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A portion of the non-exempt AVF vas historically flood irrigated with a por Lion subirrigaced and another portion potentially flood irrigable. Surface water used to irrigate the non-exempted AVF vas diverted from the High:ine Canal. Water '_a the Highline Canal is diverted from the Colorado River ap- prozimate'_y one mile upstream from the disturbance and it will not be affected by subsidence or by nine discharge. Discharge from the Roadside and Cameo Piines will have a minor salt loading effect on the Colorado River by increa- sing specific conductance aad total dissolved solids by O.7.z. This will have a small effect on the eater supplying the subirrigaced portion of the AVF, since recharge water from the river is the source of alluvial ground water. During mining, the sediment control system will temporarily reduce surface `loos, remove sediment loads and increase salt loads. Salt loading effects of the sediment pond discharges are uaquantifiable at present since none of the ponds have discharged. However, the comparatively minor quantities of dis- charge from the ponds will result in a negligible effect on water quality of the Colorado River. The mini~ operations have already disturbed most of the alluvial valley floor with construction of the overland conveyor and loadout facility and no addi- tlonal disturbance is planned. The compa~ will be required to restore [he essential hydrologic functions on the entire alluvial valley floor where dis- turbance has occurred. The compa~ identified subirrigati~on and flood irriga- tion as the essential hydrologic functions of the AVF. Previously, the High- 11ne Canal (which upslope of the AVF) has been the eater source for irrigating a portion of the. AVF. No irrigation presently takes place in the site area and sublrrigation is controlled by the eater level is the Colorado River. Reclamation aad restoration of the essential hydrologic functions will *_nvolve removing all facilities rega:-ding to the approximate original river terrace topography, replacing topsoil and revegetating and restabillzing a flood irri- gation system. Powderhorn Coal Company will monitor shallow ground water levels at 3 piezometers locations and at one yell near the unit train loadout facility. The vel'_ is located near the coal storage pile to monitor the effects of leaching of the coal storage pile. Water levels will be taken aon- thly, sad water quality samples will be collected on a quarterly basis from the well. -d-