Napa County contains massive Lake Berryessa, the seventh-largest reservoir in California, and receives what in the water world amounts to a thimbleful from it.

Almost all of Lake Berryessa’s water goes to neighboring Solano County. Only a small portion goes to Napa County and none to Napa Valley cities or its world-famous wine country vineyards.

Amid a drought, it’s like being parched next to an oasis. This oasis is mostly off-limits because Napa County during the 1940s and 1950s didn't help fund — and in fact opposed — the creation of a federal reservoir that submerged a townsite and farmland.
Still, there’s this following goal in Napa County’s 2022 legislative platform — obtain additional water from Lake Berryessa.

“It’s a bit of a long shot,” acknowledged Richard Thomasser of the Napa County Flood Control and Water Conservation District.

He stressed the idea isn’t to infringe on Solano County’s water allocations from the reservoir. But maybe Napa County could get a slug of Berryessa water during droughts or make better use of the small amount it has.

“I don’t think anyone thinks Berryessa is a large source of water for Napa,” Thomasser said. “But I think we’re interested in just being flexible with our resources.”

Every drop counts, he said.

Napa County cities have their own local reservoirs that they use for water. But the biggest — Lake Hennessey — holds a mere 2% of the water that’s in a full Lake Berryessa.

Lake Berryessa is 23 miles long and three miles wide, with 165 miles of winding shoreline. It can hold 1.6 million acre-feet of water when full behind Monticello Dam, a 300-foot-tall concrete plug across Putah Creek at Devil’s Gate.

The reservoir is presently only 66% full amid the three-year drought. Still, 66% for Berryessa is more than a million acre-feet.
Solano County farms, cities and other interests have entitlements for 181,000 acre-feet annually. That’s enough water as calculated by the Water Education Foundation to serve 181,000 to 362,000 households annually.

Napa County, in contrast, has a small straw in Lake Berryessa. The county’s contract with the U.S. Bureau of Reclamation allows for up to 1,500 acre-feet of water annually.

In addition, the county contractually can use this water only for communities in the Putah Creek watershed, such as remote, tiny Berryessa Highlands and Spanish Flat. None can come to Napa Valley.

That’s the situation Napa County faces if it wants to eke out more Berryessa water.

Getting more water

One idea is for Napa County to buy Lake Berryessa water from Solano County to take the edge off of droughts.

The two counties considered such a move during the 2014 drought. Solano County was willing to sell Napa County up to 10,000 acre-feet of emergency Berryessa water from its own allocations.

That drought ended before the water deal came to fruition. The idea is being revived amid the current drought but has yet to move forward.

“So far, nobody in the Solano users has stepped forward to say, ‘We have some water we are willing to sell,’ so the discussion hasn’t gone any further,” said Roland Sanford, general manager of the Solano County Water Agency.

Another possibility is to move some of Napa County’s own 1,500-acre-foot allocation from Lake Berryessa to Napa Valley. That would mean getting that federal restriction lifted that requires the water to be used only in the Berryessa area.

Even if planned resort renovations come to fruition, the county might use only about half of its allocation at the lake.

“There’s a fair amount of water we’re leaving on the table,” Thomasser said. “But we’d have to look at expanding our service area.”

Napa County could soon have that chance. The county’s water contract with the U.S. Bureau of Reclamation is up for renewal in 2024 and the county could seek changes for the next contract.

Continue reading the full article from the Napa Valley Register here.