Hydrogeologic Framework, Groundwater Movement, and 

Water Budget in the Chambers-Clover Creek Watershed and 

Vicinity, Pierce County, Washington 

Scientific Investigations Report 2010–5055

Prepared in cooperation with the Pierce Conservation District and the 

Washington State Department of Ecology

U.S. Department of the Interior

U.S. Geological Survey
Cover: Photograph showing confluence of Chambers Creek and Leach Creek. 

Photograph taken by Don Russell, Chambers-Clover Creek project team member, 2009.
Hydrogeologic Framework, Groundwater 

Movement, and Water Budget in the 

Chambers–Clover Creek Watershed and 

Vicinity, Pierce County, Washington

By Mark E. Savoca, Wendy B. Welch, Kenneth H. Johnson, R.C. Lane, U.S. 

Geological Survey; Burt G. Clothier, Robinson & Noble Inc., and Elisabeth T. 

Fasser, U.S. Geological Survey

Prepared in cooperation with the Pierce Conservation District and the 

Washington State Department of Ecology

Scientific Investigations Report 2010–5055

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod

To order this and other USGS information products, visit http://store.usgs.gov

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Savoca, M.E., Welch, W.B., Johnson, K.H., Lane, R.C., Clothier, B.G., and Fasser, E.T., 2010, Hydrogeologic framework, 

groundwater movement, and water budget in the Chambers-Clover Creek Watershed and vicinity, Pierce County, 

Washington: U.S. Geological Survey Scientific Investigations Report 2010–5055, 46 p.
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope .......................................................................................................................................2

Description of Study Area ............................................................................................................................2

Methods of Investigation..............................................................................................................................4

Well Inventory and Water-Level Measurements ............................................................................4

Hydrogeology.........................................................................................................................................4

Streamflow.............................................................................................................................................8

Hydrogeologic Framework...........................................................................................................................8

Geologic Setting....................................................................................................................................8

Hydrogeologic Units.............................................................................................................................8

Hydraulic Conductivity.......................................................................................................................21

Groundwater Movement.............................................................................................................................22

Recharge .............................................................................................................................................22

Groundwater-Flow Directions ..........................................................................................................26

Discharge.............................................................................................................................................33

Groundwater and Surface-Water Interactions .............................................................................34

Groundwater-Level Fluctuations......................................................................................................40

Water Budget ...............................................................................................................................................42

Summary and Conclusions.........................................................................................................................42

Acknowledgments.......................................................................................................................................43

References Cited..........................................................................................................................................44

Plates

Plate 1. Maps showing locations of selected wells and surface-water discharge sites in the 

Chambers-Clover Creek Watershed and vicinity, Pierce County, Washington.

Plate 2. Map and hydrogeologic sections showing surficial hydrogeology, hydrogeologic 

units, and locations of selected wells in the Chambers-Clover Creek Watershed and 

vicinity, Pierce County, Washington.
iv

Figures

Figure 1. Map showing location of Chambers-Clover Creek Watershed and vicinity, 

Washington ................................................................................. 3

Figure 2. Graphs showing residuals between hydrogeologic unit correlation altitudes 

and altitudes of interpolated digital hydrogeologic surfaces ........................ 7

Figure 3. Map showing extent and thickness of AL alluvial valley aquifer in 

Chambers-Clover Creek Watershed and vicinity, Washington ........................ 10

Figure 4. Map showing extent and thickness of A1 aquifer in Chambers-Clover 

Creek Watershed and vicinity, Washington ............................................. 11

Figure 5. Map showing extent and thickness of A2 confining unit in Chambers-Clover 

Creek Watershed and vicinity, Washington ............................................. 12

Figure 6. Map showing extent and thickness of A3 aquifer in Chambers-Clover 

Creek Watershed and vicinity, Washington ............................................. 14

Figure 7. Map showing extent and thickness of B confining unit in Chambers-Clover 

Creek Watershed and vicinity, Washington ............................................. 15

Figure 8. Map showing extent and thickness of C aquifer in Chambers-Clover 

Creek Watershed and vicinity, Washington ............................................. 16

Figue 9. Map showing extent and thickness of D confining unit in Chambers-Clover 

Creek Watershed and vicinity, Washington ............................................. 17

Figure 10. Map showing extent and thickness of E aquifer in Chambers-Clover Creek 

Watershed and vicinity, Washington...................................................... 18

Figure 11. Map showing extent and thickness of F confining unit in Chambers-Clover 

Creek Watershed and vicinity, Washington ............................................. 19

Figure 12. Map showing extent and thickness of G undifferentiated deposits in 

Chambers-Clover Creek Watershed and vicinity, Washington ........................ 20

Figure 13. Map showing average annual precipitation, canopy cover, and impervious 

surface across the Chambers-Clover Creek Watershed and vicinity, 

Washington, September 2006–August 2008 ............................................. 23

Figure 14. Graph showing precipitation-recharge relations used in this study, 

Chambers-Clover Creek Watershed and vicinity, Washington ........................ 24

