http://frankrevelo.com/hiking/dest_us_lassen.htm

These forests are located in northeast California and are a perfect place to tour in the summer months (June through October), since temperatures are usually mild due to the elevation, especially at night, and there is plenty of shade in the vast forests. Towns of Susanville, Chester, Greenville, Old Station, together with the Eagle Lake campground offer a wide variety of resupply and lodging options, so there will be no need to carry huge amounts of food or water and it will be possible to clean up in a motel room or campground shower every few days and thus avoiding being filthy all the time. The huge network of dirt roads means travel along dangerous paved roads can be mostly avoided. Much of the area is covered by national forests, where it is legal to camp anywhere, so long as you follow "leave-no-trace" principles. Please do not make campfires, as the area is prone to wildfires in the dry summer months. The area is easy to reach (via mostly dirt roads) from either Chico to the west or Reno to the east. Though the area is mountainous, it is possible to avoid huge ascents/descents if these don't interest you (other than getting from/to Chico, if that is your starting point, since Chico is near sea level and the Lassen area is between 4000 and 8000 feet for the most part).