SPOKANE - A large melting snowpack and a cold, wet spring have led to huge water releases on the bloated Columbia River that a company says are responsible for a massive fish kill at its farm south of the Grand Coulee Dam.

The operators of Pacific Aquaculture Inc. have sent a letter to the Northwest congressional delegation asking the government to reduce the releases, saying the large amount water is pumping toxic gases into the river that kill 100,000 fish a day.

But the Columbia River Inter-tribal Fish Commission said the snowpack, plus heavy spring rains, make it impossible for the dams to store all the water flowing through the river system.

The Columbia Basin has gotten above-average precipitation, setting the stage for what's expected to be the river's biggest water year since 1997. Making things worse has been a cold, wet spring that has delayed runoff.

"We have a lot more snow in the mountains than we usually do at this time of year," said Steve Barton, the U.S. Army Corps of Engineers chief of reservoir control for the Columbia Basin.

Charles Hudson, head of governmental affairs for the commission, said the river "is running at a fevered peak right now. The fact is that Mother Nature is running the river right now, not federal agencies, not judges and certainly not Congress."

He said snowpack is at 200 percent above normal in some parts of the Columbia River Basin, and that in a normal year the dams capture only about one-third of the runoff. Flood warnings were issued throughout the region on Thursday, and heavy rains and snow fell in the mountains. The Silver Mountain ski area in Idaho said it was taking the unusual step of opening for the Memorial Day weekend because of a heavy snowpack.

Barton said the corps is aware of the complaint but it must manage the river to prevent flooding - a problem repeated throughout the West and Midwest as persistent spring rains swamp rivers and waterlogged earth. That means federal officials are releasing water from the Grand Coulee Dam now to keep the reservoir low so it can handle that mountain runoff when it finally melts, he said.

Turbulence as the huge releases of water spills from the dams is producing the dissolved gases that Pacific Aquaculture blames for the fish kill. Hudson acknowledged that current levels of dissolved gases are higher than normal, which is usually below 115 parts per million. Pacific Aquaculture said dissolved gases were running above 125 parts per million, which is toxic to fish, and that particular stretch of river faces extermination of aquatic life.

"If this practice isn't stopped immediately, it will result in more than $30 million in economic damage to our company alone," the company said in the letter to lawmakers in Oregon and Washington.

The company's 2.7 million fish on the farm are under threat by gas levels in the water, the letter said. "This will have disastrous results on wild fish in the river, including multiple endangered or threatened species," the company wrote.

Hudson said there is no evidence that wild fish are being hurt by the releases and that salmon prefer higher water flows. "All this spill generally contributes to higher survival.

The offices of Washington Senators Patty Murray and Maria Cantwell did not immediately comment on the letter from Pacific Aquaculture.

The surge in river flows recently affected wind farms in the region because the Columbia's hydroelectric dams supplied all the power the grid could handle.