SacWAM Contact

Scott Ligare
(916) 341-5382

San Francisco Bay/Sacramento-San Joaquin Delta Estuary (Bay-Delta) Program

Sacramento Water Allocation Model (SacWAM)

News and Events


The Sacramento Water Allocation Model (SacWAM) is a hydrologic and system operations model developed by the Stockholm Environment Institute (SEI) and State Water Resources Control Board (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 2006 Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Estuary (2006 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.

sacwam domain

(Example SacWAM representation of a section of the Feather River)

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 SacWAM model domain is shown below. 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 Project Pumping Plants in the Delta, upper reaches of California Aqueduct and Delta Mendota Canal as well as San Luis Reservoir.


To download and load SacWAM, first download and install the WEAP software from the link below. Then download SacWAM and load it through the WEAP interface. The XA solver is now included in the free WEAP license for use with SacWAM, license information is found below.

Past Activity

SacWAM Domain





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.

GNU General Public License


The WEAP software is licensed by the Stockholm Environment Institute. Downloads, pricing, and online license applications can be found at Employees of California public agencies can obtain a WEAP license free of charge. To do so, apply for the license on the WEAP web page and indicate your employer’s name and that it is a California public agency. Any user can download an evaluation version of the software that has full functionality except for the ability to save new results. The evaluation version can be used to explore the SacWAM model and view results.

XA Solver

SacWAM requires the XA linear programming solver to run. Information on the XA Solver is available at