The high valleys were eroded into rocky canyons for ten miles north of Cloverdale and for five miles east of Cloverdale.
After establishing a connection to Clear Lake, the Russian River was beheaded from Clear Lake by a slide (at Cow Mountain, east of Ukiah). Juan Rodríguez Cabrillo and his expedition may have made it as far north as the Russian River in November 1542, before storms forced them to turn back south towards Monterey.
This vulnerability was demonstrated in March 1982 when a tank car of formaldehyde was vandalized in Ukiah.
Emergency response personnel were able to clean up approximately half of the 21,000 US gallons (79,000 l) spilled, and a fortuitous combination of Lake Mendocino reservoir inventory and late winter storms helped flush the remainder through the river and into the ocean before local water storage inventories were exhausted.
James Weeks, a member of Young's 1833 fur brigade wrote: "They broke up all the beaver lodges on the lake, I believe the finest and largest beaver we caught there, we arrived at the Russian River and pitched camp sent out, trappers found signs set traps caught beavers..." The Russian River State Marine Reserve and Russian River State Marine Conservation Area protect the Russian River Estuary.
Like underwater parks, these marine protected areas help conserve ocean and freshwater wildlife and marine ecosystems.
The Russian River is the largest river in the Central California Coast Steelhead trout (Oncorhynchus mykiss) Distinct population segment.
Natural waterfalls and the two major dams, Warm Springs (built in 1982) and Coyote (built in 1959), have isolated anadromous steelhead from its non-oceangoing rainbow trout form above the impassable barriers.
The earliest European name for the river, Slavyanka, appears on a Russian-American Company chart dated 1817.
The river takes its current name from Russian Ivan Kuskov of the Russian-American Company, who explored the river in the early 19th century and established the Fort Ross colony 10 mi (16 km) northwest of its mouth.
The Russian River springs from the Laughlin Range about 5 mi (8 km) east of Willits in Mendocino County.
It flows generally southward to Redwood Valley, then past Calpella, where it is bordered by U. Route 101, to join the East Fork Russian River just below Lake Mendocino. Route 101, it descends into the Alexander Valley, where it is joined by Big Sulphur Creek.
The mouth is about 60 mi (100 km) north of the San Francisco Bay's Golden Gate bridge.