Figure 15. Map showing distribution of average annual groundwater recharge from 

precipitation in Chambers-Clover Creek Watershed and vicinity, Washington, 

September 2006–August 2008 ............................................................ 25

Figure 16. Map showing water-level altitudes and direction of groundwater flow in 

AL alluvial valley aquifer, Chambers-Clover Creek Watershed and vicinity, 

Washington, September 2006–September 2008 ....................................... 27

Figure 17. Map showing water-level altitudes and direction of groundwater flow in 

A1 aquifer, Chambers-Clover Creek Watershed and vicinity, Washington, 

September 2006–September 2008 ......................................................... 28

Figure 18. Map showing water-level altitudes and direction of groundwater flow in 

A3 aquifer, Chambers-Clover Creek Watershed and vicinity, Washington, 

September 2006–September 2008 ......................................................... 29

Figure 19. Map showing water-level altitudes and direction of groundwater flow in 

C aquifer, Chambers-Clover Creek Watershed and vicinity, Washington, 

September 2006–September 2008 ......................................................... 30
v

Figure 20. Map showing water-level altitudes and direction of groundwater flow in 

E aquifer, Chambers-Clover Creek Watershed and vicinity, Washington, 

September 2006–September 2008 ......................................................... 31

Figure 21. Map showing water-level altitudes and direction of groundwater flow in 

G undifferentiated deposits, Chambers-Clover Creek Watershed and vicinity, 

Washington, September 2006–September 2008 ....................................... 32

Figure 22. Graph showing mean monthly streamflow at U.S. Geological Survey 

streamflow-gaging stations for Clover Creek, Chambers Creek, and Clarks 

Creek, Chambers-Clover Creek Watershed and vicinity, Washington ............... 38

Figure 23. Graph showing daily streamflow for U.S. Geological Survey 

streamflow-gaging stations on Clover Creek, Chambers Creek, and 

Clarks Creek, Chambers-Clover Creek Watershed and vicinity, 

Washington, September 5–15, 2007 ...................................................... 38

Figure 24. Graph showing daily streamflow for U.S. Geological Survey 

streamflow-gaging stations on Clover Creek, Chambers Creek, 

and Clarks Creek, Chambers-Clover Creek Watershed and vicinity, 

Washington, July 4-14, 2008 ............................................................... 39

Figure 25. Hydrographs of water levels in well 20N/02E-35P01, stream stage at 

U.S. Geological Survey streamflow-gaging station on Chambers Creek, and 

precipitation at Tacoma, Chambers-Clover Creek Watershed and vicinity, 

Washington, September 2007–September 2008 ....................................... 40

Figure 26. Hydrographs of water levels in well 19N02E-19LF402C, stream stage at 

U.S. Geological Survey streamflow-gaging station on Clover Creek, and 

precipitation at Tacoma, Chambers-Clover Creek Watershed and vicinity, 

Washington, September 2007–September 2008 ....................................... 41

Tables

Table 1. Hydrogeologic units defined in this study and correlation with geologic and

hydrostratigraphic units from previous investigations ................................. 5

Table 2. Statistics for interpolated digital hydrogeologic surfaces.............................. 6

Table 3. Summary of hydraulic conductivity values estimated from specific-capacity

data and aquifers tests, by hydrogeologic unit, Chambers-Clover Creek

Watershed and vicinity, Washington...................................................... 22

Table 4. Synoptic streamflow measurements and estimates of evaporative loss from

lakes used to determine groundwater discharge in the Chambers-Clover Creek

Watershed and vicinity, Washington, September 2007 and July 2008 ............... 33

Table 5. Synoptic streamflow measurements and estimates of gains and losses in the

Chambers-Clover Creek Watershed and vicinity, Washington, September 2007

and July 2008................................................................................. 35

Table 6. Summary of groundwater-level fluctuations and well depths by hydrogeologic

unit, Chambers-Clover Creek Watershed, Washington, March 2007 through

September 2008.............................................................................. 41

Table 7. Estimated annual water budget for Chambers-Clover Creek Watershed and

vicinity, Washington, September 1, 2006, to August 31, 2008........................... 42

Figures—Continued
vi

Conversion Factors and Datums

Conversion Factors

Multiply By To obtain

acre-foot (acre-ft) 1,233 cubic meter

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

cubic foot per day (ft3/d) 0.02832 cubic meter per day (m3/d)

cubic foot per second per mile (ft3/s)/mi 0.01760 cubic meter per second per kilometer 

(m3/s/km)

cubic foot per second per square mile 

(ft3/s)/mi2

0.01093 cubic meter per second per square kilometer

(m3/s/km2)

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

inch per year (in/yr) 25.4 millimeter per year (mm/yr)

foot (ft) 0.3048 meter (m)

foot per day (ft/d) 0.3048 meter per day (m/d)

gallon (gal) 0.003785 cubic meter (m3) 

gallon per day (gal/d) 0.003785 cubic meter per day (m3/d)

square mile (mi2) 2.590 square kilometer (km2) 

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32.

