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- 4 - The Hat Creek Ditch water right would be combined with the Board's existing decreed ISF water rights on Hat Creek and East Brush Creek to maintain flows on those creeks in the amounts decreed in Case No. 87CW271 (Hat Creek) and Case No. 77W3627 (East Brush Creek). 8. Historic Use and Historic Return Flows of the Hat Creek Ditch Water RiQht The cwr has provided a report prepared by Tom Williamsen, P.E., attached as Exhibit 3, that provides background and historical use information on the Hat Creek Ditch water right. In a study period spanning 1951 - 2004, diversions were recorded for 23 years. The Ditch has not been used since 1993. For the 23 years when diversions were recorded, the diversions averaged 230 af/y. Peak day diversion rates averaged 1.4 cfs and ranged from 0.6 cfs in 1977 to 2.1 cfs in 1984. The diversion records also show that the first day of recorded diversion normally occurred in late May to early June and the last day of recorded diversion normally occurred in late August to early October. Diversions were nearly 100% depletive to Hat Creek, as most return flows accrued to East Brush Creek. Therefore, the historical depletion to Hat Creek is equal to the diversion rate, 2 cfs. The acquisition and change to instream flow use of the Hat Creek Ditch water right would enhance the seniority of the Board's existing Hat Creek ISF right in the amount of this diversion rate during the historical irrigation season. Mr. Williamsen also evaluated historical consumptive use for the Hat Creek Ditch. From 1951 through 2004, which includes the 15 years of non-use, the consumptive use is estimated to be approximately 21 af/y. The historical consumptive use amount available for ISF use on East Brush Creek ranges from 0.01-0.09 cfs during the historical irrigation season. The Hat Creek Ditch water right is a moderately senior water right in the Brush Creek basin. There are no call records for Brush Creek and apparently no evidence of any downstream senior call on Brush Creek that has called out the Hat Creek Ditch water right. The diversion records for 1977, considered to be a very dry year, show that the Hat Creek Ditch diverted a total of 114 AF from late June through late September. However, it is reasonable to note that in a dry year, the Hat Creek Ditch right could be called out in mid to late summer. 9. Potential Benefits of Donation Hat Creek - The Board currently holds an ISF water right on Hat Creek for 2 cfs during the summer and 1 cfs during the winter, adjudicated in 1987. This proposed acquisition would increase the reliability of the streamflows available to the existing ISF water right during a portion of the summer months since the acquired water would no longer be diverted. The increased flows will benefit resting and refuge habitat for the East Brush Creek brook and brown trout populations. In addition to providing benefits on Hat Creek below the historical diversion point, the Board's acquisition of this water right will protect flows above the diversion point from new junior water rights and thereby benefit the self-sustaining population of Colorado River cutthroat trout existing in that upstream reach. East Brush Creek -The Board holds an instream flow water right on East Brush Creek for 7 cfs during the summer and 4 cfs during the winter, adjudicated in 1977. The consumptive use associated with the Hat Creek Ditch water right could supplement the streamflows available to the East Brush Creek ISF water right, benefiting habitat for self-sustaining East Brush Creek populations of brook and brown trout. Flood Protection' Water Project Planning and Fmance . Stream and Lake Protection Water Supply Protection. Conservation Planning