Hydrology of Crater, East and Davis Lakes, Oregon by Kenneth N. Phillips
EAST LAKE
WATER SUPPLY TO THE LAKE
PRECIPITATION ON THE LAKE
There are no year-round records of precipitation near the lake. The total snowfall is known to be considerably less than at Crater Lake, and the average annual precipitation on the lake and in the basin has been estimated for this report as 35 inches, on the basis of a comparison of records of snow accumulation at Paulina Lake, 1955-62, with records -of precipitation at Bend in the same period. This is practically three times the average -annual precipitation at Bend, and more than three times that at Fremont, the two nearest long-term weather stations on the plateau. This total average annual precipitation, even though estimated, is better known and more reliable than other hydrologic data for the area.
The estimated mean annual precipitation of 35 inches on the surface of the two lakes is assumed to be applicable to the entire area of the caldera, and the average annual total water supply from precipitation as direct infall to the lakes is as follows: East Lake, 2,740 acre-feet and Paulina Lake, 3,910 acre-feet. The sum for the two lakes is 6,650 acre feet. The total average annual precipitation is 13,900 acre-feet in East Lake basin and is 18,800 acre-feet in Paulina Lake basin. The sum for the two basins is 32,700 acre-feet. In the 30-year period, January 1931 to December 1960, sometimes used to compute “normal” precipitation, East Lake rose about 7 feet, and the mean annual precipitation for that period was probably about 37 inches.
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