The outage began at 12:58 p.m. CDT Wednesday, said Lt. Col. James Schreiner, deputy commander of the Army Corps of Engineers' Chicago district. Two of three barriers were operating at the time and both failed. Backup generators were activated, but a power surge prevented them from immediately delivering electricity to the barriers. Personnel at the site manually reset a circuit breaker to get the generators working.
The barriers emit rapid pulses to scare away fish and jolt those that don't turn back. They are located in the man-made Chicago Sanitary and Ship Canal about 37 miles by water from Lake Michigan. There's no immediate indication that Asian carp or other fish advanced past the barrier during the outage, but experts are still looking into that, Schreiner said.
Officials with the Asian Carp Regional Coordinating Committee, which includes state, federal and local agencies, are investigating what caused the outage and the initial problem with the generators, he said. Also participating are representatives of ComEd — the utility that supplies electricity to the barrier — and the company that manufactured the generators.
"The corps is working extremely hard right now to bring closure to this and make improvements to the system if need be," Schreiner told The Associated Press in a phone interview.
Federal officials consider the barriers a crucial part of their strategy for preventing bighead and silver carp from invading the Great Lakes. The fish escaped from southern sewage lagoons and fish farms decades ago and have infested the Mississippi and its tributary rivers.
"These barriers are the only thing standing between the Asian carp and our Great Lakes," said Sen. Debbie Stabenow, a Michigan Democrat. "If carp had been able to get through while the barriers were down, it could have been absolutely devastating to our economy and our way of life."
The corps says only a few adult Asian carp, if any, are near the barrier. The largest known population is about 18 miles farther south, Schreiner said.
Stabenow and Rep. Dave Camp, a Michigan Republican, are co-sponsoring bills that would order the corps to speed up development of a plan to prevent migrations between the Mississippi and Great Lakes watersheds. It's scheduled for release in late 2015. The corps and other agencies have identified 39 species that could slip from one drainage basin to the other and disrupt native ecosystems.
Of special concern are Asian carp, which gobble huge volumes of plankton — tiny plants and animals at the base of aquatic food chains. Scientists say if the large, aggressive species reaches the Great Lakes, they could damage the region's $7 billion fishing industry.
The Chicago shipping canal is part of a waterway network that links the two giant basins. Between 2002 and 2010, the Army corps placed three electric barriers in the canal; two operate continually and the third acts as a backup.
Wednesday's incident was the second in which the network inadvertently lost power, Schreiner said. The other was in 2010 and lasted four minutes. He said that outage was weather-related but didn't have additional details.
"Right now we just don't have enough to data to say" if weather played a role this week, he said.
Officials shut down the system for maintenance in 2009 and dumped poison in the water to prevent Asian carp from getting through.
Camp and Stabenow are among critics who contend the electric barrier network is inadequate. They favor erecting solid obstacles to permanently separate the Great Lakes and Mississippi watersheds, which a study this year said would cost billions.
"While the Corps was fortunately able to respond quickly to the barrier losing power, this glitch illustrates what we already know — electric barriers and chain-link fences will not hold back Asian carp forever," Camp said.
Schreiner said the electric network is "extremely effective."
Biologists have tagged 182 fish south of the barriers to determine whether any are evading the barriers. No tagged fish — which don't include Asian carp — are known to have moved past the field while power was down, Schreiner said.