2023-09-01_PERMIT FILE - M2023015

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M MW Sorter VV This water balance was peer reviewed in 1974 under the Woodward Clevenger Report adopted by the Water Court, and is summarized in the submission to CDWR(2017) here: Given this geologic framework, the hydrogeology of the area is dominated by local geologic structure and limited available outcrop areas for recharge. Where saturated,the Paleozoic carbonate rock formations form the aquifer of the London Syncline(Misantoni,2001).Fracture and solution permeability are predominant within this aquifer,and are generally unimpaired by mineralization or vein fillings(WCA, 1974). The network of ancillary faults in the footwall also increases the permeability of the aquifer and they are typically wateryielding(Singewald and Butler, 1941;Misantoni,2001).In fact,the currentflow of waterfrom the London Mine Tunnel appears to the direct result of mining through the water transmitting "W"Fault,shown on Figure 3. Due to uplift along the London and Mosquito Faults,removal of the Paleozoic sedimentary rocks, and emplacement of approximately 40 to 100 feet of impermeable faultgouge along the London Fault, the aquifer appears to be limited in areal extent locally to approximately 3.8 square miles as shown on Figure 5. The Belden Shale confines the Leadville Aquifer due to its very limited permeability,and acts as an aquitard or aquiclude depending upon how thick the formation is (WCA, 1974). The aquifer is recharged by direct precipitation and snowmelt overAmerican Flats and adjacent catchments,but the amount of recharge is subject to debate. Within these areas,recharge to the aquifer occurs over outcrops of the Paleozoic carbonate rocks, through outcrops of highly fractured porphyry intrusive rocks, and to a limited extent, where the Belden Shale cover is thin and fractured orfaulted.Different amounts of recharge have been proposed as follows: 1. WCA(1974)proposed that the recharge area was limited to an area of approximately 3.5 square miles,and assuming a 25%recharge rate over this area,estimated that annual recharge may be 1,830 AF based on an average annual precipitation of 40 inches falling over 2,200 acres. 2.In contrast,Jehn Water Consultants(1999)reported that the decreed average recharge amount of 7.4 cfs or 5,357AF/yr under Case No. W-8314-76 was based on a maximum recharge area of up to 10 square miles,or almost three times the area identified by WCA (1974). This area included seven square miles of land located in the adjoining catchment south of Pennsylvania Mountain. WCA (1974)suggested that the recharge rate and volume could be high due to local faulting, fracturing,exposure of the synclinal axis, and lack of streams in the recharge areas, but did not directly measure the recharge rate during their investigation.Instead, WCA selected a 25%rate which in their judgment was consistent with estimates obtained in other similar mountain catchments. In addition, the volume ofgroundwater storage in the aquifer is considered significant due to the good water quality and trace element analytical results(WCA, 1974;Brown and Caldwell,2007),and relatively consistent discharge from the London Mine Tunnel that ranged from 682 to 781 gpm between 1992 and 1998(Jehn Water Consultants, 1999;Jehn Water Consultants, 2002). Based on limited available water level data and outcrop patterns for the Leadville Limestone to the south, the smaller recharge area presented by WCA appears to be supported. Groundwater generally appears to flow east southeastward toward the London Syncline based on water levels obtained in August 2006 from the Leach Well,AF-10,and the Salvator Drill hole at locations shown on Figure 1 (Brown and Caldwell,2007). Once the water reaches the syncline,it appears to flow 171 Page