(PD) - The Sonoma County Water Agency has cut flows in the Russian River by about 30 percent since Tuesday in an effort to preserve dwindling supplies in Lake Mendocino.

State regulators granted the agency permission to cut flows late Tuesday and the agency promptly dropped from releasing about 100 cubic feet per second at the dam, or about 748 gallons, to 90. On Thursday, the agency dropped that number down to 70 cfs, and could go lower this week or next.

“We don’t like to take it down really quickly,” agency Assistant General Manager Pam Jeane said.

That means flows in the river downstream could fall to below 55 cfs at its lowest point by early next week. During a normal rain year, the agency would need to keep that flow at around 150 cfs at the lowest point; even on a moderately dry year, it can’t cut the flow lower than 75 cfs.

But as of Thursday morning, the reservoir had just 26,280 acre feet of water in reserve, about 8.6 billion gallons, or just 38.7 percent of its capacity.

The region is coming out of a record dry year, with just 7.67 inches of rain falling in the upper reaches of the Russian River, as measured at Ukiah; the area usually sees at least 34 inches of rain.

With no major rain predicted for the early weeks of January, the agency is preparing to face a second straight dry year. Without cutting the flows dramatically now, there is a risk of the reservoir effectively running dry next summer should the drought continue, the agency said.

The State Water Resources Control Board agreed, saying cutting the flow now will affect downstream farmers, cities, and wildlife less than if the reservoir were allowed to dry out next summer.

“Any effects associated with such flow reductions would not be unreasonable, considering the potential catastrophic impacts on fish, wildlife and other instream beneficial uses” should the reservoir fall too low to pump any water into the system during the summer, the agency wrote in its order approving the slashed flows.