REP11025

• Permit No: C1981019
• IBM Index Class Name: Report
• Doc Date: 8/22/2006
• Doc Name: 2005 AHR Review Memo
• From: Kent Gorham
• To: Jim Stark
• Annual Report Year: 2005
• Permit Index Doc Type: Hydrology Report
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone] Interoffice Memo
To: Jim Stark
From: Kent Gorha , ;~j
CC: Sandy Brown
RE: 2005 AHR review memo, Colowyo Mine, #C-81-019
COLORADO
DIVISION OF
RECLAMATION
MINING
- &-
SAFFTY
Bill Owens
Governor
Russell George
Executive Director
Ronald W. Ca[lany
Division Director
Natural Resource Trustee
Jim, as per your email request dated August 15, 2006 I have completed my adequacy review
of the 2005 Annual Hydrology Report for the Colowyo Mine, #C-81-019. The focus of my
review was the three surface water sites and the three alluvial ground water wells required to
be monitored. I did not review ponds or pond discharge.
Monitoring Freouencv
The operator completed the required monitoring in accordance with the plan as presented
beginning on page 4.05-10 of the approved permit. All sites were visited at the required
frequency and samples were taken as required with no excursions or misses.
All samples taken were tested for the required constituents with no noted exceptions.
Water Quality
Currently, deep bedrock aquifers are not monitored due to the demonstrated lack of bedrock
ground water that could be impacted by mining activities. Potential impacts at the present
time are limited to surface water quality impacts along Taylor Creek and Good Spring Creek.
Presently, Taylor Creek flows are limited due to the presence of large-scale mining
disturbance in the watershed and retention of water in the pit areas.
Total dissolved solids in Good Spring Creek increases from about 1300 mg/I upstream of
mining discharge (sediment pond outtalls) to around 1600 mg/I at LGSC, the downstream
surface water monitoring point. This increase could be attributable to irrigation return flows,
natural degradation due to geology, ormine-related springs from the Streeter Fill area.
Currently there are not sufficient monitoring points to determine the cause of the increase in
salinity.
The operator predicts flow volumes may be impacted in Good Spring Creek due to the mine
exercising their water rights. However, they predict that the actual impact will be less than
the accuracy of the flow monitoring devices to measure such small impacts. Increases of
TDS in the backfilled spoil areas are predicted.
Based on review of the data, the impacts to the hydrologic balance appear limited and are
within the limits of the predicted consequences.
Office of Office of
Mined Land Reclamation Adive and Inactive Mines