Fishermen reported the fish die-off Friday morning in the two retainment ponds that border the town. A tour of the area revealed more than 300 dead trout, kokanee salmon and carp ranging in size from 6 inches to 18 inches floating on the shores of both large ponds.
“I came down to fish and this is what I found,” said Dolores fisherman Jim Koenig. “It makes me sick to see it.”
The ponds are isolated from the main body of the reservoir because of low water levels. They were recently iced over, but have melted in the past few days.
“You could see the fish frozen in the ice a week ago and the eagles eating them,” said fisherman Shane Brisnin. “Now they’ve been blown to the shore. I grew up fishing here and never saw this many die off.”
Jim White, a fish biologist with Colorado Parks and Wildlife, said this is the time of year when there can be natural fish kills in shallow bodies of water because of ice and lack of oxygen. He said the McPhee fish die-off is not from a toxic pollution source.
“I’m certain they died from lack of dissolved oxygen in the water,” he said. “The ponds do not have regular flushing, and the fish become trapped in there.”
A headgate and pipe from the adjacent Dolores River is designed to keep the ponds full of fresh water, but the system is not working because the intake pipe is often above the flow of the river.
“Winter fish die-off is natural, but in this case it is exacerbated by an engineering problem,” White said.
It’s uncertain who has jurisdiction for maintaining the intake pipe, a question that’s been debated by federal agencies for the past year.
The San Juan National Forest manages the shores and the lake bottom when it is dry. The U.S. Bureau of Reclamation built the reservoir’s infrastructure. The Dolores Water Conservancy District manages the water for irrigation. And the Colorado Parks and Wildlife is responsible for the fishery.
McPhee Reservoir is the key component of the Dolores Project, a $500 million irrigation system constructed by the Bureau of Reclamation in the 1970s and 1980s.
It began filling in the 1980s, and in 1986 the BOR transferred management of the shores and exposed lake bottom to the San Juan National Forest under a Memorandum of Agreement.
“We build the infrastructure then turn over maintenance and operations,” explained Vern Harrell, a BOR engineer in the Cortez office.
But the Forest Service is not so certain about who has management authority for the headgate and pipe into the ponds.
“The BOR did reserve jurisdiction on certain structures associated with the dam operation,” said Derek Padilla, Dolores District ranger for the Forest Service. “Unfortunately, there is not a detailed list of what those structures are so that is still being researched by the regional office.”
Once it is determined which agency is responsible, additional analysis would be needed to determine if and when the inlet system can be made functional.
Reservoir officials toured the area last summer. They said the headgate is open, but the pipe is likely partially filled with sediment.
A suggested solution is to place boulders in the river near the headgate to raise the water level, allowing fresh water to flow into the pipe and ponds.
Koenig has been raising awareness of the problem to elected officials and federal agencies for two years. But he said the lack of action has been frustrating.
“Somebody has the responsibility,” he said. “The taxpayer’s paid for these ponds and they should be maintained and operated like they are designed to, with regular fresh water running through so they don’t get stagnant and kill our fishing spot.”