Arvada officials outline $330 million plan to replace aging Arvada water treatment capacity, warn of risks if delayed

Arvada staff told the City Council on Monday night that the city needs to replace the Arvada Water Treatment Plant to keep the system safe, resilient and able to meet summer peak demand, and outlined a phased construction and financing plan with a current Class IV cost estimate of about $330,000,000.

City engineers said the Arvada plant, which is permitted at 16 million gallons per day (MGD) but does not consistently reach that level in practice, is “not designed to current standards” and that the system relies on two treatment plants — the Ralston Water Treatment Plant (36 MGD permitted) and the Arvada plant — to meet peak-day demand. Mary Stahl, utilities engineering manager, said the city’s utility-level goals are to provide water that is “safe, good, and enough.”

The master plan and follow-up studies concluded the Arvada facility should be replaced rather than repaired. Bethany Kolb, a utilities engineer, told the council that based on staff analysis and consultant input “the Arvada treatment plant will only last another 5 years before failing,” and that waiting carries risks including extended outdoor watering restrictions and possible inability to take Ralston offline for repairs without compromising service.

Why this matters: The city’s peak summer maximum day in 2024 was about 40 MGD, which exceeds Ralston’s 36 MGD; staff said two plants are required to meet peak demand and resilience goals. The Arvada facility’s constrained site, located at the toe of a dam, also limits options to repair or expand the existing footprint. Staff estimated that replacing the Arvada plant at its current site would be costly and risky — a preliminary optimistic cost…