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CLEAR LAKE is California's largest natural lake, located in Lake County, which is in turn within northern California.


Clear Lake is 19 miles long, 8 miles wide (at its widest point), and has 100 miles of shoreline. The depth of the lake is 27 feet on average, and at its deepest part exceeds 100 feet. The lake covers an area of 177 square kilometers, or about 43,000 acres.

Like most lakes, Clear Lake is dotted with resorts, many if not most of which have their own launch ramps and gas docks, in addition to the 11 free public ramps around the lake. Ten cities in Lake County also wrap directly around the Lake; Clearlake, Clearlake Oaks, Finley, Lower Lake, Kelseyville, Lakeport, Lucerne, Nice, Soda Bay, and Upper Lake. The public facilities in Lakeport are quite complete, including a large parking lot for vehicles with attached trailers, two launch ramps, and a gas dock.

The lake is overlooked by Mt. Konocti, a 1km high arguably active volcano (The area is still volcanic, but currently lacking an eruptive center, possibly due to nearby geysers and hot springs) which some time ago sprayed the valley with obsidian and other igneous rocks, as well as providing a volcanic dam which blocks one end of the lake. The other is blocked by what was once a massive landslide.


The climate is fairly mediterranean, featuring hot, fairly humid springs, summers and falls, and fairly cold winters, usually accompanied by snow at some elevations. In some years, it has snowed all the way down to the waterline. The lake is eutrophic, meaning rich in nutrient content, and polymictic, meaning the water undergoes a complete turnover due to seasonal changes in temperature and its exposure to the wind.


Clear Lake is teeming with life and is anything but clear - It should probably be renamed Green Lake. Often choked with hydrilla and blue-green algae, an elevated view of Clear Lake often shows large green blotches on the surface of the water, covering tens of square kilometers. Hydrilla clogs jet boat and personal watercraft intake ports, gets wrapped around propellers, and generally makes the lake look and smell distasteful. High algae and bacteria counts in the summer often make it a fairly unpleasant place to swim, as it will make your skin itch, dye your bathing suit green, and potentially infect your mucus membranes. On the other hand, following a particularly spectacular dieoff of algae, accompanied by an awe-inspiring odor, the lake often settles down and becomes quite pleasant to use for a season. However, its primary attraction continues to be use for boating and sport fishing.

Perhaps as a result of the lake's more negative properties, fishing is the greatest attraction of Clear Lake. The lake is home to blue gill, crappie, bass, sunfish, catfish, and many other pisceans. There are a number of fishing tournaments which make a stop on Clear Lake, as well as local competitions; Mostly bass fishing, both fly and bow fishing.


Clear Lake is known to have toxic levels of mercury built up due to local cinnibar mining. Mining for sulfur began at the Sulphur Bank Mine on the Oaks Arm of the lake in 1865, and cinnabar was soon discovered at the same site, which soon became one of the largest mercury-producing locations in the nation. Unfortunately, mercury is bioaccumulative, and therefore it is dangerous to eat both any older fish, which have been around long enough to pick up and concentrate the mercury on their own accord, and also large fish which eat smaller fish, and collect their mercury, passing the savings on to you. The mine has since been abandoned, but drainage from the mine still carries new mercury into the water. Core samples collected from the lake bed detect a tenfold increase in mercury content in 1927, even though 72% of the mercury to be collected from the mine had been harvested by 1873. There is so much mercury contamination of the lake, in fact, that one should not eat more than one pound per month of large mouth bass over fifteen inches, for example, and no more than two pounds for those under fifteen pounds. More information can be found at the OEHHA (Office of Environmental Health Hazard Assessment) webpage at "http://www.oehha.ca.gov".


Mercury contamination doesn't slow down sport fishers any, and a number of tournaments are regularly held on Clear Lake, mostly being run out of Lakeport (as the place with the most comprehensive launch facilities, plus a very nice park near the lake from which one can conduct business.) On April 25, 26, and 27, Clear Lake will host a Western Open tournament of the Citgo BASSMASTER tournament. A number of boat races are also held seasonally on Clear Lake, both sailing regattas and powerboat racing of various classes. In particular, the Small Boat Racing Association of Northern California (SBRA) has been conducting operations on Clear Lake for more than forty years.


Clear Lake is thought to have been formed 2.5 million years ago when the coastal mountain range in the area rose, cracking and forming a basin. The lake originally drained eastward, into the Sacramento Valley. As the land changed over time, the flow was diverted West to the Russian River. Sometime around 400 years ago, a landslide west of Clear Lake blocked this route, and the lake again began to drain inland. The Sacramento Perch is a fish thought to be present in the Sacramento River due to this activity.

Both more and less recently, the area was the home of the Pomo Indians, a tribe which occupied the area around 1,500 years ago.


Website: The University of California at Davis, Clear Lake Environmental Research Center (http://ice.ucdavis.edu/ucdclerc/)

Webpage: Stewart, Kelly. The Mercury Poisoning of Clear Lake. March 16, 1997. (http://www.anthro.ucdavis.edu/features/stp/stpclrlk.htm)

Webpage: Office of Environmental Health Hazard Assessment (OEHHA), California Sport Fish Consumption Advisories (http://www.oehha.ca.gov/fish/general/99fish.html)

Pamphlet: Clear Lake State Park Interpretive Association, Clear Lake State Park.

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