SAN FRANCISCO – The U.S. Army Corps of Engineers has begun flood control releases from Coyote Valley Dam at Lake Mendocino and late tonight will begin releasing water from Warm Springs Dam at Lake Sonoma in response to significant rainfall and the likelihood of more in the coming days.
Recent storms have significantly increased reservoir levels in the flood control pool at both facilities. The releases are intended to accommodate additional rainfall and are in accordance with the U.S. Army Corps of Engineers Water Control Manuals. The first flood control release occurred today at 11 am at Lake Mendocino. Flood control releases at Warm Springs Dam will begin at midnight, Jan. 12.
The Corps’ San Francisco District is responsible for running both federal dams on the Russian River. Lake levels, river levels as well as weather forecasts are constantly being monitored to ensure the safety of downstream communities.
The Corps has determined the magnitude of necessary flood control releases following the recent series of rainstorms across the Russian River Watershed. Release scenarios are being evaluated with consideration given to conditions downstream and in light of the likelihood of future storms.
Lake Sonoma (Warm Springs Dam) Lake Mendocino (Coyote Valley Dam)
Pool elevation (in feet) 475.2 753.88
Water Stored (acre-foot/gallons) 314,519/103 billion 96,727/32 billion
Storage Capacity (acre-foot/gallons) 381,000/124 billion 116,500/38 billion
Figures as of 9am Jan. 12
Over the past week, Warm Springs Dam has been releasing approximately 105 cubic feet per second (cfs) and Coyote Valley Dam has been releasing 200 cfs. The flood control space of each reservoir is over 50% full. The San Francisco District has evaluated potential flood control releases from the dams as a result of the recent storms and in anticipation of next week’s forecasted precipitation. Significant flood control releases of up to 3,000 cfs will be made at Coyote Valley Dam and up to 6,000 cfs at Warm Springs Dam.
The releases are being timed to allow downstream river levels to recede while still allowing for as much time as possible to evacuate water from the dams prior to the next storm. When releases are made, it is anticipated that the ramping up rates for both dams will be gradual. Releases are expected to increase by no more than 500 cfs per hour, and the released water will not contribute to flooding at downstream locations. This schedule is subject to change as the San Francisco District monitors lake levels and river levels, and receives updated forecasted information.
For more information on timing, magnitude, and duration of potential flood releases please visit the California Data Exchange Center (CDEC) website at http://cdec.water.ca.gov/queryRes.html.
The purposes of both dams is to help reduce flooding downstream and to provide water for the Sonoma County Water Agency (SCWA) and the Russian River Water Control and Conservation Agency and Flood Control District (RRWCCFCD).