CHAPTER III WATER SUPPLY Talent division water supply will be entirely independent of the supplies for other divisions of the Rogue River Basin project. No part of the supply will be obtained from the main stem of Rogue River, and no main-stem structures will be required. Over half the division productive acreage is irrigated. A majority of the irrigators obtain water from Talent Irrigation District, and the remainder depend on diversions from natural streamflow under private water rights with priorities as early as 1851. Available supplies of the district are inadequate in all but the years of highest runoff. Water is seldom available to any but the highest priority private water rights after midsummer. Irrigation is essential to successful crop production in this area because of the warm summers and the paucity of growing season precipitation. The need for irrigation in the Bear Creek Basin was recognized by the earliest settlers, as evidenced by the relatively large number of water rights bearing priority dates of 1851 to 1870. Över 90 percent of the annual runoff of Emigrant Creek occurs during the 6-month period from December through May, and other streams which would contribute to the division supply have similar characteristics. Storage of flood runoff is therefore essential to successful development in this area. Available water supplies limit the size of Talent division to 17,890 irrigable acres. Inadequate supplies presently available to the district and to certain private rights will be supplemented, and the residual will be applied to classes 1, 2, and 3 dry lands. WATER RESOURCES Talent Irrigation District obtains its water supply from Bear and Emigrant Creeks and several of their tributaries, from Keene Creek in Jenny Creek Basin, and from McDonald Creek in Applegate River watershed. Storage is provided in Emigrant Reservoir on Emigrant Creek, and in Hyatt Prairie Reservoir on Keene Creek, with usable capacities of approximately 8,000 and 16,000 acre-feet, respectively. These sources would be supplemented by constructing Howard Prairie Reservoir on Beaver Creek in Jenny Creek Basin. Beaver Creek inflow will be supplemented by diversions into the reservoir from South Fork of Little Butte Creek, Deadwood Creek, Daley Creek, Big Draw Creek, and Dead Indian Creek, all in Little Butte Creek drainage. Releases from Howard Prairie and Hyatt Prairie Reservoirs will enter Bear Creek Basin at a common point about 2,000 feet in elevation above the flowline of Emigrant Reservoir. The plan of develop 46 ment includes generation of hydroelectric power at the proposed Green Springs powerplant to utilize this drop. Howard Prairie and Hyatt Prairie Reservoirs will be operated in coordination primarily to supply the powerplant. Conservation of the power releases for irrigation will necessitate provision of reregulation by storage in the enlarged Emigrant Reservoir, since the bulk of these releases will be made outside of the irrigation season. Emigrant Reservoir would provide the ultimate source of irrigation water for all division lands except those under the Ashland lateral. CRITICAL PERIOD Flow of Rogue River has been recorded at Raygold, near Medford, continuously since 1906. Lowest recorded runoff was in 1931; and in 1926 and 1934, equal runoff was second lowest. Lowest runoff during 2 consecutive years occurred in 1930 and 1931, and runoff during 1929-34 was lowest of any 6-year period. Runoff during 1935-49 averaged 100 percent of the 1906-49 mean. There is indication from tree-ring studies made in the Deschutes and Great Basins that this drought was one of the most severe for several centuries. This apparent infrequency indicates the economic desirability of a division plan which would permit a tolerable water shortage during the critical period. PERIOD OF STUDY The period of study, 1927-49, includes 2 years of approximately normal runoff preceding the critical period, and as many years thereafter as runoff records were available. RUNOFF RECORDS Records for the major streams are adequate. Runoff of the smaller streams has been measured only sporadically or not at all, and extensive estimates were necessary to evaluate the division water supply. Diversions by Talent Irrigation District from various tributaries of Bear Creek have not been recorded, nor have farm deliveries from district canals, diversions by owners of private water rights, or diversions for municipal use from Ashland Creek. Streamflow records have been collected by the State engineer of Oregon, Geological Survey, and Bureau of Reclamation. The recorded and estimated runoff of 4 of the more important streams discussed below is summarized for the period 1927-49 in tables 5 to 8. TABLE 5.-Unregulated runoff of Emigrant Creek at Emigrant Dam, Talent division, Rogue River Basin project, Oregon Year [Unit: 1,000 acre-feet] Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Sept. Total TABLE 6.—Unregulated runoff of Keene Creek at Hyatt Prairie Dam, Talent division, Rogue River Basin project, Oregon Year [Unit: 1,000 acre-feet] Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Sept. Total TABLE 7.—Runoff of Beaver Creek at Howard Prairie Dam site, Talent division, Rogue River Basin project, Oregon Year [Unit: 1,000 acre-feet] Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Sept. Total TABLE 8.-Total runoff divertible 1 from Little Butte Creek drainage, Talent division, Rogue River Basin project, Oregon 1 Residual after deductions for prior water rights, flows in excess of canal capacity, losses, and waste. Emigrant Creek runoff The unregulated runoff of Emigrant Creek at Emigrant Dam was computed from records of releases and spills from Emigrant Reservoir, change in storage content, district diversions above the reservoir, and transbasin importations from Hyatt Prairie Reservoir. Seepage and evaporation losses from existing Emigrant Reservoir are minor; consequently, no adjustments were made to the computed runoff to include these factors. Runoff of Emigrant Creek at the Ashland lateral diversion dam site was estimated from the unregulated runoff at Emigrant Dam by a direct relationship between runoff and contributing drainage area at the two locations. Inflow to Emigrant Creek between the gage below Emigrant Dam and the gage below the mouth of Walker Creek was obtained by determining the difference for the period of record of the gage below Walker Creek, October 1943 through September 1949. Inflow for the water years 1927-43 was estimated by correlating recorded inflow with unregulated runoff of Emigrant Creek below the dam. Neil Creek runoff Runoff of Neil Creek was recorded at a station located near its mouth during January 15-April 26, 1924. Runoff during the period of study was estimated by correlation with the unregulated runoff of Emigrant Creek at the dam. Recorded Neil Creek runoff was of small magnitude, necessitating location of the correlation curve for higher flows by assuming the same runoff per square mile of drainage area for Neil Čreek as was computed for Emigrant Creek. Neil Creek runoff was recorded at Ashland lateral crossing during July 1-November 15, 1913. Estimates of runoff based on correlation of these records were not possible because no concurrent long-time records are available for other comparable streams in the area. Ashland Creek runoff Ashland Creek heads on Mount Ashland at an elevation of about 7,500 feet, and has a comparatively well sustained summer flow from snow melt and/or ground water. It has been extensively developed for irrigation, power, industrial, and municipal uses, which appropriate most of the late summer flow. Division rights to this stream have relatively low priority. Reeder (or Walker) Reservoir, located at the junction of East and West Forks, stores 800 acre-feet for city of Ashland municipal supply. No records of the operation of this reservoir are available. The city operates, with Ashland Creek flows, a hydroelectric plant of 600horsepower installed capacity. Ashland Creek runoff is diverted near the mouth by the district through a pipeline which discharges into Bear Creek above Talent lateral diversion. Regulated runoff at the mouth was computed for the period May 1928-September 1929 and April 1930-September 1931 by subtracting the runoff recorded at the gage on Bear Creek above Ashland Creek from the sum of the runoff of Bear Creek at Jackson Hot Springs and Talent lateral near Ashland. For the remainder of the period 1927-49, the regulated runoff at the mouth was estimated by adding to the combined runoff of the East and West Forks of Ashland Creek the average net gain or depletion |