Green Lake is the larger of the two lakes in Green Lakes State Park, which lies about east of downtown Syracuse in Onondaga County, New York. Round Lake is the smaller lake located west of Green Lake. Both lakes are meromictic, which means no seasonal mixing of surface and bottom waters occurs. Meromictic lakes are fairly rare; they have been extensively studied, in part because their sediments can preserve a historical record extending back thousands of years, and because of the euxinic (anoxic, sulfidic) conditions which can form in the deep water. Description Green Lake has a maximum depth of 195 feet (59 metres). Deep lakes tend to appear bluish because the wavelengths of light that can penetrate (and be dispersed at) great depths are those closer to the blue end of the spectrum. Because of its depth and the high salinity of the basin waters, the lake is meromictic and does not turn over and intermix waters like many other lakes in this region do. Green Lake's cold and dense bottom waters tend to stay separate from the shallower, warmer waters. Because of this, sediment sinks and collects in the bottom and undergoes virtually no decay. Since the sediment is not disturbed by mixing, the lake does not take on a muddy, turbid appearance like other lakes do. Meromictic lakes also have still, mirror-like waters. Green Lake's tranquil, reflective water makes it photogenic. The lake is glacial in origin, likely developed by glacial meltwater during the most recent North American glaciation. Its calcium and sulfate-rich waters are due to groundwater percolating through marine shale with a high gypsum content. The lake, which resembles a large river in shape, is unusually deep for its size and was considered sacred by the native Onondaga tribe, which originally settled in the area. Fishing Fish species present in the lake include rainbow trout, pumpkinseed sunfish, and brook trout. Access is only by rental boats or shore fishing. History Fayetteville Green Lake (FGL) was the first lake in North America identified as meromictic, and is the best-studied meromictic lake in the world, with records dating back to 1839. Green Lake was referred to as Lake Sodom by Lardner Vanuxem, who was the first to study Green Lake in 1839, and the presence of sulfide in the deeper waters of the lake was known by 1849. FGL is believed to have formed as a plunge