Western Municipal Water District (Western) developed a Groundwater Sustainability Plan (GSP) for the Upper Santa Ana Valley Riverside-Arlington Subbasin (Basin Number 8-002.03), also referred to as the Riverside-Arlington Subbasin. The Riverside-Arlington Subbasin is partially adjudicated under the Western-San Bernardino Watermaster, per the 1969 Western Judgement. The Watermaster manages groundwater under the adjudicated portion of the basin. Western elected to serve as the groundwater sustainability agency (GSA) for all portions of the Subbasin underlying (or within) Western’s jurisdictional boundaries, which is also the portion of the basin that is unadjudicated and designated as a low priority basin by the California Department of Water Resources (DWR).
Activities associated with with planning, development, and preparation of a Groundwater Sustainability Plan (GSP) for the Upper Santa Ana Valley Riverside-Arlington Subbasin (Basin Number 8-002.03) include, but are not limited to, developing a data management framework, stakeholder engagement, and developing a planning document that builds upon past studies and data collected to establish current and historic groundwater conditions, develop a water budget that aligns with sustainable management and yield of the basin, and describes potential projects and management actions that will help the basin achieve sustainability.