources are
The system of irrigation should depend on the species and its method of gathering water.
For a wet riparian species such as willow or cottonwood, which needs access to the water
table, the irrigation timing and amount should encourage deep root growth. Other species
develop shallow, widespread root systems that enable them to effectively and
immediately use any precipitation that falls. Irrigation emitters should be placed an
adequate distance from the base of the plant to promote adequate root growth. Unless
there is a sufficient source of water at the site to enable the plantings to survive without
supplemental irrigation (a rare situation in Arizona), irrigation placement, timing, and
quantity are keys to successful mitigation.
Insufficient maintenance of the irrigation system was commonly reported. Regular
maintenance and system checks should be enforced to ensure that irrigation problems do
not limit a project's success. Another consideration, based on discussions with
interviewees, the technical review committee, and the internal research team, is to alter
the current contractor bonding system, which could increase the likelihood of mitigation
Staff turnover at ADOT, project transition between departments, insufficient training of
personnel, or inadequate project organization can impede the progress of mitigation and
oversight of the contractor during mitigation implementation or establishment periods.
The current bonding system does not provide a financial incentive for the contractor to
ensure long-term mitigation establishment success. Creating an additional bond or a
separate bond specifically for the irrigation system and mitigation plantings would
provide an incentive for the contractor to more carefully monitor irrigation system
effectiveness and change other practices that may put the bond in jeopardy. It would also
provide ADOT with a solid enforcement tool, which is currently lacking.
Project transition, either within a department or across departments, can cause a
disconnect in ADOT oversight that can interfere with the mitigation's success. If
mitigation practices specific to a site are not fully detailed or project documentation is
incomplete, the new project manager may not know what the measure of mitigation
success should be. Specifying one staff position in ADOT to follow the mitigation aspect
of a project from design to Corps acceptance of establishment would provide a valuable
link between the previous project manager and the current project manager. This position
would retain a copy of all documentation regarding the mitigation and would be familiar
with the specifics of each site to prevent disconnects during transition.
Most interviewees said the DEC was the most appropriate person for this responsibility,
and the research team concurs, provided there is a standard understanding of the role and
responsibility of this position in reviewing mitigation plans and tracking implementation
and results. The first monitoring report following planting should document as-built
conditions, including a thorough assessment of mitigation that actually occurred, the
limits of the mitigation area, species and number of individuals planted compared to
required plantings specified in the mitigation plan, planting locations, irrigation system
information, and other pertinent information that would aid future project managers or
DECs in supervising mitigation establishment.
Good mitigation planning is vital to the success of a project as is having clear objectives,
specific measures of success, and a clear monitoring plan that will provide data on those
measures (Kondolf et al. 2007). The Corps, as the permitting agency, is involved in
determining an appropriate replacement ratio and planting scheme. The agency has
specific guidance for mitigation projects under Section 404 of the Clean Water Act that
should be incorporated into mitigation plans. A rule on mitigation was issued by the
Corps in April 2008 and became effective in June 2008 (EPA 2008). The Corps also
determines when the mitigation is accepted as complete as specified in the permit and any
associated documentation for the site, such as mitigation plans. Replacement ratios
should be determined based on site-specific characteristics and multiple reference plots in
related areas because they capture the inherent variation and are more likely to provide a
representative source of standards to determine mitigation success (Ruiz-Jaen and Aide
2005). Cooperation with the Corps and any other agencies with a stake in the project area
during the early phases of project planning will ensure that all agencies agree about the
objectives and success criteria of a mitigation project.
Mitigation plans should be based on at least one, but preferably multiple, reference plots;
should be site-specific; and should include a specific plan to monitor the success of the
project. Because of Arizona's large variation in biozones, a one-size-fits-all plan is not
effective. Not only do plans need to adapt to each geographical zone, but within each of
these zones, plans need to vary based on the status of the impacted wash (ephemeral,
intermittent, or perennial); the nature of the adjacent area (rural vs. urban); and the level
of prior disturbance. The mitigation plan should be developed, in cooperation with the
Corps and other applicable agencies, by a consultant with a clear understanding of natural
environments and with a background in biology or restoration ecology. This could
include landscape architects with a background in, or adequate experience with,
restoration of natural environments. Landscape architects with purely urban landscaping
experience should not be considered qualified to develop a mitigation plan because the
requirements, distribution, and needs of species when restoring a natural riparian area are
quite different from the average urban landscape.
