San Bernardino Valley Municipal Water District, Upper Santa Ana River Integrated Model

San Bernardino and Riverside Counties, CA

The Santa Ana River (SAR) watershed is the largest in Southern California and home to some of the fastest population growth in the country. The communities in the upper watershed from the Seven Oaks Dam upstream, to the Prado Dam downstream, rely on groundwater for much of their water supply. Currently, the SAR passes over four groundwater basins in the area, multiple water districts, and nine separate groundwater and watershed models—making it difficult to identify current conditions and potential impacts that planned projects could have on groundwater and the watershed as a whole. Complicating matters is that the basins are hydrologically connected to several other basins in the area.

San Bernardino Valley Municipal Water District formed a joint effort with Riverside Public Utilities, Western Municipal Water District, Inland Empire Utilities Agency, Orange County Water District, the U.S. Geological Survey, the California Department of Fish and Wildlife, and the U.S. Fish and Wildlife Service. This effort will develop a combined model for the SAR that will help determine baseline hydrological conditions and the potential effects of proposed projects on the SAR and groundwater levels for the entire upper watershed.

The goals of the project are:

  • Develop a tool to help riparian habitat and endangered species protection efforts
  • Identify any perennial rising or shallow groundwater locations and how these areas might be affected by current and proposed projects
  • Enhance the Habitat Conservation Plan (HCP) baseline condition to include both streamflow and groundwater levels 
  • Develop a better understanding of how current projects (i.e. groundwater operations in the various basins, etc.) impact flow in the SAR and groundwater levels
  • Predict how proposed projects and mitigation measures addressed in the HCP will impact flow in the SAR and groundwater levels in the area

Currently, our team is using the existing groundwater and surface water models to develop an integrated watershed model. The resulting Upper SAR Integrated Model (or Integrated SAR Model), will be used to determine what factors may contribute to declines SAR flows, and assess cumulative effects on SAR surface flows and groundwater levels from approved, outstanding, and proposed projects, including Upper SAR Habitat Conservation Plan Covered Activities. 

Details at a Glance:
  • Client: San Bernardino Valley Municipal Water District
  • Date: Ongoing