Western Municipal Water District, Riverside- Arlington Basin Groundwater Sustainability Plan

Riverside, CA

Western Municipal Water District was formed in 1954 to bring supplemental water (the Colorado River and State Water Project) to western Riverside County, and serves more than 23,000 retail water customers and 130 irrigation customers. To meet demand, the District also uses supplemental groundwater from the Arlington Subbasin. 

Geoscience is leading efforts to develop a Groundwater Sustainability Plan (GSP), building upon previous work in the basin we have completed. Our team is working in conjunction with the District to complete all studies and investigations necessary to complete a compliant GSP. Specific activities include supporting grant administration and stakeholder engagement, assessing and developing a data management system, reviewing monitoring networks and providing recommendations, and defining the plan area. 

Prior to this project, Geoscience began developing the Santa Ana River Integrated model that will combine nine ground and surface water models into one integrated model for the upper watershed. Because the integrated model will cover the Riverside-Arlington Basin, we are using the model to either complete, or provide guidance for several studies required to complete the GSP. Specifically, we will use the model to assess the basin’s current and historical conditions, provide a detailed basin characterization, develop the water budget, assess sustainable management criteria, and determine the effectiveness of proposed projects and management actions. 

Scope of Work Items:

  • Grant Administration and Support
  • GSP Components
  • Plan Area and Basin Setting
  • Hydrogeologic Conceptual Model, Groundwater Flow Modeling, and Water Budget
  • Management Goals and Objectives
  • Monitoring Network
  • Environmental Compliance and Permitting
  • Cost of Schedule and Implementation
  • Stakeholder Outreach
  • Monitoring Well Planning, Evaluation, Design and Construction, and Monitoring Plan

As each GSP component and study are completed, we are developing Technical Memoranda for the District to review and comment upon. Each approved and finalized Technical Memoranda will become a section of the final GSP. Our team will compile the final GSP document for public review and comment prior to final District and State Approval.

Details at a Glance:
  • Client: Western Municipal Water District
  • Date: Ongoing