Clear Lake
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| Clear Lake | |
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| Location | Lake County, California |
| Coordinates | |
| Lake type | eutrophic, alkaline, polymictic |
| Primary inflows | numerous streams |
| Primary outflows | Cache Creek |
| Basin countries | United States |
| Max. length | 19 mi (31 km) |
| Max. width | 8 mi (13 km) |
| Surface area | 43,785 acres (177.2 km²) |
| Average depth | 27 ft (8 m) |
| Max. depth | 60 ft (18 m) |
| Water volume | 1,155,000 acre·ft (1.425 km³) |
| Surface elevation | 1,318 ft (402 m) |
| Islands | Rattlesnake Island |
Clear Lake is the largest natural lake entirely in California, and has the largest surface area of any freshwater lake entirely in California, the tenth largest by capacity. It is located in Lake County and is fed by many streams, but its sole outlet is Cache Creek. There is a dam on Cache Creek to increase the lake's capacity and to regulate outflow.
Clear Lake is 19 miles (30.6 km) long, 8 mi (12.8 km) wide at widest point, with surface area of 43,785 acres (177.19 km²) and a capacity of 1.42 km³ (1,155,000 acre-feet). Average depth is 27 ft (8 m), maximum is 60 feet (18 m), lake elevation is 1,318 feet (401.7 m) minimum, average water temp is 40 °F (4 °C) in winter and 76 °F (24 °C) in summer. Location (per USGS).
Clear Lake is believed to be one of the oldest lakes in North America, due to a geological fluke. The lake sits on a huge block of stone which slowly tilts in the northern direction at the same rate as the lake fills in with sediment, thus keeping the water at roughly the same depth. Core samples of the lake's sediments, taken by U.S. Geological Survey geologists in 1973 and 1980, indicate that the lake is at least 480,000 years old. Some experts feel that Mono Lake, to the east of the Sierra Nevada in California, is older than Clear Lake. However, the sedimentary history of Clear Lake is unbroken, while Mono Lake's sediments have been disturbed by past eruptions of the Long Valley Caldera and associated volcanoes.
The geology of Clear Lake is chaotic, with numerous small faults being present in the south end of the lake as well as many old volcanoes, the largest being Mount Konocti, sitting at the middle of the lake's south shore.
Yolo County Flood Control District, not to be confused with Yolo County has historical water rights over the lake because the runoff was used for irrigation before other uses were established for the lake. This causes disputes. In winter, Yolo would like to use the lake for water storage, while the lake residents fear flooding. In summer, Yolo would like to divert water for irrigation, while residents want the lake to have a high water volume to increase its oxygen content and fishery. The water rights issues interfere with Lake County's plans to manage the lake and utilize the water. The water rights have since been contested, and new injunctions and compromises regarding the lake and creek levels, and the water needed for agriculture in Yolo County, have been put into effect. The ongoing water rights dispute has also misled real estate investors into thinking that potable water is abundant in Lake County, which is not really correct. Several attempted housing developments have been stymied by lack of legally-acceptable water rights, as well as inadequate sewage-processing facilities in the lake area.
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[edit] History
At one time Clear Lake was even bigger than it is now, and included the Blue Lakes (to the northwest of Clear Lake). Volcanic eruptions and subsequent landslides changed the landscape dramatically, forever separating Clear Lake from the Blue Lakes and from its former westward drainage into the Russian River.
Archaeologists believe that the Clear Lake basin has been occupied by Native Americans for at least 11,000 years. Evidence of this has been found at nearby Borax Lake and on Rattlesnake Island in the lake's south arm. Abundant fish, game and waterbirds made Clear Lake an oasis in the otherwise harsh conditions of Northern California's mountains. The native Clear Lake hitch, Lavinia exilicauda, was once so abundant that millions of hitch clogged the lake's feeder streams in dry months. When the Spanish missionaries came to California, they found that thousands of Native Americans lived in the Clear Lake Basin, primarily Pomo people and Yuki-Wappo with some Lake Miwok.
