Water Resources:

An In-Depth Look at Overflow Dredging on the Great Lakes

RCED-88-200BR: Published: Aug 11, 1988. Publicly Released: Sep 12, 1988.

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Pursuant to a congressional request, GAO provided information regarding the Army Corps of Engineers' use of overflow dredging on the Great Lakes, focusing on: (1) its environmental impact; (2) relevant legislation and guidance; (3) cost-effectiveness; and (4) extent of use in areas with highly contaminated sediment.

GAO found that the Corps: (1) did not assess the environmental impact of overflow dredging, but did research its cost-effectiveness and the impact of sediment resuspension on open water disposal; (2) estimated that research regarding the environmental impact of overflow dredging could take 7 years and cost $8 million; (3) allowed overflow dredging in 18 percent of the 74 Great Lakes projects it conducted during fiscal years 1986 and 1987; (4) complied with Environmental Protection Agency (EPA) regulations by identifying sediment composition and forwarding the results and its proposed methods to EPA, the Fish and Wildlife Service, and the state for concurrence before soliciting bids for dredging; (5) determined that, since overflow dredging was the least expensive dredging method in many areas, banning it could increase dredging costs by 30 to 55 percent; and (6) allowed overflow dredging in only one area of highly contaminated sediment and restricted its use according to EPA guidelines. GAO also found that: (1) EPA lacked national and regional guidelines regarding overflow dredging; (2) states used EPA regional guidelines regarding open water disposal of sediment to make decisions regarding overflow dredging; and (3) the Corps believed that some of the states' restrictions affected its ability to carry out its dredging responsibilities.

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