Dredging a lake can be an expensive and arduous task, but it?s necessary for most man-made lakes, scientists say.
“You are moving a lot of material ? it?s not an exercise for the financially embarrassed,” said Dan Soeder, hydrologist with the U.S. Geological Services.
Many of Columbia?s largest lakes and ponds, including Jackson Pond, Lake Kittamaqundi, Lake Elkhorn and Wilde Lake, are man-made, so they may have to be dredged more frequently than natural bodies of water.
When dams are built to form a man-made lake, the natural progression of water is slowed down, which makes the sediment build up faster.
Over time, the sediment begins to fill in the lakes? bottoms, which can be harmful to fish.
“It turns the lake into a wetland,” Soeder said.
How frequently lakes need to be dredged depends on the bed load of the river and how many other dams are upstream, said Laura A.S. Wildman director of River Science for Washington, D.C.-based American Rivers, a nonprofit conservation group focused on protecting and restoring U.S. rivers and promoting river stewardship.
Dredging may be necessary to clear out built-up sediment, but environmentalists agree it is only a temporary solution.
Stormwater management plans must be implemented to control pollution, said Fred Tutman, a Patuxent Riverkeeper advocate who aims to protects and improves water quality in the Patuxent River.
“If you are going to be dredging this stuff out, you better do something about the causes that put it there,” he said.
The Patuxent Riverkeeper is a nonprofit group that works on strategic programs aimed at benefiting the entire watershed.
