Orange County Water District uses Firo and a digital twin to balance water supply, flood control and riparian habitat

CORONA, Calif. — Orange County Water District presented its use of forecast‑informed reservoir operations (Firo) and an environmental “digital twin” to the Environmental Flows Work Group on Oct. 5, saying the approaches can increase water capture from storm events while providing data to show effects on riparian habitat behind Prado Dam.

Lisa Haney, executive director for planning and natural resources at Orange County Water District, described Prado’s operations and the basin’s natural riparian forest, which supports the endangered Least Bell’s vireo and is the largest riparian stand in Southern California. Haney said the district has a long partnership with Scripps/CW3E on AI‑enhanced weather forecasting for Firo and that the technology has produced higher‑confidence forecasts that allow more aggressive capture of storm inflows for groundwater recharge.

Haney gave concrete examples from the current implementation year: Prado’s historical conservative operation maintained a maximum operational elevation of 505 feet; using Firo and increased forecast confidence, the district said it received a minor deviation to operate at 508 feet for a five‑year period and that this season’s operational shift yielded roughly 6,000 acre‑feet of additional supply, which the district equated in its remarks to about $6 million in value.

Why this matters: OCWD said roughly 40 percent of its local water portfolio depends on the Santa Ana River base flows and storm capture, with the Groundwater Replenishment System (GWRS) supplying another roughly 35 percent. Haney emphasized that many upstream wastewater recycle projects and planned capital projects could reduce river baseflows in future decades; the ability to predict and manage flood inflows and to document ecological responses is important to sustain both supply and habitat.

Digital twin and regulatory use: OCWD said it developed an environmental digital twin that combines historic monitoring, satellite imagery and AI methods to map vegetation change, inundation, sedimentation and vireo nesting. Haney described a 12‑month pilot in which two independent consultant teams—one from CW3E (weather/AI) and one a technical AI consultant—worked on standardized datasets; the two teams reached similar conclusions about vegetation responses to inundation. She said U.S. Fish and Wildlife and other regulators participated in the process and that OCWD received what she described as “the green light to use this as our regulatory compliance tool moving forward.”

OCWD also said the digital twin will be expanded to add groundwater distance layers, LIDAR‑derived sediment mapping and weather forecasts to better correlate operations with plant recruitment and vireo nesting dynamics. Haney said the district hopes the model could be extended watershed‑wide to track effects of upstream reclaimed‑water projects and to inform regional mitigation and planning.

Questions from the work group covered species history, permitting and regional coordination. On permitting, Haney said a long‑standing judgment requires certain discharges from upstream utilities and that local agencies have rights up to that judgment amount, but she cautioned that collective planning and a regional monitoring plan are needed to quantify cumulative impacts when multiple agencies implement recycled‑water projects.

Ending: OCWD asked for continued technical collaboration and said Firo and the digital twin together can help the district optimize for water supply, flood protection and environmental benefit while documenting outcomes for regulators.