The Lahontan Regional Water Quality Control Board (Region 6) oversees a region about 570 miles long and has a total area of 39,210 square miles covering 20 percent of California. This region spans an area from the Oregon border south along the eastern crest of the Sierra Nevada through the northern Mojave Desert and contains a diverse range of landscapes and habitats. Important components of the Region’s economy are tourism, mining (gold, borax, rare earth), energy production, silviculture, agriculture (mostly livestock grazing), and defense-related activities.
The region’s name is derived from an ancient sea located in the Great Basin. The Great Basin is that portion of western North America that has no drainage to the sea. It encompasses almost the entire state of Nevada and portions of Oregon, Wyoming, Idaho, and California. In the course of geologic time, the waters of this great sea were separated into two lakes. The eastern portion was called Lake Bonneville; the remnant of this lake is the Great Salt Lake. The western portion of this lake was called Lahontan; the remains of which are Pyramid Lake, Honey Lake, the Carson Sink, and other features.
The region’s streams, rivers and lakes carry water to the Western states’ Great Basin and, via diversion, to Southern California. Approximately 85 percent of lands in the region are federally managed, and 77 percent of the region is undeveloped. Many of the waters found in the region are pristine and support diverse plant and animal communities.
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 Mountains and the Sierra Nevada, the northern slopes of the San Bernardino and San Gabriel Mountains; the southern slopes of the Tehachapi Mountains, and all or part of other ranges including the White, Providence, and Granite Mountains and the western slopes of the New York and Ivanpah Mountains. Topographic depressions include the Madeline Plains, Surprise, Honey Lake, Bridgeport, Owens, Antelope, and Victor Valleys. Within this area are over 700 lakes including the nationally significant Lake Tahoe and Mono Lake, 3,170 miles of streams and 19,710 square miles of ground water basins.
The Lahontan Regional Water Quality Control Board’s region itself is divided into two basins: the North Lahontan Basin, administered by the South Lake Tahoe office, and the South Lahontan Basin, which is administered by the Victorville office. Both offices work together as custodians of the waters in the region and include teams of engineers, geologists and scientists. The Water Board strives to protect and restore supplies of clean water, recreational opportunities, wildlife health and diversity, and agricultural and industrial opportunities for communities in the region. Water quality in the region is protected through the development of regulations and permitting processes based on scientific research, inspecting permitted facilities and, if necessary, taking enforcement actions against entities violating state or federal water laws.
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 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 Scotty's Castle at Death Valley.
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 of the Region (about 800,000 in 1995) is low in relation to that of more urbanized Regions, 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.
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.
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.
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. 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.
- The Regional Board has played a key role in cleanup activities at regional military bases. It also authorized, in coordination with the State Resources Agency, the payment of over $2.2 million from the Tahoe Keys Mitigation Fund to construct projects in the Lake Tahoe Basin.
- The Regional Board completed a Watercraft Emission Study at Lake Tahoe and found measurable concentrations of Methyl Tertiary Butyl Ether (MTBE) and benzene in the lake. Based, in part, on the results of the study, the Tahoe Regional Planning Agency adopted ordinances banning the use of two-stroke watercraft engines at Lake Tahoe. Cleanup of the Leviathan Mine, an inactive sulfur mine acquired by the State in 1984, continues. The Regional Board has treated about 11 million gallons of acid mine drainage, revegetated more than five acres of disturbed area, and constructed treatment lagoons capable of passively treating the drainage. The Board monitors flow and water quality at the site.
- The Regional Board has been instrumental in setting new standards to control pollutants in snowmelt and road runoff entering a tributary to Lake Tahoe. The Regional Board issued a Notice of Violation to the California Department of Transportation requesting changes in their operations. Subsequently, Governor Davis directed the Department to cease the practice.
- Problems associated with the contamination of drinking water wells in the South Lake Tahoe area by MTBE continue. Since 1998, the Regional Board has continued to clean up MTBE contamination from a recalcitrant owner’s site in Meyers using funds from the State’s “Emergency, Abandoned, and Recalcitrant” account.
- In 2001 the Regional Board adopted its first Total Maximum Daily Load (TMDL) to control sediment loading to Heavenly Valley Creek in the Lake Tahoe Basin from past ski resort development. The Board's new TMDL unit is working on several other TMDLs affecting the Lake Tahoe, Truckee River, Walker River, and Owens River watersheds.
Resources:
Lahontan Regional Water Quality Control Board Website www.waterboards.ca.gov/lahontan/
Fact Sheet: Lahontan Regional Water Quality Control Board www.waterboards.ca.gov/lahontan/water_issues/available_documents/misc/r6facts2.pdf
Lahontan Water Board Basin Plan Program www.waterboards.ca.gov/lahontan/water_issues/programs/basin_plan/
Lahontan Water Board Guiding Principles (Revised July 2015) www.waterboards.ca.gov/lahontan/about_us/docs/2015_guiding_principles.pdf
Lahontan Water Board Workshop and Program Update Schedule 2017 www.waterboards.ca.gov/lahontan/about_us/docs/wkshop_pgm_update.pdf
SWAMP - Region 6 (Lahontan) Monitoring Program www.waterboards.ca.gov/water_issues/programs/swamp/monitoring/regional_monitoring_programs/region_6.html
What we Do: Lahontan Regional Water Quality Control Board www.waterboards.ca.gov/lahontan/about_us/docs/r6info.pdf
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