Quilcene Bay Completed

9722-CYV - Evaluation of Potential Hydrologic Effects of Future Ground-Water Withdrawals in the Chimacum Creek Basin, Jefferson County, WA - Completed FY2011

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.

Objective - 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:

• Describe natural ground-water recharge for historical, current and possible future climate conditions and assuming current land-use conditions;
• Describe effects of current and potential future ground-water withdrawal and recharge conditions on ground-water levels in the Chimacum Creek Basin and streamflows in Chimacum Creek;
• Identify which ground-water withdrawal options are expected to minimize impacts on streamflow in Chimacum Creek under various recharge conditions; and
• Identify how the understanding of water resources of the Chimacum Creek Basin can be improved in the future.

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.

9722-9EI - Hydrologic Assessment of the Quilcene Bay Area and Chimacum Creek Basin, WRIA 17, Jefferson County, Washington - Completed FY2004

Introduction - Water Resources Inventory Area 17 (WRIA 17) is located on the northeastern corner of the Olympic Peninsula in western Washington (figure 1). The area encompasses about 400 square miles, primarily in eastern Jefferson County, and is part of the Puget Sound lowland. Population growth within WRIA 17 has been concentrated in the lower parts of the Big and Little Quilcene River basins and in the Chimacum Creek Basin (figure 2). Competition for water resources in these areas has generated a need for a better understanding of the distribution of ground water and the interactions between the shallow aquifer and local rivers and creeks.

The shallow water-table aquifer that underlies the study area is composed of unconsolidated alluvium and glacial outwash deposits that vary in thickness. Little is known about the location of the water table or the direction of deeper ground-water movement in the area. In addition, rivers and creeks that drain the Olympic Mountains and lowland areas are believed to contribute water to the shallow aquifer in some areas and receive ground-water discharge in other areas. However, little is known of this complex relation and the magnitudes and seasonal variations of ground-water recharge and discharge.

Objectives - The broad objectives of the study are to improve understanding of the interactions between surface-water and ground-water systems of the Big and Little Quilcene Rivers, Tarboo Creek, and the Chimacum Creek Basin, and to define the ground-water system in the unconsolidated deposits of the Chimacum Creek Basin.

Relevance and Benefits - This study will address the USGS strategic goal to "provide and improve long-term environmental and natural resources information, systematic analyses and investigations." The study will also further the USGS' understanding of the interactions between ground water and surface water, a research topic of great interest to both the Water Resources Discipline and the Washington District. The understanding gained of the hydrologic system will also be of use to local watershed managers in evaluating water supply and land management options that optimize the quantity and quality of water resources available for a variety of competing water uses.

Approach

1. To better understand how ground water and surface water interact in the study area, two seepage runs will be conducted on each major stream. The first seepage run will be conducted during spring or summer of 2002 and another during low-flow conditions in the fall of 2002. Point ground-water surveys will be conducted with in-stream piezometers in conjunction with the seepage runs, and several piezometer sites will also be monitored to determine continuous temperature gradients across streambeds.
2. To define the geometry of aquifers and confining units in the unconsolidated ground-water system of the Chimacum Creek Basin, available well records will be compiled and a subset of approximately 100 wells will be located in the field. Hydrogeologic units will be mapped and aquifer characteristics will be determined where possible.
3. To define the movement of ground water within the ground-water system of the Chimacum Creek Basin, water levels will be measured in approximately 50 of the inventoried wells and water-table maps constructed. Water levels will be measured monthly in about 12 wells for a 1-year period to determine seasonal variations.