2018-03-09_REPORT - C1981044 ‎(2)‎

• Permit No: C1981044
• IBM Index Class Name: Report
• Doc Date: 3/9/2018
• Doc Name: Annual Hydrology Report
• From: Moffat County Mining, LLC
• To: DRMS
• Annual Report Year: 2017
• Permit Index Doc Type: Hydrology Report
• Email Name: TNL
• Media Type: D
• Archive: No

2017 ANNUAL HYDROLOGY REPORT
1.0 INTRODUCTION
The following Annual Hydrology Report (AHR) presents hydrologic monitoring data from the Williams Fork
underground mine sites near Craig, Colorado for the 2017 calendar year. Site locations are described below.
This AHR is provided in fulfillment of reporting requirements under the Colorado State Division of
Reclamation, Mining and Safety (DRMS), Permit No. C-81-044. All references to "2017" in this report refer
to the 2017 calendar year (January 1, 2017 through December 31, 2017). Monitoring results for prior
calendar years (1983 through 2016) are presented in previous AHRs, although selected historical data (period
of record — POR) are summarized in some of the tables and figures within this AHR.
Following a discussion of Site Location and Background, this AHR provides a section on the 2017
Hydrologic Monitoring Program, which is further divided into the following subsections:
1) Groundwater Monitoring
2) Surface Water Monitoring
This is followed by the Summary and Conclusions Section. Tables, Figures, and back-up documentation are
located in the tabbed sections at the back of this AHR.
2.0 SITE LOCATION AND BACKGROUND
Williams Fork No. 5 and Eagle No. 6 Mines are underground coal mines located approximately seven miles
south of Craig, Colorado, on State Highway 13. The mine sites, and adjacent area lie along the northern foot
of the Williams Fork Mountains, which trend east to west. The elevation of the permit area ranges from a low
of approximately 6,130 feet in the Big Bottom area, to a high of about 7,400 feet in the Williams Fork
Mountains. The entire operation is located in Moffat County, Colorado. The general location of the site is
shown on Figure 1.
There are two (2) major northwestern Colorado Rivers, which intersect the permit area. These are: 1) the
Yampa River and 2) the Williams Fork River. The Yampa River runs from north to south through the permit
area, while the Williams Fork River runs from south to north and intersects the Yampa River just north of the
mine facilities area. The northern portion of the permit area is dominated by the Big Bottom alluvium, while
the southern and eastern portions of the permit area are dominated by the Williams Fork Mountains and the
river beds of the Yampa and Williams Fork Rivers.
C-81-044 2017 AHR