Forecast Informed Reservoir Operations

FIRO is a proposed management strategy that uses data from watershed monitoring and modern weather and water forecasting to help water managers selectively retain or release water from reservoirs in a manner that reflects current and forecasted conditions.

FIRO is being developed and tested as a collaborative effort focused on Lake Mendocino that engages experts in civil engineering, hydrology, meteorology, biology, economics and climate from several federal, state and local agencies, universities and others.


Executive Summary
Preliminary Viability Assessment
Watershed Characteristics and Challenges
Interagency Cooperation

Jay Jasperse

(Sonoma County Water Agency)

F. Martin Ralph

(Center for Western Weather and Water Extremes at Scripps Institution of Oceanography)

Michael Anderson

(California State Climate Office, Department of Water Resources)

Levi Brekke

(Bureau of Reclamation)

Michael Dettinger

(United States Geologic Survey)

Nick Malasavage

(US Army Corps of Engineers)

Alan Haynes

(Caifornia Nevada River Forecast Center, NWS)

Joseph Forbis

(US Army Corps of Engineers)

Patrick Rutten

(NOAA NMFS Restoration Center)

Cary Talbot

(US Army Corps of Engineers)

Robert Webb

(NOAA’s Earth System Research Laboratory)

Arleen O’Donnell

(Eastern Research Group)

Ann Dubay

(Sonoma County Water Agency)

David Ford

(David Ford Consulting)

Rob Hartman

(RKH Consulting Services)

Water Challenges

There are multiple, significant challenges associated with the operation of the Coyote Valley Dam (CVD). A key challenge is illustrated to the right. It shows how, avearged over the water years from 2004 to 2014 (blue line), the Lake Mendocino reservoir has not been able to refill in the spring.

The Sonoma County Water Agency (Water Agency) is the local sponsor for Lake Mendocino and controls and coordinates water supply releases from the CVD. There are several water supply challenges, including minimal coordination with people who use water downstream; a federal biological opinion that requires flow changes; an out-of-date rule curve for determining flows; and reduced inflows from the Eel River watershed.

The Water Agency controls water releases from CVD in accordance with its water rights permits and provisions of Decision 1610, which the State Water Resources Control Board (State Water Board) adopted on April 17, 1986. The Water Agency’s permits authorize diversions to storage in Lake Mendocino, re-diversions of water released from storage and direct diversions at points downstream. The Water Agency makes releases from CVD to:

  1. Meet downstream demands of agricultural and residential water users and several public and municipal systems; and
  2. maintain minimum in-stream flows in the upper river to its confluence with Dry Creek.


Graph illustrating June 2015 water level at Lake Mendocino (black line), courtesy of Sonoma County Water Agency. Atmospheric river storms in early December and February brought water level up to roughly normal for 1 March. However, very little precipitation and inflow occurred after that, which has been common in the past several years. Thus the reservoir has been unable to refill to provide adequate water supply through the dry summer [Water year 2014 (green line) and average of Water years 2004-2014 (blue line)]. (Click above for full size image)

The hydrologic year type for the Russian River system is based on cumulative inflow into Lake Pillsbury, which is located on the upper Eel River and was formed in 1921 by the construction of Scott Dam (Figure 7). This hydrologic index is not located in the Russian River watershed and reflects Lake Mendocino’s dependence of PG&E’s Potter Valley Hydroelectric Project (PVP). Lake Pillsbury is part of the PVP, 9.4 megawatt storage and diversion project, that has been in operation for more than 100 years. PG&E’s operation of the project results in an inter-basin transfer of water from the upper Eel River into the East Branch Russian River across a natural divide.

CVD operations are governed by the Water Control Manual that dictates ranges of release flows depending on pool level, non-regulated flows in the Russian, damaging flood stages downstream of the dam and on current releases. The rate-of-change (ramping) standards were developed as part of consultations with NMFS and from geotechnical considerations to prevent stranding fish and to minimize bank damage. In general, the operation is designed to store water during a flood event, then release soon thereafter to create storage space for another potential event. Seasonal differences in required flood space are the result of nearly 100 years of hydromet data, and are based on typical weather patterns — wet during the winter, dry otherwise. Since much of the basin is not regulated by dam operations, the Water Control Manual is designed to prevent flooding when possible in the Hopland and Guerneville areas, and in concert with Warm Springs dam operations.

The National Marine Fisheries Service (NMFS) has issued two biological opinions that pertain to water storage in the Russian River: (1) the PVP Biological Opinion in 2002 (Eel and Russian rivers transbasin diversion); and (2) the Russian River Biological Opinion in 2008. Project elements addressed in the Russian River Biological Opinion include operations and water supply releases at Warm Springs and CVD, flood control operations, channel maintenance (Water Agency and Mendocino Flood Control Agency), estuary/lagoon management, fish hatchery operations at Don Clausen Fish Hatchery and Coyote Valley Fish Facility, and other Water Agency diversion facilities and operations. Specific to Lake Mendocino and CVD operations, the Russian River Biological Opinion identifies three primary project elements impacting fisheries: (1) higher summer flows/velocity from CVD releases effecting juvenile steelhead rearing habitat in the upper main stem Russian River (modify Decision 1610); (2) chronic turbidity issues associated with Lake Mendocino discharge; and (3) water discharge ramping rates (up/down) and annual dam inspections (suspended releases to the East Branch Russian River).