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i formed when sediment during historical flooding of the Mokelumne River was deposited creating a barrier across Jahant Slough. This theory is supported by fact that the soil between the lakes and the river consists of a sandy organic loam extending to a depth of at least 20 feet along the bank of the river, while the soil in the lakes consists of fine silty clay loam which is more typical of the Jahant Slough drainage basin soil type. Furthermore the area between the lakes and the river contains remnants of several large oxbows which were once river channels and are now covered with dense riparian forest vegetation. This is in stark contrast to the sparsely treed oak-buckeye savanna which wraps around the lakes. ' Together, the two lakes cover 350 acres and have a combined capacity of 2,300 acre feet. The northern area (North Lake)drains an area of approximately 1 square mile. When full, ' at elevation +25 feet (U.S.G.S. Datum), North Lake contains approximately 600 acre feet of water and covers an area of approximately 85 acres. The southern area (South Lake) drains an area of approximately 16.5 square miles when full, at elevation +25 feet, South Lake contains about 1,700 acre feet of water and covers an area of approximately 265 acres. Historically, the two bodies of water would have occasionally joined in the winter or spring. This would happen when the water level was relatively high; the lakes would then separate as the water level receded during the summer months Water surface elevation at the lakes depends upon the amount and duration of winter rainfall. It is noteworthy that the first several inches of winter rains do not result in the Lake filling. But after substantial rains (6-7 inches)over a relatively short period of time, the soil profiles become thoroughly wetted, and the lakes quickly fill to capacity. During an "average" year the Lakes fill by mid-winter. Examination of topographic contour maps indicates that during large flood events, overflow from Dry Creek, which lies about 1 mile to the north, probably enters the Jahant Slough drainage. This is also suggested by examination of aerial photographs taken in Buckeye Ranch Resource Plan (November, 1993) 26