A member of Congress from Michigan called for a federal review Thursday of water releases from Lake Michigan through an outlet at Chicago, a century-old practice that she said should end as Great Lakes levels approach record lows.
Rep. Candice Miller asked the U.S. Army Corps of Engineers to determine whether the Lake Michigan outflows are partly responsible for the recent drop-off, although she acknowledged that experts say the biggest culprits are drought and evaporation.
"I know there are cycles and Mother Nature has a lot to do with it, but I've never seen things so bad," said Miller, a Republican from Macomb County and co-chairwoman of the House Great Lakes Task Force.
Man-made water diversion from Lake Michigan in the Chicago area dates to the mid-1800s. A massive engineering project completed in 1900 reversed the flow of the Chicago and Calumet rivers and constructed a shipping canal, sending the city's sewage toward the Illinois and Mississippi rivers.
The diversion has drawn legal challenges but was upheld by a U.S. Supreme Court ruling that limits outflows to 2 billion gallons per day. That reduces the lake's level by roughly 2 inches, said John Nevin, a spokesman for the International Joint Commission, a U.S.-Canadian agency that deals with boundary waters issues. But he said it's offset by diversion of water from a Canadian river into Lake Superior.
Even so, Miller said she's suspicious that the Chicago diversion might be making a bigger difference than officials believe. The Army Corps' Chicago district office monitors the diversion to make sure it stays within the legal maximum but its last report was published in 2009.
Corps officials said this week that all the Great Lakes are below their historical average levels, while Lakes Michigan and Huron - which have the same surface level because they're connected - just missed setting a record low for October.
Keith Kompoltowicz, chief of watershed hydrology for the Corps district office in Detroit, said last winter's lack of snow and the hot, dry summer were to blame - along with milder winters that have shrunk the ice cap and promoted evaporation.
Miller said regardless of how big a role the Chicago diversion plays, it should stop. The shipping canal through which the water flows is also the focal point of a debate over invasive species, as scientists fear it may provide a pathway for Asian carp to reach the Great Lakes. Michigan and four other states are suing in federal court to place barriers in the Chicago waterways, which business and government leaders in Illinois say would devastate the city's economy.
In a letter to Jo-Ellen Darcy, assistant secretary of the Army, Miller complained that "the Great Lakes are continually forced to take a back seat to the needs of others on nearly every important issue that comes forward."
Locks and gates control the Lake Michigan outflow. The Corps has no authority to change the limit, which is set under a consent decree reached after the Supreme Court ruling, said T.Y. Su, a hydraulics and hydrological engineering specialist.