European settlers arrived, starting around 1845. Frequently they abused and exploited the native Pomo people. One of the most notorious incidents was the Bloody Island Massacre of spring 1850 [1]. A number of Pomo were enslaved and abused by settlers Andrew Kelsey, whose name is attached to the town of Kelseyville today, and Charles Stone. The Pomo finally revolted and killed Kelsey and Stone. A United States Army contingent under Gen. Nathaniel Lyon cornered as many as 200 Pomo on an island in Clear Lake, and slaughtered most of them--including scores of women and children. The historical marker for Bloody Island is on Highway 20 between Upper Lake and the Robinson Rancheria.
Later, the Pomo were forced to live in small "rancherias" set aside by the federal government. For most of the 20th century, the few Pomo people left had to live on these tiny reservations in poverty. Ironically, today the fastest-growing businesses around Lake County are the gambling casinos presently operated by four Pomo rancherias, with more casinos planned.
Exhibits and programs about the region's culture and history are maintained and presented by rangers and docents at Clear Lake State Park and at Anderson Marsh State Historic Park. Lake County has two county museums, the Lake County Museum in Lakeport and the Lower Lake Historical Schoolhouse Museum in Lower Lake. There are also numerous state and local historical landmarks identified throughout the county.
[edit] Pollution
There is no doubt that the lake has eutrophication. The smell of algae is present year-round, and on hot summer days the smell can be overpowering. The cyanobacteria bloom in the summer due to long, hot days and the relative shallowness and warmth of the lake. The blooms form a mat. When the mat dies and rots, the smell lasts until rotting is complete, or the wind and currents turn over the lake, and move the mat away from the air.
Some authorities say that the lake is not now, and never has been, polluted. Core samples going back many years, taken by the United States Department of Agriculture in conjunction with the University of California, Davis, prove that the cyanobacteria are natural parts of the food chain in the lake and the riparian zone which surrounds it. It is known that many Native American settlements were near the lake, and the native Pomo prized the lake for its large population of fish, which could not be supported without large quantities of algae.
Other authorities say that the eutrophication indicates a lack of oxygen caused because the lake was polluted by poorly managed sewage from local septic tanks, and unregulated spills from Southlake settlement's primitive sewage systems. When combined with diversion of water, the lake's oxygen content has declined far from its natural state. They cite historical records, including the name of the lake (the modern lake is far from clear), to indicate that the changes are clearly caused by human settlement.
There is a sewage treatment plant in the city of Clearlake on the north shore of the south arm of the lake. Some treated wastewater is also diverted to The Geysers, a collection of geothermal power plants. Neither of these release directly to the lake. Local residents insist that some older lakefront homes dump their sewage directly into the lake; however, the county has not pursued this problem due to lack of evidence and lack of political interest[citation needed].
The injection of treated wastewaster at The Geysers geothermal area has allegedly caused hundreds of small earthquakes in the Anderson Springs/Cobb Mountain area, south of the lake, since 1996. The matter is being investigated to see if the increase in microquakes is natural.
The lake may also be heavily contaminated with mercury from the nearby Sulphur Bank Mercury Mine. [2] The California Department of Fish and Game presently recommends that women of childbearing age and children limit their consumption of sport fish from Clear Lake, due to the presence of methylmercury compounds in lake sediments. [3]
[edit] Wildlife
The Clear Lake basin attracts large quantities of waterfowl, including mallards, Western grebe, coots, various species of goose, ospreys, plovers, mergansers and many others. Wild turkeys and black-tailed deer are abundant, as are opossums, red-tailed hawks, turkey vultures, raccoons, and other species. The endangered northern spotted owl is seen occasionally. The county hosts a growing population of the rare tule elk, recently reintroduced after being locally hunted to extinction 100 years before. A large colony of bald eagles is found in the Cache Creek canyon.
