State regulators Friday added to the growing list of water rights holders who have been told to stop drawing from rivers and streams as the drought shrivels summer flows.
The State Water Resources Control Board is curtailing 16 water rights held by senior diverters on the upper San Joaquin River and the Merced River, as well as some of San Francisco's rights on the Tuolumne River.
The action will have little practical effect on San Francisco because the city can continue to draw from its main water source, Hetch Hetchy Reservoir, which is 95% full, thanks in part to spring storms.
Steve Ritchie, an assistant general manager of the San Francisco Public Utilities Commission, said the city will be "in good shape" even if the state orders an end to all of San Francisco's diversions in the Tuolumne watershed this summer.
On the Merced River, the board action affects rights dating to 1858. On the upper San Joaquin, it hits all rights except riparian, which allow landowners to divert water flowing by their property.
The affected diverters include several irrigation districts, a ranch, a dairy and
Friday's order comes after the board on June 12 directed more than 100 growers and irrigation districts with rights dating to 1903 to stop taking supplies from Central Valley rivers and streams. The San Francisco rights in Friday's notice should have been included in the earlier order, the board said, but were omitted because of inaccuracies in the state database.
Thousands of junior rights holders were ordered to halt diversions last summer and again this year. But this month's actions marked the first time since the 1976-77 drought that the state board has moved to stop withdrawals by senior diverters with rights more than a century old.
Several irrigation districts and the San Joaquin Tributaries Authority are suing the board, claiming the state has no authority over pre-1914 water rights.
San Francisco is a member of the authority, but Ritchie said that if the city decides to challenge the state order, it would consider filing a separate lawsuit.
"We're considering all our options," he said. "We don't think the state board has the authority to do this."
The board is expected to continue issuing more curtailments as river and stream flows decline this summer. Conditions "certainly aren't getting any better," said board spokesman Tim Moran.