2004-12-07_PERMIT FILE - C1984063

• Permit No: C1984063
• IBM Index Class Name: Permit File
• Doc Date: 12/7/2004
• Section_Exhibit Name: Rule 2.04 Environmental Resources
• Media Type: D
• Archive: No

• Stream gaging has not been conducted in the permit area.
The United States Geological Survey (USGS) has operated, or
is currently operating, several gaging stations nearby. A
stream gage was operated on East Rifle Creek from 1937 to
1943, and from 1957 to 1982. The USGS has also conducted
stream gaging on Main Rifle Creek, and Main Elk Creek. None
of the above USGS stream gaging records are representative
of streamflow conditions in the permit area. Each of the
gaged streams is perennial, with a large watershed area.
Their headwaters are on the White River Plateau at an
elevation above 10,000 feet. The majority of runoff from
the gaged streams is derived from these headwater areas.
Unlike the low e]evation, ephemeral tributaries of the
permit area, the gaged streams are relatively high water
producers. Their streamflow characteristics are very
different than those of the tributaries at the permit area.
Because of the lack of representative, quantitative
streamflow data, the following discussion of water quantity
of the mine area is qualitative in nature.
With the exception of Harvey Gap, the tributaries draining
the area yield surface runoff only following precipitation
events or snowmelt. Peak discharges generally occur in
association with thunderstorm events during late summer or
. early fall. snowmelt runoff can occur during any winter
month, but is most common during the months of March and
April.
Grass Valley Reservoir releases irrigation water through
Harvey Gap drainage. Irrigation water is released from
April 15th through October 15th (personal communication,
Silt Water Conservancy District). The amount of water
released is dependent upon irrigation demands (see Figure
13: Harvey Gap Discharge - 1983). On Saturday mornings,
Silt Protect water users inform the Silt Water Conservancy
District of their water requirements for the following week.
Releases from the reservoir vary from 10 to 70 cfs, and
average about 35 to 45 cfs. Releases during the the early
irrigation season are generally less than those during the
mid to late summer months. Also, wet period releases are
less than those that occur during dry periods.
By the end of the irrigation season, reservoir storage has
been substantially reduced. Water diverted from East Rifle
Creek throughout the winter is stored in the reservoir so
that prior to the next irrigation season, reservoir capacity
is reached. Durrng the non-irrigation season, the flow of
Harvey Gap is about 0.5 cfs. The baseflow originates from
seepage from Grass Valley Reservoir.

50 Revised 5/87