By Kimberly Hirai
It took eight years of moving 40 million cubic yards of dirt and stone to create the 28 miles of canal that reversed the Chicago River. Flushing Chicago’s sewage away from Lake Michigan, the city’s main drinking water source, and down the Mississippi River required a manmade marvel. But since 1900, the Chicago Sanitary and Ship Canal has also served as a gateway for invasive species between the Great Lakes and Mississippi River Basin.
Serving as a “pass go” to the Great Lakes, they use the canal as an underwater highway, discovering new habitat, new resources and leaving economic and ecological problems in their wake.
The Asian carp is the latest to this invasive family — leaving muddy Mississippi waters for the cold, glacier-formed Great Lakes. The U.S. Army Corps of Engineers had hoped to stop the fish’s advance with electrical barriers on the canal. But tests revealed the Asian carp’s presence above those barriers in late November.
It is a familiar story. The failed fight to keep species from moving between the Great Lakes and the Mississippi River Basin started nearly 20 years ago with an invader from the opposite direction.
The round goby, a pucker-mouthed bottom dweller about the size of a pencil, first spurred action to sever the connection when it left the Great Lakes — the world’s largest freshwater source — in the 1990s for the Mississippi River Basin — home to almost one-third of all North American freshwater fish.
From Lake to Stream
Residents knew the Chicago River as the “stinking river” before engineers and the city’s sanitation department completed the Chicago Sanitary and Ship Canal in 1900. Through a series of locks, the canal took Chicago’s sewage away from Lake Michigan — 1.7 million Chicago residents’ drinking water source — and dumped it into the Des Plaines River, eventually flowing into the Mississippi River.
In 1930, the canal was made navigable, allowing boats to pass between the Great Lakes and the Mississippi River via the Illinois River. Scientists later discovered invasive species could take the same route.
In 1990 University of Michigan research scientist David Jude became the first to find a round goby in the Great Lakes system. It was in a clogged water-cooling system uptake filter at the Belle River Power Plant on the St. Clair River which connects Lake Huron with Lake St. Clair. By the mid- ‘90s, hitching rides in the ballast tanks of ships that spread it through the lakes, the fish was found near the Chicago Sanitary and Ship Canal.
The round goby first threatened native fish that might compete with it in the Great Lakes. It now threatened those living in the Mississippi River Basin.
What the round goby lacks in size it makes up for in might. It aggressively defends the eggs it spawns multiple times a season. Even young round gobies outcompete young native fish for food, such as zooplankton. Once grown, it’s like a voracious Texan oil tycoon, swallowing vital resources. It eats native fish and their eggs. It captures the best habitat, displacing fish like the sculpin, an important link in the food web for native lake trout. The round goby is also a strong competitor — it can survive the turbid waters uncharacteristic of any clear, pristine lake.
Jude worried the tiny fish would make a big splash in the Mississippi River basin. He and other scientists believed electrical barriers offered the best chance to stop its spread. They experimented to discover how much voltage is needed to stop the goby advance. Then the U.S. Army Corps of Engineers designed two barriers and an initial experimental one on the Chicago Sanitary and Ship Canal in Romeoville, Ill. The experimental barrier went into operation in April 2002. The first of two permanent barriers followed in 2008; completion of the second is expected in 2010.
Meanwhile, Phil Moy, fisheries and invasive species specialist for the University of Wisconsin Sea Grant Institute, tracked the round gobies’ progress. They were in Calumet Harbor on the southwest shore of Lake Michigan in 1994 and entered Calumet River soon after. By summer 1999, they were just below the site proposed for the electrical barrier.
The government moved slower than the round goby. They were found downstream of the barrier sites in October 1999.
“It was too late,” says Moy.
Management had failed.
Now fisheries managers and scientists are fighting a similar threat from the Asian carp — a fish whose bighead species can grow up to 4 feet long and whose silver species has an affinity for above-surface acrobatics.
Those efforts may also be too little, too late.
The Last Stand
Silver and bighead carp were imported from Eurasia in the 1970s to eat algae from Arkansas catfish ponds. They made a jail break during floods in the 1990s and have since occupied the Mississippi River Basin.
Hungry bottom feeders, young silver and bighead carp can outcompete other native Great Lakes fish for plankton. Silver carp have a healthy appetite, eating up to 40 percent of their body weight each day. Carp commonly weigh 3 to 10 pounds, but bighead carp can reach more than 100 pounds, according to the U.S. Geological Survey. A 10-pound silver carp can eat 4 pounds of zooplankton a day that would otherwise feed Great Lakes fish species. That’s a significant threat to the Great Lakes’ $7 billion sports fishing industry.
Silver carp also pack a punch — they jump out of the water when spooked by boat motors and have left boaters with black eyes, broken bones, cuts and concussions. A government fact sheet says it’s like getting hit with a thrown bowling ball.
The Asian carp have been elusive. They dodged efforts by agencies to electrify the water where tests have suggested their presence. Electro-fishing stuns or kills fish, allowing agencies to collect them at the surface and determine which species are in the water.
Carp were within 5 miles of the electrical barriers in mid-August, when the Army Corps increased voltage from quick pulses of one volt to two volts per inch.
The Illinois Department of Natural Resources announced plans in November to poison the canal and remove the carp before performing routine maintenance on the electrical barriers.
