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Engi neer, 1983). The mai n reason for thi s di fference appeared to be that the lakebed immediately upstream from the dam embankment was 6,4 ft higher than the i nl et e 1 evat i on of the outl et pi pe whi ch was located on bedrock. Thi s outflow control probably had been present since construction of the dam, and was not reflected in earlier lake surveys, Determination of the capacity of Cascade Lake dam was more difficult, as severe bed eros i on (fi g, 9E) occurred after the dam fail ure. Postflood surveys indicated that approximately 1.53 acre-ft (table 3) of sediment was removed from the lakebed during the flood. Therefore, field inspections and surveys were made to reconstruct the preflood 1 akebed. All the evi dence indicated that the preflood lakebed was at an elevation of 8,56D ft, plus or minus 1 ft. Contours in plate 2 reflect postflood contours; extensive scour occurred with a maximum of approximately 12 ft. Storage-capacity data and other pertinent data for Cascade Lake, assuming a lakebed elevation of 8,560 ft, are shown in table 3, Cascade lake contained approximately 12,1 acre-ft of water prior to the flood, and 25,1 acre-ft of water at the time of the Cascade Lake dam failure. The total volume of water released from the failures of the Lawn Lake dam and the Cascade Lake dam was approximately 686 acre-ft. For the period 0845 MDT on July 15, to 1200 MOT on July 16, C, W. Huntley (U, S. Bureau of Reclamation, written commun., 1982) estimated the inflow to Lake Estes, resulting from the failures of Lawn lake and Cascade lake dams, was 663 acre-ft. The di fference between the vo 1 ume re 1 eased from the two 1 akes and the volume enteri ng lake Estes probab ly was the result of water remaining in valley storage, which had not reached lake Estes by July 16 at Figure 12,--lawn lake about 1 week after the dam failure, showing the amount of water still remaining in the natural depression formi ng the ori gi na 1 1 ake (aeri a 1). 25