An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Water Infrastructure Finance and Innovation Act (WIFIA)

San Mateo Wastewater Treatment Plant Upgrade and Expansion Project

San Mateo, California
Borrower: City of San Mateo (City) and Estero Improvement District (District)
Location: San Mateo and Foster City, California
WIFIA Loan Amounts: $210.4 million (City), $66.9 million (District)
Total WIFIA Project Costs: $566 million
Population Served by Project: 143,000 people

Number of Jobs Created: 1,810 jobs

Project Description

Together, the city of San Mateo and the Estero Municipal Improvement District will rehabilitate their aging wastewater treatment plant to provide capacity for wet weather flows, produce higher quality effluent, enhance system reliability, and support sustainability goals. The project is designed to meet current and future regulatory requirements and provide future water reuse opportunities. The upgrade will include new treatment facilities to comply with National Pollutant Discharge Elimination System (NPDES) permit limits. It will also increase the system’s capacity to manage wastewater during storms and help eliminate sanitary sewer overflows in the San Francisco Bay.

Project Benefits

  • Repairs and rehabilitates the aging wastewater treatment plant.
  • Reduces ammonia and nitrogen effluent concentrations as required under the NPDES permit.
  • Reduces sewer overflows and unauthorized discharges in the San Francisco Bay.
  • Saves the city of San Mateo an estimated $43.5 million and the Estero Municipal Improvement District an estimated $12 million from financing with a WIFIA loan.
You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.

Water Infrastructure Finance and Innovation Act (WIFIA)