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8.

Datums

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 29), referred to in this report as “sea level.”

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above or below sea level.

Abbreviations and Acronyms

ANUDEM Australian National University Digital Elevation Model

DEM digital elevation model

CCCW Chambers-Clover Creek Watershed

GIS geographic information system

GPS global positioning system

LiDAR light detections and ranging

NAD North American Datum

NGVD National Geodetic Vertical Datum

NWS National Weather Service

PRISM parameter elevation regressions on Independent Slopes Model

RCW Revised Code Washington

USGS U.S. Geological Survey

WRIA Water Resources Inventory Area
vii

Well-Numbering System

Wells in the State of Washington are assigned a local well number that identifies each well 

based on its location in a township, range, section, and 40-acre tract. For example, local well 

number 20N/02E-26C01 indicates that the well is in township 20 north of the Willamette Base 

Line, and range 2 east of the Willamette Meridian. The numbers immediately following the 

hyphen indicate the section (26) in the township, and the letter following the section (C) gives 

the 40-acre tract of the section. The two-digit sequence number (01) following the letter is used 

to distinguish individual wells in the same 40-acre tract. A “D” following the sequence number 

indicates a well that has been deepened. In the plates of this report, wells are identified using 

only the section and 40-acre tract, such as 26C01; the township and range are shown on the 

map borders.

Willamette Meridian

Willamette Base Line

W A S H I N G T O N

Study area

SECTION 26

TOWNSHIP

Well 20N/02E-26C01

ABCD

E F G H

JKLM

N P Q R

R. 2 E.

T.

20

 N.

123456

7 12

18 13

19 24

30 25

31 32 33 34 35 36

Diagram showing well-numbering system used in Washington.
viii

This page intentionally left blank.
Hydrogeologic Framework, Groundwater Movement, and 

Water Budget in the Chambers-Clover Creek Watershed and 

Vicinity, Pierce County, Washington

By Mark E. Savoca, Wendy B. Welch, Kenneth H. Johnson, R.C. Lane, U.S. Geological Survey; Burt G. Clothier, 

Robinson & Noble Inc., and Elisabeth T. Fasser, U.S. Geological Survey

Abstract

This report presents information used to characterize 

the groundwater-flow system in the Chambers-Clover Creek 

Watershed and vicinity, and includes descriptions of the 

geology and hydrogeologic framework; groundwater recharge 

and discharge; groundwater levels and flow directions; 

seasonal groundwater level fluctuations; interactions between 

aquifers and the surface-water system; and a water budget. The 

study area covers about 706 square miles in western Pierce 

County, Washington, and extends north to the Puyallup River, 

southwest to the Nisqually River, and is bounded on the south 

and east by foothills of the Cascade Range and on the west by 

Puget Sound. The area is underlain by a northwest-thickening 

sequence of unconsolidated glacial and interglacial deposits 

which overlie sedimentary and volcanic bedrock units that 

crop out in the foothills along the southern and southeastern 

margin of the study area. Geologic units were grouped into 

11 hydrogeologic units consisting of aquifers, confining units, 

and an underlying bedrock unit. A surficial hydrogeologic 

unit map was developed and used with well information from 

450 drillers’ logs to construct 6 hydrogeologic sections, and 

unit extent and thickness maps.

 Groundwater in unconsolidated glacial and interglacial 

aquifers generally flows to the northwest towards Puget 

Sound, and to the north and northeast towards the Puyallup 

River. These generalized flow patterns likely are complicated 

by the presence of low permeability confining units that 

separate discontinuous bodies of aquifer material and act 

as local groundwater-flow barriers. Water levels in wells 

completed in the unconsolidated hydrogeologic units show 

seasonal variations ranging from less than 1 to about 50 feet. 

The largest groundwater-level fluctuation (78 feet) observed 

during the monitoring period (March 2007–September 2008) 

was in a well completed in the bedrock unit.

Synoptic streamflow measurements made in September 

2007 and July 2008 indicated a total groundwater discharge 

to streams in the study area of 87,310 and 92,160 acre-feet 

per year, respectively. The synoptic streamflow measurements 

show a complex pattern of gains and losses to streamflows that 

varies throughout the study area, and appears to be influenced 

in places by local topography. Groundwater discharge occurs 

at numerous springs in the area and the total previously 

reported discharge of springs in the area is approximately 

80,000 acre-feet per year. There are, in addition, many 

unmeasured springs and the total spring discharge in the area 

is unknown.

The water-budget area (432 mi2 located within the 

larger study area) received an annual average (September1, 

2006, to August 31, 2008) of about 1,025,000 acre-ft or 

about 45 inches of precipitation a year. About 44 percent 

of precipitation enters the groundwater system as recharge. 

Almost one-half of this recharge (49 percent) discharges to 

the Puyallup and Nisqually Rivers and leaves the groundwater 

system as submarine groundwater discharge to Puget Sound. 

The remaining groundwater recharge discharges to streams 

(20 percent) and springs (18 percent) or is withdrawn from 

wells (13 percent).

