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The Colorado Cooperative Ditch Company diverts as much as 155 cfs of water from the San Miguel River approximately ten miles east of the town of Nucla, The main diversion ditch then flows westerly passing just north of the town of Nucla. It then flows northwestward passing north of the Nucla Mine. Diversion ditches distribute water to mainly agricultural users in the area. Additional uses include domestic, municipal and stock pond consumption. The Nucla Mine is located downslope from the main ditch in the gently sloped upland of Second Park. This is just north of Tuttle Draw and is totally within its watershed. The proposed Nuc1a East Mine site is just west of the town of Nucla and is located in the mildly sloping upland area immediately north of Calamity Draw, approximately in the middle of First Park. The above mentioned Parks consist of recent undifferentiated aeolian silts and sands overlaying the Dakota and Burro Canyon Formations. Since the completion of the irrigation system for this area in about 1910, these areas have been intensively reworked for irrigated agriculture. Especially in the Nucla East mining area the surface water system is characterized by a "disjointed" tributary drainage system almost completely controlled by return flow ditches of the local irrigation network. The perennial flow nature of both Tuttle and Calamity Draws is largely due to the local irrigation practices. Over the years this more or less constant source of water in these drainage systems has encouraged the growth of vegetation, This has resulted in the channels becoming more erosionally stable but more incised. In the Nucla Mine area the Second Park Lateral Irrigation Ditch is in continuous operation from mid-April through mid-October, While this water is primarily used for irrigation, important secondary uses include maintaining water levels in Stock ponds and domestic cisterns. During the non-irrigation season the ditch is occasionally turned on to maintain the water levels in the stock ponds and cisterns. The flow in Tuttle Draw, as discussed in Tab 7- Pages 112 to 119 of the permit revision application, is primarily from irrigation return waters. Occasional precipitation and snowmelt events contribute waters to this Draw. Sediment Pond 001 discharges water to this drainage system regularly with flows characterized by lows in April, averaging about 0.01 cfs, to highs in September of 0.9 cfs. Sediment Pond 006 discharges significant flow to Tuttle Draw beginning in May and continuing through August. Average flow for this period is 0.4 cfs. In September discharges from Sediment Pond 006 rapidly decline. In January through April the average discharge is insignificant. This discharge has been monitored for eight years. These flows appear to be greatly influenced by local irrigation practices. Impacts on water quality from these ponds on Tuttle Draw are very limited due to the high dilution ratios. These discharges occur upstream of surface water monitoring site SW-N3 (see Exhibit 7-1 of the permit revision application). Measurements of water flow at SW-N3 show rates from 0.019 cfs to 9.35 cfs. Flows in April were measured at 0.665 cfs and at 9.35 cfs in September. The West Return Ditch is also tributary to Tuttle Draw just upstream of SW-N3, Contributions from this source generally decline to near zero during the non-irrigation period. These flows vary from 0.006 cfs during April to 0.856 cfs in June. Flows in Calamity Draw (see Tab 7 -pages 119 to 122) generally reflect local irrigation practices. Water from the West lateral Ditch's return irrigation -9-