Hydrology – 28 WATER BUDGET

Hydrology of Crater, East and Davis Lakes, Oregon by Kenneth N. Phillips
 EAST LAKE

 

WATER BUDGET

The average annual potential water supply (sum of infalling precipitation and runoff) in the entire caldera is about 23,800 acre-feet. The estimated annual evaporation loss from the lake surfaces is 5,300 acre-feet, and about 18,500 acre-feet is to be expected as runoff from the basin, if none of the water supply in the caldera is depleted by outflow as seepage. The average annual outflow from Paulina Lake is estimated at 14,500 acre-feet.

The elements comprising the average annual water budget of East Lake are about as follows:

  1. Infalling precipitation, 35 inches depth (2,740 acre-ft).
  2. Inflow from tributary area, 1.5 cfs (1,150 acre-ft).
  3. Evaporation loss, 28 inches depth (2,190 acre-ft).
  4. Outflow by seepage, 2.3 cfs (1,700 acre-ft).
  5. Average annual ground-water loss from tributary area that does not reach East Lake is about 6,200 acre-feet. A part of this loss probably goes into Paulina Lake and the rest elsewhere.

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