2009-07-31_HYDROLOGY - M1977036 - Laserfiche WebLink

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Mr. Richard Raines July 29, 2009 Middle Poudre Combined Plan Amendment - Lafarge West, Inc. Page 2 of 4 Exhibit. With this land exchange, the portion where the 8.9-acre pond is located was included in the East Rigden Pit permit boundary. Since the 8.9-acre pond is located within the East Rigden Pit permit boundary, Lafarge will also assume the augmentation responsibility of this additional 8.9-acre pond. With the addition of the 8.9-acre pond, the total exposed surface area at the East Rigden Pit site is 32.1 acres. According to the information submitted, 25 acres of water surface was exposed within the reclamation permit boundary prior to January 1, 1981. The net exposed surface area that requires augmentation is 7.1 acres. Depletions During the period of this SWSP amendment, the anticipated evaporative depletions at the East Rigden Pit are 14.5 acre-feet. The total consumptive use for evaporation and operational losses will increase to 15.6 acre-feet for the East Rigden pit site and the lagged depletions at this site are 14.3 acre-feet. Thus, the total lagged depletions for all the seven sites included in the Middle Poudre Combined Plan are 440.1 acre-feet per year (Table 2). Note, that due to a change in administration of evaporation from ground water exposed to the atmosphere prior to 1981, pre-1981 credits will no longer be allowed for gravel pits which exposed ground water to the atmosphere prior to 1981 and were actively mined on or after January 1, 1981. Accordingly, evaporative depletions for such gravel pits will need to be replaced from the entire surface area of the ground water exposed in the pits. In order to allow owners and operators of the affected pits time to comply with this change in the administration requirements, the owners and operators will have until January 1, 2010 to comply with the replacement requirements. If the area included in the DRMS mining permit site contains individual gravel pit ponds that were not altered or mined after December 31, 1980, you may still be able to maintain the "pre-81" credit provided you can document when mining in the individual ponds ceased. The Applicant is hereby notified that in accordance with the above described change in administration, the evaporation from ground water exposed prior to 1981 must be replaced after January 1, 2010 in any subsequent SWSP renewal for the gravel pits included in the combined plan that have ground water exposed prior to 1981. Replacements Replacement water for this amended combined plan will come from the following sources: accretion credits from recharge of 8.5 shares of the Box Elder Ditch, accretion credits from dewatering at the Three Bells Pit, a lease from the City of Greeley ("Greeley") for fully consumable effluent and an additional lease from the Lake Canal and Reservoir Company ("LCRC"). During the months of April 2009 through September 2009, a lease of 6.52 acre-feet from the LCRC will make replacements for depletions not covered by the recharge program or the City of Greeley lease. A copy of the LCRC lease was submitted to this office on May 30, 2009. The source of the replacement water will be from Gray Lakes, which can deliver water to Box Elder Creek and from there to the Cache La Poudre River. The water storage right for the Gray Lakes owned by LCRC is not presently decreed for augmentation, therefore a change of use application for the Gray Lakes water storage right was filed with the Division 1 Water Court in case no. 2006CW276. A detailed historical consumptive use analysis has not been provided in case no. 2006CW276. According to previous information provided by TZA Water Engineers, Inc. (`TZA") in a letter dated March 15, 2006, LCRC water rights have historically been used to provide supplemental water to irrigated lands within the Lake Canal Service area. Based upon