Ophir Water Treatment Plant — Auburn, California

Placer County is building for the water demand it can already see coming. The $210 million Ophir Water Treatment Plant, planned on a 22-acre site along Ophir Road in Auburn, will give the Placer County Water Agency a new source of treated water in a fast-growing stretch of the Sierra foothills. Groundbreaking is targeted for fall 2026, with operations set for 2030.

Project Scope

Phase one delivers 10 million gallons per day of treatment capacity, enough for roughly 10,000 families, on a site master-planned to scale up to 30 MGD as the county grows. Placer County Water Agency selected Carollo Engineers to run construction management and to handle SCADA programming, the supervisory control software that automates the plant’s pumps, valves and monitoring. A new surface-water plant of this size is a multi-year sequence of civil work, process mechanical, and instrumentation, and the SCADA layer is what ties thousands of field devices into a system operators can run from a single control room.

Why It Matters

Much of Placer County still leans on a limited set of treatment facilities that strain during peak summer months, when demand and wildfire risk both spike. Adding a scalable plant gives the agency headroom instead of forcing emergency responses when a hot, dry stretch pushes the system to its limit. Building in modular capacity, 10 MGD now with room for 30, is the pragmatic way to fund water infrastructure: size it for today’s ratepayers, but leave the footprint and hydraulics ready for the next decade of growth.

Project Team & Details