Clear Lake (Pomo: Lypoyomi) is a natural freshwater lake in Lake County in the U.S. state of California, north of Napa County and San Francisco. It is the largest natural freshwater lake wholly within the state, with of surface area. At an age of 2.5 million years, it is the oldest lake in North America. It is the latest lake to occupy a site with a history of lakes stretching back at least 2,500,000 years. Clear Lake supports large populations of largemouth bass, crappie, bluegill, carp and catfish. Two-thirds of the fish caught in Clear Lake are largemouth bass, with a record of . In addition to fish, there is abundant wildlife within the Clear Lake basin. There are year-round populations of ducks, pelicans, grebes, blue herons, egrets, osprey, and bald eagles, and the basin supports sizable populations of deer, bear, mountain lion, raccoon and other animals. The expansive, warm water of Clear Lake makes it popular for watersports, such as swimming, water skiing, wakeboarding, sailing, boat races, and jet skiing. Background and geology Clear Lake is by at its widest point, with a surface area of and a capacity. Average depth is , maximum is , lake elevation is , and average water temperature is in winter and in summer. Clear Lake is believed to be one of the oldest lakes in North America. The lake sits on a huge block of stone which slowly tilts northward 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. 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. Clear Lake lies within the Clear Lake Volcanic Field, as designated by the United States Geological Survey. The volcanic