In addition to the native Clear Lake hitch Lavinia exilicauda (called chi by the native Pomo), the lake hosts catfish, crappie, and other native fish species, as well as farmed largemouth bass, trout and carp placed by the Department of Fish and Game for sporting purposes. Lake waters host quantities of tule and other riparian plants commonly seen around California lakes, as well as the massive cyanobacteria blooms that peak in late summer.
The rugged coastal mountains surrounding Clear Lake are covered with thick stands of oak-madrone forest, manzanita, sage shrubs, chaparral, grasses etc. Most common trees include valley oak, interior live oak, pacific madrone, California scrub oak, plus very occasional coast redwoods and tanoak. Large stands of Western White Pine may be seen in the higher elevations. The heavy forestation and ruggedness of this part of California has helped prevent wholesale real-estate development or farming. On the northeast slope of Mount Konocti is a heavily forested area known locally as the "Black Forest", because it never gets direct sunshine. This area has some Douglas fir in very heavy stands.
At every entry to Lake County, signs warn boaters not to spread hydrilla in the county's bodies of water. Extensive manangement efforts have controlled the presence of hydrilla in Clear Lake, although it may return at any time.
One thing that makes Clear Lake notorious among entomologists is the Clear Lake gnat (Chaoborus astictopus). This species of "phantom midge" resembles a large mosquito, but is harmless. Major gnat hatches start anytime from March through June, depending on weather. Before pesticide use began in the 1940s, the gnat was so abundant around the lake in the summer that large piles of dead gnats appeared beneath streetlights, looking like dirty green snow. C. astictopus was a unique species, found nowhere else--until recently, when it was found to be spreading to other lakes in California. Starting in 1949, dichloro diphenyl dichloroethane (DDD) was poured into the lake in heavy doses to eradicate the gnats which drove summer tourists away, in an effort to boost the local economy. It worked, at first. When the gnats returned the following year, DDD was again applied to the lake by the ton. Numbers of western grebe were found dead, their tissues containing high concentrations of DDD. The effects were devastating to the local ecology. Since the 1960s, gnat and mosquito remediation has consisted of carefully planned applications of various pesticides, currently methyl parathion, to lake waters, with limited success--the gnat has apparently developed some resistance to common pesticides, and is rumored to currently occur in numbers not seen since the 1950s.
A number of mosquitoes also call Clear Lake home, including two species that are known spreaders of malaria. Abatement programs have reduced the threat of this disease, though scientists suspect that malaria might still reappear in the area, given the right conditions. West Nile virus was recently discovered in wild birds in the lake area, as in surrounding counties.
[edit] Recreation
With over 100 miles (160 km) of shoreline, Clear Lake is a popular spot for watersports enthusiasts. Fishing, swimming, sailing, wind surfing, waterskiing, boating, and riding personal water craft are all popular activities, primarily in the summer. There are 11 free boat launch ramps around the lake that are open to the public. Individuals may rent boats and personal water craft from many businesses around the lake. There is also a community aquatic center, Clear Lake Scullers, in Lakeport that offers rowing, paddling, and water safety programs for adults and youth for the community.
Clear Lake is sometimes called the "Bass Capital of the West." Largemouth bass, which are farmed and planted in the lake by California Department of Fish and Game, crappie, catfish, bluegill, and rainbow trout can be found in the county's lakes. Fishing boats can be rented, and many stores and facilities around the lake specialize in fishing equipment. Numerous fishing tournaments and derbies are held through the year.
Area wineries with tasting rooms include Guenoc and Langtry Estate Vineyards and Winery, Ployez Winery, Steele Wines, and Wildhurst Vineyards.
[edit] See also
[edit] External links
- Ample Charms of a Well-Fed LakePDF (112 KiB)
- Article about Clear Lake from California Wild magazine, Spring 2004
- An excellent overview of Clear Lake's multiply-stressed ecosystemPDF (2.50 MiB)
- Clear Lake Scullers
- Lake County
- Lake County News online
- Lake County Visitor Guide
- Lakeport Newspaper
- Smithsonian Institution Global Volcanism Program: Clear Lake
