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Surface water within the Purgatoire River basin is used primarily for irrigation of strath and alluvial terraces. The width of the valley ranges from a few hundred to a few thousand feet. Where the geometry of the valley permits, limited flood irrigation is practiced. It is estimated that 6,000 ac-ft are diverted from the Purgatoire for irrigation above the Madrid station. Irrigated lands are, for the most part, located on the strath terraces. Irrigation on the lower alluvial terraces is also practiced, but the small size often precludes viable irrigated agriculture. Much more extensive irrigation occurs in the valley downstream of Trinidad. Surface water is also used for domestic, livestock, and municipal purposes. PROBABLE HYDROLOGIC CONSEQUENCES OF MINING A. The Golden Eagle Mine Mining activities at the Golden Eagle Mine began in 1976. Hydrologic effects from this operation would be expected to increase as the production increase. Many of these effects have been assessed in the applicant's hydrologic analysis provided in Exhibit 6 of the permit. The area of mine discharges measured during the first half of 1988 at the Golden Eagle Mine were higher than the estimates of inflow to the mine presented in Exhibit 6. The discharge rate has ranged up to nearly 500 gpm in 1988, but has dropped to just under 200 gpm at present. Earlier estimates ranged from ]79 gpm to 193 gpm depending on the transmissivity of the coal, The recent increase in discharge, however, is due primarily to the inflow experienced when a water bearing fracture zone was encountered in the Second Right entries in early 1988. No such point source flow was anticipated in the earlier study. The most recent inflow study for the Golden Eagle Mine was conducted in August 1989 and is included in Exhibit 10. The study consisted of mapping all mine inflows at the time, measuring or estimating inflow rates, and determining inflow sources. A total of 28 sources of inflow were reported, including nine new points of flow, and a total inflow of 454 gpm was estimated. A figure of 176 gpm had been recorded during a 1989 study. At this point, the mine was experiencing inflow above the preliminary estimates, The sources identified at that time were fault related; significant faults or fracture sy stems had been encountered in the Golden Eagle Mine in early 1988. Impact by the mine on the quantity of water available on the artesian bedrock aquifer being tapped by the fracture zone in the Second Right entry area is probable. The identity of this aquifer is uncertain, but the Trinidad Sandstone is a possibility. The Trinidad Sandstone is a regional aquifer with potential recharge areas at appropriate elevations southwest and west of the mines. -15-