PURPOSE:
The Lake Mendocino Forecast Informed Reservoir Operations (FIRO) Preliminary Viability Assessment Work
Plan (Work Plan) describes an approach for using modeling, forecasting tools and improved information
to determine whether the Lake Mendocino Water Control Manual can be adjusted to improve flood-control
and water supply operations. This proof-of-concept FIRO viability assessment uses Lake Mendocino as a
model that could have applicability to other reservoirs.
BACKGROUND:
The 1959 Lake Mendocino Water Control Manual (with minor updates in 1986), specifies reservoir
elevations to control flooding and establishes the volume of storage that may be used for water
supply. The Manual was developed using the best information available at the time, but it has
not been adjusted to reflect changing climate conditions and reduced inflows over the past
30 years.
FIRO WORK PLAN:
The FIRO Steering Committee has developed a work plan for assessing the viability of FIRO that takes
advantage of current science and technology. FIRO envisions modern observation and prediction
technology that could provide water managers more lead time to selectively retain or release water
from reservoirs based on longer-term forecasts. Optimizing reservoir operations potentially
benefits water supply and environmental flows without diminishing flood control or
dam safety.
This Work Plan presents an approach for considering a proof-of-concept FIRO viability assessment using
Lake Mendocino as a model. Specifically, it outlines a process for evaluating whether FIRO can
support adjustments to the Manual. The work plan describes current technical and
scientific capabilities, and outlines technical/scientific analyses and future efforts to
demonstrate the potentioal of FIRO to improve reservoir management.
The assessment will present a suite of actions ranging from practical, short-term steps to longer-term
research needs. If deemed viable, FIRO will likely be implemented incrementally, as science
evolves and implementation criteria are met. FIRO follows adaptive management principles for
continual improvement of reservoir operations. In the case of Lake Mendocino, and
much of the west coast, this hinges on opportunistically applying advances in
monitoring and predicting atmospheric rivers, their associated precipitation and runoff.
While aimed at benefitting Lake Mendocino, the project has transferability potential, thus the
Work Plan will document a process that can be replicated in other watersheds. It consists of
the following steps:
- Develop evaluation criteria and methodology
- Develop evaluation scenarios
- Identify science needs and carry out necessary research projects
- Evaluate model results
- Evaluate FIRO viability (preliminary) and assess benefits
- Develop implementation strategies
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In late December 2013 an Atmospheric River storm greatly increased the amount of
water in Lake Mendocino (thick blue line shows reservoir storage; green dashed line
shows cumulative rainfall). The “rule curve” (dashed orange line) led to the release
of this water. The lack of later rains (to February 2014) led to drought conditions and
extremely low lake levels. Figure courtesy of F. M. Ralph (UC San Diego/ Scripps /CW3E;
mralph@ucsd.edu) and J. Jasperse (Sonoma County Water Agency) – FIRO Steering
Committee Co-Chairs.
(Click above for full size image)
(Click above for full size image)
The flow chart shows how the assessment decisions will be made.
(Click above for full size image)
Atmospheric river type storms are the cause of most floods on the Russian River,
and across much of the west coast. Figure is from Ralph and Dettinger 2012, EOS.
(Click above for full size image)
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