About the Lahontan Regional Board


The primary responsibility for the protection of water quality in California rests with the State Water Resources Control Board (State Board) and nine Regional Water Quality Control Boards. The State Board sets statewide policy for the implementation of state and federal laws and regulations. The Regional Boards adopt and implement Water Quality Control Plans (Basin Plans) which recognize regional differences in natural water quality, actual and potential beneficial uses, and water quality problems associated with human activities.

The jurisdiction of the California Regional Water Quality Control Board, Lahontan Region (Regional Board) extends from the Oregon border to the northern Mojave Desert and includes all of California east of the Sierra Nevada crest. The name of the Region is derived from prehistoric Lake Lahontan, which once covered much of the State of Nevada. Most of the waters of the North Lahontan Basin drain into closed basins which were previously part of Lake Lahontan. Waters of the South Lahontan Basin also drain into closed basin remnants of prehistoric lakes.

The Lahontan Regional Board is a seven-member decision making body appointed by the Governor. The Board holds regular meetings, typically monthly at different sites throughout the Region. Its day-to-day work is carried out by a technical and administrative support civil service staff under an Executive Officer appointed by the Board. There are two Regional Board offices, at South Lake Tahoe and Victorville.

Regional Setting

The following is a brief overview of the environmental and socio-economic setting of the Lahontan Region.

The Lahontan Region is defined in terms of drainage basins by Section 13200(h) of the Porter-Cologne Act. For planning purposes, it has historically been divided into North and South Lahontan Basins at the boundary between the Mono Lake and East Walker River watersheds (see Boundary Map). It is about 570 miles long and has a total area of 33,131 square miles.

The Lahontan Region includes the highest (Mount Whitney) and lowest (Death Valley) points in the contiguous United States, and the topography of the remainder of the Region is diverse. The Region includes the eastern slopes of the Warner, Sierra Nevada, San Bernardino, Tehachapi and San Gabriel Mountains, and all or part of other ranges including the White, Providence, and Granite Mountains. Topographic depressions include the Madeline Plains, Surprise, Honey Lake, Bridgeport, Owens, Antelope, and Victor Valleys.

The geology and soils of the Lahontan Region have been shaped by a variety of processes, and are correspondingly diverse. Parent materials in the northern mountains are granitic or volcanic; evidence of glacial action is widespread. Soils in the desert valleys of the Region are derived from alluvium. Severe seismic activity has occurred in the past; the Owens Valley earthquake of 1872 formed a 20-foot fault scarp, and earthquakes in the Mammoth area have recently damaged sewer lines. Volcanic activity has occurred fairly recently in the Mono Lake area, and the presence of geothermal springs throughout the Lahontan Region indicates that it could occur in the future. Economically valuable minerals, including gold, silver, copper, sulfur, tungsten, borax, and rare earth metals, have been or are being mined at various locations within the Lahontan Region.

The Lahontan Region also has a variety of climates. The Region is generally in a rain shadow; however, precipitation amounts can be high (up to 70 inches) at higher elevations. Most precipitation in the mountainous areas falls as snow. Desert areas receive relatively little annual precipitation (less than 2 inches in some locations) but this can be concentrated and lead to flash flooding. Recorded temperature extremes in the Lahontan Region range from -45 degrees Fahrenheit at Boca in the Truckee River watershed to 134 degrees Fahrenheit in Death Valley.

The varied topography, soils, and microclimates of the Lahontan Region support a corresponding variety of plant and animal communities. Vegetation ranges from sagebrush and creosote bush scrub in the desert areas to pinyon-juniper and mixed conifer forest at higher elevations. Subalpine and alpine cushion plant communities occur on the highest peaks. Wetland and riparian plant communities, including marshes, meadows, sphagnum bogs, riparian deciduous forest, and desert washes, are particularly important for wildlife, given the general scarcity of water in the Region.

The existence of ecological islands, as a result of topography, glaciation, and climatic changes, has led to the evolution of species, subspecies, and genetic strains of plants and animals in the Lahontan Region which are found nowhere else. Particularly notable are fish such as the Eagle Lake trout, Lahontan and Paiute cutthroat trout, Mojave chub, and several kinds of desert pupfish.

The Lahontan Region is rich in cultural resources (archaeological and historic sites). These range from remnants of Native American irrigation systems to Comstock mining era ghost towns such as Bodie and 1920s resort homes at Lake Tahoe and Death Valley (Scotty's Castle).