Introduction

In 1998, the Washington State Legislature established 

the Washington State Watershed Management Act (codified 

under RCW 90.82) to address diminishing water availability 

and quality and the loss of critical habitat for fish and wildlife. 

Watershed studies under this act were started in 1998 in 

the Chambers-Clover Creek Watershed (CCCW) Water 

Resources Inventory Area (WRIA 12) by a group of Initiating 

Governments and local stakeholders (Planning Unit). After 

completion of a technical assessment of the watershed, some 

members of the Planning Unit concluded that additional data, 

including development of a numerical groundwater-flow 

model, would contribute to an improved understanding of 

water resources in the CCCW.
2 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

In May 2006, the U.S. Geological Survey (USGS) 

in ooperation with Pierce Conservation District (serving 

as sponsoring agency for local public water suppliers and 

Pierce County Surface Water Management Division) and the 

Washington State Department of Ecology began a project to 

characterize the groundwater-flow system in the CCCW and 

vicinity. A second phase of this project will integrate this and 

other information into a numerical groundwater-flow model to 

contribute to an improved understanding of water resources in 

the CCCW.

Purpose and Scope

This report presents information used to characterize 

the groundwater-flow system in the CCCW and vicinity. The 

report includes descriptions of the geology and hydrogeologic 

framework of the area; groundwater recharge and 

discharge; groundwater levels and flow directions; seasonal 

groundwater‐level fluctuations; interactions between aquifers 

and the surface-water system; and a water budget.

Description of Study Area

The study area covers about 706 mi2 in western Pierce 

County, Washington (fig. 1), and initially was selected to 

include major hydrologic features that could be used as 

regional model boundaries during the second phase of this 

project. The study area defines the region of groundwater and 

surface-water data collection, and coincides with the area 

in which the hydrogeologic framework was developed. The 

study area extends northeast to the Puyallup River, southwest 

to the Nisqually River, and is bounded on the south and east 

by foothills of the Cascade Range and on the northwest by 

Puget Sound. The water-budget area (432 mi2) is located 

within the larger study area (fig. 1), and was delineated 

after completion of the hydrogeologic framework to more 

closely approximate the area to be used in development of 

the numerical flow model of the CCCW and vicinity. The 

water-budget area is bounded by the Puyallup and Nisqually 

Rivers, Puget Sound, and extends southeast to Tanwax Creek. 

The water‐budget area includes most of the groundwater‐level 

and all streamflow data- collection sites. Tanwax Creek 

approximates the southeastern extent of most of the waterbearing hydrogeologic units (pls. 1 and 2). The Puyallup and 

Nisqually Rivers and Puget Sound constitute regional scale 

hydrologic features that will coincide with model boundaries. 

In this report, the water-budget area defines the region in 

which water-budget components were estimated.

The study area is underlain by a northwest-thickening 

sequence of unconsolidated glacial (till and outwash) and 

interglacial (fluvial and lacustrine) deposits. Sedimentary 

and volcanic bedrock units underlie the unconsolidated 

deposits and crop out in the foothills along the southern and 

southeastern margin of the study area. Land-surface altitude 

in the study area ranges from sea level along the Puget Sound 

coast and western extent of major river valleys to near 2,340 ft 

in the southeastern foothills.

The Puyallup and Nisqually Rivers occupy large, 

relatively flat alluvial valleys that are separated by a broad, 

poorly drained upland area that covers most of the study area. 

The northwest-flowing Puyallup River receives streamflow 

from several north-flowing streams (Swan, Clear, and Clarks 

Creeks) that originate in the northern uplands. Chambers and 

Clover Creeks drain much of the central uplands and flow 

westward to the Puget Sound. Muck and Lacamas Creeks, and 

several small tributaries to the northwest-flowing Nisqually 

River drain the southern part of the study area. Many stream 

reaches flow year-round; however, intermittent and ephemeral 

flow conditions also are common in many stream reaches, 

especially during the summer months. Numerous springs 

are present throughout the study area, and contribute to 

late‐summer baseflow to streams and year-round groundwater 

discharge to Puget Sound along shoreline bluffs. Major lakes 

in the study area include Steilacoom, Gravelly, American, and 

Spanaway. These lakes likely are of glacial (kettle) origin and 

generally reflect water levels in the shallow groundwater‐flow 

system. Outflows from Gravelly and American Lakes 

are unregulated. Steilacoom and Spanaway Lakes have 

fixed‐elevation controlled outfalls. Many small lakes in the 

area are associated with poorly drained wetland areas typically 

formed on glacial till deposits.

The study area has a temperate marine climate with 

warm, dry summers, and cool, wet winters. Temperatures 

are moderated by the Pacific Ocean and Puget Sound. The 

ocean provides an abundant supply of moisture for winter 

storms that typically approach the area from the southwest. 

