GENERAL32420

• Permit No: C1981013
• IBM Index Class Name: General Documents
• Doc Date: 6/28/1990
• Doc Name: Proposed Decision & Findings of Compliance for PR1
• Permit Index Doc Type: Findings
• Media Type: D
• Archive: No

The Golden Eagle Mine is located downstream of the confluence of the
North and Middle Forks of the Purgatoire River, and approximately two
miles upstream of the confluence of the South Fork and the main stem of
the Purgatoire River at Weston.
The headwaters of the Purgatoire River system are in excess of 9,000 ft.
elevation and receive substantial snowfall, For example, the mean annual
precipitation at North Lake at the head of the North Fork (elevation
8,800 ft.) is 20.55 in, of which 7.48 in. is in the form of snow. On the
other hand, the mean annual precipitation at Trinidad (elevation
6,030 ft.) is 13.22 in. and only 2.19 in, of this total is in the form of
snow, The disturbed areas of the mine sites are between 7,000 and
7,500 ft. in elevation and are located between the Trinidad and
North lake stations. The mean annual precipitation at the New Elk Mine
is calculated to be 16.9 in. with snowfall contributing 5.00 in, to this
total .
In order to assess the effect of mining operations on the river the mine
operator has monitored surface water flow and quality at three stations
along the Purgatoire River since February 1984. The stations are
designated PRS-1, 2, and 3. The records of this monitoring appear in
Exhibit 10 of the application. PRS-1 is located upstream from the
surface facilities at New Elk Mine and the confluence of the North and
Middle forks of the Purgatoire River. PRS-2 is below the New Elk surface
facilities and confluence of the North and Middle Forks of the Purgatoire
River but above surface facilities at the Golden Eagle Mine. PRS-3 is
located downstream from the Golden Eagle Mine facilities. The locations
of these stations are shown on Map 7.
Although peak flows in the Purgatoire occur in response to intense
precipitation events during the summer, the monitoring records
demonstrate that the bulk of the flow in the Purgatoire River results
from snowmelt and normally occurs during the months of April and May. In
monitoring year 1987, for example, the highest flow recorded at PRS-3 was
102,13 CFS and occurred in April. Low flow for the year at PRS-3 was
8.22 CFS and occurred in January. Average flow for the Purgatoire River
in 1987 was 38.80 CFS at this station.
Water quality data for Stations PRS-1, 2, and 3 is also reported in
Exhibit 10, The water in the Purgatoire is a calcium-bicarbonate type
water. Total dissolved solids concentrations in the area of the mines
normally run below 300 mg/1 throughout the year.
Monitoring below the New Elk Mine shows some increase in sodium
reflecting the effects of past mining activities. This effect is diluted
by flow from the North Fork of the Purgatoire River which joins the
Purgatoire River between the New Elk and Golden Eagle mines.
E. Water Use
Ground water used in the area comes primarily from shallow alluvial
sources. This water is used primarily for domestic, livestock and
irrigation purposes. Alluvial ground water is also used for municipal
water downstream from the mines. A few deeper wells in the vicinity of
the New Elk Mine may tap bedrock ground water sources. Water from these
bedrock wells is used for watering livestock and wildlife,
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