Westmorland, California, USA

Wastewater Treatment Plant Expansion for the City of Westmorland, California

Status: Completed


The city of Westmorland owns and operates a wastewater treatment plant constructed in 1985 with an average daily flow capacity of 375,000 gallons per day (gpd). The plant provides secondary treatment by means of two aeration basins followed by four stabilization ponds. The treated effluent is discharged into an agricultural drain that flows into the New
River, a tributary of the Salton Sea.

In recent years, the plant had experienced problems with seepage of untreated wastewater from the existing ponds and the influent pump had deteriorated with age to the point that it was no longer reliable. In addition, the treatment system lacked the disinfection facilities required under its operating permit.


To correct these deficiencies and bring the plant into compliance with state water quality and health regulations, the city undertook a project to upgrade and expand the plant. Major components of the project included:

  • Expanding treatment capacity from 375,000 to 500,000 gpd.
  • Replacing the existing treatment ponds with an extended aeration
    oxidation ditch.
  • Incorporating secondary clarification, effluent disinfection and
    sludge handling processes into the treatment system.


Improvements in the wastewater treatment system corrected deficiencies in the system thereby bringing the plant into compliance with state regulations, as well as reducing the likelihood of contamination and disease transmission from untreated wastewater seepage and spills. System expansion will also ensure sufficient treatment capacity for the
next 15 years.

Project Financing

Total Project Cost US 4.41M
NADBank Funding US 1.78M - NADBank Grant: BEIF
Other Funding Partners Border Environment Infrastructure Fund
Institutional Development Cooperation Program (IDP)
United States Department of Agriculture Rural Development (USDA - RD)
State of California Water Resources Control Board