DWR updates California Water Plan model, plans to add environmental‑flow metrics for 2028 update

SACRAMENTO, Calif. — The Department of Water Resources told the Environmental Flows Work Group on Oct. 5 that the California Water Plan update for 2028 will expand geographic coverage of its planning model, run a larger range of future climates and add a refined environmental‑flow metric using the state’s functional‑flows framework.

The announcement came during a presentation by Paul Shipman, who identified himself as a senior water source engineer in DWR’s Division of Planning. Shipman said the change responds to the 2023 plan’s finding that the environmental metric was the weakest of the update’s six vulnerability measures. “The California Water Plan is a strategic plan, for California water management,” Shipman said in the meeting.

The Water Plan model used for 2023 will be reworked before the 2028 release. Shipman outlined several technical changes: migrating model geography to USGS HUC‑8 units for higher consistency, representing groundwater basins with integrated nodes rather than a single abstract groundwater node, replacing simplified crop water methods with a crop‑growth approach, and incorporating a weather generator that produces many novel…