Appraisal Evaluation of Columbia River Mainstem Off-Channel Storage Options Executive Summary U.S. Department of the Interior Washington State Department of Ecology Bureau of Reclamation Pacifi c Northwest Region May 2007 Cover Photos: Left to right: Crab Creek, Sand Hollow, Foster Creek, and Hawk Creek RECLAMATION Managing Water in the West Appraisal Evaluation of Columbia River Mainstem Off-Channel Storage Options Executive Summary U.S. Department of the Interior Washington State Department of Ecology Bureau of Reclamation Pacifi c Northwest Region Prepared by the following contractors under Contract No. 03CA10150B Washington Group International John Petrovsky Associates ESA Adolfson Larry Von Thun, Consulting Engineering Kim de Rubertis, Consulting Geologist May 2007 Printed on 30% recycled content paper Executive Summary Steps in Selecting an The Appraisal Evaluation of Columbia Off-Channel Storage Site River Mainstem Off-Channel Storage Options (Appraisal Evaluation) is part of an effort to identify and assess off-channel storage opportunities along the Columbia River. The purpose of the Appraisal Evaluation is to investigate four off- channel sites with an overall objective to determine if one or more of these sites should be recommended for investigation at a feasibility level of detail. The U.S. Bureau of Reclamation (Reclamation) and the Washington State Department of Ecology (Ecology) determined that out of the 11 sites initially considered and evaluated in the Pre- Purpose and Need for Appraisal, the following four off-channel Columbia Basin Storage storage alternatives warrant being carried forward into the Appraisal Evaluation The purpose of the Appraisal Evaluation is (Figure ES-1, Location Map): to conduct appraisal-level investigations of four off-channel sites with an overall • Crab Creek objective to determine if one or more of • Sand Hollow these sites should be approved for • Foster Creek investigation at a feasibility level of detail. • Hawk Creek The need for additional storage and water Appraisal-level designs for the dam and along the Columbia River Mainstem is for appurtenant structures, which include the following anticipated or projected intake structures, inlet/outlet conveyance water requirements: facilities, pumping/power plants, and • Agriculture transmission lines, were developed to support evaluation of the suitability of • Flow augmentation for protection and each project. A decision support model enhancement of fishery resources was applied to objectively evaluate the • Domestic, commercial, municipal, and alternatives. Findings and conclusions industrial (DCM&I) based on this analysis indicate that the proposed Crab Creek Dam and Reservoir • Flexibility to respond to potential site should be carried forward, if a detailed impacts of climate change and address Feasibility Study is conducted. water needs under different conditions For the purpose of the Appraisal Evaluation, recreation and power production are considered secondary benefits. BOI071210001.DOC ES-1 Executive Summary Republic Colville Douglas Lincoln County County Grant CountyOkanogan Columbia River Chief Joseph Dam FOSTER CREEK and Rufus Woods Lake Grand Coulee Dam and MIDDLE FOSTER CR E FOSTER CR Franklin D. Roosevelt Lake FOSTER CR Chelan W FOSTER CR SNOOK CANYON Dry Falls Dam and HAWK CR INDIAN CR Banks Lake HAWK CR Spokane Davenport Waterville HAWK CREEK ver Ri Cheney bia Pinto Dam and Billy Clapp Reservoir Wenatchee Ephrata Moses Lake Ritzville O’Sullivan Dam and Reservoir SAND HOLLOW (Potholes Reservoir) SAND HOLLOW Wanapum Dam and Reservoir Othello LOWER CRAB CR CRAB CREEK Priest Rapids Columbia River Dam and Reservoir Cities Pomeroy Interstate Route State Route Toppenish US Route Dayton Sunnyside West Richland Rivers, Lakes, and Waterbodies Richland County Grandview Pasco Prosser Kennewick 05 10203040 Miles Shaded Relief Map Source: WSDOT Walla Walla Figure ES-1 May 2007 Location Map Executive Summary Storage Study Goals • Selecting facility locations: Where Reclamation and Ecology developed the following should the dam and other facilities be storage study goals for the Appraisal Evaluation: placed for maximum efficiency? • Improve the water supply for proratable • Characterizing facilities by developing irrigation water rights in dry years as well as appraisal-level layouts and designs: secure water for future irrigation What might the project look like, and • Improve anadromous fish habitat by restoring how much would it cost? and supplementing the flow regimes of the Columbia River Sites were also evaluated early in the process for the presence of any “fatal flaws” that • Meet future municipal, domestic, and industrial supply needs for existing users, and provide an would preclude development. The Foster