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.
California needs one and a half times the maximum volume of water in Lake Mead, the largest US reservoir, to end its drought.
A new study by the National Oceanic and Atmospheric Administration says natural occurring climate patterns –not climate change- are the primary drivers of California’s drought.
A Republican- backed drought relief bill for California is headed to the floor of the US House of Representatives for a vote Tuesday. The legislation ignited an hour of debate Monday.
Pollution from abandoned mines in the Sierra Nevada could threaten California's primary water supply.
The City of Roseville hopes to break the 20-percent water conservation mark for the year. The city posted its best conservation mark for the year in November.