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A4ichael A. Sayler, P.E. August 28, 2003 Page 2 LaFarge estimates that the batch plant will produce a maximum of 250,000 cubic yards of concrete per year. With a projected water requirement of 50 gallons per cubic yard, approximatety 3&.4 acre-feet of water will be required annually for concrete production. An additional 2 to 3 acre- feet vdill be required annually for limited irrigation during reclamation of the Heaton property. All water used on the site will be considered to be fully consumed, therefore a maximum of 41.4 acre- feetwill be pumped from the reservoir annually, for use at the batch plant. Chancre of lNater Rights The Rural Ditch shares were historically used for irrigation purposes on the Heaton property. The property consisted of approximately EO acres, however, a portion of the property is farm houses and residential areas, five acres were sold in 1970 and the irrigation declined over the years due to mining activities. Aerial photographs taken in 1953, 1575, 1980 and 199 were evaluated to determine the historical irrigafed acreage. From these photographs it was determined that 68.9 acres were irrigated from 1950 to 1961, 52 acres were irrigated from 1962 to 1969 and 47 acres were irrigated from 1970 to ~ 998. The Rural Ditch water was historically used to flood irrigate the property which consisted of roughly 50 percent silage corn and 50 percent alfalfa. The crops have.vahed throughout the years, however, this was thought to be a reasonable estimate of the long term crop distribution. Based on this crop distribution and irrigated acreage, the average historic consumptive irrigation requirement v:as determined to be 88.8 acre-feet. However, based on 1950 through 1998 farm headgate deliveries, the annual on-site depletions attribui=_d to the two rural ditch shares were calculated to average approximately 86.8 acre-feet per year. The historical consumptive use of 86.8 acre-feet per year and return riows from the Rural Ditch shares were determined assuming a 20% ditch conveyance loss with return flows distributed as 35 percent surface runoff and 65 percent deep percolation. The historic farm deliveries were determined to be 174.5 acre-feet, assuming a pro rata portion of the river diversions were delivered to the farm headgate. Ground water return floevs were lagged back to the stream system using the Glover method. See attached Table 7 the consumptive use. Return flow factors were developed 2s shown in attached Table 8. These return ;low factors will be used to determine the monthly return flow obligations. Water will be released from the reservoir at as constant rate as possible to account for the return flow oblications whenever there is a valid downstrezm call. From May through September, the amount released to the stream will be calculated by multiplying the monthly f2cior in Table E by the daily diversion to the reservoir during that month. During the October through April period, the amount released to the stream will be calculated by multiplying the monthly factor by the previous irrigation season total deliveries. This substitute water supply plan is hereby approved pursuant to Section 37-92-308(A) C.R.S subject to the following conditions: Pursuant to 37-92-308(4), C.R.S., this approval shall expire on one year from the date of approval of this letter. If a renewal of this SVVSP is requested, the applicant shall apply pursuant to the provisions of 37-92-308(4)(b). The statutory fee of S300 will be required pursuant to 37-92-308(8). 2. Water use at the batch plant must be limited to 41.4 acre-reel per year. This will include 38.4 acre-feet for batch plant uses and, 3 acre-feet for irrigation uses. The overall use must be metered at the point where it is pumped from the reservoir.