While developing the mitigation plan, it is important to verify that the desired plants are
available in local nurseries. Following mitigation plan implementation, a qualified
consultant with a background in biology should monitor the project. Monitoring reports
should be submitted to the ADOT project manager, the DEC, the Corps, and any other
agency involved in the project. Under the 2008 rule from the Corps, all mitigation must
be monitored for a minimum of five years. Monitoring detail depends on the scope and
should be determined on a project-specific basis.
Seasonality was a concern in mitigation plan implementation. Often with transportation
projects, on-site mitigation plans are implemented after construction rather than during
the season conducive to planting success, which can lead to mitigation failures.
In off-site mitigation, in-lieu fees may be appropriate. According to the Corps project
managers, these may especially be appropriate for linear projects where the impacts are
small and occur within the right of way. In-lieu fees can also be an efficient and practical
alternative or companion to on-site mitigation. The 2008 Corps mitigation rule
encourages the use of mitigation banks and in-lieu fee programs over permittee-responsible
mitigation in which the permittee retains direct responsibility for seeing that
mitigation is implemented, monitored, and successful. Under this rule, existing in-lieu fee
programs may continue to operate under the terms of their existing instrument (the legal
document for the establishment, operation, and use of an in-lieu fee program) for two
years, and the Corps may grant an extension for up to three additional years. Any
revisions made to an existing in-lieu fee program instrument as well as all new in-lieu fee
instruments must be consistent with the rule. The Corps has estimated that decisions
regarding the establishment of mitigation banks and in-lieu programs would be made
within approximately 225 days of federal agency review time, but the amount of time
required to prepare the documentation as well as actual review times are not yet known.
Under the Corps' 2008 rule, mitigation bank credits are the preferred form of
compensatory mitigation, in-lieu fee program credits are second, and permittee-responsible
mitigation is the least-preferred choice. Mitigation banks would be more
likely to keep the benefits of mitigation within the same watershed as the impacts—the
preferred result of any off-site mitigation. Currently no mitigation banks are set up in
Arizona; the Corps has approved 10 in-lieu fee recipient organizations in Arizona and
one in California.
This chapter provides a list of recommendations for addressing administrative process
and biological issues in mitigation projects.
Enlist an ADOT employee or consultant with a clear understanding of
natural environments and a background in landscape ecological design,
landscape ecological restoration, plant biology, or restoration ecology to
develop and monitor land disturbance mitigation plans. Findings from the
interviews and project file reviews indicate that mitigation plans are more likely
to succeed and to be in line with the objective of restoring an area to a more
natural aspect when created by someone with a background in natural resources.
Landscape architects who do not have natural habitat replacement experience and
whose experience is limited to urban landscape planning should not be considered
qualified to develop a mitigation plan because the needs for a mitigation plan are
different from the average urban landscape. ADOT should require mitigation
designers and installation supervisors to attend a class on ecologically sound
mitigation practices prior to involvement on mitigation projects.
Outline clear performance objectives in the mitigation plans with specific
success criteria and a monitoring plan that defines quantitative data needed
to determine success. Viable mitigation planning and supportive data are keys to
realistic assessments of project success. Projects often have unspecified objectives
that make it difficult to judge success, particularly if success is gauged by
"eyeballing it," as is sometimes done. Clear objectives, transparent methods, and
quantitative data will not only provide more convincing signs of project success,
they also will aid future efforts to determine which mitigation practices work and
which should be refined or discarded.
Designate an ADOT staff position in each district to be responsible for
following all mitigation projects—from initial development through
implementation, monitoring, and final acceptance by the Corps—to ensure
that each project has met success criteria. Ensure that the employees in those
positions have a similar understanding of their responsibilities and receive
training, if warranted. Many of the administrative process problems noted from
the file review and interviews, such as lack of follow-through and lack of ADOT
oversight, could be resolved with this suggestion. The research team recommends
using the DECs for this position, assuming all DECs would have a standard
understanding of their roles and responsibilities.
Ensure corresponding planting plans are prepared jointly by a qualified
landscape architect and the individual charged with the development of the
mitigation plan. To ensure that planting plans for a specific project agree with
the requirements laid out in the mitigation plan, the landscape architect and the
individual who developed the original mitigation plan should coordinate closely
during design of the planting plan.
Brief the landscape and irrigation contractors and the biological monitor
once the mitigation plantings are in place to ensure that the contractors
understand the requirements of the mitigation plan. The review of the project
files and interview results indicated that disconnects occur whe
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