This story has been updated with additional facilities information.

LAKE COUNTY, Calif. – The California Department of Water Resources Division of Safety of Dams recently released updated information on the 1,246 dams under the state’s jurisdiction, listing each dam’s downstream hazard classification, condition assessment, and reservoir restriction status.

The 2018 update reflects several changes, including adjustments to some hazard classifications based on inundation maps submitted by dam owners as required by Senate Bill 92 (Committee on Budget and Fiscal Review).

The downstream hazard is based solely on potential downstream impacts to life and property should the dam fail when operating with a full reservoir. This hazard is not related to the condition of the dam or its appurtenant structures.

The report lists numerous dams in Lake County, including several owned by the county of Lake and a Yolo County agency, and the Hidden Valley Lake Association.

County-owned facilities include two owned and operated by Lake County Sanitation District, located in Clearlake Oaks and Upper Lake, as well as the Adobe Creek and Highland Creek dams, operated by the Lake County Watershed Protection District, and the Spring Valley dam east of Clearlake Oaks.

There also is the Cache Creek Dam near Lower Lake, owned by Yolo County Flood Control and Water Conservation District, and the Coyote Creek dam owned by the Hidden Valley Lake Association.

In addition, there are numerous privately owned dams.

All but one of of Lake County’s dams are listed as being in “satisfactory” condition in the report. One of the dams owned by Langtry Farms is listed as “fair.”

Division of Safety of Dams, or DSOD, engineers and engineering geologists assess dam conditions based on annual physical inspections and comprehensive re-evaluation studies, as well as technical analyses submitted by dam owners.

This information can change from year to year as new deficiencies are identified and others are remediated.

If DSOD identifies an issue that presents a significant dam safety concern, it may place restrictions on a reservoir’s operations until deficiencies are corrected.

“Public safety is the foundation of DSOD’s independent dam safety oversight,” said Sharon Tapia, chief of DSOD. “With California’s infrastructure aging, we take our job very seriously, inspecting each jurisdictional dam annually and working closely with dam owners to correct identified issues on an ongoing basis.”

The 2018 update also includes dams taken out of, or brought into DSOD’s jurisdiction. Over the past year, five dams became non-jurisdictional by either being completely removed or reduced to less than jurisdictional size. Two existing dams were added into DSOD’s inventory.

California continues its efforts in the statewide bolstering of dam safety. New legislation requires inundation maps and emergency action plans for all significant, high, and extremely high hazard dams and their critical appurtenant structures.

In addition to continuous reevaluations since the 1960s, currently under way is a focused reevaluation of spillways of 93 dams similar to Oroville.

DSOD also continues its efforts on seismic reevaluations of dams and their appurtenances, which located near active faults and in densely populated areas.

More comprehensive than physical inspections, reevaluations are used to identify dam deficiencies, which often take many years and hundreds of millions of dollars to address.

Recently, the seismic rehabilitation of DWR’s Perris Dam was completed after four years of construction at a cost of $122 million.

The project resulted in the dam’s condition assessment improving from fair to satisfactory.

Dams Within Jurisdiction of the State of California 2018 Alphabetically by Dam Name (1) by LakeCoNews on Scribd