1994-10-21_GENERAL DOCUMENTS - C1980007

• Permit No: C1980007
• IBM Index Class Name: General Documents
• Doc Date: 10/21/1994
• Doc Name: Proposed Decision & Findings of Compliance for PR5
• From: Jumbo Mountain Lease
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

The Minnesota Creek drainage extends approximately
53.5 square miles (Figure 2) . The West Elk life-of-mine
area is drained by five tributaries to Minnesota Creek_
These tributaries include East Fork, Horse Creek, South
Prong, Lick Creek, and Dry Fork. Characteristics of the
drainages are given in Table 3 . Lick Creek and Dry Fork
average slopes are generally steeper and the watersheds are
at higher elevations than those tributary to the North
Fork. Based upon streamflows measured in water year 1978,
the water yields from these drainages are nearly an order
of magnitude greater than that from Sylvester Gulch.
The evaluation of flow within the Minnesota Creek drainage
can only be considered an approximation due to infiltration
and seepage losses, seasonal variations in precipitation
and potential evaporation and sampling difficulties.
Nevertheless, approximately 1,000 acre-feet is annually
transferred from the Little Gunnison Creek to the Dry Fork
of Minnesota Creek, and the average annual flow of the East
Fork of Minnesota Creek is approximately 19,921) acre-feet.
Irrigation ditches annually remove about 20,001) acre-feet
from Minnesota Creek.
Two reservoirs are located within the Minnesota Creek
drainage. Minnesota Reservoir is located on the Dry Fork.
It has a decreed capacity of 1,285 acre-feet, but the
actual capacity may be closer to 500 acre- feet_. Beaver
Reservoir is located on the East Fork of Minnesota Creek
and has an absolute decreed capacity of 1,620 acre-feet and
a conditional decree of 522 acre- feet. Both reservoirs
store water for irrigation purposes and are filled during
spring :-=off. They are usually drained by late August or
early September.
Water quality data have been collected at several sites
throughout the Minnesota Creek drainage. The data indicate
that these waters are of a calcium bicarbonate type with
relatively low total dissolved solids concentration.
Minnesota Reservoir appears to have an effect on the water
quality characteristics of Dry Fork. Detention of Dry Fork
flows in the Minnesota Reservoir results in a decrease in
total suspended solids (TSS) or turbidity, a slight
increase in temperature, dissolved oxygen (DO) , and total
dissolved solids (TDS) . The increase in TDS is most likely
a result of evaporation losses. There is a slight increase
in alkalinity and, as a result, a slight increase in pH.
In all :Likelihood, these changes are also a result of
evaporation losses. All of the changes in water quality
observed are what would be expected as a result of
impounding water in a shallow reservoir in a semi-arid
climate.
There are over a hundred (100) springs located throughout
the Wes- Elk study area. Measurements indicate that spring
flows generally decrease from a high in the early summer to
a low in the fall. A number of the springs are ephemeral,
indicating that their sources are small localized aquifers
(i .e. landslide deposits, colluvium, lenticular sandstones,
etc. ) . There are a total of nineteen (19) decreed spring
water rights on or near the West Elk permit area.
2 . Probable Hydrologic Consequences of the west Elk Mine
A determination of the probable hydrologic consequences of the
proposed mining and reclamation activities at the West Elk Mine
24