Reservoir Operations

    Recent storms have increased Lake Mendocino’s target water supply capacity to over 100 percent, which means water is now encroaching into the flood control pool.  Keeping as much water in the reservoir without compromising flood protection or dam safety is now the goal of reservoir operators including the Sonoma County Water Agency and the U.S. Army Corps of Engineers. 

    The Water Agency manages reservoir releases when water levels remain in the water supply pool. When water rises enough to enter the flood control pool of the reservoir, the Corps takes charge of releasing water for flood protection and dam safety purposes.  

    In order to maximize that additional water storage, on December 16, 2016, the Water Agency has requested that the Corps allow an additional 5,825 acre feet of water to be stored in the flood control pool – the Corps calls this action a "temporary deviation" from its flood control manual.  This manual that was written in the 1950s and mandates when and how much water must be released from the reservoir for flood control and dam safety purposes. In January of 2017, the Corps approved this request - this will allow an increase of water in the flood control pool from 68,400 acre feet to 74, 225 acre feet.  

    View the Request for Temporary Deviation to the Water Control Manual, 12/16/16

    View the Approved Planned Minor Deviation, 1/26/17

    Water Storage Graph

    Please note: the charts above are updated weekly. View daily updated reservoir levels here.

    Long-term reservoir operations strategies

    Forecast Informed Reservoir Operations

    The Water Agency has entered into a cooperative agreement with Scripps Institution of Oceanography and the Center for Western Weather and Water Extremes (CW3E) to advance research in ocean science and meteorology.  The research will help define the role of atmospheric rivers in filling Lake Mendocino and potentially offering predictability to retain water without increasing flood risk. The partnership will also develop a feasibility assessment project for the potential use of forecast-informed reservoir operations (FIRO) for Lake Mendocino in cooperation with the US Army Corps of Engineers. Learn more here.

    Legislative Approach

    The Water Agency is working closely with its representatives in Washington, D.C. to develop legislative solutions to authorize the U.S. Army Corps of Engineers to use scientific reservoir management data to better manage reservoir releases.  Such legislative efforts have included the introduction of language by U.S. Representative Jared Huffman (FORECAST ACT) and U.S. Senator Dianne Feinstein (DRAFT DROUGHT BILL).