USGS Washington Water Science Center
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Evaluation of potential hydrologic effects of future ground-water withdrawals in the Chimacum Creek Basin, Jefferson County, Washington - Completed FY2013
Problem - Projected increases in population and development in northeastern Jefferson County, Washington, are expected to lead to increased ground-water withdrawals in the Chimacum Creek Basin. In addition, land-use and climate change could reduce ground-water recharge in the basin, thereby reducing ground-water levels in the basin and reducing discharge from the ground-water system to Chimacum Creek. Ground-water discharge to the creek, also referred to as baseflow, is critical for maintaining ecological health in the creek throughout the year and it is especially important during the summer and early autumn, when it supplies most, if not all, streamflow. Chimacum Creek provides habitat for salmonids, including species listed under the Endangered Species Act (ESA), such as summer-run chum salmon (threatened), coho salmon (species of concern), and steelhead (proposed for listing as threatened in March 2006) (National Oceanic and Atmospheric Administration, 2006). Decision makers and water-resources managers need quantitative tools to assess the impact of different water-management options so they can plan for future growth and development in ways that minimize adverse impacts on Chimacum Creek.
Objectives - The general objective of the proposed study is to assess the effects of potential increases in ground-water withdrawals and potential decreases in ground-water recharge on ground-water and surface-water resources in the Chimacum Creek Basin.
Specific objectives are to:
Relevance and Benefits - This study is consistent with the national USGS mission and goals and water-resources issues identified in the USGS Washington Water Science Center Science Plan. Specifically, the study addresses the following issues in "Strategic Directions of the Water Resources Division 1999-2008": effects of urbanization and suburbanization on water resources (issue 1); effects of land use and population increases on water resources in the coastal zone (issue 2); drinking water availability and quality (issue 3); effects of climate on water-resource management (issue 7); surface-water and ground-water interactions as related to water-resource management (issue 8); and hydrologic-system management, including optimization of ground-water and surface-water use (issue 9). The study creates tools (simulation and combined simulation-optimization models) to help local decision makers evaluate complex management strategies and manage water-resources in the Chimacum Creek Basin.
Approach - The objectives will be met by creating a transient (time-varying) ground-water flow model for the study area and a combined simulation-optimization model. The simulation-optimization model can be used to directly incorporate specific management goals and constraints with respect to study objectives 2 and 3 into the modeling process. Water-management goals and constraints will be identified by Jefferson County and the WRIA 17 Planning Unit in consultation with the USGS.