Just after the announcement, David Lodge broke the bad news: Evidence of carp was discovered beyond the barrier.
Lodge, director of the University of Notre Dame’s Center for Aquatic Conservation, samples water for silver and bighead carp DNA shed in the form of feces, slime or urine. His team found it in the Calumet River just 6 miles south of Lake Michigan. The carp are there, but in what numbers is unclear.
How did they get past the electrical barriers? “We don’t know,” says Maj. Gen. John Peabody of the U.S. Army Corps of Engineers.
That doesn’t mean they’ve made it to Lake Michigan. But Jude thinks the carp’s presence in the Great Lakes is inevitable.
“I am really frankly surprised that they haven’t made it through already,” he says. A large storm could overwhelm the Des Plaines River and spill silver carp into the canal. The Illinois and Michigan Canal might also offer an alternative route to the Great Lakes through its connections to the canal. Though backup generators protect against electrical failures, potential for human error, natural disasters or other accidents make the electrical barriers vulnerable.
The barriers also have another Achilles’ heel — they can’t screen fish larvae, plankton and invasive plant species. Still, Peabody says, “the barrier is the single most effective defense against the broad movement of Asian carp into the Great Lakes.”
Additional tests will confirm or deny the DNA samples, but members of the Environmental Protection Agency and the U.S. Army Corps of Engineers said no actual carp had been sighted or caught above the barriers in November.
Whether there are or not, a key question remains: Should a permanent physical barrier be installed to bar all invaders?
In 2002 the U.S. Fish and Wildlife Service called the electrical barrier a Band-Aid: “The barrier will not stop all fish species from moving freely between the basins and will not stop unwanted non-fish invaders,” the agency reported. “However, it will slow species movement and allow more time to develop permanent solutions.”
Joel Brammeier, president of the Alliance for the Great Lakes, thinks a permanent barrier is the solution.
A Permanent Barrier
“If your goal is really to eliminate the movement of organisms, the only real solution is a physical barrier,” says Brammeier, a Detroit native and lifelong resident of the Great Lakes watershed. It could be as simple as a concrete wall.
His organization began conversation about a barrier to prevent water from moving between systems in 2006. It spent two years and $120,000 studying recreational and commercial shipping in the two water systems, taking ecological inventories, interviewing stakeholders and examining six possible sites. Brammeier identified two preferred sites: one between the south branch of the Chicago River and the Chicago Sanitary and Ship Canal; and another between the main branch of the Chicago River and Lake Michigan.
Any solution creates problems and requires large investments. A physical barrier at either location would disrupt some shipping and recreational routes.
“There’s no cheaper way to move … goods than on water,” Moy says.
Barges moved 5.2 million tons of material – mainly coal, sand and gravel – between the south branch of the Chicago River and the ship canal in 2004, according to the Alliance for the Great Lakes. A barge moves the equivalent of 16 railcars or 70 semi-tractor trailers, according to the Texas Transportation Institute. Using trucks and trains is more expensive and could create a lot of opposition to a permanent physical barrier.
The cost of disrupting the transportation industry is easier to calculate than the cost of disrupting a distant ecosystem. Brammeier says the solution would have to satisfy both concerns:“The goal is really to maintain and improve the ability of the waterways to support the economy of the Chicago region while recognizing we have a problem to solve.”
Brammeier’s work is beginning to pay off.
In September, the U.S. Army Corps of Engineers received $400,000 in federal funding to analyze permanent ways to stop invasive species — including plants, mussels and plankton. It’s a small start — Shea estimated in 2005 that large-scale feasibility studies for regional physical barrier projects might cost upwards of $20 to $30 million.
Congress and the Illinois Department of Natural Resources will have spent $20 million, not including operations, on electrical barriers once a second one is completed sometime next year. It spans a larger area of the canal, contains improvements based on experience with the first barrier and is built to last longer.
Brammeier thinks a permanent physical barrier is cheaper and requires less maintenance. It might also end one front of an invasive species battle that has lasted for years.
Meanwhile, officials are bracing for an invader that they have no official plan to handle once it reaches the Great Lakes.
The consequences of a silver carp invasion are severe.
“Asian carp are like cancer cells,” says Cameron Davis, senior Great Lakes adviser to EPA chief Lisa Jackson. “They can grow and spread very quickly and overtake other healthy living organisms in ecosystems where they don’t exist.”
A 40-pound female silver carp can produce 2.5 million eggs, which typically float for two weeks before completing development in a riverbed. Moy says miles of free-flowing water are required — Chicago Sanitary and Ship Canal’s concrete walls are hardly ideal habitat.
But should the silver carp overcome the odds, both manmade and natural, “It would be a traditional insult to the food web,” says Cindy Kolar, assistant program coordinator for the U.S. Geological Survey’s Invasive Species Program.
No one knows how and if Asian carp could survive moving to bigger, colder lakes from rivers. Great Lakes and Mississippi River Basin officials aren’t giving up hope.
“We should not assume that all is lost,” Lodge says.
It took eight years to build the Chicago Sanitary and Ship Canal — it may take only days for another invasive species to slip through.
Kimberly Hirai is a first-year graduate student studying environmental journalism at MSU. Contact her at firstname.lastname@example.org.