2012-12-26_HYDROLOGY - M2003091 - Laserfiche WebLink

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Dave Bailey, Esq. November 12, 2010 Page 2 photographs and to identify the changes of irrigated lands throughout the study period. A water balance program was used to determine historic depletions for the Rural Ditch shares using the measured irrigated acreage and consumptive irrigation requirements (CIR) for silage corn and alfalfa, the two crops described by Tom Adams and Rosie Heaton as the most prominently grown crops on the property. This analysis was performed using a study period of 1911 through 1998. This period reflects the availability of diversion data and represents the majority of the years the water right has been used for decreed purposes. The period also includes a good variation of wet and dry years. Ownership Two shares of the Rural Ditch Company have been associated with this parcel of land historically. The land and water rights were owned by the Heaton family from at least 1950. Lafarge acquired the shares from the Heatons in the late 1990's. The two shares represent four percent of a total of 50 shares in the ditch company. The Lafarge shares equate to an ownership interest of 0.91 cfs in the senior (May 10, 1862) water right and 2.41 cfs in the remaining junior (March 10, 1863) water right. Diversions and Ditch Loss Rural Ditch diversions for the 1911 through 1998 study period were obtained from State Engineer's Office from 1911 through 1949 and from the CDSS database for 1950 through 1998. Records for the years 1934 — 1936 were not available, so the monthly averages for the remaining study period were used for the water balance analysis for these three years. Diversion of water other than under the ditch's direct flow rights was deducted from the records. Diversions for the Rural Ditch water rights are summarized in Table 1. Based on conversations with the Water Commissioner, there are two headgates that can be used to divert the Rural Ditch, the decreed headgate on Boulder Creek, and the Idaho Creek diversion point. According to the Water Commissioner, the diversion records show total diversions at both points. Water has been consistently diverted throughout the study period, and diversions have averaged approximately 5,105 acre -feet per year (ac -ft /yr) as shown in Table 1. Annual diversions have varied from a maximum of 8,775 ac -ft in 1998 to a minimum of 2,406 ac -ft in 1949. Although the Rural Ditch priorities are very senior rights within the basin, diversions in dry years such as 1954 and 1977 were slightly less than the study period average. However, in most years the diversion records indicate frequent diversions later in the irrigation season (August, September, and October) which supports the reliability of this water right. According to Mr. Adams and Mr. Frank Sewald, the ditch company president, the ditch shareholders do not have measuring devices at their farm headgates. Individual users decide how much water to take based upon what they need. On occasion, shareholders are asked to reduce the amount of water taken in order to ensure supply to all the other users. For this analysis, the deliveries to the Heaton farm headgate were assumed to be equal to a pro rata portion of the river diversion, less ditch loss. Based on the seven mile length and size of the ditch, a conservative estimate of 20 percent ditch loss was assumed to be reasonable for this analysis. Therefore, the average historic delivery to the Heaton property was estimated to equal four percent of the river diversion, less twenty percent ditch loss. These values are shown in Table 2. Historic deliveries ranged from 77.0 ac -ft /yr to 280.8 ac -ft /yr, and an average of 163.4 ac -ft /yr was delivered to the Heaton property. This is the delivery that can be expected to be available on average in the future for possible diversion into storage or for other uses.