Mean annual precipitation (average annual precipitation for 

1971–2000) is 38.9 in. at Tacoma, and 43.1 in. at McMillin 

Reservoir (National Oceanic and Atmospheric Administration, 

2007). The distribution of precipitation varies throughout 

the year. Summers (June–August) typically are dry with a 

mean total precipitation of 3.3 in. at Tacoma, and 4.6 in. at 

McMillin Reservoir. Winters (December–February) are wetter 

than summers with a mean total precipitation of 15.7 in. at 

Tacoma and 16.1 in. at McMillin Reservoir. Mean monthly 

temperature (average monthly temperature for 1971–2000) 

at these locations ranges from about 39oF in January to 

about 64oF in August (National Oceanic and Atmospheric 

Administration, 2007).
Description of Study Area 3

Figure 1. Location of Chambers-Clover Creek Watershed and vicinity, Washington.

tac09-0409_Fig 01

R. 05 E.

T.

15

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

R. 01 E. R. 02 E. R. 03 E. R. 04 E.

SR

7

SR

161

SR

512

I-5

I-5

SR

16

Puget

Sound

Lake

Tapps

American

Lake

Gravelly

Lake

Spanaway

Lake

Steilacoom

Lake

Ohop

Lake

Tanwax

Lake

Lake

Kapowsin

Swan Creek

Puyallup

River

Clover Creek

Chambers Creek

Nisqually

River

Nisqually River

Puyallup

River

Carbon

River

Mashel River

Nisqually River

Muck Creek

Muck

Creek

Lacamas Creek

Clear Creek

Clarks Creek

Ohop

Creek

Puallup

River

No. Fork C .C.

Clov e r Creek

South

Creek

Tanwax

Creek

47°

46°

50'

47°

10'

47°

20'

122°40' 122°30' 122°20' 122°10'

Base from U.S. Geological Survey digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

Tacoma

Lakewood

Federal Way

Fife

Puyallup

Yelm

Sumner

Edgewood

DuPont

University Place

Orting

Milton

Pacific

Algona

Auburn

Rainier

Fircrest

Steilacoom

Eatonville

Roy

Ruston

Bonney

Lake

WASHINGTON

Figure location

EXPLANATION

0 2 4 6 8 MILES

0 2 4 6 8 KILOMETERS

Boundary of study area

Boundary of Chambers-

 Clover Creek watershed

Boundary of water-budget 

 area
4 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

Methods of Investigation

Methods used to compile and analyze information for the 

characterization of the groundwater-flow system in the study 

area are described in this section. Methods used to determine 

groundwater movement and estimate water budget are 

included with the respective sections later in this report. 

Well Inventory and Water-Level Measurements

The groundwater-flow system was characterized based 

on the analysis of spatially distributed information about 

groundwater levels and the physical and hydraulic properties 

of the geologic units encountered during well construction. 

Spatial information was obtained through the measurement 

of water levels in wells, and the compilation and analysis of 

hydrogeologic descriptions and well tests from well drillers’ 

logs. Well records that document the drilling (drillers’ 

log description of borehole lithology), construction, and, 

sometimes, hydraulic testing of wells were compiled from 

USGS and Washington State Department of Ecology databases 

to identify potential wells to be used in this study. Candidate 

wells were selected for field inventory based on the location 

and depth of the well, and the availability of a complete 

well record with drillers’ log. Well records with insufficient 

well location and construction information or incomplete 

or poorly constrained drillers’ logs were not considered for 

field inventory and were not used in this study. The goal of 

the inventory was to obtain an even distribution of wells 

throughout the study area. However, this was not possible 

for the entire study area because of a lack of wells in less 

populated areas and also in some areas within the limits of 

the city of Tacoma. During an initial field inventory 

(September–December 2006), permission was obtained from 

selected well owners and synoptic water-level measurements 

were made in 229 wells; synoptic water-level measurements 

also were made in an additional 29 wells during a subsequent 

field inventory (February through April 2007) to address 

remaining data gaps (pl. 1). Water levels were measured on a 

monthly basis from March 2007 –September 2008 in 137 of 

the inventoried wells (pl. 1). Continuous water-level recorders 

were installed in six of the monthly monitoring wells (pl. 1).

Latitude and longitude locations were determined for 

each well using a Global Positioning System (GPS) receiver 

with a horizontal accuracy of one-tenth of a second (about 

10 ft). Light Detection and Ranging (LiDAR) data were 

obtained through the Puget Sound LiDAR Consortium 

(http://pugetsoundlidar.ess.washington.edu/) and were used 

to determine the altitude of land surface at each well and 

to compute water-level altitudes. Vertical accuracy of the 

LiDAR data typically was ±1 ft. Water level, reported as 

depth to water below land surface, was measured using a 

calibrated electric tape or graduated steel tape, both with a 

stated accuracy of 0.01 ft. There also is the potential for error 

in depth-to-water measurements associated with borehole 

deviation in sub-vertical wells. All water-level measurements 

were made by USGS personnel in accordance with standard 

techniques of the USGS (Drost, 2005). Water-level altitudes 

were determined by subtracting the measured depth-to-water 

below land surface from the LiDAR derived land-surface 

altitude at the well.

