Integrated Santa Ana River Model

Customer Profile

The Upper Santa Ana River watershed encompasses four groundwater basins, nine separate groundwater and watershed models that cover more than a thousand square miles and serve more than four million people.

The stakeholders include:

San Bernardino Valley Municipal Water District

Western Municipal Water District 

Inland Empire Utilities Agency 

Orange County Water District 

City of Riverside Public Utilities 

United States Geological Survey 

United States Fish and Wildlife Survey 

California Department of Fish and Wildlife 

Challenge

The San Bernardino Valley Municipal Water District (SBVMWD) was seeking ways to increase recharge to regional water supply aquifers and to improve recycled water reuse in the Upper Santa Ana River (SAR) watershed. Additional recharge and water reuse are keys to improving water supply reliability of the groundwater supply in the region. And therein lay the challenge.designated as very low priority and thus was not required to develop a GSP. However, being committed to good basin management, the WMWD didn’t take advantage of this loophole, but instead decided to continue meeting with stakeholders to establish a 14-month, 5-step plan to develop a GSP.

The Upper Santa Ana watershed encompasses four groundwater basins, multiple water districts, and nine separate groundwater and watershed models. To complicate matters further, the four basins are hydrologically connected to one another. That means water management actions upstream have the potential to affect downstream water uses. To permit new recharge and reuse projects, the agencies needed to develop a regional hydrologic model to assess the effects of the projects.

Geoscience Solution

The stakeholder group of water districts and related agencies identified five goals for the project:

1. Develop a modeling tool to simulate both streamflows and groundwater levels to support protection efforts for riparian habitat and endangered species
2. Identify perennial rising or shallow groundwater locations and assess how current and proposed projects would affect the riparian habitat
3. Develop a better understanding of how current projects in the various basins, such as groundwater operations, impact flow in groundwater levels and the SAR
4. Predict how proposed projects and mitigation measures addressed in the Habitat Conservation Plan would impact flow in the SAR and groundwater levels in the area

To help with both the technical challenge and the permitting challenge, SBVMWD and its partners needed someone with local expertise and knowledge of the hydrology and hydrogeology of the area, technical expertise in modeling ground and surface water, and a proven track record of working with stakeholder groups in a collaborative technical advisory process.

Customer Results

Geoscience integrated the four regional groundwater models and the watershed to cover the area under consideration, and then used the results to support a draft Habitat Conservation Plan and a draft Environmental Impact Report. Since the initial engagement, Geoscience has continued to develop the model and to help the various agencies on other projects.

The Integrated Santa Ana River Model provides an important management tool, simulating surface water, groundwater, and the important interactions between the two in the Upper Santa Ana River watershed, enabling the assessment of a wide range of groundwater basin management strategies.