|
Steering Committee
Co-Chairs
Jay Jasperse
(Sonoma County Water Agency)
F. Martin Ralph
(Center for Western Weather and Water
Extremes at Scripps Institution of Oceanography)
Members
Michael Anderson
(California State Climate Office, Department of Water Resources)
Levi Brekke
(Bureau of Reclamation)
Michael Dettinger
(United States Geological Survey)
Mike Dillabough
(US Army Corps of Engineers)
Rob Hartman
(NOAA's National Weather Service)
Christy Jones
(US Army Corps of Engineers)
Patrick Rutten
(NOAA Restoration Center)
Cary Talbot
(US Army Corps of Engineers)
Robert Webb
(NOAA's Earth System Research Laboratory)
Support Staff
Ann DuBay
(Sonoma County Water Agency)
David Ford
(David Ford Consulting Engineers)
Arleen O'Donnell
(Eastern Research Group)
|
|
Water Challenges
Water Supply Management
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downstream; a federal biological opinion that requires flow changes; an out-of-date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.
Flood Control Management
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.
Environmental Resource Management
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).
|
|
