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and consists of vegetation sampling data, valley floor cross-sections, and a transect location maps. The applicant also refers to the narrow and deeply incised nature of Middle Creek. There is no indication of past or current flood irrigation of these areas along Middle Creek and the geomorphic chazacteristics of this azea would not lend themselves to the development of an irrigation system. Based on the lack of flood irrigation potential, the narrow and incised nature of the valley bottom, and the lack of meaningful differences between the creekside and upland vegetative communities, the Division has determined that areas upstream of the Connel ditch lateral crossing of Middle Creek, as shown on Map 15, are not alluvial valley floors. In this case, the extent of farmable acreage would be 10 acres or less. The azeas are not presently and have not historically been farmed and evidence presented indicates that farming is not typically practiced on similaz pazcels in the region. A previous negative determination had already been made for those lands along Middle Creek downstream from the County Road No. 33 in section 12 to the first irrigation ditch crossing (Connel ditch lateral). Effects of Mining on Identified Alluvial Valley Floors Due to elevated levels of salinity documented in current and future mine discharge water, and to potential inhibitory effects of increased soil and alluvial ground water salinity on flood- irrigated and subirrigated crops, the potential for material damage caused by salt loading was a major concern which had to be evaluated for each of the AVFs identified above. Material damage was projected for sub-irrigation and for flood irrigation, using data obtained during low-flow-of-record years. The sub-irrigation scenario assumed streamflow would recharge alluvium during high springtime flows. The flood irrigation case utilized the period between June 1 and August 31. Assumptions and equations used in projecting water quality impacts are discussed in the Yampa River CHIA, which is on file at the Division office. Salt loading projections were arrived at by stream flow modeling and analysis of past monitoring results and projected dewatering activities. In the supplemental information package dated September 22, 1986, the applicant submitted information on vegetation cover and production by species for flood irrigated and sub-irrigated croplands on the affected alluvial valley floors. Alluvial bodies, irrigated fields and vegetation sample locations aze depicted on supplemental Map No. 1 "Twentymile Pazk Salt Loading Study Land Use and Hydrologic -Boundaries." This and other information was used by the Division to make the required findings with regazd to material damage. Required findings for identified alluvial valley floors on Fish Creek, Trout Creek, and Foidel Creek/Middle Creek confluence aze presented sepazately below. Fish Creek 1. The proposed mining operations will not interrupt, discontinue, or preclude farming of the alluvial floor. 31