USGS Washington Water Science Center
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WA440 - Estimating runoff season inflows to the Howard A. Hanson Reservoir, Green River, Washington - Completed FY2002
Problem and Needs - The City of Tacoma relies on surface water stored in the Howard A. Hanson Reservoir, Green River Basin, Washington to meet municipal needs and demands. These demands are growing and must be met by optimal use of the water resources. Ongoing activities in the basin for enhancement of fisheries and rules implemented under the Endangered Species Act for salmonid fish that are proposed for listing may affect the allocation and use of the resource. Additional tools are needed in order to improve reservoir management strategies.
Objectives - The objective of the study is to develop a means to estimate or forecast at long-lead times the monthly mean reservoir inflows for the months of April through July. At the latest, the estimates need to be made by mid-January. The estimates will be based on four different multi-linear regression equations.
Relevance and Benefits - The study addresses many issues identified in the Water Resources Division's strategic plan and the Districts priority program opportunities for meeting the Nation's needs. These issues include developing tools for effectively managing the Nation's watersheds and improving tools for transference to others. The assessment of availability of America's water is also an important issue. The study also addresses river-basin simulation. Last, the U.S. Geological Survey (USGS) is a neutral scientific party for providing information, and is building partnerships for developing and using methods to solve important problems that are common in the Nation.
Approach - The study will have three phases. The first phase includes preliminary exploration of the relations between the monthly inflows and climatic information, precipitation, and temperature. The second phase consists of identifying important variables that will be used in the regression equations, developing a list of these variables for each of the inflow months, and identifying the appropriate lead time to use with the variables. The last phase will be to develop regression equations to estimate the reservoir inflows.