Sacramento Water Allocation Model (SacWAM)


On September 28, 2023, the State Water Board released the latest version of SacWAM (SacWAM 2023.06.12).


SacWAM is a hydrologic and system operations model developed by the Stockholm Environment Institute (SEI) and State Water Board to assess potential revisions to instream flow and other requirements in the Bay-Delta watershed, including the current Sacramento/Delta review and update of the Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Estuary (Bay-Delta Plan). SacWAM was developed using the Water Evaluation and Planning (WEAP) software platform, and is intended to be user-friendly and usable for efficient comparison of multiple scenarios.

Stream flows estimated by SacWAM may be used to inform various types of analyses as part of the State Water Board’s assessment of potential alternative regulatory requirements:

  • Estimates of flow conditions under a range of alternative regulatory requirements.
  • Estimates of changes in water diversions for use in an evaluation of the impacts of alternative regulatory requirements on agricultural resources, water suppliers, and groundwater.
  • Estimates of changes in reservoir storage for use in an analysis of the impacts of alternative regulatory requirements on hydropower generation, recreation, fisheries and water supply.
  • To inform other analyses or models, such as delta hydrodynamics, temperature and economic.

SacWAM is used in a comparative manner in which a model scenario is compared to a model base condition and the difference in model outputs is used to assess potential impacts of proposed regulatory actions.

The model represents the Sacramento River Hydrologic Region, the Trinity River watershed above the Lewiston gauge, and the northern part of the San Joaquin River Hydrologic Region downstream from the gauge at Vernalis. The model includes the entire Sacramento-San Joaquin Delta (Delta), and the Delta eastside streams comprising the Cosumnes, Mokelumne, and Calaveras Rivers. The model simulates pumping plants in the Delta, the California Aqueduct and Delta Mendota Canal, as well as San Luis Reservoir.


Three copies of the SacWAM version 2023.06.12 are available to download below:

How to load SacWAM into WEAP:

  1. Download and install WEAP software (full version) or SacWAM-only version (free)
  2. Download SacWAM
  3. Open WEAP
  4. Click Area > Manage Areas > Restore
  5. Navigate to location of saved SacWAM download


SacWAM is copyrighted by the State of California, Water Resources Control Board. It is licensed under the GNU General Public License, Version 3. It can be copied, distributed, and modified freely, but you may not restrict others in their ability to copy, distribute, and modify it.


The WEAP software is licensed by the Stockholm Environment Institute. Downloads, pricing, and online license applications can be found on the WEAP website. Members of the public may obtain a WEAP license free of charge for the purpose of use with SacWAM. To do so, download and install the SacWAM-only version of WEAP.

Prior Events and Actions


SacWAM Contact


SacWAM Domain

SacWAM domain

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Example SacWAM Representation

Example SacWAM representation of a section of the Feather River

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