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Secricst - 2.04.7 <br />included, as a minimum, analysis of surface water samples for pH, electrical conductivity (EQ, total <br />• suspended solids (TSS, total dissolved solids (TDS), total iron (Fe), and total manganese W. <br />Table 2.04.7-T1, Surface and Ground Water Parameters, lists the analysis parameters for ongoing <br />operational hydrologic monitoring. Generally, baseline and operational surface water monitoring have <br />focused on specific mine disturbance areas, so there have been some changes over time in the <br />designated surface water monitoring sites. <br />Table 2.04.7-T5, Historic Surface Water Monitoring Summary, identifies all of the sites for which <br />surface water monitoring records are available and notes the monitoring interval(s) for each. The <br />following sections suunmatize water quality characteristics, based on available monitoring and analysis <br />information, for each of the identified surface drainages or drainage categories. <br />North Fork of the Gunnison River - Information on the quality and characteristics of surface water <br />flows in the North Fork of the Gunnison River is based on sampling and analysis of water samples <br />from monitoring Stations R-1, R-2, G1, G2, NF-1, and NF-2. Based on available surface water <br />quality analysis results for the North Fork and as shown on Figure 2.04.7-F12, North Fork of the <br />Gunnison River Trilinear Diagram, the North Fork surface water is a calcium-carbonate chemical <br />type. Analysis values indicate a neutral to moderately allcaline pH and low to moderate EC, TSS, and <br />'IDS values, as summarized by Table 2.04.7-T6, North Fork of the Gunnison River Surface Water <br />Quality Surmnaty. <br />In general, surface flows in the North Fork increase significantly following spring runoff, with a lag <br />corresponding to filling of Paonia Reservoir upstream and initiation of releases from the reservoir. <br />Elevated flows continue throughout the summer, during irrigation season, declining in late surnmer to <br />early fall. The increase in spring stream flows is typically accompanied by significant increases in TSS, <br />minor increases in TDS, and minor to moderate increases in Fe and Mg. Decreases in stream flows in <br />late summer and through the fall and winter are commonly accompanied by minor to moderate <br />increases in TDS as dilution effects decline with reduced flows. While the noted changes reflect <br />general trends, it is important to recognize that the pattern and range of water quality fluctuations are <br />not consistent over time. Generally, the quality of the North Fork surface water is good in the <br />vicinity of the mine permit area. Some degradation of North Fork water quality occurs well <br />downstream from the mine as a result of irrigation return flows. <br />Hubbard Creek - Information on the quality and characteristics of surface water flows in Hubbard <br />Creek is based on sampling and analysis of water samples from monitoring Stations H-1 and 1-1-2. <br />Based on available surface water quality analysis results for the Hubbard Creek and as shown on <br />Figure 2.04.7-F13, Hubbard Creek Trilinear Diagram, Hubbard Creek surface water is a calcium- <br />carbonate chemical type. Analysis values indicate a neutral to moderately alkaline pH and low to <br />moderate EC, TSS, and TDS values, as summarized by Table 2.04.7-T7, Hubbard Creek Surface <br />Water Quality Summary. The general pattern of seasonal water quality variation previously discussed <br />for the North Fork is also observed for Hubbard Creek, with fluctuations being slightly more <br />pronounced and occurring earlier in the year due to a shorter flow path for runoff and reduced <br />dilution effects. Generally, the quality of the Hubbard Creek surface water is good in the mine permit <br />and adjacent areas. <br />Intermittent and Ephemeral Drainages - Information on the quality and characteristics of surface <br />water flows in the numerous small intermittent and ephemeral drainages within the urine permit and <br />adjacent areas is based on sampling and analysis of water samples from those monitoring stations <br />identified on Table 2.04.7-T5, Surface Water Monitoring Summary. Based on available surface water <br />quality analysis results for the intermittent and ephemeral drainages and as shown on Figures 2.04.7- <br />F14 Intermittent Drainages Trilinear Diagram, and 2.04.7-F15, Ephemeral Drainages Trilinear <br />• Diagram, surface water in these drainages is typically a calcium-carbonate chemical type, with some of <br />the intemuttent drainages tending toward a sodium-carbonate type. <br />PR04 2.04-69 Revised August 2000