Napa City Hall. Howard Yune, Register

Napa City Council passes water management plan update and water shortage plan

Jan 5, 2022 at 11:50am

Edward Booth

Despite the 2021 drought, which resulted in mid-year restrictions on outdoor irrigation and trucked water, the city of Napa is projecting it will likely meet water demands through 2045 with only minor restrictions in the case of dry years or multiple dry years.

That is, of course, unless the city faces historically unprecedented dry conditions, in which case greater restrictions could be put in place to limit the demand on the city’s water resources.

That’s according to the city’s 2020 Urban Water Management Plan, a long-term evaluation of the city’s water supply and demand through 2045, approved by the Napa City Council late last month. The council also approved a Water Shortage Contingency Plan and an amendment that shows the city’s reduced reliance on water supplies from the Sacramento-San Joaquin Delta over time.

The management plan is a state-mandated document; California requires water suppliers that supply water to over 3,000 customers to create such a plan and update it every five years. The 255-page document examines a wide range of projections for water demand, conservation, water supply, use of recycled water, and drought contingencies.

Patrick Costello, a city water analyst, told the council the city’s water demand in 2020 was 14,092 acre-feet or over 4 billion gallons — one acre-foot is roughly 325,000 gallons — with 47% of that supply going to single-family homes, 13% going to multi-family and 20% going to commercial and institutional uses. The remaining 20% went to a mix of city water use, acre-feet bought by St. Helena, landscape, and agricultural uses.

City water demand is expected to increase to 15,555 acre-feet by 2045, along with a projected 20,000 increase in the population served by the city, Costello said. The overall trend is more efficient water use over time despite the projected increase in population, he added.

“I know when I came here in 2005, our assumptions projected our demands today would be over 30 million gallons per day, and right now we’re at 18 to 20 million gallons per day,” said Joy Eldredge, the city’s deputy utilities director.

On top of greater efficiency, the city has been using a higher quantity of NapaSan recycled water over time, which could mitigate the need for water restrictions. Costello said in 2020, the city used 568 acre-feet of recycled water that would’ve otherwise been city drinking water, up from 437-acre feet in 2015 and 288-acre feet in 2010. The city projects recycled water use will level out at about 1,095-acre feet per year by 2030, Costello said.

As part of the management plan, the city is required to project how its projected water supplies will do in a normal year, a single dry year, and multiple dry years.  The city’s water supplies come mostly from Lake Hennessey and the State Water Project, and a small portion of the water — about 700-acre feet — is from the Milliken Reservoir.

In a normal year, Costello said, the city has about 31,000-acre feet of water overall — an estimate that doesn’t include NapaSan recycled water. That projected water supply is cut down to about 17,000-acre feet in a single dry year, and about 15,000 acre-feet in multiple dry years.

Continue reading the article from the Napa Valley Register here