The spatial distribution of hydrogeologic data compiled 

solely from inventoried wells was insufficient to accurately 

characterize the spatial variability of hydrogeologic units 

across the study area. Therefore, an additional 206 wells 

with available drillers’ logs were analyzed during this study 

to better represent the hydrogeologic framework in areas 

where inventory wells were lacking (pl. 1). Well locations and 

drillers’ logs for these additional wells were obtained from the 

records of local public water supply systems, environmental 

consulting firms, and the USGS. Well information collected 

during the field inventory, monthly monitoring network, and 

construction of the hydrogeologic framework were entered 

into the USGS National Water Information System (NWIS) 

database and published in Justin and others (2009).

Hydrogeology

The hydrogeologic units in the Chambers-Clover Creek 

Watershed and vicinity were defined using a combination 

of geologic data including existing surficial geologic maps, 

well records with drillers’ logs available from the Washington 

State Department of Ecology, and previous investigations by 

Robinson & Noble, Inc., and others (2003) and Brown and 

Caldwell (1985).

The surficial hydrogeologic map for the study area (pl. 2; 

scale 1:100,000) was produced by merging available digital 

surficial geologic maps (Schasse, 1987, scale 1:100,000, 

Walsh, 1987, scale 1:100,000) with scanned and digitized 

geologic maps by Troost (in press, scale 1:24,000) and 

Troost and others (in press, scale 1:24,000). Fifty geologic 

units delineated on these source maps were grouped into 

11 hydrogeologic units based on similarities in lithology (grain 

size and sorting), hydrologic characteristics, and relative 

stratigraphic position (table 1).
Methods of Investigation 5

Period Epoch Hydrogeologic units defined in this study

Geologic units in 

Troost (in press) and 

Troost and Booth 

(in press)

Geologic units in 

Schasse (1987) and 

Walsh (1987)

Hydrostratigraphic 

units in Robinson & 

Noble, Inc., and others 

(2003)

Stratigraphic

units

Quaternary 

Holocene, Pleistocene

AL alluvial valley

aquifer Qal, af, Qp Qa, Qvl(e)

Aquifer A: includes

Steilacoom gravel,

Vashon Till, Vashon

Advance Outwash,

Esperance Sand

Recent alluvium, 

mudflows/ lahars and 

marine deposits

A1 aquifer Qal, Qv, Qvr, Qvry, Qvs, Qw Qa, Qgd, Qgo, Qgog, Qgos, Qp, Qvl(lc), Qvl(o) Vashon Drift (Steilacoom gravel, recessional outwash

A2 confining unit Qvi, Qvt, Qvrl Qgm, Qgt, Qgl

Vashon Drift 

(VashonTill), 

ice-contact and

moraine deposits

A3 aquifer Qva, Qpfc Qga Vashon Drift (advance outwash)

B confining unit

 m, af, Qal, Qb, Qf,

Qls, Qns, Qob, Qpdc,

Qpf, Qpoc, Qpon, Qtf,

Qvlc, Qwbc

Qc(k) Layer B

Olympia Beds 

(Kitsap Formation), 

Lawton Clay

C aquifer Qpog, Qpogc Qgp Aquifer C

Salmon Springs Drift,

Penultimate Drift,

Hayden Creek Drift,

Wingate Hill Drift

D confining unit Layer D Puyallup Formation

E aquifer Aquifer E Stuck Drift

F confining unit Layer F Alderton Formation

G Undifferentiated

deposits Aquifer G Orting Drift

Tertiary

Miocene

to Eocene Bedrock Unit Qap, Qap(h), Qapt(h), Qap(wh), Qapt(wh), and all pre-Quaternary deposits Basement confining unit and some alpine glacial deposits

Table 1. Hydrogeologic units defined in this study and correlation with geologic and hydrostratigraphic units from previous investigations.
6 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

The surficial hydrogeologic map and lithologic data 

from more than 450 drillers’ logs were used to construct more 

than 25 hydrogeologic sections using A-Prime Software’s 

CrossViewTM for ArcGIS® to identify and correlate the 

hydrogeologic units in the subsurface. Six representative 

hydrogeologic sections are shown on plate 2. Hydrogeologic 

units were assigned to the various lithologic layers depicted 

in each well log. Hydrogeologic unit assignments were used 

to delineate the extent of each unit throughout the study area. 

The altitude of the unit top surface was interpolated in a 

Geographic Information System (GIS) at a 100 ft interpolation 

grid cell size, using a method based on the Australian National 

University Digital Elevation Model (ANUDEM) procedure 

developed by Hutchinson (1989). Hydrogeologic unit top 

surfaces were constrained to a LiDAR-derived land-surface 

digital elevation model (DEM) where the unit cropped out. 

