The Corps approves major deviation for Forecast Informed Reservoir Operations effort

By Carol ColemanJanuary 26, 2019

Russian River
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CW3E Forecast
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Water Release
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VICKSBURG, Miss. -- The U.S. Army Corps of Engineers, South Pacific Division has approved a major deviation that allows for Forecast Informed Reservoir Operations-developed tools and concepts to be tested this winter at the pilot reservoir Lake Mendocino in the Russian River valley in northern California. This request will allow a maximum of 3.8 billion gallons of additional water, enough to supply approximately 97,000 people for a year, to be stored in Lake Mendocino during the winter rainy season to improve water supply reliability and environmental conditions in the Russian River while continuing to ensure flood management capacity of the reservoir.

"This is a major step along the way in defining how FIRO can be implemented," said Cary Talbot, a division chief at the U.S. Army Engineer Research and Development Center's Coastal and Hydraulics Laboratory and program manager for ERDC's FIRO effort. "The goal is to incorporate forecasting safely in water management and support an update to the Lake Mendocino water control manual."

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. Since 2014, a large interagency group consisting of experts in civil engineering, hydrology, meteorology, biology, economics and climate from several federal, state and local agencies and universities has been investigating how weather forecast information can inform water management decisions such that a better balance between flood risk management, water supply and ecological concerns can be realized and safely put into practice.

"The Corps changed their policy in 2016 to allow for forecast information to be used in water management," said Talbot. "But while this policy change opened the door, it didn't spell out how this was to be done. That's what FIRO is doing, defining the how."

The deviation request was submitted on behalf of the Lake Mendocino FIRO Steering Committee. The committee was formed to explore methods for better balancing flood risk management and water supply needs. Representatives from ERDC, Corps Districts, Sonoma Water, the Center for Western Weather and Water Extremes at Scripps Institution of Oceanography, the National Oceanic and Atmospheric Administration, the U.S. Geologic Survey, the U.S. Bureau of Reclamation and the California Department of Water Resources are participating in the committee.

"This is a unique situation," said Talbot. "There is daily interaction between all participating organizations generating multiple perspectives. From day one the research effort has been designed with the water management operators at the table."

Last year, members of the group filed the request to allow a 10 percent deviation from established flood risk management operating rules, which was supported by a Preliminary Viability Assessment that contained detailed modeling, analysis and scientific research, and demonstrated that FIRO can provide water managers the information they need, with adequate lead time, to selectively retain or release water from reservoirs.

"When it comes right down to it, the goal is to inform the reservoir operator to make better decisions to release or retain water," said Talbot. "FIRO has more flexibility. The more data they have, the better."

Lake Mendocino, located near Ukiah, California, is operated jointly by the Corps and Sonoma Water. The Corps manages the flood risk management operations at the reservoir while Sonoma Water manages the water stored expressly for water supply. Following a severe drought in California, Lake Mendocino was chosen as a pilot reservoir when Congress asked the Corps to conduct a research project investigating improving forecast capabilities to help with water management.

"The ability to leverage newer technology and knowledge base as it pertains to weather forecast enhances our ability to safely deliver the multiple missions at Lake Mendocino," said Nick Malasavage, chief of Operations and Readiness Division for the U.S. Army Corps of Engineers San Francisco District. "In particular, the steps we are now taking to further develop and incrementally implement the FIRO concept adds an additional tool to maintain our primary responsibilities for flood risk management."

With the success of the effort in Lake Mendocino, the committee hopes to effect change and put FIRO into action and expand to other areas of the country.

"Each reservoir is different and must be looked at individually," said Talbot. "We don't get to do a lot of research in water operations as most of the tools already in place are working well. The FIRO effort allows for investing into next generation water management tools and investigating how those tools might inform water managers to make better water management decisions."