More Russian River diversions halted as supplies in upper basin grow increasingly scarce
State regulators expanded their drought-era halt of Russian River diversions Tuesday, ordering more than 300 additional grape growers, ranchers and other landowners to cease taking water from the basin as authorities seek to conserve rapidly diminishing reservoir supplies and meager stream flows.
The curtailments, which take effect Wednesday, cover a range of Sonoma County water right holders in southern portion of the watershed, known as the lower river, though many are located in the Dry Creek Valley and other tributary areas around the middle reaches.
The new orders come amid signs of inadequate compliance among more than 1,500 water rights holder in the upper river who fell under a wider curtailment last week. Supplies released from Lake Mendocino continue to all but vanish from segments of the river downstream, according to stream gauge data and observations from regulators.
Dam managers outside of Ukiah have had to maintain higher reservoir releases over the past two weeks than at any other time this summer to ensure a minimum flow in the river at Healdsburg, even though diverters have been under orders since Aug. 3 to take only enough for basic human health and safety needs.
Jule Rizzardo, permitting and enforcement branch chief for the Division of Water Rights at the State Water Resources Control Board, cautioned that some curtailed diverters may still be receiving their notifications and may not have had time to adjust their operations.
But Sam Boland-Brien, supervising engineer for permitting and enforcement, said the reservoir release and stream gauge data reflect unexpected losses that imply continued diversions beyond what should be occurring both legally and given the months spent communicating broadly with stakeholders about the severity of the drought.
“A couple of months ago, it was very clear how dire the issues were that we were trying to address,” Boland-Brien said.
Lake Mendocino, the smaller of the region’s two major reservoirs, has dropped to its second-lowest level ever and held just more than 23,000 acre feet of water at midnight Monday, putting it about two weeks away from reaching the minimum threshold of 20,000 acre feet that had been set for Oct. 1. (An acre foot is a unit of measure equal to about 326,000 gallons, or enough to flood most of a football field one foot deep.)
Lake Mendocino sustains flow in the upper Russian River and supplies water to about 60,000 people in Mendocino and northern Sonoma counties.
Current storage is about 30% of what water managers hope to have in Lake Mendocino at this time of year, as they approach the final months of dry weather and hope that rain arrives in fall.
The reservoir pool is still augmented by a small amount of inflow diverted through Potter Valley from the Eel River and Lake Pillsbury, which is also severely diminished by drought. But those diversions are just about enough to offset evaporation, said Don Seymour, principal engineer with Sonoma Water, the region’s primary drinking water supplier.
Water managers are “extremely” concerned about having sufficient water going into what could be another dry winter, said Seymour.
“At the rate we’re seeing right now, the reservoir could be, by Oct. 1, below 15- or 14,000 acre feet, which is terrifying to me,” Seymour said.
In a dry winter during the last big drought, between Oct. 1, 2013 and February 2014, Lake Mendocino dropped by 15,000 acre feet. A repeat of that would leave “no water other than whatever would try to pass through the reservoir from some small diversions through the Potter Valley Project,” he said.
The river would run so low that it probably would become discontinuous in spots, potentially preventing domestic users from withdrawing enough even for basic health and safety needs, Seymour said.
It likely would prompt declaration of a state of emergency and intervention by the state Department of Drinking Water and the Office of Emergency Services, he said. “Basically, you’re in a situation similar to a wildfire,” he said.
Seymour said it was possible some losses from the upper Russian River were the delayed result of heavy groundwater withdrawals that drew water from the river into surrounding aquifers, combined with ongoing diversions.
Rizzardo said more would be known when her division had “boots on the ground” for compliance inspections, expected to begin soon.
She said anyone who observes or suspects illegal diversions also is encouraged to report them to the State Water Board.
Violations of the curtailment orders can draw a fine of up to $1,000 a day or $2,500 for each acre foot diverted.
That includes refusal to file a required response confirming cessation of curtailed diversions and identifying alternate water sources in use, Rizzardo said. The responses are due within seven calendar says of the curtailment order, though technically it’s enforced based on the date the mailed notice is received, she said.
Curtailed water right holders also may apply for exemptions to take water for basic human health and safety needs, an allowance generally set at 55 gallons per person per day.
Boland-Brien said about 50% of those issued curtailment orders Aug. 2 had responded by Tuesday.
The new orders were issued to a less than half of about 800 lower Russian River water right holders eligible to have their diversions curtailed. The decisions were based on complex analyses of hydrologic modeling and climate data, as well as water use reporting in 13 sub-basins and seniority among water rights holders.
Boland-Brien said those not yet under orders could still be affected in the future, depending on conditions, but noted that withdrawals from the river typically slow in September.
The Sweetwater Springs Water District, which supplies about 8,000 customers from Rio Nido, Guerneville, Monte Rio and beyond was not affected by this round of curtailments.
You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.
