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On August 9, 2008 a storm caused an overflow of Prospect Pond and mud flowed over the <br />embankment and onto Highway 13; the return event for this storm is not certain. The next week <br />(August 13) water quality data was collected at point LGSC and the recorded value for TSS was <br />516 mg /1. Mitigation measures have since been implemented in the watershed. <br />Surface water data from Colowyo's monitoring program and observations by the Division have <br />to date agreed with the prediction of no significant impacts to surface water quality. While water <br />quality in and near the permit area is highly variable, changing in response to seasonal trends and <br />precipitation events, the data for monitoring sites LGC and LGSC indicate that there are no <br />significant long -term trends during the record of data (1982 — 2012) for Total Dissolved Solids <br />(TDS), TSS, or other parameters. <br />Potential Effects on Ground Water <br />Colowyo's operations may affect bedrock ground water of one formation, the Williams Fork <br />Formation, which contains the 10 coal seams to be mined and is the surface outcrop on the <br />permit area. However, impacts to the Williams Fork are deemed minimal because water <br />produced from coal zones is of known poor quality (documented in USGS and U.S. <br />Environmental Protection Administration (EPA) reports) and well yields are low. <br />There is little development of the ground water resource in the local area. The few wells that <br />have been completed in the Williams Fork interbedded sandstones yield less than five gallons per <br />minute and their uses are limited to domestic and /or livestock use. Nearby residents haul <br />drinking water supplies from Craig and Meeker. <br />The lack of a continuous, regional ground water system on the property within the stratigraphic <br />section of the Williams Fork Formation was documented in the 1979 report prepared by Leonard <br />Rice Consulting Water Engineers (Exhibit 7A of the PAP). <br />In addition, 17 test holes were drilled and their corresponding records collected when the <br />property was originally explored. All well data confirmed that where water was encountered, it <br />was limited both vertically and laterally, and it was encountered under perched conditions (a <br />discussion of well test data is in Section 2.04.7 of the PAP). <br />A slight potential for degradation of alluvial ground water was recognized in the 1982 Findings <br />Document. A plan to monitor alluvial ground water on Good Spring and Wilson Creek was <br />developed by Colowyo. Results of monitoring in AHRs indicate some detectable impacts on <br />alluvial ground water to date. A slight increase in TDS at New Good Spring Well from 1989 to <br />2012 is not significant. An increase in TDS in Gossard well from 1983 to 2006 was detected, but <br />the concentrations have been decreasing in recent years. <br />Pursuant to Rule 2.07.6(2)(c), the assessment of the probable consequences of the proposed <br />Proposed Decision and Findings of Compliance January 2012 <br />Permit Renewal 06 Page 137 <br />