Don Phillips and Larry Riat were both amazed and perplexed about a week ago when they fished at Milford Reservoir.

The amazing part included a massive run on channel catfish as they fished from a boat, using jig lures.

What alarmed and perplexed the 76-year-old retirees was the thousands of dead carp and other less desirable species in the water and on the shore.

"There were two dead carp about every foot. They were floating in the water about everywhere," said Riat, of Abilene.

The channel catfish were spawning, said Phillips, of Salina.

"We caught many, many of them and turned them back," he said. "They were good eatin' size."

The pair were after walleye and crappie. They caught a few crappie, but turned them back.

But what they wondered about most was the dead carp.

Why the dead carp?

Fisheries officials at the lake have been fielding reports about dead fish -- 99 percent of them carp -- for a couple of weeks, starting from the north end, said R.J. Harms, Milford operations manager for the U.S. Army Corps of Engineers.

Experts at the lake investigated, and Harms shared a theory that suggests the dead fish came from the Republican River, which flows into the lake.

"A lot of the (dead) fish look to be oxygen-stressed. Our oxygen profiles (in Milford) seem to be fine," Harms said.

The theory is that rain patterns over the past several weeks have caused the river flows to fluctuate and the fish to move.

Experts think that the increased flows caused carp, and perhaps some drum and other fish, to float downstream. Then, as the heavy flows subsided, the fish would get caught in shallow pools, become oxygen-stressed and die.

"Next time it rains, they would get pushed into the lake," Harms said.

High winds have contributed, as well, he said.

"That's the latest theory. We haven't heard anything different," he said. "There is nothing showing an oxygen problem (at Milford)."

Mud-covered carp

The theory makes sense, Phillips said.

"I saw several carp that were covered in mud. They had been buried for some time," he said. "Of course, a carp can live for a time without water on them, if they're in the mud."

Phillips said he harbors no concern over the quality of fish at Milford and would have no problem eating fish caught there.