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Coal View Gulch occurs to the east of the reclaimed mine pit and drains into the Yampa River. The mine has not physically disturbed Coal View Gulch or the unconsolidated streamlaid deposits in Coal View Gulch. These deposits are approximately one mile downstream from the reclaimed pit area. Land use along Coal View Gulch is undeveloped rangeland. No portions of Coal View Gulch are currently, or have been historically, flood irrigated. The unconsolidated streamlaid deposits in Coal View Gulch are approximately 200 vertical feet above the level of the Yampa River. Regional flood irrigation practices utilize diverted water from the Yampa River to flood irrigate fields contained within the terraces of Yampa River alluvium at nearly the same elevation as the river. Therefore, it would not be a regional practice to irrigate such deposits as are contained in Coal View Gulch from the Yampa River 200 feet below. The possibility exists that the average annual water yield from Coal View Gulch may be sufficient to practice flood irrigation on the unconsolidated sediments in Coal View Gulch. The applicant has submitted no information refuting this possibility: therefore, Coal View Gulch is determined to be an AVF. No portions of Coal View Gulch have been disturbed. Potential impacts to the Coal View AVF are discussed later. Description of Applicant's Proposal Sun Coal Company does not propose to physically disturb any areas underlain by unconsolidated streamlaid deposits. All areas that meet the geomorphic criteria of an AVF are located either downstream of the mine or on the other side of a drainage divide. There is a slight potential for the quality of water supplied to the AVFs to be degraded as a result of mining. This is discussed in the following sections. Discussion of Potential Impacts to AVFs The potential for the Yampa River AVF to be impacted by the operation is negligible. The applicant states that all mine facilities located next to the Yampa River have been designed and maintained to prevent contamination of the river. All facilities are located above the level of the 100-year flood event, and sedimentation facilities are designed and maintained to meet effluent limitations for any waters being discharged. The reclaimed pit area to the south of the Yampa River is largely isolated from contributing either ground or surface water to the Yampa River AVF. Bedrock strata dip to the west and largely parallel the course of the Yampa River. Any ground water contribution would have to proceed downgradient through the bedrock aquifers for long distances before eventually reaching the regional synclinal axis (Hayden Syncline) and contacting alluvial water. In the course of this travel, the potential effects of ground water degradation would be largely nullified by dilution. Surface water runoff from the reclaimed pit area is controlled by sedimentation facilities. The potential to impact the Yampa River AVF through impacts on surface water is negligible. _17_