Much of the Lahontan Region is in public ownership, with land use controlled by agencies such as the U.S. Forest Service, National Park Service, and Bureau of Land Management, various branches of the military, the California State Department of Parks and Recreation, and the City of Los Angeles Department of Water and Power. While the permanent resident population (about 500,000 in 1990) of the Region is low, most of it is concentrated in high density communities in the South Lahontan Basin. In addition, millions of visitors use the Lahontan Region for recreation each year. Rapid population growth has occurred recently and is expected to continue in the Victor and Antelope Valleys and within commuting distance of Reno, Nevada. Principal communities of the North Lahontan Basin include Susanville, Truckee, Tahoe City, South Lake Tahoe, Markleeville, and Bridgeport. The South Lahontan Basin includes the communities of Mammoth Lakes, Bishop, Ridgecrest, Mojave, Adelanto, Palmdale, Lancaster, Victorville, and Barstow.

Recreational and scenic attractions of the Lahontan Region include Eagle Lake, Lake Tahoe, Mono Lake, Mammoth Lakes, Death Valley, and portions of many wilderness areas. Segments of the East Fork Carson and West Walker Rivers are included in the State Wild and Scenic River system. Both developed (e.g., camping, skiing, day use) and undeveloped (e.g., hiking, fishing) recreation are important components of the Region's economy.

In addition to tourism, other major sectors of the economy are resource extraction (mining, energy production, and silviculture), agriculture (mostly livestock grazing), and defense-related activities. There is relatively little manufacturing industry in the Region in comparison to major urban areas of the state.

Water Resources and Water Use

The Lahontan Region includes over 700 lakes, 3,170 miles of streams and 1,581 square miles of ground water basins. There are twelve major watersheds (called hydrologic units under the Department of Water Resources' mapping system) in the North Lahontan Basin. Among these are the Eagle Lake, Susan River/Honey Lake, Truckee, Carson, and Walker River watersheds. The South Lahontan Basin includes three major surface water systems (the Mono Lake, Owens River, and Mojave River watersheds) and a number of separate closed ground water basins. Very little quantitative information is available on most of the water bodies in the Region.

The natural quality of most high elevation waters, which are derived from snowmelt, is assumed to be very good or excellent, although localized problems related to heavy metals and radioactive elements occur. The soils and waters of the Sierra Nevada have low buffering capacity for acids, and its lakes and streams are considered sensitive to acidification as a result of wet and dry deposition of pollutants from urban areas. Although high quality water supplies are available near streams in desert areas of the Lahontan Region, many desert waters have naturally poor quality (e.g., high concentrations of salts, and minerals such as arsenic and selenium). Threats to beneficial uses from naturally high concentrations of salts, toxic minerals, or radioactive substances can be aggravated by geothermal and agricultural discharges, ground water overdraft which concentrates salts, and disposal of stormwater under conditions where it is unlikely to receive adequate treatment by soils and vegetation.

Water quality problems in the Lahontan Region are largely related to nonpoint sources (including erosion from construction, timber harvesting, and livestock grazing), stormwater, acid drainage from inactive mines, and individual wastewater disposal systems. (The concentration of most of the Region's population in a few high density communities has important implications for areas with no community wastewater treatment facilities.) There are relatively few point source discharges; these include several wastewater treatment plants, fish hatcheries operated by the Department of Fish and Game, and some geothermal discharges. Some types of discharges may be considered either point source or nonpoint source depending upon site-specific circumstances. For example, stormwater which enters one lake through a pipe may be regulated as a point source, while stormwater which enters another lake via sheet flow is considered a nonpoint source discharge.

Consumptive municipal and agricultural use of water is relatively low in most parts of the Lahontan Region compared to other parts of California, due to the low resident population and the agricultural emphasis on range livestock grazing rather than crops. Irrigation is mostly for pasture, rather than for row crops and orchards. Large volumes of water are exported for consumptive use outside the Lahontan Region. The waters of the Truckee, Carson and Walker Rivers, and of Lake Tahoe, are allocated by court decisions, federal law, and interstate agreements among water users in California and Nevada. The City of Los Angeles Department of Water and Power diverts water from the Mono and Owens River Basins via the Los Angeles Aqueduct for use in the Los Angeles area. Some water is imported to the South Lahontan Basin via the State Water Project's California Aqueduct.

Careful consideration of the relationships between water quality and water quantity will be needed in future Regional Board planning activities. Reasons for concern include projected increases in population and consequent demands for water, and possible future water shortages due to drought, global climate change, and contamination of some water supplies by toxic substances. There is also increasing scientific and public awareness of environmental values associated with natural water volumes in streams, lakes, wetlands and ground water aquifers.