According to an EPA official, the agency has addressed noncompliance  with stormwater and wastewater requirements of the Clean Water Act by  entering into consent decrees with over 50 municipalities from 1998  through 2016. Surveyed Municipalities Use of Green Infrastructure to Manage Stormwater Is Limited and Funded through General Revenues and Fees Charged to Utility Customers

Most of the 31 municipalities we surveyed use green infrastructure to  comply with NPDES permits or CSO consent decrees, but almost half  said that less than 5 percent of the area covered by their permits or  consent decrees drains into green infrastructure. Of the 30 municipalities that reported using green infrastructure to help  meet the provisions of their permits or CSO consent decrees, many of  them also reported on the percentages of the areas subject to permits or  consent decrees that drain into green infrastructure, with the remaining  areas draining into gray infrastructure or directly into creeks, lakes, or  rivers. Of the 30 municipalities that reported using green  infrastructure, 22 reported that developing an operation and maintenance  cost estimate was usually more challenging than doing so for gray  infrastructure, while none said that it was usually less challenging. In describing instances where they used green infrastructure  even though it was more challenging, some municipalities reported that  they continued to use green infrastructure to help comply with their  permits or CSO consent decrees for three primary reasons: they saw  using green infrastructure as a learning opportunity, they believed that  green infrastructure would perform better or provide additional benefits  compared to gray infrastructure, or the community wanted to use green  infrastructure. Several municipalities also reported that they were discouraged from  using green infrastructure because it was more expensive than using gray  infrastructure. EPA Helped to Facilitate Municipalities’ Use of Green Infrastructure, but in Launching a New Pilot Project Has Not Yet Developed Collaboration Agreements with Municipalities

Over the last 10 years since EPA began encouraging the use of green  infrastructure to manage stormwater, the agency’s efforts have provided  information, technical assistance, and funding to help municipalities use  green infrastructure. According to the document, it is for use by EPA,  states, and local governments to develop and implement integrated  plans under the Clean Water Act. EPA’s pilot project  with five municipalities is a good way to focus on developing long-term  stormwater plans. When working with the municipal departments and other  stakeholders, such as those in each of the five groups in the pilot project,  EPA could have a better assurance that the groups will successfully  develop long-term stormwater plans if they document their agreement on  how they will collaborate, such as in a memorandum of understanding,  aligned with our key considerations for implementing interagency  collaborative mechanisms. EPA stated that it is in  the early stages of the pilot project to assist municipalities in developing  long-term stormwater plans and will utilize the collaborative practices  recommended by GAO as it implements the project over the next 12 to 18  months. Key contributors to this report are listed in  appendix IV. Appendix I: Objectives, Scope, and Methodology

In this report, we (1) describe to what extent selected municipalities are  incorporating green infrastructure into their efforts to comply with National  Pollutant Discharge Elimination System (NPDES) permits and consent  decrees that address combined sewer overflows (CSO), and what is  known about funding for such efforts; (2) describe what challenges, if any,  these municipalities reported facing to incorporate green infrastructure  into their efforts to comply with those permits and consent decrees; and  (3) examine efforts the Environmental Protection Agency (EPA) is taking  to help municipalities use green infrastructure. We selected 20 municipalities that had NPDES  permits required of municipalities to discharge stormwater into nearby  water bodies, such as creeks, lakes, and rivers.
Why GAO Did This Study

Urban stormwater runoff is a major contributor to pollution in U.S. waters. Municipalities historically managed stormwater with gray infrastructure. In 2007, EPA began encouraging the use of green infrastructure to manage stormwater and reduce the need for gray infrastructure.
GAO was asked to examine the use of green infrastructure by municipalities to meet EPA's stormwater requirements. This report (1) describes the extent to which selected municipalities are incorporating, and funding, green infrastructure in stormwater management efforts; (2) describes what challenges, if any, municipalities reported facing in incorporating green infrastructure into stormwater management efforts; and (3) examines efforts EPA is taking to help municipalities use green infrastructure.
GAO surveyed two nongeneralizable samples totaling 31 municipalities with stormwater permits or consent decrees for CSOs and interviewed EPA officials to examine EPA efforts to help municipalities use green infrastructure. The municipalities were randomly selected from lists of municipalities that are required to have permits and have consent decrees.

What GAO Found

Almost all 31 municipalities GAO surveyed reported using green infrastructure to comply with their Clean Water Act permits or combined sewer overflow (CSO) consent decrees. The Environmental Protection Agency (EPA) regulates stormwater pollution under the Clean Water Act, which requires municipalities to obtain permits to discharge stormwater into waterbodies. EPA has also entered into consent decrees with municipalities that have CSOs—events where raw sewage is discharged into waterbodies. Green infrastructure uses natural processes to manage stormwater, such as capturing stormwater so it can seep into soil (see figure). However, of 27 municipalities responding, 15 reported that less than 5 percent of the area subject to their permit or consent decree drained into green infrastructure, with the remaining area draining into gray infrastructure, such as concrete sewers, or directly to waterbodies. Most of the municipalities reported funding green infrastructure with fees and general revenues.
Of the 31 municipalities GAO surveyed, 26 reported that green infrastructure was more challenging than gray infrastructure in aspects of infrastructure development, such as developing project operation and maintenance cost estimates. Nevertheless, 25 of these municipalities reported instances where they used green infrastructure even though it was more challenging. Some municipalities reported that they were less familiar with green infrastructure but used it anyway because it performed better or it provided additional benefits, the community wanted to use it, and the municipality saw an opportunity to learn about green infrastructure.
EPA provides multiple resources to educate and assist municipalities on the use of green infrastructure. In 2016, the agency launched a pilot project with five municipalities to encourage states, communities, and municipalities to develop long-term stormwater plans to increase their use of green infrastructure. Key to the success of the pilot project is collaboration among many stakeholders from across each community, such as members of the local utility, transportation, and recreation departments, as well as local organizations. GAO has previously identified key considerations, such as documenting agreements on how to collaborate that can benefit collaborative efforts. However, EPA has not yet documented collaborative agreements with pilot stakeholders. EPA could better assure that the stakeholders will successfully develop long-term stormwater plans if it documents how the stakeholders will collaborate.

What GAO Recommends

GAO recommends that EPA document agreements, when working with municipalities and other stakeholders, on how they will collaborate when developing long-term stormwater plans. EPA generally agreed with GAO's recommendation and plans to implement it over the next 12 to 18 months.