Water Conservation Study for Manastash Creek Water Users, Kittias County, Washington, Final Report 2002.

[摘要] Manastash Creek is tributary of the Yakima River and is located southwest and across the Yakima River from the City of Ellensburg. The creek drains mountainous terrain that ranges in elevation from 2,000 feet to over 5,500 feet and is primarily snowmelt fed, with largest flows occurring in spring and early summer. The creek flows through a narrow canyon until reaching a large, open plain that slopes gently toward the Yakima River and enters the main stem of the Yakima River at river mile 154.5. This area, formed by the alluvial fan of the Creek as it leaves the canyon, is the subject of this study. The area is presently dominated by irrigated agriculture, but development pressures are evident as Ellensburg grows and develops as an urban center. Since the mid to late nineteenth century when irrigated agriculture was established in a significant manner in the Yakima River Basin, Manastash Creek has been used to supply irrigation water for farming in the area. Adjudicated water rights dating back to 1871 for 4,465 acres adjacent to Manastash Creek allow appropriation of up to 26,273 acre-feet of creek water for agricultural irrigation and stock water. The diversion of water from Manastash Creek for irrigation has created two main problems for fisheries. They are low flows or dewatered reaches of Manastash Creek and fish passage barriers at the irrigation diversion dams. The primary goal of this study, as expressed by Yakama Nation and BPA, is to reestablish safe access in tributaries of the Yakima River by removing physical barriers and unscreened diversions and by adding instream flow where needed for fisheries. The goal expressed by irrigators who would be affected by these projects is to support sustainable and profitable agricultural use of land that currently uses Manastash Creek water for irrigation. This study provides preliminary costs and recommendations for a range of alternative projects that will partially or fully meet the goal of establishing safe access for fisheries in Manastash Creek by reducing or eliminating diversions and eliminating fish passage barriers. Further study and design will be necessary to more fully develop the alternatives, evaluate their environmental benefits and impacts and determine the effect on Manastash Creek water users. Those studies will be needed to determine which alternative has the best combination of benefits and costs, and meets the goal of the Manastash Creek water users.

[发布日期] 2002-12-31 [发布机构] United States. Bonneville Power Administration.

[关键词] Blowers;Irrigation;Streams;Dams;Fishes - Migration - Washington (State) - Yakima River Watershed