RIVERDALE (AP) - An Army Corps of Engineers official says a project to prevent the coldest water in Lake Sakakawea from being sucked into hydroelectric turbines is a success so far, and is continuing.

The cold water at the bottom of the lake is in danger of disappearing because of low water levels due to drought. Deep cold water is prime habitat for rainbow smelt, the primary forage base for such fish as walleye and salmon.

To protect the cold water, crews have been partially covering intakes that drain water out of the lake to rotate huge turbines that make electricity.

Todd Lindquist, a lake operations manager for the corps, said the crews have been hoisting up slimy grates called trash racks that protect the water intakes from debris, and covering the lower half with plywood. The work continued last week and over the weekend.

"What we're trying to do is force the water we pull through the power plant from a higher elevation in the reservoir," Lindquist said. "We're taking warmer water and preserving colder water for the smelt and other cold-water species."

Lindquist said the first two years of the project, to install plywood on two of the five water intakes, have "proven to reach the benefits we were striving for." A third intake was fitted with plywood over the weekend.

"We're still at risk, depending on how warm the summer is and how low the water level," Lindquist said. "The lower the reservoir, the more severe the cold water problem becomes."

Lindquist said the cold-water measures will continue until the lake rises about 15 feet, to an elevation of around 1,825 feet.

The corps has been releasing more water from the lake to provide habitat for threatened and endangered species along the Missouri River and to bring up its level in the Bismarck-Mandan area in time for Memorial Day.