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~, OSM Comments for the Draft Proposed Decision and Findings of Compliance for Mt. Gunnison Hine, 320 Acre Modification 1. The text, on page 27, states that there is insufficient data and that qualifying assumptions for application of the methods were not in analyses of mine inflow and extent of the cone of depression caused by mining, This inadequacy should be explained. 2, The text, on page 31, refers to consequences, "during the first five years of mining***". It is not clear whether this section is referring to the 5-year term now in effect or five years beginning with approval of the proposed 320 acre modification. Please clarify. 3, The paragraph explaining Stipulation No. 8, on page 31, states that, "The applicant has not considered the possibility of increased total dissolved solids because of pond retention". This apparent inadequacy in analysis of hydrologic consequences should be explained. 4, The Proposed Decision document should include a summary of the analysis of the depletion of flow to [he upper Colorado River with respect to the U.S, Fish and Wildlife Service's Windy Gap policy. We understand that the applicant's response on depletion of flow was submitted after this draft of the Proposed Decision document was prepared. We have reviewed the applicant's submittal determining the depletion of streamflow to the Upper Colorado River basin (UCRB), dated April 22, 1985, The applicant appears to have included "precipitation runoff" as an augmentation to streamflow in [he UCRB. Neither natural runoff from unaffected areas of the permit area, nor treated surface discharge from affected areas are factors in the computation of depletion. Non-alluvial ground water made Sn the workings and discharged to the surface-water system may be used to offset surface depletions. 5. The subsidence effects section (pages 33-37) should specifically note that mining has not been approved and will not be approved in the Minnesota Creek basin with this proposed decision.