Willits is located about 150 miles north of San Francisco on Highway 101. The town is nestled in Little Lake Valley (about 6,000 acres, mostly in grazing use) and surrounded by wooded hills and mountains. Five salmon-spawning streams drain from the coastal mountains and feed into Outlet Creek at the northern end of the Valley, which in turn feeds into the southern end of the Eel River - the longest remaining spawning run in California. From Willits, it's only 30 miles west to the Mendocino coast on Highway 20.
The incorporated City of Willits has a population of just under 5,000, while the whole 95490 zip code - which comprises most of the watershed - has a population of 13,000. Of the 8,000 residents in the unincorporated County area, about 3,000 live in the hilly Brooktrails subdivision northwest of town, with its own community service district. Others are scattered throughout the valley and hills, relying on wells and septic systems and some are off-grid.