Clear Lake (California)

For the California wine region, see Clear Lake AVA.

Clear Lake
Location	Mendocino National Forest Lake County, California
Coordinates	39.0616°N 122.8272°W / 39.0616; -122.8272
Primary inflows	Forbes Creek Morrison Creek Seigler Canyon Creek Shindler Creek
Primary outflows	Cache Creek
Basin countries	United States
Max. length	19 mi (31 km)
Max. width	8 mi (13 km)
Surface area	68 sq mi (180 km2)
Average depth	27 ft (8.2 m)
Max. depth	60 ft (18 m)
Water volume	1,155,000 acre⋅ft (1.425×109 m3)
Shore length1	100
Surface elevation	1,329 ft (405 m)
Islands	Anderson Island Fruit Island Garner Island Indian Island Rattlesnake Island Slater Island Tule Island Weekend Island
Settlements	Clear Lake, California Lakeport, California Lower Lake, California Lucerne, California Nice, California
References	[2]
1 Shore length is not a well-defined measure.

Clear Lake is the largest natural freshwater 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 runoff flowing into many streams as well as springs in Soda Bay. Its sole outlet is Cache Creek. There is a dam on Cache Creek to increase the lake's capacity and to regulate outflow.

Background

Clear Lake is 19 mi (31 km) by 8 mi (13 km) at its widest point, with surface area of 43,785 acres (17,719 ha) and a 1,155,000 acre⋅ft (1.425×10⁹ m³) capacity. Average depth is 27 ft (8.2 m), maximum is 60 ft (18 m), lake elevation is 1,329 ft (405 m), average water temp is 40 °F (4 °C) in winter and 76 °F (24 °C) in summer.

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.

History

Satellite photo of Clear Lake (the larger lake to the west) and Indian Valley Reservoir

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, Yuki, and 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 [3]. 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.

Clear Lake was used as an outlying seaplane base for Alameda Naval Air Station during World War II and the early years of the cold war. Flying boats could land on Clear Lake when landing conditions were unsafe on San Francisco Bay.

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.

Heavy metal contamination

The lake is heavily contaminated with mercury from the nearby Sulphur Bank Mercury Mine. The nearby abandoned mine was declared a Superfund site in the early 1990s and is still undergoing cleanup. The California Department of Fish and Game presently recommends that women of childbearing age and children limit their consumption of certain fish from Clear Lake, due to the presence of methylmercury compounds in lake sediments.

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, turtles, 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 blue oak, 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.

Clear Lake is well-known among entomologists for the Clear Lake gnat (Chaoborus astictopus) and historical control efforts. This species of "phantom midge" (so called because the larvae are transparent and very difficult to see) measures less than 1/4" long and resembles a tiny mosquito, but is non-biting. Clear Lake gnat hatches start anytime from March through June, depending on weather. Before pesticide use began in the 1940s (Refer to Rachel Carson's book Silent Spring, chapter 4), the gnat was so abundant around the lake in the summer that large piles of dead gnats appeared beneath streetlights, looking like dirty snow. The gnat swarms were so thick that people driving along the edge of the lake reported stopping every 1/4 mile to clean off the gnats off the windshields and headlights of their cars so they could see, and pedestrians tied kerchiefs over their faces to avoid inhaling the gnats. In 1949, as part of an effort to boost tourism and improve the local economy, dichloro diphenyl dichloroethane (DDD) was applied to the lake in heavy doses to eradicate the gnats that were driving summer tourists away from the lake. The treatment succeeded in controlling the gnats that year and for the following year, however in 1953 the gnat population rebounded, prompting another application in 1954. The final application of DDD to Clear Lake was made in 1957 (Cook 1963). Numbers of Western grebe were found dead, their tissues containing high concentrations of DDD. The effects were devastating to the local ecology. From 1962 to 1975 carefully planned applications of methyl parathion were made for Clear Lake gnat control ((Refer to Rachel Carson's book Silent Spring, chapter 3). The gnat still occurs in Clear Lake, but at much lower numbers than in the 1940s-1970s. The Clear Lake gnat's population is believed to be kept in check now by two introduced fish species (the Threadfin Shad (Dorosoma petenense) and the Inland Silverside (Menidia beryllina)) that compete with the Clear Lake gnat for its preferred zooplankton for food.

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.

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.

View of Clear Lake and Mount Konocti from CA Highway 175

See also

• Clearlake, California
• Clear Lake Reservoir
• Lake Tahoe
• List of lakes in California
• List of largest reservoirs of California
• Post Pattern

External links

• Template:PDFlink
• "Forgotten Lake" California Wild magazine, Spring 2004
• Template:PDFlink
• Virtual Field Trip Geological discussion with multiple photographs
• Lake County
• Lake County News online
• Lake County Visitor Guide
• Lakeport Newspaper
• "Clear Lake". Global Volcanism Program. Smithsonian Institution. Retrieved 2008-12-20.