PERMFILE59745

• Permit No: M1976056
• IBM Index Class Name: Permit File
• Doc Date: 12/10/1976
• Doc Name: APPLICATION FOR MINING AND RECLAMATION PERMIT
• Media Type: D
• Archive: No

~J
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will evaporate from the remaining 26.95 acres of lakes in
' excess of precipitation constitutes the amount by which
water use on the dredging area will increase as a result of
dredging. To determine the increase in water use, values
for net evapotranspiration have been derived.
' Records of total evaporation measured by a Class "A"
evaporation pan at Wiggins, Colorado, as published by the
' U.S. Weather Bureau from 1961 through 1970, were analyzed to
determine lake surface evaporation. Date published in the
Climatological Atlas of the United States by the U.S.
' Environmental Data Service indicate comparable rates and
values of evaporation occur at Wiggins and Sterling. The
period 1961 through 1970 includes both wet and dry intervals.
Monthly data for the period is contained in Table 1. The
' rate of evaporation from a Class "A" pan is greater than that
for a large open surface and it is necessary to convert pan
' evaporation measurements to lake surface evaporation. A
coefficient of 0.70, which is applicable in the Wiggins-
Sterling area, has been applied to the data in Table 1 to
' derive total lake surface evaporation contained in Table 2.
Evaporation measurements are limited to the months of
April through October because during the winter months the
evaporation rates are low and freezing weather precludes
accurate measurement. Information published by the U.S.
Environmental Data Service indicates that for the Wiggins-
Sterling area May-October evaporation represents 738 of the
annual total. Using this coefficient the annual lake
evaporation was computed as shown in Table 2. The evaporation
for November through March was then determined by deducting
' the April through October amount from the annual total and
is also shown in Table 2.
1

' ~ Leonard Rice Consulting Water Engineers. Inc 17