If part of a unit surface was interpolated above the top of 

an overlying unit then minimum thickness values for the 

overlying unit were used in the calculations to adjust the 

altitude of the top of the underlying unit where needed. This 

over-interpolation primarily occurred in areas where bedrock 

is overlain by relatively thin unconsolidated deposits (less 

than 100 ft thick) or where there were large gaps in the data 

coverage. Unit thickness maps were created by using GIS 

to calculate the difference between the top of a unit and the 

interpolated top of the underlying unit(s). Residuals were 

calculated as the difference between the unit surface altitudes 

assigned for a specific well log and unit altitudes of the 

interpolated digital hydrogeologic surfaces at the location 

of the well. Statistics on the residuals were determined for 

each hydrogeologic unit, excluding the alluvial valley aquifer 

(AL) and the A1 aquifer, to provide a quantitative comparison 

between the specific well log data and the interpolated 

surfaces for the entire study area (table 2; fig. 2). Residuals 

commonly were within ±1 ft for all hydrogeologic units except 

the A2 confining and A3 aquifer units. Residuals typically 

were within ±5 ft for the A2 confining unit and within ±4 ft 

for the A3 aquifer unit. The absolute mean difference for all 

hydrogeologic units was within 5.5 ft.

Table 2. Statistics for interpolated digital hydrogeologic surfaces.

[Count refers to number of wells used for interpolation of altitudes of digital hydrogeologic surfaces. Absolute 

mean difference is average absolute difference between interpreted hydrogeologic unit altitudes taken from the 

well logs and altitudes of interpolated digital hydrogeologic surfaces. Minimum and maximum differences

are those measured from interpreted hydrogeologic unit altitudes taken from the well logs and the altitudes of 

interpolated digital hydrogeologic surfaces]

Hydrogeologic 

units Count

Difference (feet)

Absolute 

mean

Minimum Maximum 

A2 confining unit 328 2.43 -66.68 24.49

A3 aquifer 308 1.83 -32.57 32.82

B confining unit 189 .86 -11.16 18.70

C aquifer 209 1.24 -32.37 33.50

D confining unit 111 1.65 -22.46 33.66

E aquifer 79 1.90 -28.39 49.53

F confining unit 58 5.27 -78.79 96.34

G undifferentiated 

deposits

44 5.48 -75.33 86.38
Methods of Investigation 7

Figure 2. Residuals between hydrogeologic unit correlation altitudes and altitudes of interpolated digital hydrogeologic 

surfaces.

wa0409_ fig02

B Confining Unit

D Confining Unit

A2 Confining Unit

F Confining Unit

C Aquifer

E Aquifer

A3 Aquifer

G Undifferentiated Deposits

0

50

100

150

200

250

0

192496

45

18

012

-9-2-1

-75-14

86

5 

28

012

-7-3-1

-28

1150

11

0129

-1

-79-26-19-11

11233034

1239

-1

0

-7-5-4-3-2

-22

111216171819

1

-4-3-1

0

-9

-11

16172634

12345

-10

-3-1

0

-32-27

11141833

135

-3-1

-18-14-10

-6

-27-24

131620

0246

-4-2

-22-17-13

-7

-33-25

141821

1358

-4-2

-20-13

-8-6

-47-26

111719202324

6

16

24

-1

0

-5-3

-24-14-11

-7

-67-29

50

100

150

200

250

0

50

100

150

200

250

0

50

100

150

200

250

0

50

100

150

200

250

0

50

100

150

200

250

0

50

100

150

200

250

0

50

100

150

200

250

COUNT COUNT COUNT COUNT

RESIDUALS, IN FEET RESIDUALS, IN FEET
8 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

Streamflow

Streamflow analysis in the study area included the 

evaluation of continuous streamflow data from 7 USGS 

streamflow-gaging stations and 2 streamflow measurements 

from 44 synoptic streamflow sites (pl. 1). These data were 

used to quantify the amount of surface water leaving the 

study area and to delineate gaining and losing stream reaches 

during low-flow conditions. Streamflow measurements at 

USGS streamflow-gaging stations and synoptic sites were 

made by USGS personnel, assisted by Pierce Conservation 

District Stream Team volunteers, using Price (pygmy or AA) 

and FlowTracker Handheld ADV® current velocity meters 

according to standard techniques of the USGS (Rantz, 1982). 

The USGS assigns an accuracy to streamflow measurements 

based on the equipment, character of the measurement section, 

number of observations, stability of stage, wind conditions, 

and the accuracy of depth and velocity measurements (Rantz, 

1982, p. 179). Accuracy ratings of “good” indicate that the 

measurements are judged to be within 5 percent of true values, 

ratings of “fair” indicate that the measurements are judged 

to be within 8 percent of true values, and ratings of “poor” 

indicate that the measurements are judged not to be within 

8 percent of true values (assumed to be within 11 percent 

of true values for this study). Estimates of streamflow were 

required at some sites where direct measurements could not 

be made because of sub-optimal flow conditions (low velocity, 

shallow water depth, or the presence of aquatic vegetation) 

or the need to visually estimate the streamflow value (lack 

of access to stream). Estimates of streamflow were based 

on (1) visual approximations of flow widths, depths, and 

velocities; (2) discharge measurements from nearby sites; or 

(3) discharge measurements from prior years. All estimated 

streamflow values were rated “poor.” Additional streamflow 

data specific to streams in the study area was provided by state 

and county agencies, and military installations.

