PERMFILE103876

• Permit No: C1981019
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 10 VEGETATION INFORMATION
• Media Type: D
• Archive: No

33
vegetative cover and changes in the soil surface (i.e., surface
• drying and the formation of cracks) acted to curb runoff.
Factors affecting the amount of runoff and sediment yield for
the spring period deal primarily with snow conditions. Rarely did
• snow remain on the revegetation test plot for any length of time.
Early snowstorms in January and February 1976 were blown from the
plot, snowstorms in March and April were wetter and did not blow,
howe~~er, they melted rapidly and gave laroe quantities of runoff
water. The soil remained frozen during early spring, thus water
quality was high (Table 10).
Intensity of a summer thunderstorm and the duration of that
thunderstorm are the most important factors affecting summer runoff.
Amounts of precipitation and intensity of storms are recorded in
Appendix Table 1 (more detailed intensity data can be obtained from
-~d.A. Berg; Department of Agronomy; Colorado State University). The
condition of the soil is also an important factor affecting summer
runoff. The storms that contributed to runoff and sediment yield on
June 24 were only moderate in intensity and only 17.5 mm of precipi-
tation fell in that period. Because of the high runoff values and
the relatively small amount of precipitation that fell between June 2
and June 24, we feel that the soil surface must have been saturated
and essentially all precipitation that fell ran off.
Total precipitation recorded in gages on the revegetation test
plot starting October 30, 1975 through November 14, 1976 is 289 mm
• or 11.4 inches. There are no long-term records with which to com-
pare this value because the closest weather station is at Meeker
and this station may have different precipitation patterns. However,
it is felt that the 289 mm is lower than normal, thus the total values
for sediment loss and runoff could be considerably higher fora normal
year.
Snowpack measurements were attempted during the winter months;
on March 6, a snow depth transect was run across the revegetation
test plot and there was an average value of 10 inches of snow, per-
cent moisture of the snow was 18. However, for most storms the
snow either blew from the revegetation test plot or melted and a
Snowpack did not accumulate.
Results 1976
Runoff and Sediment Yields
Variation in both the amount of runoff and sediment yield is
extreme even for plots with similar treatments (Table 10). However,
some valuable conclusions can be readily drawn from the data; spring
runoff for treatments that were not mulched had much higher sediment
yields than treatments that were mulched. The sediment yield per
u