The US Army Corps of Engineers released a study looking at how to prevent invasive species like the Asian carp from entering the Great Lakes. None of the solutions is foolproof, it said. 
 
 As the snowpack piles up, is California's drought over? No, say experts. 
 
 This file photo shows Travis Schepker, a biology intern, holding an Asian carp pulled from the Illinois River near Havana, Ill. Keeping the fish out of the Great Lakes is a priority for the US Army Corps of Engineers. AP Photo/Robert Ray 
 
 To keep Asian carp and other invasive species out of the Great Lakes will require at least 25 years and billions of dollars, according to a study released Monday by the US Army Corps of Engineers. 
 
 The report, commissioned by Congress in July 2012, offered eight strategies for protecting the Great Lakes ecosystem from an infiltration of at least 13 invasive species moving upstream from the Mississippi River. Six of the options include permanent barriers, which independent authorities say is most foolproof, but which threatens barging interests. 
 
 The corps did not recommend which option it considers most effective, but Dave Wethington, Chicago-area waterway system project manager for the US Army Corps of Engineers, told reporters Monday that physical separation has the greatest “ability to buy down risk.” None of the options are guaranteed to fully prevent invasive species from reaching the Great Lakes, he added, because the carp will still have the potential to bypass the barriers via intentional or accidental bird or human transfer. Other forms of invasive species, like red algae or reed sweetgrass, may have greater success in breaching the barriers. 
 
 “There is a residual risk for all of these [options],” Mr. Wethington said. “The ultimate decision is up to the collaborative group of stakeholders.” 
 
 The study focuses on the Chicago Area Waterway System (CAWS), a 128-mile stretch of canals and rivers in metropolitan Chicago connecting Lake Michigan and the Mississippi River. Environmental DNA evidence of live Asian carp has been discovered in and around CAWS for several years, triggering an outcry from officials in all the Great Lakes states for more federal action. Carp would threaten a $7 billion annual recreational and commercial fishing industry. 
 
 Congress will need to authorize any new plan. Wethington emphasized that the cost will be shared among federal, state, and local agencies. The “best possible scenario” for a start date is 2017, but that depends on speed: how fast Congress authorizes a plan, as well as how fast subsequent local permitting and environmental review periods take. The 25-year estimate includes both design and construction phases. 
 
 The eight plans include a combination of structural controls (such as screened gates, locks, electric and physical barriers), nonstructural controls (such as pesticide use, education, and mechanical removal), and a buffer zone (such as waterways created to control up-and-downstream water flow) . Wethington said that cost estimates of each plan include the construction of reservoirs, sediment remediation, and other methods needed to protect the surrounding communities from floods or drinking-water contamination. 
 
 “We wanted to make sure [any plan] did not have an adverse impact on the way the system operates today,” he said. 
 
 The corps is soliciting public input through a series of public meetings throughout the Midwest. The first is Thursday in Chicago, the last is Jan. 30 in St. Louis. Some of the meetings will be streamed online. Comments will be accepted through March 3 via the agency’s website. 
 
 A coalition of conservation leaders from the Great Lakes that is advocating for a permanent barrier says it will comment further on the report Tuesday. In the meantime, the organization released a statement saying, “actions that do not move [toward a barrier] are a distraction that further delays the permanent solution so desperately needed here.” 
 
 The Asian carp is a bottom-feeder fish that was introduced to catfish farms in Mississippi and Arkansas in the 1970s to help control algae growth. The fish is presumed to have traveled to Chicago through the Mississippi River, which connects to Lake Michigan through the Chicago Sanitary and Ship Canal. ||||| Voracious Asian carp were first brought to the southern United States in the 1970s and have been eating their way up the Mississippi and Ohio rivers for years. (Scott Strazzante, Chicago Tribune / ) 
 
 Blocking Asian carp from invading the Great Lakes could require an engineering marvel that rivals the reversal of the Chicago River more than a century ago, according to a new federal study that promises to reignite a fierce debate about the region's waterways. 
 
 Among the options outlined Monday by the Army Corps of Engineers to thwart the voracious fish and other invasive species from spreading is permanently separating Lake Michigan from the river and its connected waterways. Such a project would restore the once natural divide between the Great Lakes and rivers southwest of Chicago that drain into the Mississippi River. 
 
 Chicago blasted through that hydrological barrier when it dug the Sanitary and Ship Canal and Cal-Sag Channel at the turn of the last century to divert the region's sewage away from its source of drinking water. It also created a shipping link between two of the nation's major trade routes. 
 
 Separating the lake and the river again could cost more than $18 billion and take up to 25 years, the Corps' study concluded, making that option the most expensive of the eight studied. Another option, carrying a $15 billion price tag, would allow portions of the Chicago River, Sanitary and Ship Canal and Calumet River to flow into Lake Michigan. 
 
 Reflecting the development of Chicago from a swampy prairie outpost to a sprawling city, both of those options would require a multibillion investment in giant stormwater tunnels and massive flood-control reservoirs, according to the study. 
 
 Several political leaders said the potential cost and time frame could scuttle the plan before Congress considers it. 
 
 "I've seen too many of these long-term Corps projects languish for years and fall victim to congressional inaction," said U.S. Sen. Dick Durbin, the Illinois Democrat and assistant Senate majority leader. "We can't gamble with the threat of Asian carp ... or risk severe flood damage to the Chicago metropolitan area by pursing a risky plan at the expense of our current efforts." 
 
