Laserfiche WebLink
6.0 SURFACE WATER HYDROGEOLOGY <br /> 6.1 General Characteristics <br /> The La Plata River is a 70-mile-long river(110 km)that is tributary to the San Juan River and <br /> San Juan County,New Mexico. This small river originates at the western foot of Snow Storm <br /> Peak in the La Plata Mountains of southwestern Colorado, approximately 35 miles north of the <br /> New Mexico State line. The La Plata flows in a southerly direction until it joins the San Juan <br /> River at the western edge of the city of Farmington,New Mexico, about 19 miles south of the <br /> Colorado State line. <br /> 6.2 Surface Water Monitoring <br /> The May Day Idaho mine project area is drained by Little Deadwood Gulch, and the La Plata <br /> River. The Little Deadwood Gulch drainage area is approximately 450 acres. There are two <br /> surface water quality monitoring stations on Little Deadwood Gulch Drainage, two surface water <br /> quality monitoring stations on the La Plata River and one sampling station in the wetlands <br /> adjacent to the La Plata River. <br /> Surface water and groundwater quality monitoring station locations are depicted on Figure 6. <br /> One monitoring station is located on the La Plata River(LP-01)up steam of the active mine site <br /> activities and one surface water monitoring station(LP-02) is located downstream. Surface <br /> water samples are also obtained from a historical mine tailings pond which is a designated <br /> wetland. The wetland is located within the La Plata River floodplain and within the May Day <br /> Idaho mine permit area. <br /> There are two surface sampling stations on Little Deadwood Gulch-one station is located <br /> upgradient of the May Day Idaho permit area(DG-1) and down gradient of the adjacent Incas <br /> mine site. The second monitoring station is located on Little Deadwood Gulch(DG-2) <br /> immediately down gradient of the May Day No. 2 mine affected area. <br /> The OPERATOR has conducted surface water sampling from the project area since 2007. Site <br /> water quality sampling and characterization is ongoing and will continue during mining to <br /> determine and report if the environmental baseline water quality characteristics have changed <br /> over time. <br /> 6.3 Surface Water Quality <br /> Surface water quality and flow data are presented in Section 7.3. In summary, surface water <br /> quality data indicates there are no constituents of concern, where total dissolved solids are less <br /> than 100 milligrams per liter(mg/1). Surface water pH ranges from 7.3 to 8.1, and alkalinity is <br /> typically less than 50 mg/l. <br /> May Day Idaho Mine Complex <br /> M-1981-185 <br /> January 19, 2017 <br /> Page I -7- <br />