2017-03-23_HYDROLOGY - M1980149 - Laserfiche WebLink

Home Browse Search

Hokestra SWSP Page 5 of 11 March 20, 2017 river. Depletions occurring from October through March will rely on a release of the excess Rural Ditch water that was stored in priority during May through September. On June 22, 2015 Weld County and Central Water Conservancy District (“Central”) entered into an agreement that allows Central to store water in the lined Cells 5 and 6 (identified as the SE- 2 and SE-3 and designated as the Hokesta Pit) of the Hokestra site while mining is occurring at the Koenig Pit site. In addition, Central agrees to deliver and/or store in the Hokesta Pit water attributable to Weld County’s 3.75 shares of the Rural Ditch in order to use the stored water to satisfy the augmentation requirement at the Hokestra site. Central will manage Hokestra Pit and may store other water in the pit; in exchange Central has made free river water stored in Hokestra Pit available to Weld County to offset depletions under this plan. As of December 1, 2016 Central had 82.1 acre-feet of free-river water stored in Hokestra Pit along with 10.69 acre-feet of Weld County’s Rural Ditch water, of which 40.31 acre- feet is dedicated to Weld County and will be used to replace depletions and non-irrigation season return flows obligations attributable to deliveries of the Rural Ditch shares. Central has agreed to pay 100 percent of evaporation losses from water stored in the lined cells of the Hokestra Pit. In order to claim credit for the delivery of the 3.75 shares of the Rural Ditch to the river, the shares must be measured to the satisfaction of the water commissioner. In the 2015 water year, the repairs to the Rural Ditch farm headgate were completed and the applicant began using the repaired headgate to divert water into Hokestra Pit and return water back to the river. The June 2015 agreement also allows Central to use Rural Ditch water stored in Hokestra Pit for use in Central’s operations. An SWSP approved pursuant to section 37-92-308, or a court decree that changes the use of the shares, must be obtained prior to Central’s use of the Rural Ditch water. A change of use of the shares for use by Central is not approved under this SWSP. The 3.75 shares of the Rural Ditch were historically used to irrigate four farms. Historic consumptive use for the parcels was determined using the Colorado State University Integrated Decision Support Consumptive Use Model (IDSCU) version 3.3.151. Monthly consumptive use requirements were determined using the modified Blaney-Criddle method with the TR21 crop coefficients and the Soil Conservation Service methodology for calculation of the effective precipitation. Temperature and precipitation values were obtained from the Longmont 2ESE weather station with missing data filled in using the Fort Collins NOAA weather stations. The Applicant proposed a maximum 65 percent irrigation efficiency for all farms. The period of diversion for the shares is limited to the historic irrigation season, April 1st to October 31st. The soil information and available water holding capacity (“AWC”) for the farms was obtained from the Natural Resources Conservation Service (“NRCS”) Soil Survey. The acreage distribution for all soil types on the farms were used to determine an overall average weighted AWC for each farms. The soil moisture reservoir is a function of the soil AWC, the depth of the crop root zone and the management allowed depletion (“MAD”). Published values of crop specific MAD can be found in Broner (1987 and 1993), FAO-56 (Allen, et al. 1998), the Ames Irrigation Handbook (McCulloch, et al., 1967) and the NRCS NEH-Part 652 (1997). The table below lists the soil characteristics used in the historical use model for each farm, excluding the Adler Farm, as these properties were adapted from case no. 2003CW306.