The Ukiah Daily Journal reports that the county's Board of Supervisors on Tuesday voted unanimously to make the declaration, citing an "imminent threat of disaster" from drought conditions.
The state Department of Water Resources said Mendocino is the first to request state drought assistance.
Officials hope the declaration will result in state funds and assistance in developing a drought plan.
Gov. Jerry Brown has convened a task force to help decide if a statewide drought emergency is warranted.
State water managers say they will be able to deliver just 5 percent of the water sought by municipal agencies and nearly a million acres of farmland.
The California Legislature has sent a $1 billion emergency drought aid package to Gov. Jerry Brown. But one of the two measures in the package drew opposition from Republicans.
Californians show deep concern that the state’s drought may be a long-term problem in a new survey by the Public Policy Institute of California.
California Gov. Jerry Brown’s $1 billion drought response legislation is on its way to the Assembly after winning Senate approval Wednesday afternoon.
A little noticed provision of the proposed $1.1 billion drought relief bill could help poor communities.
The drought is creating a new way for cities to make money, including selling treated wastewater for farm irrigation.