REP34514

• Permit No: C1981071
• IBM Index Class Name: Report
• Doc Date: 3/18/1996
• Doc Name: 1994 ANNUAL HYDROLOGY REPORT PN C-81-071
• Annual Report Year: 1994
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

Permit C-81-071 1994 Annual Hydrology Report
• runoff and spoil spring flows. All of the plots show the typical seasonal variation with high flows
during spring runoff. Historically, discharges from the ponds ceased in the summer and did not
begin again until the next spring. Three ponds, A (Site 39), D (Site 84) and F (Site 87), began
discharging year round in late 1984. This is due to the spoil springs located in the drainages of
Ponds A and F and the past underground mine discharge to Pond D. Due to low runoff and
utilization of Site 114 and Site 87 for emergency water supplies by Twentymile Coal Company,
Sites 30 and 87 experienced periods of no discharge during 1994.
Pond A now has a base flow of approximately 0.7 cfs, Pond D 0.3 cfs and Pond F 0.1 cfs.
Pond F did not discharge significant amounts in the 1994 irrigation season, and showed a
decreased flow since 1991, due to periodic pumping of the pond and Spring 114 for mine use.
The discharge from Pond D decreased in 199 due to cessation of discharge from the
underground mine to Pond D. Flows from these ponds have changed Foidel Creek from an
ephemeral to a perennial stream. Peak discharges from the ponds do not seem to have
changed significantly because the spoil spring water would probably have discharged as
snowmelt runoff anyway.
Water Quality
Summaries of the water quality data for the Mine 1 ponds are presented on Tables 53 through
62 and on Figures 45 and 50 through 54. The field conductivity data shows some typical
seasonal variation: the water quality improves during spring runoff. Ponds A, D, F, and H
appear to be impacted by spoil spring inflows. The discharge rates from H are not significant
• during irrigation season and therefore do not cause any significant impacts
For the ponds affected by spoil springs, increased calcium, magnesium, sulfate, dissolved
solids, and SAR were observed. No significant changes in parameters were observed for the
ponds during the 1994. The observed Trout Creek conductivity increase between sites during
1994 was not enough to cause material damage, and occurred during a period of irrigation
withdrawals. Also, the water quality of Trout Creek was better than maximum levels predicted
in the past salt-loading calculations performed as part of the "probably hydrologic impacts"
section of the mine permit application. The only insignificant discharges at Mine 2 were
recorded during spring runoff. Therefore no impacts to Fish Creek were observed as a result of
runoff from Mine No. 2 in 1994.
IMPACTS AND FUTURE MONITORING
Increased salt loading from the Mine No. 1 discharges have been observed since 1982. They
appear to have leveled off starting in 1986. The increased salt loading was predicted as
described in the "probable hydrologic consequences" section of the permit renewal application.
Actual observed salt loading in Trout Creek during the irrigation season resulting from surtace
mining operations is less than predicted and has not caused material damage. The total
recoverable manganese levels in Foidel Creek are below the stream standard.
• Localized increases in dissolved solids in the Foidel Creek alluvium have been observed;
however, these increases are confined to areas immediately adjacent to the mine and no
EP4TE%T.DOC 03717/97 Page 8