Conversion Factors

Multiply	By	To obtain
acre	0.4047	hectare (ha)
acre	0.004047	square kilometer (km2)
foot (ft)	0.3048	meter (m)
mile (mi)	1.609	kilometer (km)
section (640 acres or 1 mi2)	259.0	square hectometer (hm2)
square mile (mi2)	259.0	hectare (ha)

Datum

Vertical coordinate information is referenced to North American Vertical Datum of 1988 (NAVD 88).

Abstract

Selected groundwater level hydrographs for the Chambers-Clover Creek watershed (CCCW) and vicinity, Washington, are presented in an interactive web-based map to illustrate changes in groundwater levels in and near the CCCW on a monthly and seasonal basis. Hydrographs are linked to points corresponding to the well location on an interactive map of the study area. Groundwater level data and well information from Federal, State, and local agencies were obtained from the U.S. Geological Survey National Water Information System (NWIS), Groundwater Site Inventory (GWSI) System.

Introduction

Data presented in this report are part of a larger study, which began in May 2006 as a cooperative effort of the U.S. Geological Survey (USGS), Pierce Conservation District, area public water suppliers, Washington State Department of Ecology, and the Pierce County Surface Water Management Division. The measurement of groundwater levels was an important component to develop an improved understanding of the groundwater flow system in the Chambers-Clover Creek Watershed (CCCW) study area (fig. 1) and its relation to surface-water resources. This information will be integrated into a numerical groundwater flow model to assist water resource managers in the development of a long-term watershed management plan.

Purpose and Scope

This report presents groundwater hydrographs for 137 wells from a monitoring network established by the USGS in and near the CCCW study area. Groundwater levels were measured monthly from March 2007 through September 2008, to provide information on the groundwater flow system and its relation to surface-water resources. All groundwater level measurements (except for well 19N/04E-27A01, which was measured by the owner) were made by USGS personnel using standard procedures described by Drost (2005).

Well-Numbering System

The USGS assigns numbers to wells and springs in Washington that identify their locations in a township, range, and section format (fig. 2). For example, for well number 20N/02E-26C01, ‘20N/02E’ indicates the township (20N) and the range (02E) north of the Willamette Base Line and east of the Willamette Meridian, respectively. The first number following the hyphen, ‘26’, indicates the section number within the township. (Most townships in the study area are divided into 36-mi² sections; however, Washington Territory Donation Land Claims of 1852-55 predate the Public Lands Survey and are not regular 1-mi² sections. These early Donation Land Claims are depicted on maps as irregularly sized and shaped sections and are assigned sequence numbers greater than 36.) The letter following the section number, C, indicates the 40-acre subdivision of the section shown in figure 2. The last number, ‘01’ is the sequence number used by USGS to differentiate multiple wells in that 40-acre tract. If the well has been deepened it also will have a ‘D1’ designation following the sequence number.

Well Locations and Hydrographs

Well locations are plotted on an interactive image of the study area (http://wa.water.usgs.gov/projects/clovercreek/hydrographs.htm). The map image can be manipulated using the buttons in the upper-left corner of the image or by clicking with the mouse to pan and double-clicking to zoom. Holding the cursor over a plotted well site opens a message box that displays the local well number. Double-clicking on the well location displays a window containing well information and associated hydrograph. A zoom feature is available to differentiate among wells in close proximity to one another. For selected wells, more well information and water-level data are available at the “View Additional Information” link that connects the reader to a corresponding page in the web interface of the USGS National Water Information System. This option allows users to view water-level measurements made before and after the operation of the CCCW network, and access a table or graph of those values. A listing of all wells shown on the map is presented on table 1. A drop-down list of wells is displayed above the map image representing each well in the network.

Each well on the map is hyperlinked to a hydrograph that illustrates groundwater level changes in the well during the study period. Each hydrograph is displayed in a window that includes local well number, land surface altitude, well depth, and the hydrograph that shows the groundwater level. The horizontal axis indicates the date water levels were measured or observed and the vertical axis indicates the water level in feet below land surface. The scale of the y-axis varies according to the data range. Water levels that are above land surface are preceded by a minus sign.

Ground-Water Level Changes

Several factors can cause groundwater levels to change over time. Recharge, groundwater withdrawals, and characteristics of the hydrogeologic system are a few factors that influence groundwater levels. Periods of wet or dry conditions may result in groundwater level rises and declines, respectively, as the amount of water stored in an aquifer responds to recharge and subsequent discharge over time. Water levels in a well may decline in response to water being withdrawn from that well or from a nearby well. The amount of time required for water level responses may vary significantly in different parts of an aquifer system. The hydrographs on the web site illustrate groundwater level changes during March 2007 through September 2008. An improved understanding of natural and human factors controlling these water level changes is a primary objective for the larger study of the aquifer system in and near the CCCW study area, and will be reported in subsequent reports.

Acknowledgments

The authors wish to thank the many well owners for their cooperation in providing access to wells. The authors also wish to thank the Washington State Department of Ecology and public water suppliers in the study area for providing assistance in the compilation of well information.

Reference Cited

Drost, B.W., 2005, Quality-assurance plan for groundwater activities: U.S. Geological Survey Open-File Report 2005-1126, 33 p.