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Ettecutiue Summary Agency Preferred Alternative. Formal consultation with the U.S. Fish and Wildlife Service was conducted on potential effects to Colorado River fish (refer to Threatened and Endangered Species). Water would also be taken in priority from Piceance Creek for a short time for hydrostatic testing of the natural gas pipeline. Under the Accelerated Development Alternative, potential effects on surface water would be similaz to those described for the Proposed Action. Temporary increases in sedimentation from ground-disturbing activities would be more pronounced due to the greater azea of exposed soil at any given tune period. Water usage would increase to 3,475 acre-feet per yeaz (4.8 cfs). Groundwater. Groundwater quantity would not be affected under any of the three alternatives. Impacts to groundwater quality under the Proposed Action and Accelerated ]development Alternative could occur from accidental release of production fluids or from migration of poorer quality groundwater from the Lower Aquifer to the Upper Aquifer. The Alluvial Aquifer could be degraded if there were a liner failure at the evaporation ponds. However, the probability of adverse impacts to groundwater is low considering the project design and by leak detection monitoring and response procedures. Monitoring would be used to determine whether releases have occurred, to evaluate the impacts of a release, and to design corrective :rctions. Under the Agency Preferred Alternative, potential impacts to groundwater quality would be further lessened. It is unlikely adverse impacts would occur to groundwater quality considering the detailed monitoring and response programs and revised well plugging and abandonment procedures. Through the Groundwater and Surface Water Monitoring Plan, baseline water quality would be established. Any deviations in groundwater quality during :mining would be • identified and corrective actions implemented. The Agency Preferred Alternative also includes guidance on Quality Assurance/Quality Control procedures necessary to ensure the collection of valid water quality samples. A Well Field Response Plan has been prepazed to minimise potential impacts associated with well piping leaks or spills. Potential impac;ts.to drinking water aquifers would be minimized through the top to bottom cementing of retired wells. Air Quality. The Proposed Action and Agency Preferred Alternative would. cause increases in the emission of fugitive dust, PM,o, nitrogen oxides (NO,J and carbon mono:~ide (CO) during construction and operation from vehicles, heavy equipment, well-drilling, processing facilities, and well field operation. Maximum ground level concentrations of air pollution (including background and interacting sources) were predicted to be well below the apF~licable standards (National Ambient Air Quality Standards [NAAQS]/Colorado Ambient Air Quality Standards [CAAQS]). The cumulativer impact analysis performed for nitrogen dioxide (NOz) and PM,o from the processing facilities demonstrated that impacts would be less than the Class II increments. Results from the Class I increment evaluation indicate that the Irroject would not exceed Class I increments. A Level 1 regional haze visibility analysis indic~des no significant effects to the visibility in the Flat Tops Wilderness Area and was verified using a more detailed Level 2 analysis. An analysis performed for atmospheric deposition (i.e., acidification process) indicates that the Proposed Action and Agency Preferred Alternative would snot have a significant effect on lake water chemistry within the Flat Tops Wilderness Area. The Accelerated Development Alternative would increase emissions up to a factor of three. This would result in significant air quality impacts. A screening level review indicates that the Accelerated Development Alternative could be accomplished without exceeding the ESQ