PASO ROBLES — The Paso Robles Tertiary Treatment Facilities project was the winner of the Global Water Awards 2020 Wastewater Project of the Year. This is an annual awards program administered by an international publication called Global Water Intelligence.

The project was nominated after it won California’s Engineering and Research Achievement Award. This project was among a shortlist of wastewater projects from Egypt, China, and India.

Says Matt Thompson, Wastewater Manager for the City of Paso Robles, “Our project was primarily about switching to ultraviolet light disinfection and preparing for future water recycling, yet some other project’s features we were recognized most for are 1) repurposing old clarifiers to flow equalization basins, 2) the water flows through the new tertiary treatment process entirely by gravity (whereas most facilities have to pump the water), and 3) we added a nutrient harvesting system to turn our former struvite problem into commercial-grade fertilizer.”

The City has a master plan to produce tertiary-quality recycled water and distribute it to east Paso Robles, where it may be safely used for irrigation of City parks, golf courses, and vineyards. This will reduce the need to pump groundwater from the Paso Robles Groundwater Basin and further improve the City’s water supply sustainability.


In 2019, the City completed construction and began operating the first part of this recycled water system, which is filtration and ultraviolet light disinfection at the Plant. These new tertiary treatment facilities produce very high-quality recycled water. The project also included flow equalization basins, a recycled water storage pond and pump station, a nutrient harvesting system, and a new maintenance shop.

The City is presently designing a major distribution system to deliver recycled water to east Paso Robles.