Characterization and Numerical Simulation of the Puyallup River Watershed

Science Center Objects

Groundwater is an important resource for domestic, commercial, and industrial usage in the Puyallup River Watershed, and groundwater discharge helps maintain late-summer and early-fall streamflow (baseflow) in many area streams. Consequently, as the population grows, and commercial and industrial activity increase, so does the demand for groundwater. However, the quantity of usable groundwater, the potential effects of future natural conditions and anthropogenic activities on groundwater resources, and potential impacts of groundwater withdrawals on streamflow, are not well understood in the watershed. Additional information is required to help ensure the long-term sustainability of the area's groundwater and surface-water resources.

Groundwater is an important resource for domestic, commercial, and industrial usage in the Puyallup River Watershed, and groundwater discharge helps maintain late-summer and early-fall streamflow (baseflow) in many area streams. Consequently, as the population grows, and commercial and industrial activity increase, so does the demand for groundwater. However, the quantity of usable groundwater, the potential effects of future natural conditions and anthropogenic activities on groundwater resources, and potential impacts of groundwater withdrawals on streamflow, are not well understood in the watershed. Additional information is required to help ensure the long-term sustainability of the area's groundwater and surface-water resources.

The following project partners have provided funding and/or information to the Puyallup study: the Cities of Auburn, Bonney Lake, Buckley, Enumclaw, Fife, Milton, Orting, Puyallup, Sumner, and Tacoma, Cascade Water Alliance, Town of South Prairie, Fruitland Mutual Water Company, Firgrove Mutual Water Company, Lakehaven Utility District, Mt. View-Edgewood Water Company, Summit Water & Supply Company, Valley Water District, and Pierce Conservation District, Robinson-Noble, Inc., The Russell Family Foundation, U.S. Army Core of Engineers, and the Washington State Department of Health.

Problem - Groundwater is an important resource for domestic, commercial, and industrial usage in the Puyallup River Watershed, and groundwater discharge helps maintain late-summer and early-fall streamflow (baseflow) in many area streams. Consequently, as the population grows, and commercial and industrial activity increase, so does the demand for groundwater. However, the quantity of usable groundwater, the potential effects of future natural conditions and anthropogenic activities on groundwater resources, and potential impacts of groundwater withdrawals on streamflow, are not well understood in the watershed. Additional information is required to help ensure the long-term sustainability of the area's groundwater and surface-water resources.

Objectives - This study directly supports USGS mission and goals related to water-resource issues identified in the USGS Science Strategy. The study addresses groundwater availability and sustainability, a priority issue under the Water Census of the United States as outlined in Facing Tomorrow's challenges: USGS Science in the Decade 2007-2017. This study also will provide resource managers and stake holders in the Puyallup River watershed with the means to evaluate potential hydrologic and anthropogenic impacts on groundwater and surface-water resources. This study is appropriate for inclusion in the USGS Cooperative Program because it will provide information that advances understanding of hydrologic processes.

Approach - An initial field inventory of about 250 wells will be conducted, including the establishment of well locations using GPS and water-level measurements. Based on this initial inventory, a monthly groundwater-level monitoring network consisting of about 100 wells will be established and operated over a 2-year period. Synoptic stream baseflow measurements will be made at about 30 locations to delineate gaining and losing stream reaches. All measurements and associated information will be verified and entered into the USGS National Water Information System data base. Hydrogeologic units will be assigned to about 850 well drillers' logs, and unit extent and thickness maps will be constructed. Groundwater and surface-water data will be used to characterize the flow system, and construct a numerical ground-water flow model to simulate potential hydrologic and anthropogenic impacts on groundwater and surface-water resources.