The water model behind California’s Bay-Delta plan

The Sacramento Water Allocation Model (SacWAM), built using the Stockholm Environment Institute's Water Evaluation And Planning (WEAP) system, is being used by the California State Water Resources Control Board to update the Bay-Delta Plan. The model simulates the complex Sacramento-San Joaquin Delta water system to assess how proposed policy changes—such as new flow requirements for the Sacramento River and its tributaries—impact agriculture, water supply, and fisheries. SacWAM allows officials to compare current operations against an 'unimpaired state' to determine flow requirements that support both 25 million people and 3 million acres of farmland while restoring the Delta's ecosystem.

• The Sacramento Water Allocation Model (SacWAM) is a hydrologic and system operations model based on the Water Evaluation And Planning (WEAP) system. It is designed to simulate both the current operations of the Delta's water system and its 'unimpaired state', which represents how water would flow without the presence of infrastructure, diversions, or dams.
• The California State Water Resources Control Board uses SacWAM to update the Bay-Delta Plan (the Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Estuary). The model helps evaluate the impact of proposed policy changes on fisheries, water supply, and agriculture, including new flow requirements for the Sacramento River, the eastside tributaries (Calaveras, Cosumnes, and Mokelumne rivers), and interior Delta flows.
• Following a 2016 independent peer review, SacWAM underwent improvements including the incorporation of additional climate data, modifications to groundwater representation, and an extension of the simulation period to cover September 2009 through September 2015.

APA

Stockholm Environment Institute (2019). The water model behind California’s Bay-Delta plan. https://www.sei.org/wp-content/uploads/2019/05/the-water-model-behind-the-bay-delta-plan.pdf

Chicago

Stockholm Environment Institute. The water model behind California’s Bay-Delta plan. 2019. https://www.sei.org/wp-content/uploads/2019/05/the-water-model-behind-the-bay-delta-plan.pdf.

Wikipedia

{{cite report |author=Stockholm Environment Institute |title=The water model behind California’s Bay-Delta plan |date=May 2019 |url=https://www.sei.org/wp-content/uploads/2019/05/the-water-model-behind-the-bay-delta-plan.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{stockholmenvironmentinstitute2019water, author = {{Stockholm Environment Institute}}, title = {{The water model behind California’s Bay-Delta plan}}, institution = {Stockholm Environment Institute}, year = {2019}, month = may, url = {https://www.sei.org/wp-content/uploads/2019/05/the-water-model-behind-the-bay-delta-plan.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }