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

Inflows from faults and fractures located outside stream
valleys generally dry up with time or flow intermittently
at discrete points along the fault or fracture. Those
which continue to flow have flow rates which diminish to a
trickle. Such inflows may represent the dewatering of
lenticular sandstone units with limited recharge areas, or
may represent flows through fracture zones extending to the
surface which have narrow recharge zones on steep slopes.
Discharge of ground water occurs through numerous seeps and
springs. Over 100 springs are located in the life-of-mine
area. The locations of these springs can be found on Map
37 and 37A, Springs and Stock Ponds Location and Springs
and Ponds, Jumbo Mountain, respectively.
c. Surface Water
The North Fork of the Gunnison River is the major drainage
for the mine area. Smaller streams in or adjacent to the
life-of-mine areas are all tributary to the North Fork.
Figure 1 contains the drainage map of the study area with
the locations of streams and reservoirs which are described
in the following discussion.
The North Fork has an average annual streamflow at Somerset
of approximately 313,500 acre-feet per year (1962-1979) .
The flow is regulated by the Paonia Reservoir on Muddy
Creek five miles upstream of the town of Somerset. The
reservoir became operational in 1962. Water yields during
that period have ranged from a high of 601,800 acre feet
per year in water year 1984, to a low of 82,270 acre feet
in water year 1977. Flow records for the North Fork of the
Gunnison River near Somerset are given in Table 1. Water
quality parameters for the North Fork are given in Table 2.
As indicated, water in the North Fork is a calcium
bicarbonate type. There are also moderate levels of
sulfate and salinity averages less than 100 mg/l.
The West Elk mining operation is adjacent to Sylvester
Gulch, Lone Pine Gulch, and Gribble Gulch, which are
ephemeral streams that flow directly to the North Fork. No
flow has been observed in Lone Pine Gulch for a period of
several years. Sylvester Gulch has a drainage area of 4 .25
square miles. The hydrologic yield of Sylvester Gulch is
low compared to the other watersheds in the West Elk
life-of-mine area. This is due to the fact that it drains
an area which is lower in elevation and has gentler slopes.
Monitoring of Gribble Gulch, which could potentially be
impacted by mining in Jumbo Mountain, began in September
1993. Most of the West Elk Mine underlies the Minnesota
Creek drainage to the south.
The Minnesota Creek basin is a significant drainage system
occurring south of the five-year permit area, but within
the life-of-mine coal lease boundary. Minnesota Creek and
its tributaries drain the southern portion of the coal
lease area. These tributaries include Horse Creek, South
Prong, Lick Creek, Dry Fork, and East Fork. Lick Creek and
Dry Fork are the only tributaries of Minnesota Creek which
are proposed to be undermined. The operator has proposed a
current plan of limited extraction in these areas and has
developed a detailed mitigation plan to monitor subsidence
and to compensate for any loss, if any, in vested
downstream water rights. Minnesota Creek enters the North
Fork of the Gunnison near Paonia.
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