Raising Coyote Dam revisited

While Sonoma and Mendocino counties grapple with short-term solutions to this summer's threatened drought, a decades-old proposal addressing water needs in future years is inching forward.

Coyote Dam "is the long-term solution" to water shortages, said Mendocino County Supervisor Mike Delbar, a longtime advocate of increasing Lake Mendocino's storage capacity.

Lake Mendocino -- created when Coyote Dam was built -- supplies water to Mendocino, Sonoma and Marin county residents.

The Army Corps of Engineers has launched a $5 million study to determine whether it's cost effective to raise Coyote Dam, potentially increasing Lake Mendocino's water-holding capacity by 62 percent, from 122,500 acre-feet to 199,000 acre-feet. An acre-foot of water is about 325,851 gallons.

Officials began taking public comment on the study's environmental component during a meeting in Ukiah last week.

In addition to raising the dam, the Army Corps' study will consider several alternatives, including dredging sediment from the reservoir, allowing more water to be stored behind the dam and expanding the dam's flood spillway.

The feasibility study is the second evaluation of the project's worth since 2001. Depending on funding availability, it could be completed in three to five years, Doak said.

There are no estimates available on the cost of raising the dam or the other options. "We haven't even guessed," Doak said.

Constructed in 1959, Coyote Dam was authorized under the 1950 Flood Control Act to be raised 36 feet when there was a need for additional water.

But raising dams these days is no easy matter, Doak said, noting the trend now is toward removing them and increasing water supply through water conservation.

Raising Coyote Dam also could be hampered by seismic safety requirements, which have increased since the dam was built.

A seismic study will be conducted as part of the feasibility study, Doak said.

One of the first things the study will evaluate is whether the existing dam provides adequate protection from floods.

"To date, we haven't confirmed or been able to deny the existing structure is adequate," Doak said.

You can reach Staff Writer Glenda Anderson at 462-6473 or glenda.anderson@press

democrat.com.