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area was constructed to prevent flooding from the Mokelumne River. Examination of topographic maps indicate that overflow between the lake and the river would naturally have occurred at about elevation +25 feet along the western edge of the property where there is lower ground along the river , however , construction of the levee along this western boundary of the property now prevents that from happening . The large storm that occurred February 12-19 , 1986 produced enough runoff in Jahant Slough to completely fill the lakes to approximately elevation + 26 feet . Examination of aerial photographs taken on February 22 , 1986 indicate that the lake and the river were at approximately the same elevation and that the levee that runs along the western edge of the property prevented the lake and the river from joining at that point . The river was then flowing at approximately 5, 000 cubic feet per second as measured at the Woodbridge gauging station which is maintained by the U.S .G. S . Comparison of this flow rate with Peak Rain and Snow melt Flood Frequency Curves prepared by the Army Corps of Engineers for Camanche Reservoir, which regulates the flow downstream in the Mokelumne River, indicate that this flow rate corresponds to about a 50 year flood release . Furthermore , these same curves indicate that if the flow were unregulated by any dams that this flow rate would correspond to a flood event with about a 2 year return frequency. These curves are presented in Figures 2 and 3 . The U.S .G. S . has maintained the Woodbridge gauging station since 1926 . The first major dam on the Mokelumne River was Pardee Dam which was completed in 1930. Figures 4 and 5 show plots of the Annual Peak Discharge and Annual Peak Stage respectively for the period 1926 through 1987 for this gauging station. Also shown for comparison are the completion years of the various dams and the estimated discharge rate or stage resulting from a uncontrolled 2 year return frequency flood. These plots give some idea as to the reduction in flooding that has occurred since the various dams have been built on the Mokelumne. Even allowing for normal variation in precipitation there seems to be a definite reduction in the frequency of peak flow release equaling or exceeding the uncontrolled 2 year flood event. Of course flood control was one of the reasons that the dams were built in the first place. There is no recorded runoff information for Jahant Slough, however, Angelo Brovelli said that it would normally require about 20 inches of rainfall per year for Jahant Slough to fill the lakes . This is about 25% greater than the average annual rainfall for the area which is about 16 inches per year. He said that even after the Mokelumne was dammed and the levees were built that the lakes would pretty much have water in them all the time just from runoff from Jahant Slough. Recently, however, there hasn ' t been any water in them since the drought began in 1987, with rainfall averaging about 12 inches for the last couple of years. It is also likely that there was significantly more runoff from Jahant Slough before the watershed was modified for agriculture and crisscrossed with roads and railroads which impede runoff . Figure 6 shows the stage vs. storage relationship for both lakes combined. Also shown for comparison are estimates of the amount of 2