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Tweaking Folsom for Fish
They meander upstream, defy waterfalls, and negotiate white water on their anadromous journeys to the cold freshwater of their natal streams. But the lower American River is blocked by dams and diversions, the water is too warm, the flows are in flux, and fish are floating to the surface instead of spawning below. As dozens of Bay-Delta agencies and groups struggle to balance the needs of fish with the demands of people-and the needs of one species of fish with another-two species are vying for diminished supplies of cold water.
On the lower American, a 23-mile wild and scenic stretch of river between Folsom Dam and the Sacramento River confluence, only 20% of an estimated 168,000 fall-run chinook salmon spawned in 2001 due to water temperatures above 65ºF, according to National Marine Fisheries Service's Bruce Oppenheim. The dam's deeper, colder water is released in August-September to help threatened populations of steelhead with their migration. Thus the cold water pool behind the dam is almost depleted by the end of the water year (Sept. 30), which happens to be the start of spawning season for fall-run chinook salmon. Because steelhead are listed under the federal Endangered Species Act, their needs take precedence over those of chinook, which aren't ESA-listed but account for about 25% of the Central Valley salmon population.
"Fall-run chinook are in danger because there's no cold water left," says Oppenheim. "We usually run out by Oct. 15 every year. There's just not enough cold water in Folsom reservoir for both species."
The conflict is further compounded by the demand for hydropower, which runs more efficiently on cold water, and a flood control regime that keeps Folsom Dam up to 67% empty during the rainy season, both of which ultimately affect long-term cold water supply. BurRec, which operates the dam, tries to juggle these needs against those of recreation, agriculture, and local use, all while trying to meet Delta water quality standards and 1958 flow requirements for protecting fish. But those flow requirements are insufficient.
"The flow standard is outdated," says Leo Winternitz of the Water Forum. To protect fish, Winternitz says, a new flow standard should incorporate temperature requirements for specific locations in the river. In 1990, the State Water Resources Control Board agreed to adopt a better standard but has yet to do so.
"The river is over-allocated," admits the Bureau's Robert Schroeder. "There's been a dramatic impact on temperature and water supplies over the last 60 years."
Sacramento Area Flood Control Agency's Tim Washburn sees some solutions looming. The U.S. Army Corps of Engineers and the Bureau plan to improve Folsom Dam to better manage flood control and the cold water pool. Structural improvements include making the dam's low-level outlets bigger so that operators can fully utilize the channel's carrying capacity during the early stages of a flood. Operational improvements include relying more on weather forecasts to regulate reservoir storage. These changes may pave the way for agreements on conditional storage in the designated flood space
during the spring and late fall, potentially enlarging the volume of cold water for fish. Other solutions include developing conjunctive use with underground reservoirs, and cooperating with up-river, non-federal facilities.
A more controversial proposal would enlarge Folsom Dam and increase its flood storage capacity, which proponents claim would have the added benefit of providing more cold water behind the dam and in the river. But critics question the cost ($219 million) and safety involved in adding lots of concrete to the top of the dam, especially since the dam's low-level outlets are being hollowed out. A simpler, shorter-term solution is an automated temperature control device being installed on the dam's municipal water supply intake that will allow the Bureau to selectively withdraw water from the top of the lake while conserving the coldest water in the reservoir.
"We're really mining in the margins here figuring out how we can re-operate, rehabilitate, and re-think how we use existing facilities," says Washburn.
For now, says Felix Smith of Save the American River Association, the Bureau must decide how much water it can allow to bypass Folsom Dam's hydropower valves in order to send the reservoir's coldest water downstream to meet the needs of the fish. Adds Smith, "Pray for rain and cool temperatures."
Contact: Water Forum (916)264-1998 GS
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