additional water supply for population growth to Creek site was found to have such flaws, and the year 2050 thereafter was not analyzed in detail. Approach for Establishing How much water is needed, and at what rates of flow? the Design Components Sizing of dams, diversion/intake Developing the design components of storage structures, conveyance facilities, power projects at the Crab Creek, Sand Hollow, generation facilities, and other components Foster Creek, and Hawk Creek sites for relied on developing a water balance of analysis consisted of the following three steps: total supplies and demands over time, shown in Figure ES-2. • Establishing facility sizes: How much water is needed, and at what rates of flow? FIGURE ES-2 Water Balance Analysis Model BOI071210001.DOC ES-3 Executive Summary The water balance model was used to Three operational scenarios (OS) were optimize the flow rates (cubic feet per developed for each of the reservoir second [cfs]) and reservoir volumes (acre- alternative (except for Sand Hollow and feet) needed to meet demands, and to Foster Creek), based on reservoir volume: establish various operational scenarios for • OS1 = 1 million acre-feet each site. Principal supply and demand • OS2 = 2 million acre-feet components of the model were as follows: • OS3 = 3 million acre-feet • Supply: Columbia River “available These volumes were selected for the water” (based on 50 years of record) operational scenarios to compare how each and local precipitation potential project could meet various water • Demand: Projected future water needs demands. The maximum reservoir volume of for agricultural and DCM&I purposes; 3 million acre-feet was selected for OS3 and off-channel reservoir releases to because it was the smallest off-channel supplement flow augmentation needs reservoir volume that could meet 100 percent in the Columbia River mainstem of the agricultural, DCM&I, and flow Seepage and evaporation losses associated augmentation demands that are currently with the new off-channel reservoir were estimated (see Table ES-1) 80 percent of the also estimated and included in the model. time. The current estimate for total annual The minimum reservoir volume of 1 million demands is approximately 3,368,000 acre- acre-feet was selected for OS1 to maintain feet and includes agricultural, DCM&I, and the same minimum volume criteria used by flow augmentation. As shown in Reclamation and Ecology during the initial Table ES-1, the largest water demands are screening process. This minimum reservoir associated with agriculture, which accounts volume is far too small to yield the for approximately 75 percent of the total. 3,368,000 acre-feet of demands listed in Table ES-1. Therefore, if this operational TABLE ES-1 scenario is selected to be evaluated in the Water Demands to be Met by Direct subsequent Feasibility Study, the demands Pumping or New Off-Channel Storage should be reevaluated to determine an appropriate target for agricultural, DCM&I, Annual Demand (acre-feet) and flow augmentation needs. Columbia Basin Project 1,365,000 The 2 million acre-foot reservoir volume was Yakima Project 662,000 – 810,000 selected for OS2 to provide insight into the feasibility or differences among various Additional Agriculture 330,000 reservoir sizes at each site. As with the DCM&I 109,000 1 million acre-foot reservoir volume, the Flow Augmentation 754,0001 2 million acre-foot reservoir volume does not 1Flow augmentation demands vary from year to allow for enough reservoir carryover from year based on annual consumptive demands and month-to-month to meet the demands listed the amount of water that is available to meet demands through direct pumping. The value shown in Table ES-1. Therefore, if this operational is the median flow augmentation release from a scenario is selected to be evaluated in the new 3 million acre-foot reservoir that is intended to subsequent Feasibility Study, the demands show an order-of-magnitude estimate/proportion of flow augmentation relative to other demands. should be reevaluated to determine an appropriate target for agricultural, DCM&I, and flow augmentation needs. ES-4 BOI071210001.DOC Executive Summary Where should the dam and other As shown on Table ES-2, the alternatives facilities be placed? vary considerably in size, with dam heights The locations of the facilities (such as fish above the valley bottom ranging from about screen/diffuser structures, conveyance 130 feet to 780 feet. Figure ES-3 illustrates routes, spillways, and other features) were the comparative height of the projects. The selected principally based on the most surface area of the proposed reservoirs appropriate dam axis location. The preferred varies from about 5,000 acres to dam axis was typically located on the