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~r P. e~C confluence which '~a ve been d=t?r^tl ned h% the Ji•n •;i un to meet allUVl al valley fluor criteria based on existiny and poten~iai ~iuod irriyation and a presumed capability to support sub-irrigated vegetation. Tile required findings for the upper i4iddle Creek alluvial valley .°]oor are set forth below. 1. The proposed mining operations would nut interrupt, discontinue, or preclude farming on the alluvial valley floor. The AVF would not be directly disturbed by mining operations or associated facilities. 2. The proposed mining operations would not cause material damage to the quantity or quality of surface and ground water that supply the alluvial valley floor. Approximately 300 acres of reclaimed land in the northeast portion of Mine 1 drain into Middle Creek, and thus the potential exists for water quality changes that could affect the identified alluvial valley floor located on Upper i9iddle Creek downstream from the permit area. Based on area/discharge relationships developed for spoil aquifer springs at Mine 1 and Eckman Park, flood irrigation water salinity is projected to increase from approximately 0.5 mmhos/cm to 0.9 mmhos/cm, and the salinity of alluvial water supplying the AVF is projected to increase from approximately 0.6 mmhos/cm to approximately 1.4 mmhos/cm. Since both projected root zone soil salinity and alluvial ground water salinity would be below the 1.5 mmhos/cm threshold level for moderately sensitive species, no production decrease would result. Data contained in Exhibit 43 of Twentymile Coal Company's Foidel Creek Life-of-i4ine Revision indicate that less than 3% of the relative vegetation cover on the Middle Creek AVF is composed of moderately sensitive species. Therefore, significant decreases in crop production would not occur unless salinity levels were double the projected values. 3. The proposed operation would preserve, throughout the mining operation, the essential hydrologic functions of the alluvial valley floor. As with the Foidel/Middle Creek confluence, the AVF would not be directly affected by mining and since water quality effects would not result in material damage, the essential hydrologic functions of flood irrigation and subirrigation would be preserved. IX. Cumulative Hydrologic Impact Study and Probable Hydrologic I and 2.07.6(2)(c) This Cumulative Hydrologic Impact Study (CRIB) for a part of the Yampa River basin has been prepared by the Colorado i4ined Land Reclamation Division (CMLRD) pursuant to Rule 2.07.6(2)(c). This CHIS assesses the projected cumulative hydrologic impacts of all anticipated coal mining operations in the basins draining the Eckman Park Complex and the Little Middle Creek Tract areas. The Little Middle Creek (LMC) Tract encompasses approximately 500 acres to the south and west of Eckman Park. CYCC has recently submitted a revision application to mine the Wedge and Wolf Creek seams within the tract. The surface water and ground water areas discussed in the CHIS are defined by ~n L~