Puget Sound Groundwater Low Flows Near Term Action Project

Science Center Objects

The Issue: Groundwater discharge to streams and rivers in the Puget Sound basin is the primary source of water for sustaining summer low flows. A robust understanding of how anthropogenic and natural stressors affect summer low flows across the entire Puget Sound Regional Aquifer System is lacking, and USGS has tools and data—including current water-use data and subbasin-scale groundwater models—that can help understand the effects of current and future stressors on low flows. Recent court decisions that have heightened the conflicts between groundwater use and instream flows in Puget Sound, so it is timely for us to combine our decades of groundwater knowledge into a coherent regional-scale assessment that can substantively inform water-resource management strategies.

How USGS will help: The goal of this proposed Near –Term Action under the 2016 Action Agenda for Puget Sound is to provide hydrogeologic and water-use information to the Washington Department of Ecology and other water-resources stakeholders to foster development of water management strategies that protect instream flows while ensuring water supplies for domestic, agricultural, and other out-of-stream uses.

Problem: Groundwater discharge to streams and rivers in the Puget Sound basin is the primary source of water for sustaining summer low flows. A robust understanding of how anthropogenic and natural stressors affect summer low flows across the entire Puget Sound Regional Aquifer System is lacking, and USGS has tools and data—including current water-use data and subbasin-scale groundwater models—that can help understand the effects of current and future stressors on low flows. Recent court decisions that have heightened the conflicts between groundwater use and instream flows in Puget Sound, so it is timely for us to combine our decades of groundwater knowledge into a coherent regional-scale assessment that can substantively inform water-resource management strategies.

Objectives: The goal of this proposed Near –Term Action under the 2016 Action Agenda for Puget Sound is to provide hydrogeologic and water-use information to the Washington Department of Ecology and other water-resources stakeholders to foster development of water management strategies that protect instream flows while ensuring water supplies for domestic, agricultural, and other out-of-stream uses. Information will be compiled into subbasin water budgets to allow a holistic comparison of water demands, summer low flows in streams and rivers of various sizes, and groundwater availability in different hydrogeologic settings of Puget Sound. 

Relevance and Benefits: This study is consistent with the USGS mission and goals and the USGS Science Strategy. The study addresses regional groundwater availability and sustainability, water budgets, and water use, all of which are priorities in the President’s FY18 budget, and of the USGS Director and Water Mission Area. This study will provide state and local resource managers with information to assist in the development of long-term water management plans to meet the needs of current and future water demands within the basin, while also working to protect and improve its natural resources consistent with EPA’s National Estuary Program in Puget Sound.

Approach: USGS will generate/compile monthly groundwater budget data and related hydrogeologic information for subbasins underlain by the ~7,200 sq-mi Puget Sound Regional Aquifer System. Data will be compiled using consistent approaches for approximately 36 subbasins, and will include groundwater recharge, use, and discharge to surface water. Current surface-water withdrawals and streamflows will be compiled at a similar scale to allow a holistic comparison of water demands, summer low flows in streams, and groundwater availability in different hydrogeologic settings of Puget Sound.  USGS will run available groundwater models (Kitsap Peninsula and Chambers-Clover Creek Watershed) to generate monthly groundwater budgets that include such details such as locations of contributing areas that discharge to streams or Puget Sound. Data and information will be published/presented in a USGS technical report and ScienceBase data release, and through an interactive website that will allow interested stakeholders to explore the information in a myriad of ways.