• San Francisco and a group of Central Valley irrigation districts are suing California for implementing drought restrictions that have blocked senior water holders from diverting water from rivers and creeks.
• The lawsuit, filed in Fresno County Superior Court, argues that the California State Water Resources Control Board doesn't have the legal authority to require water holders to stop diverting water, even during a drought.
• The state board orders come as California grapples with a record-breaking drought that has depleted reservoir levels and threatened water supplies.

San Francisco and a group of Central Valley irrigation districts are suing the state of California for implementing drought restrictions that have blocked thousands of landowners and agricultural suppliers from removing water from rivers and creeks.

The city and a coalition of water agencies filed the lawsuit in Fresno County Superior Court. The suit argues that the California State Water Resources Control Board doesn't have the legal authority to require senior water holders, including farmers and agricultural suppliers, to cease diverting water, even during a drought.

The fight comes as California grapples with a record-breaking drought that has depleted reservoir levels and threatened water supplies. The U.S. Drought Monitor shows that more than 93% of the state is currently experiencing Severe to Exceptional Drought, and conditions are growing worse as the climate changes.

Similar fights could play out across the southwestern U.S. in coming years as water shortages mount. For instance, earlier this year, the U.S. Bureau of Reclamation announced plans to ration water from the Colorado River to Arizona and Nevada, paving the way for a battle with farmers and municipalities in those states.

In August, the state board ordered roughly 4,500 water right holders to halt water draws from rivers and canals that feed into the Sacramento-San Joaquin River Delta, which is experiencing low water levels from the drought. The order was one of the most aggressive curtailments ever under the state's water rights system.

State officials had argued the orders would help preserve stored water to protect drinking water supplies, prevent salinity intrusion and protect the environment. The Delta watershed provides two thirds of the state with drinking water.

"This decision is not about prioritizing one group over the other, but about preserving the watershed for all, implementing our water rights priority system and ensuring we manage through this drought," E. Joaquin Esquivel, chair of the state board, said in an August statement.

The suit argues that the state board has no authority to curtail water rights secured before 1914, the year when the state board started regulating water draws. The suit claims that only the courts have jurisdiction over the water rights of holders before 1914. It also argues that the state board hasn't adequately measured water use and thus can't properly ration it.

The San Joaquin Tributaries Authority is a coalition of water agencies whose suppliers include the Modesto Irrigation District, Turlock Irrigation District, Oakdale Irrigation District, Merced Irrigation District, South San Joaquin Irrigation District and San Francisco.

A spokesperson for the state board declined to comment on the litigation.

Doug Obegi, a senior attorney at the Natural Resources Defense Council, said in a blog post on Wednesday that, contrary to the suit's claims, San Francisco and other pre-1914 water rights holders are in fact subject to the state board's authority.

The recent suit "is just the latest example of the privileged few with senior water rights wrongly claiming they are above the law," Obegi said.