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6/15/2016 State.co.us Executive Branch Mail - Re: PSCM hydro monitor plan proposal <br />Item 1 - Discontinue all monitoring at surface water site SSC10 on lower Cow Camp Creek just <br />above the confluence of Fish Creek. Monitoring here began in 1987. This site is below Outfall <br />004. The Pond 004 basin was originally mined in the Seneca II Mine, and most of the area has <br />received final bond release in 2015. Data from this site indicated that, although Pond 004 flows <br />continuously, Site SSC10 would often dry up in the early summer, and remain dry until the <br />following spring snow melt runoff. This reduction in flow is due to stream channel infiltration and <br />evapotranspiration. It appears that the Pond 004 basin has little impact on Fish Creek. Water <br />discharged from the mine is lost to stock ponds, evapotranspiration, and the alluvium as it flows <br />through Twentymile Park. Dissolved solids from mine discharges are diluted during the snowmelt <br />runoff in March and April (prior to the irrigation season) by high stream flows with relatively low <br />TDS concentrations. Flow values in Fish Creek are several orders of magnitude greater than the <br />flow values at Site SSC10. <br />Item 2 - Suspend monitoring (until mining resumes) at surface water site SSG2 on <br />Grassy Creek. This site in downstream of Outfalls 002 and 003 on Grassy Creek. <br />However, there is a site further downstream, YSG5, where monitoring will continue. <br />Also suspend monitoring at surface water site SSLG5. This site is located on upper <br />Little Grassy Creek upstream of all mining activities. It has been monitored since <br />1980, and exhibits very little change in water quality. <br />Item 3 - Discontinue monitoring at Spoil Springs 3, 4 and 6 (aka, SSSPG3, 4 and 6). <br />These spoil springs issue from old Seneca II Mine workings in the Pond 002 basin. <br />Final bond release for these areas was approved in 2015. <br />Item 4 - Discontinue monitoring at Spoil Spring 7 (aka, SSSPG7). This spoil spring <br />issues from old Seneca II Mine workings in the Pond 002 basin. It was buried during <br />construction of the Lower Sump for the Sage Creek Mine. <br />Item 5 - Discontinue monitoring at Outfall 004 (Pond 004 on Cow Camp Creek in the <br />Fish Creek basin). The new (2016) NPDES permit has dropped monitoring at this <br />outfall, but has now required monitoring at two spoil springs above this pond: Spoil <br />Spring 1 (aka, SSSPG1 = Outfall 006) and Spoil Spring 2 (aka, SSSPG2 = Outfall <br />005). <br />Item 6 - Discontinue monitoring at wells SCAL69 (Cow Camp Creek alluvium) and <br />SSP62 (Pond 004 spoils) for reasons given in above in Item 1. <br />https://m ai l.google.com/m ai I/u/0/?ui =2&i k=e29129fcb5&view=pt&search=i nbox&th= l554f26bbd7a68d4&si m l=1554f26bbd7a68d4 315 <br />