SIOUX FALLS, S.D. - A salmon spawning station on Lake Oahe will be back in operation after being idled the past four years because of low lake levels.

State fisheries crews at the Whitlocks Bay spawning station collect salmon eggs that are sent to fish hatcheries in Rapid City and Spearfish. The nearly hatched chinook salmon are then stocked back into Oahe where there is no natural salmon reproduction.

The station, opened in 1984 and located 18 miles west of Gettysburg, was last used in 2003. It has a fish ladder, four concrete holding ponds, raceways, a spawning building and a water supply system.

Lake water is pumped into the station and released back into the lake in the concrete ladder. The spawning urge of the adult salmon drives them up the rushing water into the holding ponds. Crews then collect eggs from females and milt from the males.

In some years with low lake levels, the Game, Fish and Parks Department has used metal culverts to extend the ladder. But even that was out of the question in fall 2004 when Oahe's elevation dropped to 1,572 feet above sea level. The 300-foot concrete ladder was still 300 feet from the water's edge.

"We're well above the minimum elevation that we need to operate the station. About 1,580 is kind of our minimum," said Bob Hanten, fisheries biologist for the GF&P.

Lake Oahe's elevation has been rising since spring because of runoff from mountain snowmelt and conservation in the reservoirs. Its elevation Friday was 1,592.4 feet above sea level.

With the spawning station shut down last year, crews collected salmon eggs by electrofishing, a process using boats and a small electric charge that stuns the fish so they rise to the surface and can be scooped up in nets.

The problem with electrofishing is the timing and extra handling involved. Hatching success can suffer, Hanten said.

"We're out there basically in those back bays collecting fish that aren't ready to spawn and we don't have a good way to hold them to ripen them up," Hanten said. "So we're basically collecting all the females that we can at that time whether they're ready to spawn or not."

Crews collected about 775,000 salmon eggs last fall. This year's egg target hasn't been set yet, but Hanten said it likely will be about the same as 2007.

There have been years that electrofishing was used to supplement eggs collected in the spawning station, he said.

"We'll be ready to do that if we need to, but we're optimistic we'll be able to get all our eggs from fish that go up the ladder."