Bob Klinefelter, of Shaler, brought his 3-year-old grandson, Caleb, down to the shore of North Park Lake last week to see an unusual sight.

Working from two boats, crews from the state Fish & Boat Commission and the U.S. Army Corps of Engineers used high-voltage electric current to stun fish left in the shrinking body of water. Then they quickly scooped up the temporarily disabled creatures with dip nets and transferred them to holding tanks on the boats.

Every 15 or 20 minutes, a boat would return to shore. Volunteers used laundry baskets to carry the once-again-lively catfish, large-mouth bass, bullheads, blue gills, pumpkinseeds (a type of sunfish) and crappies to a state Bureau of Fisheries truck parked nearby.

The final stop for the aquatic travelers was North Park's Marshall Lake, about a mile-and-a-half away, where they were released.

"Look at the size of this bass," said volunteer Frank Longobardi, of Pine, holding up a fish that appeared to be about 24 inches long.

"Get it in the truck," another onlooker called out, and Mr. Longobardi headed toward the Bureau of Fisheries vehicle.

The "fish salvage," undertaken Oct. 7 and last Thursday, was one of the final steps before dredging can begin on the sediment-covered bottom of North Park Lake.

The $13 million ecosystem restoration project began Sept. 8 with a ceremonial "valve turning" to draw down, or empty, the manmade body of water. Since that time, anglers had been allowed to ignore daily catch, season and size limits.

Last week's effort sought to capture and relocate remaining game fish that had not been caught or that had not been able to swim downstream into Pine Creek.

Over the past month, the size of the lake has shrunk from about 60 acres to fewer than 15 acres. Its maximum depth, near the dam that created it, has shrunk to a few inches. The arms of the horseshoe-shaped lake have turned into mud flats that are slowly drying out.

Almost 2,000 fish from eight species were relocated from the rapidly disappearing lake, according to Rick Lorson, fisheries manager for Southwestern Pennsylvania. They included 89 large-mouth bass, some weighing up to 6 pounds; 65 channel catfish; and about 1,800 bluegills, white crappies and black crappies.

An even larger number of gizzard shad, as well as carp, white suckers and small-mouth buffalo fish were taken to a landfill, Mr. Lorson said. They could not be relocated without upsetting the existing balance of species in Marshall Lake, he said. They could not be left in the shrinking body of water, because their corpses would create an odor problem and could clog up the grates over the outflow pipe being used to drain the lake, he said.

The Pittsburgh Zoo asked for and received a few carp and buffalo fish for its native aquatic life exhibit.

About 50 people turned out to watch and assist the state, Allegheny County and federal crews with the fish-salvage effort. They included about a dozen members of the Allison Park Sportsmen's Club.

As the lake has shrunk, cans, bottles, barrel staves and other debris have appeared on the now exposed lake bottom. Club members Don Bildhauer, of McCandless, and Rich Simmen, of Shaler, were among those picking up trash while they waited for rescue boats to return to shore with their latest catches.

The long-planned restoration project is a joint effort of the county, the state and the Army Corps of Engineers. Plans call for as many as 350,000 cubic yards of sediment to be removed from the lake and hauled by truck to a county-owned disposal site along Wildwood Road.

The 65-acre tract along Wildwood Road was home to a fly-ash dump. Once the sediment is covered by topsoil, the "brownfield" area will become part of North Park.

Kathleen Anderson, project manager for the Army Corps of Engineers Pittsburgh District, said the partners in the lake restoration effort are awaiting final permits and approvals from the state Department of Environmental Resources.

North Park covers more than 3,000 acres in McCandless, Hampton and Pine. Its lake, which is to be returned to its original maximum depth of 24 feet, is to be refilled by Memorial Day 2011.

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