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
|