 A lobbyist for one of the industries that still relies on the river system was even more blunt. The study "clearly indicates that physical separation is too expensive, too slow and too uncertain to be a viable solution to the spread of invasive species," said Mark Biel, executive director of the Chemical Industry Council of Illinois. 
 
 Two years in the making, the study comes amid a series of alarming findings that raise the possibility it might be too late for new federal action to stop Asian carp from getting into the Great Lakes and threatening the region's $7 billion fishing industry. 
 
 Congress ordered the study after scientists discovered genetic material of Asian carp near Lake Michigan. More carp DNA was discovered last year in Sturgeon Bay in northern Lake Michigan, some 250 miles from stretches of the Illinois River where the fish are known to spawn. It is unclear if the DNA is from actual fish or came from the feces of birds flying from areas where the carp are commonly found, since the genetic material can stay for days in the guts of birds before being expelled. 
 
 For many who have followed the issue closely, the findings confirmed their worst fears about Asian carp, which were imported to the United States in the 1970s to help fish farmers in the South clean algae from their ponds. 
 
 The fish escaped during floods and have been eating their way up the Mississippi and Ohio rivers for years. Spawning populations are as close as 40 miles from where the Sanitary and Ship Canal spills into the Des Plaines River and flows into the Illinois River. 
 
 With no natural predators, the fish are aggressive competitors with native game fish such as walleye, perch and whitefish that depend on tiny plankton during crucial stages of development. Two types of Asian carp, bighead and silver, now dominate parts of the Illinois River. 
 
 "If you really want to prevent the movement of species and keep Lake Michigan clean, it's going to cost money," said Joel Brammeier, president of the Alliance for the Great Lakes, a nonprofit environmental group. "We can't just keep patching over these problems and hoping they go away." 
 
 Experts agree the primary routes for carp and other invasive species to cross between the Mississippi watersheds and the Great Lakes are the Chicago-area waterways. Most of the potential methods to prevent their spread would upend a freight route that in recent years has declined in significance but retains influential political backers. 
 
 A less expensive option outlined by the Corps would involve spending $68 million a year netting and poisoning carp and maintaining an electrical barrier in the Sanitary and Ship Canal north of Lockport. 
 
 But last month the Corps reported that fish can swim through the barrier when they get trapped in the wake of passing barges. Carp DNA already has been found several times on the lake side of the barrier. 
 
 Environmental groups and a coalition of mayors from the Great Lakes states say the most effective option is separating the two watersheds. They see such a project as part of a larger plan, long discussed by Chicago-area leaders, to upgrade the region's aging transportation network with new facilities that quickly transfer freight between railroads, barges and trucks. 
 
 "Whatever we do, let's do it right," said David Ullrich, executive director of the Great Lakes and St. Lawrence Cities Initiative, a group co-founded by former Mayor Richard M. Daley. "The key is to get a decision sooner rather than later." 
 
 Separating the Great Lakes from the Mississippi again wouldn't be as simple as building a few dams or filling in the waterways. 
 
 Since the highly engineered Chicago River system is designed to direct sewage and stormwater away from Lake Michigan, tweaking it would require a massive expansion of the Deep Tunnel, a $3.5 billion labyrinth of giant storm sewers and flood-control reservoirs in the works since the mid-1970s. 
 
 Under one of the options in the Corps' study, stretches of the waterways that are allowed to flow back into Lake Michigan also would need to be dredged to remove contaminated sediment. 
 
 Citing a number of recent floods that forced officials to open locks separating Lake Michigan from the river as an emergency measure that allows stormwater and sewage to flow into the lake, the Corps said there is no guarantee that a permanent separation of the system would stop the spread of Asian carp. 
 
 "Any kind of engineering structure has a point of weakness," said Dave Wethington, the study's chief author. "If there were a series of storms that totally swamp the system, you could still get transfer of species, even with a physical barrier." 
 
 In a nod to business interests that have bitterly protested legal efforts by other Great Lakes states to shut down the connection between the Great Lakes and the Mississippi, the Corps of Engineers offered other options that would maintain shipping routes by constructing special navigation locks designed to reduce the risk of Asian carp and other invasive species swimming past. 
 
 But the initial reaction to the new study suggests that tension between Illinois and the other states will not ease soon. With the Corps scheduling a series of public hearings around the region, the long-simmering and still-unresolved debate likely makes it more difficult for Congress to reach a consensus about what to do next. 
 
 mhawthorne@tribune.com
– The fight to keep Asian carp from colonizing the Great Lakes could take longer than any war America has ever fought, the Army Corps of Engineers warns in a report commissioned by Congress. The report offered eight strategies to keep the invasive species from overwhelming the ecosystem and ruining a $7 billion fishing industry, the most effective of which could take up to 25 years and cost around $18 billion, the Christian Science Monitor reports. Physical separation of the Mississippi watershed from Lake Michigan was the most drastic option, but the Army engineers also looked at methods including new locks and electronic barriers to keep out the carp and other invasive species. The $18 billion plan may be a tough sell, but environmentalists fear that cheaper options won't be enough to keep the carp out. "If you really want to prevent the movement of species and keep Lake Michigan clean, it's going to cost money," the president of the Alliance for the Great Lakes tells the Chicago Tribune. "We can't just keep patching over these problems and hoping they go away."