The Susan River is a northeastern California river of approximately 67 miles (107.8 km) length that drains from an arid plateau

Plateau

In geology and earth science, a plateau , also called a high plain or tableland, is an area of highland, usually consisting of relatively flat terrain. A highly eroded plateau is called a dissected plateau...

 of volcanic

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 highlands along the Great Basin Divide

Great Basin Divide

The Great Basin Divide is the western continental divide that separates the Great Basin from the Pacific Ocean watershed. The water divide is the perimeter of the largest set of contiguous endorheic watersheds of North America, including six entire USGS watershed subregions...

 to intermittent Honey Lake

Honey Lake

Honey Lake is an endorheic sink within the Honey Lake Valley located in northeastern California, near the Nevada border. Summer evaporation reduces the lake to a lower level of 12 km² and creates an alkali flat....

. The river flows from eastern Lassen County

Lassen County, California

Lassen County is a county located in the northeastern portion of the U.S. state of California. As of the 2010 census, the population was 34,895, up from 33,828 at the 2000 census...

 from east of Lassen Volcanic National Park

Lassen Volcanic National Park

Lassen Volcanic National Park is a United States National Park in northeastern California. The dominant feature of the park is Lassen Peak; the largest plug dome volcano in the world and the southern-most volcano in the Cascade Range...

 generally east past Susanville

Susanville, California

Susanville is the county seat of Lassen County, California, United States. Susanville is located on the Susan River in the south-central part of the county, at an elevation of 4186 feet . The population was 17,974 at the 2010 census, up from 13,541 at the 2000 census...

 and emerging into a ranching valley to enter the north end of Honey Lake. Its waters are used for irrigation

Irrigation

Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

in the surrounding ranching area and are highly regulated.