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areas along the :diddle Creek valley door in sections IZ. '_3. and ?6 TAN R36W are not alluvial callev floors. Twennmile Coal Company provided information which is contained in the permit application as Exhibit q2a and consists of veeemtion sampling data, valley floor cross-sections. and a transect location maps. The applicant also refers ro the narrow and deeply incised nature of diddle Creek. There is no indication of past or current Flood irrigation of these areas alone Middle Creek and the eeomorphic characteristics of this area would not lend themselves to the development of an irrigation system. Based on the lack of Flood irrigation potential, [he narrow and incised nature of the valley bottom, and the lack of meaningful differences benveen the creekside and upland vegetative communities- the Division has determined that areas upstream of the Connel ditch lateral crossing of Ivtiddle Creek, as shown on Ivtap I ~, are no[ alluvial valley floors. In [his case, the extent of formable acreage would be 10 acres or less. The areas are not presently and have no[ historically been farmed and evidence presented indicates that farming is not typically practiced on similar parcels in the region. A previous negative determination had already been made for those lands along Ivfiddle Creek downstream from the County Road No. 33 in section 12 to [he first irrigation ditch crossing (Cannel ditch lateral). Effects of Minine on Identified Alluvial Valley Floors Due to elevated levels of salinity documented in current attd future mine discharge water, and [o potential inhibitory effects of increased soil and alluvial ground water salinity on flood irrigated and subirrigated crops, [he potential for material damage caused by salt loading was a major concern which had to be evaluated for each of the AVF's identified above. Material damage projections were calculated in both asub-irrigation and a flood irrigation case analysis, using data obtained during low-flow-of-record years. The sub-irrigation scenario assumed that the stream would recharge the alluvial aquifer in the spring during peak 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 dewa[ering activities. In [he sttpplemen[al information package dated September 22, 1936, the applicant submitted infornta[ion 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 veeetation sample locations are depicted on supplemental Map No. I "Twentymile Park Salt Loading Study Land Use and Hydrologic -Boundaries." This and other information was used by [he Division to make the required findings with regard to material damage. Required findings for identified alluvial valley Floors on Fish Creek, Trout Creek, and Foidel Creek/Ivliddle Creek confluence are presented separately below. C:\JHB\C82056\PR05\PROS FINDINGS 62800.doc 29