The report offers eight plans for preventing Asian carp and other species from entering the Great Lakes.
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 complete.
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.
Some of the plans involve placing physical barriers in the waterways.
''This study tells us that while we have been successful to date in warding off the invasion of Asian Carp, the pathways for Asian Carp and other invasive species to enter the Great Lakes are increasing," said Senator Dick Durbin. ''Though popular with some, complete separation of the Mississippi River and Lake Michigan would be one of the most costly water projects in the nation,'' he said.
Other suggestions include locks, electric barriers and water treatments to remove invasive species.
The report has been given to congress.
Stabenow and Rep. Dave Camp, a Michigan Republican, sponsored a bill that favors placing barriers in the Chicago waterways to physically separate the two watersheds. Four of the options in the Army Corps report would use such structures to cut off some or all of the linkages.
Alternatives that stop short of complete separation propose technologies including installation of electric fish barriers in addition to one located 37 miles south of Lake Michigan. Another device that could be deployed is a new shipping lock system where water would be cleansed of floating invasive species.
The Associated Press contributed to this report.
