2021-12-22_PERMIT FILE - C1981019A

• Permit No: C1981019A
• IBM Index Class Name: Permit File
• Doc Date: 12/22/2021
• Section_Exhibit Name: Rule 2 Permits -ST
• Media Type: D
• Archive: Yes

RULE 2 PERMITS
The alluvial aquifer water quality is principally a magnesium sulfate or magnesium bicarbonate type.
Water quality from the shallow Gossard well is a mixed cation -anion type water, with neither a dominant
cation or anion. The average TDS content of the alluvium ranged from 788 mg/L in well A-6 to 2,310
mg/L in well MT -95-02. The alluvial groundwater also often exceeds the secondary drinking water
standards for dissolved iron and manganese. Results are summarized in Table 2.04.7-29.
Groundwater Use — Groundwater use in the South Taylor/Lower Wilson Permit Area is limited due to
the depth to water, the generally poor quality, and its limited overall availability. Colowyo installed and
developed two wells in the late 1970's to supply a portion of the domestic needs. The two deep wells,
Taylor Creek Nos. 1 and 3 are located in Section 33, T4N, R93W, and in Section 4, T3N, R93W
respectively (Map 11B). Taylor Creek No. 1, completed to a depth of 850 feet in the Williams Fork
Formation, produced 40 gpm with a depth to water of 110 feet from the surface. Taylor Creek No. 3,
completed to a depth of 2,284 feet in the Iles Formation, produced 20 gpm with a depth to water of 135
feet below ground surface. Neither well has been pumping since the early 1980's. Colowyo installed a
new potable water supply well in 2004. This well was completed above the Km bed (depth 1000 feet)
and is located in the NW'/4, Section 3, T3N, R93W. The production rate is less than four gpm.
The information collected from Colowyo's existing operations indicates that groundwater is very limited,
even to depths significantly below mining activities. This conclusion is supported by the depths of the
potable wells, Taylor Creek No. 1 and Taylor Creek No. 3, and the newer water well. Further evidence of
lack of significant groundwater resources in and adjacent to the mine area is that most residents in the
general area haul drinking water from the towns of Craig or Meeker. A list of wells in the permit area and
adjacent area is included in Table 2.04.7-37. Most wells are used for monitoring purposes and/or are
registered to Colowyo. 20 wells in the permit and adjacent area are registered to entities other than
Colowyo. Of these 20, four are now owned by Colowyo.
Groundwater is not currently used for industrial or mining purposes such as watering haul roads or dust
control. Water for these purposes is supplied by Wilson Reservoir located in Section 13, T4N, R93W
(Map 11 B).
2.04.7 (2) Surface Water Resource Information
Both general and detailed information regarding surface water in the vicinity of the mining areas are
presented in the following subsections.
General Surface Water Resource Information
Surface Water Characteristics — The Colowyo Coal Company's general area of operation is located
within the Lower Yampa River basin in northwestern Colorado. The physiography of the area consists of
a montane region and an upland plateau. The montane region typifies the headwater reaches of most
drainages, which are characterized by steep, narrow, bedrock controlled channels. The channels are
generally straight with limited sediment accumulation. Active erosion is limited to areas with erodible
shale or friable sandstone (CDM, 1985b).
The upland plateau region is characterized by generally flat, low-lying mesas, divided by meandering
streams with shallow gradients. The valleys of the larger streams, including Milk Creek and the Yampa
River are typically broad, with aggrading of the alluvial/colluvial materials. Erosion and sloughing of
stream banks is often severe due to the abundance of unconsolidated materials in the valley bottom, and
typically results in increasing sediment loads to the drainages (CDM, 1985b).
South Taylor/Lower Wilson— Rule 2, Page 23 Revision Date: 11/18/16
Revision No.: MR -163