2011-09-19_PERMIT FILE - M2011049 (7)

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Water Information The Treiber Lakes site is located primarily in the northeast quarter of the southwest quarter of Section 33, Township 8 north, Range 69 West of the 6 Principal Meridian, Larimer County,' Colorado. The property is immediately adjacent to the south bank of the Cache la Poudre River. Other water resources near the site include the Larimer County Canal No. 2 and Mercer Ditch, which are approximately 1,200 feet south of the proposed permit boundary (see Exhibit G -1, Water Resource Map). The site includes two groundwater lakes with a combined surface area of approximately 62.7 acres. The lake cavities were excavated in the Cache la Poudre alluvium during previous mining activities. During mining, alluvial groundwater was pumped from the pits to facilitate sand and gravel excavation and processing. Following the completion of mining and removal of the dewatering pumps, alluvial groundwater filled the pits to create the existing lakes. The lakes currently impact the Cache la Poudre River in the form of depletions due to evaporation. A Substitute Water Supply Plan (SWSP) for the replacement of stream depletions is currently in place with the Colorado State Engineer's Office (SEO). Future reclamation activities will not produce additional significant affects to the groundwater table on properties surrounding the Treiber Lakes site. No additional impacts to the Cache la Poudre River, Larimer County Canal No. 2, and New Mercer Ditch are anticipated. As delineated on Map Numbers FM08069C0957F and FM08069C0976F (National Flood Insurance Program, December 19, 2006), the majority of the Treiber Lakes site lies within the Cache la Poudre River 100 -year floodplain (see Exhibit G -1, Water Resource Map). All work performed in the floodplain will conform to the Larimer County Flood Hazard Regulations. The attached well location map (Exhibit G -1, Water Resource Map) illustrates existing recorded well permit applications within 1 mile of the permit boundary. A well permit application database search from the SEO was used to locate the surrounding wells identified on Exhibit G -1, Water Resource Map. Although there may be other wells in the area, they are not recorded with the SEO. Table G -1 provides additional information for the illustrated wells. Most applications near the site have been for groundwater monitoring wells associated with mining and reclamation activities. The closest non - monitoring well is located approximately 600 feet northwest of the permit boundary and the recorded use is for irrigation. Since lake water does not need to be removed for slurry wall installation, slurry wall construction activities will not impact wells on adjacent properties. Once the liner is constructed, impacts to the adjacent groundwater table from lake surface evaporative losses will cease. The lined reservoir will influence alluvial groundwater flow near the slurry wall, but these influences are anticipated to be very localized. Specific alluvial groundwater conditions at the Treiber Lakes site were not available. However, baseline conditions would be expected to reflect typical river and stream alluvial groundwater regimes along the Front Range. These groundwater regimes generally exhibit a relatively high Treiber Lakes DRMS 112 Permit Application EXHIBIT G Page 14