Fall River Watershed

Fall River near the confluence with Spring Creek

The Watershed at a Glance

Fall River, located in eastern Shasta County, is one of the state’s major “spring rivers.” It is formed by a series of large springs that are believed to originate from snowmelt off Mount Shasta and surrounding volcanic regions. Much of this water traverses the region through a complex network of underground lava tubes and fracture systems. The river meanders for approximately 15 miles through Fall River Valley before entering the Pit River and eventually Lake Shasta. Because of its large volume of cold, clean water, Fall River is notable for its “blue ribbon” wild trout fishery. The Fall River Valley also supports significant agricultural operations (livestock forage crops, mint, strawberries, and wild rice) and is an important waterfowl habitat area. Flow in the lower river is diverted and used by PG&E for hydropower production.


Surface waters in the Fall River Valley include mainstem Fall River, Big Lake, Tule River, and Little Tule River. The majority of flow in Fall River comes from Thousand Springs, Rainbow Springs, Spring Creek, and a number of other smaller springs and seeps. The only major tributary stream is Bear Creek near the headwaters of Fall River. Bear Creek contributes significant inflow during the winter and spring runoff season and then typically goes dry in its lower reaches by mid-summer. Fall River flows are joined by water from Big Lake and Tule River (also spring-fed) and enter the Pit River near the town of Fall River Mills. At this lower river location most of the flow is diverted by PG&E to generate electricity through the Pit 1 Powerhouse. Approximately 100 cfs is bypassed through Fall River Mills for fish, habitat, and recreation benefits in the lower reach of Fall River. Because the river is spring-fed, surface flow in Fall River is consistently high throughout the dry, summer season, even in low rainfall years. The average daily flow is around 1,000 cfs. Groundwater in this watershed is confined largely to the Fall River Valley Groundwater Basin. Storage is estimated to be 1,000,000 acrefeet to a depth of 400 feet and is an important supply source for irrigated agriculture.

Water Quality

Protecting the high quality waters of Fall River is a significant management issue. In addition to water quality and habitat needs for support of the wild trout fishery, many people living along Fall River divert water directly for their household supply. A comprehensive water quality study was conducted by the Pit River Alliance and the RWQCB during the period 2001 to 2005. Based on the findings of this study, general water quality conditions in Fall River are characterized as follows:

  • temperature range: 9C to 18C;
  • pH: 8 to 9;
  • turbidity: 2 to 4 NTU (with occasional higher spikes);
  • fecal coliform bacteria: 20 to 100 MPN (with occasional higher spikes); and
  • nitrate: 0.1 to 0.22 mg/l.

Findings from the 2001–2005 study did indicate that existing bacteria levels in the river have decreased from levels reported from data collected in the 1980s. Minimizing bacteria concentrations is a significant management objective given the ongoing domestic supply use of the river. The study found no apparent change in long-term trends for temperature and nutrients. Current concerns over Fall River water quality are focused on sediment accumulation in the upper river and the spread of the invasive weed species Eurasian milfoil. Fall River is 303(d) listed as an impaired water body for sediment. Other water quality–related issues on Fall River are bank erosion from livestock trampling, irrigation tailwater discharge, and channel and riparian habitat impacts from muskrat burrowing.

Fish and Wildlife

The wild trout fishery of Fall River is important both ecologically and economically, and while DFG fish survey records are inconclusive, many river users and fishing guides believe this valuable resource is in decline. Populations of the endangered Shasta crayfish have been found in most of the major headwater springs of the Fall River and Tule River. Protection of Shasta crayfish and rough sculpin (state-listed as threatened species) is a principal management issue. The Fall River Valley is a major habitat area for resident and migratory waterfowl, and both Ducks Unlimited and California Waterfowl Association are working with private landowners to protect and enhance waterfowl habitat.


Most of the upper watershed is dominated by mixed conifer forest that includes a well-represented hardwood component. Meadows and riparian habitat are common along the drainages and in low-lying areas. Valley lands along Fall River are mostly irrigated pasture and hay production, while recent years have seen an increase in wild rice acreage in the valley. Fuel loading and threat of catastrophic wildfire continue to be important issues as more than 70% of the watershed is composed of forest land. A large upper watershed wildfire in 1977 is believed to be a major contributor to the current problem of sediment accumulation in the Upper Fall River Watershed.

Life in the Watershed

Historically, the watershed was inhabited by the Achumawi (Pit River) tribe. Early European settlers recognized the hydropower opportunity on the Fall River and Pit River system and in 1920 embarked on establishing the largest hydropower system in northeast California at that time. In the following years, drainage and water management improvements were made to expand irrigated agriculture in the valley. Today, rural lifestyles and low population density characterize the Fall River Watershed, and a number of private homes have been built along the river. The largest town in the watershed is Fall River Mills (population 648). McArthur is another center of population. Ranching, farming, and timber production are the primary resource activities, and the principal agricultural crops are wild rice, strawberries, hay, and irrigated pasture. Tourism and recreation are very important to the local economy.

Management Objectives

Management issues in the watershed focus on protecting and enhancing the unique aquatic resources of Fall River, maintaining or improving water quality, managing upland forests for sustained timber production and fire control, and preserving the rural, agricultural lifestyle of the watershed. The Fall River RCD recently completed the Fall River Watershed Assessment and Management Strategy (March 2010). This report includes seven management goals for addressing watershed concerns. While these are listed as independent objectives, it should be recognized that they are largely interrelated:

  • restore and maintain the blue ribbon trout fishery;
  • maintain or improve water quality;
  • reduce erosion and river sedimentation;
  • control invasive species and noxious weeds;
  • protect and restore source waters (meadows, springs, etc.) to meet water use demands and ecological needs;
  • support better data collection, data sharing, and reporting; and
  • support community sustainability by strengthening natural resource–based economies.

Management Organizations Active in the Watershed

Fall River Resource Conservation District

In addition to the recently completed Fall River Watershed Assessment and Management Strategy, Fall River RCD has been actively involved in implementing watershed-improvement projects that include stream and meadow restoration, livestock enclosure fencing, muskrat control, stream-crossing improvements (on roads and railroads), and noxious weed eradication.

Fall River Conservancy

Fall River Conservancy was formed in May 2008 by a group of Fall River Valley landowners with the intent of improving water quality and aquatic habitat in Fall River. They have received their 501(c)3 nonprofit status, established a Board of Directors, and developed a 5-year strategic plan. The Conservancy hopes to attract support from private donors and work cooperatively with the RCD, state and federal agencies, and landowners to implement river improvement projects.


PG&E is a major private landowner in the watershed with approximately 13,000 acres along Fall River and the McArthur Swamp area. As part of the 2003 bankruptcy settlement, PG&E and the Pacific Forest and Watershed Lands Stewardship Council have been working on a long-term plan to manage these lands to preserve and enhance habitat, open space, recreation, forestry, and grazing and to identify and manage cultural resources. This management plan will be one of the first to be approved by the Stewardship Council and will be one of many plans that ultimately will address all 140,000 acres of PG&E watershed lands in California.


Other agencies and organizations have made important contributions to protection and improvement of Fall River Watershed conditions. This work includes livestock fencing, muskrat eradication, and habitat improvement projects. Those involved include NRCS, USFWS, DFG, Fall River Wild Trout Foundation, Cal Trout, and California Waterfowl Association.