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6 potential) or subirrigation. On the basis of the information provided, the North Fork of the Gunnison and its associated alluvium in Section 18 (T135, R9079) , and Sections 13 and 1~ (T135, R91::') are _°ourd to .-.met t :e criteria of alluvial valley floors. The alluv_al valley floor _orobablc continues downstream, but for those areas no determinaticn ..illce ...~.._ at this ti:C2. Alluvial i'a11ey Floors - .findings 1. The proposed surface coal mining operations would not interrupt, dis- continue, or preclude farming on an alluvial valley floor (Rule 2.Oo.6(5)y. Although underground mining would occur in areas adjacent to the alluvial valley floor, all surface disturbances are located more than a mile upstream from the alluvial valley floor., and would not affect agricultural activities on the alluvial valley floor. The alluvial valley floor would not be undermined by the proposed operations. 2. The proposed surface coal Wining operations would not materiallu damace the u_uantity and quality of water in surface and underground water systems- that supply those alluvial valley floors or portions of alluvial valley floors. A11 of the surface flow from the perry t area drains to the North Fork of the Gunnison. The applicant has monitored the largest t~;o drainaoes crossino the permit area. Duriro this period, Lone Pine Gulch has exoer-enced no flow. S_ulvester Gulch has experienced ephemeral stream f1o:v. The recorded yield of 208 acre -ft/y r. in 1976 is Zess ti~an 1`0 of the mean annual fZ c.; in the North Fork of the Gunnison River, Surface flo:o supplied to the alluvial valley floor along the North Fork comes primarily from areas upstream from the proposed permit area and this flow is regulated by Paonia reservoir located approximately 6 miles upstream of the alluvial valley floor. !dining operations would require approximately 150 acre-ft. of fresh water per year for sanitary and drinking water. The possible effects of this water removal ,upon the water supplied to the alluvial valley floor has not been assessed. a,~/ Stzpulati on: lJITHIN SIX MONTHS OF THE PERMIT ISSUING, THE APPLICANT SHALL DEMONSTRATE THAT THE MINING OPERATIONS' FRESH WATER USRGE WOULD NOT MATERIALLY DAMAGE THE QUANTITY AND QUALITY OF THOSE WATERS SUPPLYING ALLUVIAL VALLEY FLOORS. The applicant's discussion of probably hydrologic consequences has identified no anticipated changes in surface water quality. A11 runoff from disturbed surface areas, including runoff from the waste disposal site, would drain through an approved sediment control system. A11 discharges would be made under the conditions of the applicant's NPDES permit, and any effluent must meet the water gaulity standards for the receiving streams. If necessary, discharges would be~treated to assure compliance with water quality standards. As a result, no degradation in the quality of surface waters supplied to the alluvial valley floor is anticipated.