Mad River is a Census County Division (CCD) in southern Trinity County, CA. The population was 838 at the 2000 census. Most of the region is covered by the Six Rivers National Forest and the Shasta-Trinity National Forest. This small community is near the western extent of Ruth Lake, the major water reservoir for the populated area around Humboldt Bay within Humboldt County located to the northwest. The ZIP Code is 95552 and this CCD is inside area code 530.
Most of the communities that encompass the Mad River area are off main highways and at least 100 miles (160 km) from a major city. The area code for most of the region is 707, because phone service comes from larger communities in Humboldt County, such as Bridgeville or Garberville.
Mad River, formerly Kuntz, is a small unincorporated communityon the Trinity-Humboldt County line. It has the last services on State Highway 36 until the Wildwood Store, 5 miles (8.0 km) west of Platina. That is 39 miles (63 km) away. Its post office serves itself and the communities of Ruth, Dinsmore (Humboldt County), and Van Duzen; all using 95552 as their ZIP code. It is home to Southern Trinity High School, the region's only high school with an enrollment of 45 students. It is also home to Van Duzen Elementary School.
Ruth is a small town 18 miles (29 km) south of State Highway 36. It is home to Ruth Lake, a long narrow lake primarily used to control flow of water in the Mad River to supply the Humboldt Bay area with drinking water and water for industrial activities. The lake is also used for recreation, irrigation, and hydroelectric power. It has two stores and gas stations and a church.
Zenia is a with only a post office (ZIP Code 95595) that is used for Zenia, Kettenpom, Hoaglin, and Hettenshaw Valley. Telephone service is from Garberville. It is 30 miles (48 km) east of US Highway 101.
Kettenpom is a larger community east of Zenia. It has all of the services needed south of Ruth Lake. It also has a community hall, church, store, elementary school, camgrounds, gas, and many other services. It is located near the Six Rivers National Forest.
Hoaglin is a much tinier community outside of the Kettenpom Valley. It is home to Church Wilburn.
Hettenshaw is a tiny community with absolutely no services. The headwaters of the north fork of the Eel River are found here.
Forest Glen is a community along State Highway 36, 23 miles (37 km) southwest of Hayfork. It has a Cal Fire station, a ranger station, and a store that is now closed. Mail and telephone service is from Hayfork. Its former ZIP code is 96030.
According to the United States Census Bureau, the CCD has a total area of 830.8 km² (155.6 mi²) all land.
As of the census of 2000, there were 838 people and 433 families residing in the CCD. The population density was 0.4/km² (1/mi²). The racial makeup of the CCD was 86.8% White, 0% African American, 0% Native American, 0% Asian, 8.9% from other races, and 4.3% from two or more races. Hispanic or Latino of any race were 2.1% of the population.
In the state legislature Mad River is located in the 4th Senate District, represented by Republican Sam Aanestad, and in the 1st Assembly District, represented by Democrat Patty Berg. Federally, Mad River is located in California's 2nd congressional district, which has a Cook PVI of R +13 and is represented by Republican Wally Herger.