Project Description

The Western Municipal Water District (WMWD) was formed to bring supplemental water to growing western Riverside County. The Arlington Desalter is a groundwater treatment facility owned and operated by WMWD, which currently consist of five (5) production wells and a reverse osmosis treatment facility. The Arlington Desalter overlies and pumps groundwater from the Arlington Basin near Riverside, California. WMWD is contemplating expanding the Arlington Desalter from 8 million gallons per day (mgd) to 11 mgd, but is concerned that expansion of the Arlington Desalter will cause excessive drawdown of groundwater levels leading to reduced yields at the existing desalter wells and subsequently reduced production at the desalter. WMWD is also concerned about drawdown impacts on other producers.

WEI was retained by WMWD to perform a feasibility study for the expansion of the Arlington Desalter. The questions to be answered by the investigation were:

  • Can future groundwater production be sustained with the Arlington Desalter expanded to 11 mgd?
  • What are the impacts in the Arlington Basin and adjacent groundwater basins?

The investigative work plan includes: the collection and review of all relevant historical studies and data, the establishment of a comprehensive groundwater-level monitoring program (which included the installation of water-level recording transducers at about 18 wells across the basin and the conducting of controlled pumping tests), the construction of a basin-wide hydrogeologic model in the project GIS, and the development and use of a groundwater flow model. The model results were used to answer the above questions, and supply information for the pre-design engineering of the facility expansion and CEQA reporting requirements.

  • Western Municipal Water District