TRAVERSE CITY, Mich. (AP) - A federal agency sent Congress a list of
alternatives Monday for shielding the Great Lakes from an invasion by Asian
carp that could devastate native fish, including construction projects in
Chicago waterways that could cost more than $18 billion and take 25 years to
The U.S. Army Corps of Engineers declined to endorse a single plan after
studying the matter since 2009, disappointing sponsors of legislation that
ordered the agency to move faster. Instead, the Corps provided a 232-page
analysis with eight possible approaches.
Two would place dams in the Chicago waterway system to seal off Lake
Michigan from the carp-infested Mississippi River watershed.
Environmentalists and five states that unsuccessfully sued the Corps in
federal court favor that approach, while Illinois, Indiana and local
shipping interests oppose it.
Other proposals would use different mixtures of equipment and technology,
including construction of additional electric fish barriers and a new type
of navigational lock that would treat water to remove floating plants and
fish as vessels move through the system.
Bighead and silver carp are a big concern for the Great Lakes because they
could threaten a fishing industry valued at $7 billion a year. Also, silver
carp are notorious for springing from the water when disturbed by motorboats
and colliding with their occupants, posing a risk to outdoor recreation.
Dave Wethington of the Corps’ Chicago district office, project manager for
the study, said battling invasive species is “a shared responsibility” that
will require support from Congress and state governments, which would have
to settle on a strategy and provide the money.
“We’re providing this information to the decision-makers,” Wethington said
in a phone conference. “We are standing by to move forward to the next
The Great Lakes and Mississippi watersheds share a boundary nearly 1,500
miles long. But the study focused on a network of rivers and canals in and
near Chicago with five direct links between the two giant drainage basins,
considered the likeliest route by which Asian carp could reach the lakes.
The Chicago waterways are connected to the Illinois River, where a large
carp population has advanced to within 55 miles of Lake Michigan. The Corps
says an electric barrier 37 miles from the lake is preventing any
individuals from slipping through. Scientists have detected Asian carp DNA
in dozens of water samples past the barrier, although whether they came from
live fish remains in dispute.
The Corps said the measures in its report could shut down pathways for 13
potential animal and plant attackers, from the bloody red shrimp to reed
sweetgrass and a deadly fish virus. But public and congressional interest is
riveted on bighead and silver carp - voracious Asian fish imported in the
early 1970s to gobble algae in Deep South fish ponds and sewage plants.
They escaped during floods and have migrated up the Mississippi and Ohio
rivers and tributaries in more than two dozen states. Scientists say they
can destabilize ecosystems by devouring plankton, a vital link in aquatic
U.S. Sen. Debbie Stabenow, a Michigan Democrat, and Rep. Dave Camp, a
Michigan Republican, said the Corps should have picked one approach and
developed it more thoroughly. They favor separating the two watersheds and
sponsored a bill that would do that.
“The only real solution that will truly protect the Great Lakes is the
complete separation of the Great Lakes and Mississippi River,” said Rep.
Candice Miller, a Michigan Republican.
Two options in the Corps’ report would achieve that by placing barriers
along the Lake Michigan waterfront or farther inland. Both would severely
disrupt commercial shipping and pollute the lake by preventing Chicago sewer
discharges from flowing downstream as they do now, the report said.
Two other alternatives would use barriers to cut off some of the aquatic
pathways while deploying additional electric barriers, screened gates, locks
and water treatment plants.
The options achieving the greatest degrees of physical separation tend to be
most expensive and time-consuming, with costs reaching $15 billion to $18.4
billion and a 25-year timetable. That’s because they would require extensive
reworking of Chicago’s flood-control and sewage treatment systems in
addition to building the dams, Wethington said.
The report also offers two middle-of-the-road alternatives that would
maintain the waterway system’s current shipping operations. One could be
carried out in 10 years and cost $7.8 billion, a relative bargain. It would
create a “buffer zone” with a series of control technologies.
Aside from doing nothing new, the cheapest approach would step up use of
existing measures such as netting carp and treating the water with
chemicals, at a cost of $68 million a year.
American Waterways Operators, a group representing barges and tugboats in
the Chicago area, said the report makes clear that physical separation “is
neither economically feasible nor will it be effective at eliminating all
identified pathways for the spread of invasive species, including Asian