Evaluating The Feasibility For Forecast Informed Reservoir Operations (firo) Improvements At Reclamation Facilities

Reclamation water management is increasingly restricted by greater human usage, larger environmental compliance demands, and accelerating climate change. These factors interact to intensify the requirements on water resources infrastructure and the scrutiny regarding how those resources are managed. Forecast Informed Reservoir Operations (FIRO) are an approach through which Reclamation can adapt to these factors. FIRO pilot studies have demonstrated the feasibility of utilizing improved meteorological/hydrological forecasts combined with better management techniques to simultaneously improve dam safety and water availability. This work summarizes the current status of a FIRO pilot studies at two Reclamation facilities -- Folsom Dam and Link River Dam (Upper Klamath Lake) -- what, if any, water management alternatives are available to increase water availability, improve environmental compliance, and adapt to a changing climate

Folsom Dam is of interest to Reclamation due to its buffering role in managing the Central Valley Project and its significant environmental demands, a demand aspect not present in previous FIRO projects. With a nominal storage of a million acre-feet and generation of slightly less than 200 MW, Folsom is often utilized to balance operations across the CVP due to its short travel time to the Delta. The basin comprises 1900 square miles with hydrology typically dominated by snowmelt that is re-released by upstream storage facilities. The basin is shifting from snowmelt driven inflows toward more rainfall under climate change which may increase pressure its limited storage. The recent installation of an axillary spillway shifted space from the flood to the conservation pools. Under consultation with the USACE, a revision to the rule curve was created which allows for limited incorporation of forecast information. The plan to raise the facility to provide additional storage gives an opportunity to revisit operations and determine if additional operations improvements can be obtained through forecasting.

Water availability issues are also prevalent in the Upper Klamath Lake basin where water supply cannot be carried over year-to-year due to limited water storage capacity. High flows occurring from November through May must sustain the Klamath Project’s 230,000 acres of farmland from April through September; therefore, improving operational releases during high flows is vital to maintaining adequate water supply for irrigation. Recent extreme drought conditions have made the need for innovative solutions more urgent than ever. Currently, the flood season guide curve is determined based on long-term forecasted inflow. Absent short-term decision guidance, operators make qualitative release decisions, which may not be sufficient during extreme conditions with limited margin for error. A FIRO model for the reservoir can optimize flood releases to provide additional supply while managing flood risk by utilizing meteorological/hydrological forecasts and optimized operations decision-making.