The Headwaters Forest Reserve is a group of old growth coast redwood (Sequoia sempervirens) groves, comprising about 7,472 acres (30.24 km²), managed by the Bureau of Land Management as part of the National Landscape Conservation System. Located in the Northern California coastal forests ecoregion near Humboldt Bay of the U.S. state of California, most of it was owned by the now defunct Pacific Lumber Company, which was owned byCharles Hurwitz and Maxxam Inc, as the result of a hostile takeover in 1985. The Headwaters Forest has been the site of many tree sits and anti-logging demonstrations, which ensued after Maxxam changed generations old policies of sustained-yield logging at PALCO with clearcutting to finance debt they incurred in the junk bonds used to purchase the once storied company.

Climate is characterized by maritime conditions of cool, wet and foggy winters and cool to warm cloudy summers. Elevations range from 100 feet (30 m) to over 2,000 feet (610 m).