Laserfiche WebLink
10 acres or less. The areas are not presently and have not historically been farmed and evidence <br />presented indicates that farming is not typically practiced on similar parcels in the region. <br />During PR03 review, the Division determined that areas upstream of the Leiske ditch crossing of Foidel <br />Creek as shown on Map 15 (Sections l4, 21, 22, 23, and 28, TSN, R86W) are not alluvial valley floors. <br />This determination was based on the lack of sufficient water for flood ircigation, the lack of flood <br />irrigation, the small size of the valley bottom and the narcow nature of the stream, and the lack of <br />meaningful production or cover differences between the creekside and upland vegetative communities. <br />Therefore, in summary, the Division finds that all valley bottom areas along Foidel Creek above the <br />County Road No. 33 crossing are not alluvial valley floors. <br />Middle Creek <br />Prior to PR-03, no previous AVF determination had been made for areas above the Foidel/Middle <br />Creek confluence AVF on Middle Creek as these areas were not proposed to be affected or impacted by <br />the Foidel Creek mine operation. During the PR-03 review process, the applicant submitted <br />information to support that areas along the Middle Creek valley floor in sections 12, 23, and 26 TSN <br />R86W are not alluvial valley floors. Twentymile Coal Company provided information which is <br />contained in the permit application as Exhibit 42a and consists of vegetation sampling data, valley floor <br />cross-sections, and a transect location maps. The applicant also refers to the narcow and deeply incised <br />nature of Middle Creek. <br />There is no indication of past or current flood ircigation of these areas along Middle Creek and the <br />geomorphic characteristics of this azea would not lend themselves to the development of an irrigation <br />system. Based on the lack of flood ircigation potential, the narcow and incised nature of the valley <br />bottom, and the lack of meaningful differences between the creekside and upland vegetative <br />communities, the Division has determined that areas upstream of the Connel ditch lateral crossing of <br />Middle Creek, as shown on Map I5, are not alluvial valley floors. In this case, the extent of farmable <br />acreage would be 10 acres or less. The areas are not presently and have not historically been farmed <br />and evidence presented indicates that farming is not typically practiced on similaz parcels in the region. <br />A previous negative determination had already been made for those lands along Middle Creek <br />downstream from the County Road No. 33 in section 12 to the first irrigation ditch crossing (Connel <br />ditch lateral). <br />Effects of Minine on Identified Alluvial Valley Floors <br />Due to elevated levels of salinity documented in current and future mine discharge water, and to <br />potential inhibitory effects of increased soil and alluvial ground water salinity on flood irrigated and <br />subircigated crops, the potential for material damage caused by salt loading was a major concern which <br />had to be evaluated for each of the AVF's identified above. <br />Material damage projections were calculated in both asub-irrigation and a flood irrigation case analysis, <br />using data obtained during low-flow-of-record years. The sub-irrigation scenario assumed that the <br />stream would recharge the alluvial aquifer in the spring during peak flows. The flood irrigation case <br />utilized the period between June 1 and August 31. Assumptions and equations used in projecting water <br />quality impacts are discussed in the Yampa River CHIA, which is on file at the Division office. Salt <br />26 <br />