ShareThisBy MATT WEISER
Sacramento Bee
Monday, July 30, 2007
Drought and rapid water releases out of Folsom Dam are causing some American River observers to warn that a massive fish kill could be in store this fall.
The U.S. Bureau of Reclamation released water from Folsom Dam at around 4,000 cubic feet per second every day in July -- far more than in the two previous dry years, in 2001 and 2004.
That's been good for river recreation but may mean trouble for fish. It could deplete cold water in Folsom Lake that would otherwise be available to release when salmon return to spawn and young steelhead wait to travel downstream.
Salmon and steelhead are both protected by state and federal endangered species laws. Ironically, a crisis with another protected fish contributed to the problem this year.
In June, state and federal water exports from the Sacramento-San Joaquin Delta were slashed to protect the Delta smelt. Hundreds of the tiny fish were dying in the pumps, when their total population was already known to be at historic lows.
To continue serving farms and cities south of the Delta, water was delivered instead from San Luis Reservoir near Los Banos, a waystation along the state and federal canal system.
Extra releases from Folsom Dam are meant to refill San Luis Reservoir and make up for the shortfall in deliveries to San Joaquin Valley farmers during the smelt crisis, said Jeff McCracken, spokesman for the federal Bureau of Reclamation.
But he emphasized that federal water customers are feeling the pain, too: They're only getting about half their contracted deliveries because of the dry year.
Tim Horner, a geology professor at California State University, Sacramento, who studies the river, said the conflict highlights a perennial struggle for water between the environment and thirsty farms and cities _ one that worsens in dry years.
"I can almost guarantee we will have a large fish kill this fall," he said. "We're going to kill a bunch of fish before they spawn, and maybe we'll finally realize we've got to do things differently. We can't deliver all the (water) contracts and still have enough water for fish."
The Bureau of Reclamation plans to cut releases from the dam to 2,500 cfs in mid-August. This strategy will leave enough cold water in the lake for fall releases, when the fish need it, McCracken said.
"We're going to ensure we meet all of our requirements in the American River for all our fishery needs," he said. "That's part of our operation just as it is to deliver water to the people who pay for it."
Fall-run chinook salmon normally start returning from the ocean to the American River in early September, with the run peaking around Thanksgiving. Steelhead born in January stay in the river for about a year before heading out to sea. Both need the water at 62 degrees or colder in early fall.
Historically, cold water flowed out of the mountains unhindered. Riverbanks offered more shade to keep the water cool. Fish could also migrate farther upstream to find cooler conditions.
Modern dams, however, capture mountain runoff and cause it to heat up. Water usually becomes stratified behind dams, remaining cool below a certain depth but warmer at the surface. By adjusting operations, dam managers try to bank deeper cold water to release in the fall, when weather is still warm but rains haven't arrived to cool down rivers naturally.
When water levels drop in dry years, the entire water volume in the reservoir can heat up, leaving no cold reserve.
In other cases, the cold pool might shrink too low in the reservoir, beyond reach of the dam's outlet gates.
"I believe we're going to have a very tough year water-wise," said Felix Smith, a retired U.S. Fish and Wildlife Service biologist and now a board member of Save the American River Association. "It's going to be touch and go."
Water has been released from Folsom Dam this month at a much higher rate than in the last two July droughts, in 2001 and 2004.
In July 2001, releases hovered around 2,500 cfs, compared to the 4,000 cfs this month. Folsom Lake storage was about the same at this point in both years: just over 500,000 acre-feet, or half the total capacity.
The faster rate of releases this month means Folsom Lake has lost about 70,000 acre-feet more water than in July 2001. That's enough to provide a month of cold water for migrating salmon in the fall.
Even so, in 2001, thousands of salmon died in the American River because of warm water, Smith said.
"We are in a river system that is on the edge, temperature-wise, in years in which there's not much water available, like this one," said Ronald Stork, senior policy advocate at Friends of the River. "This may be a year in which those problems are going to be demonstrated."
(Matt Weiser can be reached at mweiser(at)sacbee.com)
