Sonoma County Water Agency/Sonoma Valley County Sanitation District

LWA has assisted the Sonoma Valley County Sanitation District (District) with NPDES and recycled water permit activities since 2000.

The Sonoma Valley Wastewater Treatment Plant discharges treated effluent to a slough during high inflow events, produces disinfected tertiary recycled water for agricultural irrigation, and beneficially reuses effluent for habitat management in cooperation with the California Department of Fish and Wildlife.

LWA supported Regional San during the 2002, 2008, and 2014 NPDES permit reissuance activities. The work involved negotiating operational requirements, compiling effluent and receiving water quality data, determining Reasonable Potential, checking effluent limit calculations, assessing compliance feasibilty, and designing an appropriate compliance monitoring program. During the NPDES permit terms, LWA developed site-specific metals translators, implemented studies to determine effluent copper and cyanide impacts, provided updates to Regional San on changes to regulatory policies, and participated in the San Francisco Bay Nutrient Strategy Stakeholder Advisory Group.

LWA prepared Regional San’s current recycled water program and obtained permit coverage under General Water Reuse Order No. R2-1996-011. To receive program approval, LWA updated the CCR Title 22 Engineering Report (when Regional San upgraded from “disinfected secondary-23 recycled water” to “disinfected tertiary recycled water”), verified minimum modal contact time, prepared materials (i.e., permits, self-monitoring reports, site inspection reports, user guidelines), and developed a cross-connection control program.