Laserfiche WebLink
In accordance with the requirements of the Colorado Reclamation Act and the Mineral Rules and <br /> Regulations of the Colorado Mined Land Reclamation Board for the Extraction of Construction Materials, <br /> reclamation plans must ensure minimization of disturbances to the prevailing hydrologic balance, including <br /> disturbances to the quantity of water in the area affected by mining.A letter dated April 30, 2010 issued by <br /> the DRMS requires operators of sand and gravel mines to demonstrate long-term stream depletions can <br /> be replaced. In order to assist mining operators in achieving compliance, the DRMS letter identifies 4 <br /> approaches. Everist chose approach#4,which requires documentation to identify what water rights or other <br /> permanent water source(s) will be dedicated to the SWSP to assure that all permanent depletions will be <br /> replaced so as to prevent injury to other water rights. On 9/22/2015, Everist prepared an affidavit identifying <br /> these water replacement sources; a copy of the affidavit is included in Attachment E. <br /> 2.3 TIMING OF DEPLETIONS <br /> The MCR mining cells are located further than 100 feet from the Blue River; therefore, stream depletions <br /> are not instantaneous and the lagged effect must be calculated. Lagged depletions to the Blue River were <br /> obtained using the Glover technique. Calculations were performed with the spreadsheet developed by <br /> Western Water Consulting, Inc. (WWC), based on the Analytical Stream Depletion Model (Schroeder, D.R., <br /> 1987. S.E.O. Ground Water Software Publication No. 1). The following Glover parameters were used in the <br /> analysis (based upon data in the USGS Circular No. 11): an average aquifer transmissivity of 180,000 <br /> gallons per day per foot and a specific yield of 0.18.An average of 1,482 feet was estimated as the distance <br /> from the point of depletion to the stream (area-weighted average of the distances from the centroid of each <br /> pond to the approximate centerline of the Blue River). In addition, 2,000 feet was the assumed distance <br /> from the no-flow boundary to the Blue River. The long-term effects of the lagged depletions were simulated <br /> by cycling the estimated monthly depletion rates for 20 years. Input data and the output table produced by <br /> the WWC spreadsheet are included for reference in Attachment F. <br /> 3.0 REPLACEMENT SUPPLY <br /> Three sources of replacement water have been available for this SWSP since its original approval: <br /> 1. Consumptive use from the dry-up of historically irrigated lands; <br /> 2. Releases from Green Mountain Reservoir; and <br /> 3. Releases from Dillon Reservoir <br /> 3.1 CONSUMPTIVE USE CREDITS FROM HISTORIC IRRIGATION <br /> A total of 162 acres of historically irrigated fields have been effectively dried-up and permanently removed <br /> from irrigation as a result of gravel mining operations in MCR. The water rights utilized for such historic <br /> irrigation are shown in Table 7 below. Attachment G contains the Bargain and Sale Deed for these water <br /> rights. Figure A-4, attached, is a map which depicts the MCR irrigation water rights and the corresponding <br /> historically irrigated fields. The map included in Figure A-5 shows the historically irrigated fields where dry- <br /> up associated with gravel mining has occurred. <br /> 8 ;:;::RESOURCE <br />