REP28646

• Permit No: C1980007
• IBM Index Class Name: Report
• Doc Date: 4/30/1993
• Doc Name: 1993 Annual Hydrology Report
• Annual Report Year: 1993
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

Uera lrunnrcmrion and
Assessment of Surface
Water and AVF'S
Efforts were made in previous annual repons to
characterize baseline river water quality. The
purpose was to evaluate potential changes in
surface water quality due to mining activities at the
West Elk Mine. Continuous moniwrine of stream
^ows and periodic monitoring of spring discharge
rates are performed to provide the long term data
base from which possible impacts of mining can he
assessed.
Baseline Characterization of
Water Quality and Streamflow
A baseline characterization ut North Furk water
quality was performed in previous annual reports
to evaluate the potential changes in North Furk
water quality that could result IYom discharges at
the West Elk Mine. Baseline characterization was
performed downstream of the mine before the star
of construction in August 1981. Data sources were
• the USGS stream gauging station on the North
Fork near Somerset and the Mountain Coal
Company's water quality monitoring station on the
North Fork below the mine. Both s[atiuns were
downstream of the surface facilities area and d~wn-
stream of all discharge points. Baseline data and
analysis of these data are provided in the Mining
and Reclamation Plan for the West Elk Minc and
in the first annual hydrolo,~ry report.
Comparison of Baseline Water
Quality with Operational Data
Of the ten parameters selected for baseline charac-
terization, seasonal trends are apparent fur TDS,
TSS, and tidal iron. The other parameters do not
exhibi[ seasonal variation. Total dissolved solids
arc least concentrated in the North Fork during
the period between about May and July. The likely
reason for this pattern is during this period high-
TDS groundwater is diluted by snow runoff. Total
iron is most concentrated during this period. Total
suspended solids are most concentrated from April
to July.
At.~tssrnrnt for rho Pamir wrd ,t djanm itrcun
A comparison of baseline water yualin-data in the
North Furk of the Gunnison Rivu with 199'_
nwnitoring data shows no significant changes in
water quality in the Noah Fork. Nu apparent
changes in the water quality of the North Fork of
the Gunnison River can be auributed to allects of
mining during water year 1992.
Mine Water Management and
Impact Assessment
The discussion of the mine water system and
hydrologic impact assessment is organized by the
four sources of water:
• North Fork water
• sanitary wastewater
• mint water, and
• runoff from disturbed areas.
Use and discharge of water from that sources is
studied for its putemial to affect the North Fork.
North Fork Water
During water year 1982, the conditional right to
withdraw water Crom the North Fork wus deemed
absolute. When this water right is in priurity, water
can be pumped from the intake point to the
Ueshwater storage pond(s) within the surface
facilities area. In average years, this water right is
expected to be out of priurity from July to Septem-
ber. In 1977, it would have been out of priorirv
from April to September. fn water v'ear 1936,
MCC's Mt. Gunnison Pipeline water right met
quadrennial diligence fur the wnditionat portion.
Accordingly, an additional portion was deemed
absolute by the Division 4 Water Court. That
decision brought the absolute portion ro 0.33 cfs.
Pond FW-1 provides for water storage. Water can
also be stored in Sediment Ponds MB-I, MB-3,
and MB-3 under a separate decree. Storage is
usually limited to the maximum sediment level
elevation. Transfer to FW-I is possible as outlined
in the M 8c R Plan. Average withdrawals arc not
expected to exceed 400,000 gpd during the term u(
permit and are likely to be on the order of
2lA).000 gpd during start-up of longnvall operations
in the West Elk Mine and depending un product
Lion levels and requirements. During 1993 avcrane
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