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The Clow in Tuttle Draw 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 dischazge is insignificant. This discharge has been monitored for ten 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. 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 neaz zero during the non-irrigation period. These flows vary from 0.006 cfs during April to 0.856 cfs in June. The New Horizon Mine 2 site is just west of the town of Nucla and is located in the mildly sloping upland azea of both Tuttle Draw and Calamity Draw, approximately in the middle of First Pazk. Especially in the New Horizon Mine 2 mining area, the surface water system is chazacterized by a "disjointed" tributary drainage system almost completely controlled by return flow ditches of the local irrigation network. West Lateral Imgation Ditch -The West Lateral irrigation ditch is part of the Colorado Co-operative Company's main ditch system that originates on the San Miguel River just upstream of Cottonwood Canyon (about 12 miles upstream of Naturita). Construction of the main ditch commenced in 1896, and water began flowing to the First Pazk azea via the ditch in the spring of 1904 (Mercer, 1967). The main ditch, as well as the main laterals, is basically an unlined open-channel excavated in shallow soils and sandstone. Where the ditch crosses drainages, pipes and aquaducts have been constructed to carry the flow. The main ditch has an average gravity run of four feet per mile from the San Miguel River to the First Park azea (Mercer, 1967). For a more historical discussion on the Colorado Co-operative Company's development of the regional ditch system, the reader should refer to Section 2.04.3, Site Description and Land Use Information. The West Lateral splits off the main ditch near the northern boundary of the Nucla Townsite. The West Lateral follows aridge-top course westwazd from Nucla through the New Horizon Mine 2 PR- OS area to the main north-south county road, then winds south and southwest until the conveyed irrigation water is used by the various shazeholders located along the ditch's course. A total of 18 diversions have been identified on this lateral; many consist of wooden "splitte boxes" that divert a consistent proportion of the irrigation water from the lateral to fields via small ditches and channels. Some diversions simply consist of pipes and hoses that also route irrigation water to slightly lower elevation fields. The West Lateral irrigation ditch is an unlined open channel. Where the ditch courses on the ridge-top sepazating Tuttle Draw to the north and the Calatity Draw Valley to the south, the ditch has been excavated through shallow soils into the highly fractured and weathered sandstone. Over 5