By GUY KOVNER
THE PRESS DEMOCRAT
Citing an “urgent need” to preserve the water supply in Lake Mendocino during an abnormally dry year, the state Water Resources Control Board on Wednesday approved a plan to reduce the summertime flows in the Russian River.
Without lowered river flows, the Sonoma County Water Agency had warned that Lake Mendocino, one of the North Coast’s two major reservoirs, would drop so low by fall that it might not be able to discharge any water into the river, jeopardizing water supplies, recreation and endangered fish.
The reservoir near Ukiah, now only 70 percent full, could run nearly bone dry by October, officials said, well below its all-time low mark of 12,000 acre feet, set in 1977 at the peak of the region’s two-year drought.
With the lowered river flows, Lake Mendocino should still hold 22,000 acre feet in October, the Water Agency said. The reservoir was built to hold about 90,000 acre-feet, a year’s supply of water for about 360,000 people.
Scant spring rainfall and new limits on the amount of water diverted from the Eel River into Lake Mendocino combined to lower the lake’s level at the start of a long, dry summer, officials said. Seeking relief, the Water Agency — which provides water to 600,000 customers in Sonoma and Marin counties — asked the state board for permission to lower the mandatory flows in the river, in turn allowing more water to stay behind Coyote Dam.
The National Marine Fisheries Service and the state Department of Fish and Game supported the county’s request, both citing the need for sufficient cool water from Lake Mendocino to support the Chinook salmon fall migration in the river.
Lower summertime flows will enable the water agency to “bank” water in Lake Mendocino for the fall fish run, the fisheries service said in a letter.
Wednesday’s order allows the water agency to: Reduce the flow in the river above Healdsburg from 185 cubic feet per second to 75 cfs. One cubic foot is about 7.5 gallons. Reduce the flow downstream from Healdsburg from 125 cfs to 85 cfs.
The lower flows “may impair instream beneficial uses, including recreation,” the state board said in its decision.
But it concluded that the impairment is “not unreasonable considering the potential impacts to fisheries, water supply and recreation in Lake Mendocino” if the lower flows were not allowed. Sonoma County officials could not immediately be reached for comment on the ruling Wednesday.
You can reach Staff Writer Guy Kovner at 521-5457 or firstname.lastname@example.org.