Numerous springs are present throughout the study 

area, and contribute to late-summer baseflow to streams 

and year-round groundwater discharge to the Puget Sound 

along shoreline bluffs. A field inventory of springs was not 

conducted during this investigation. Descriptions of spring 

locations and historical discharge provided by Blair (1929), 

Sceva and others (1955), Walters and Kimmel (1968), and 

Jones and others (1999) were evaluated.

Hydrogeologic Framework

This section describes the geology and hydrogeologic 

framework, which define the physical, lithologic, and 

hydrologic characteristics of the hydrogeologic units that 

compose the groundwater-flow system in the study area. 

An understanding of these characteristics is important in 

determining the occurrence, movement, and availability of 

groundwater in the aquifer system, and the exchange of water 

between the aquifer system and surface-water features.

Geologic Setting

A brief summary of major geologic events in the study 

area is given below and is based on the work of Walters and 

Kimmel (1968), Jones (1999), and Borden and Troost (2001). 

Plate tectonics and glacial processes are the two major forces 

that have shaped the present-day Puget Lowland. The most 

recent advance and retreat of continental glaciers in the 

Pleistocene epoch of the Quaternary Period left behind more 

than 3,000 ft of unconsolidated deposits in the lowland and 

about 2,000 ft of deposits in the study area. These deposits 

form the hydrogeologic units defined in this study and will be 

the focus of the remaining discussion.

The Puget Lobe of the Cordilleran ice sheet has advanced 

and retreated several times into the Puget Lowland from 

the mountains of British Columbia since the beginning of 

the Quaternary and has left behind a complex sequence of 

alternating glacial and interglacial sediments. The Vashon 

Stade of the Fraser Glaciation was the most recent and 

extensive of the major advances. Because every glacial 

advance partially removes and reworks deposits from earlier 

glaciations, deposits from the Vashon Glacier offer the most 

complete glacial drift sequence. Glacial deposits typically 

contain (in order of deposition) advance outwash sand and 

gravels; glacial till (hard and poorly sorted mixture of clay, 

silt, sand, and gravel) and ice-contact deposits, and recessional 

outwash sand and gravels at the top of the sequence.

Each major glacial interval is followed by an extended 

interglacial period where fluvial, lacustrine, bog, and marsh 

deposition dominate. Interglacial deposits typically consist 

of clay, silt, or discontinuous lenses of sand and gravel or 

peat. Underlying these unconsolidated glacial and interglacial 

deposits are Tertiary bedrock units consisting primarily of 

sedimentary claystone, siltstone, sandstone, beds of coal, and 

volcanic rocks (Walters and Kimmel, 1968). Alpine glacial 

deposits are locally present in areas of exposed bedrock.

Hydrogeologic Units

Geologic units were grouped into hydrogeologic units 

consisting of aquifers and confining units (table 1) based on 

similarities in lithology (grain size and sorting), hydrologic 

characteristics, and relative stratigraphic position. The 

hydrogeologic units defined in this study are based on units 

defined by previous investigations in the study area (Brown 

and Caldwell, 1985; Robinson & Noble, Inc., and others 

2003). Differences between units defined in this study and 
Hydrogeologic Framework 9

previous investigations include (1) the differentiation of 

unit A into four units for this study (table 1); and (2) the 

discontinued use of hydrostratigraphic units in which all 

glacial deposits are characterized as aquifers and interglacial 

deposits are characterized as confining units, in favor of the 

use of hydrogeologic units in which aquifers and confining 

unit designations are based on the lithologic and hydrologic 

characteristics of deposits regardless of depositional 

environment (for example, an aquifer unit may consist of 

both glacial outwash and interglacial alluvial deposits). 

Hydrogeologic units defined in this study are not directly 

comparable (unit extent or thickness) to previously published 

units. 

An aquifer is saturated geologic material that is 

sufficiently permeable to yield water in significant quantities 

to a well or spring, whereas a confining unit has low 

permeability that restricts the movement of groundwater and 

limits the usefulness of the unit as a water source. Unconfined 

and confined aquifer conditions are present in the study area. 

Unconfined or “water-table” conditions occur when the upper 

surface of the saturated zone is at atmospheric pressure and is 

free to rise and decline in response to changes in groundwater 

recharge and discharge. The position of the water table is 

represented by water levels in shallow wells. Confined or 

“artesian” conditions occur when an aquifer is overlain by a 

less permeable confining unit and the groundwater is under 

pressure greater than atmospheric pressure. Water in a tightly 

cased well drilled into a confined aquifer will rise to a height 

corresponding to the hydraulic head (the potentiometric 

surface) of the confined groundwater at that location. If the 

hydraulic head is sufficient to raise the water above land 

surface, the well will flow and is called a flowing artesian 

well. The potentiometric surface in a confined aquifer is 

analogous to the water table in an unconfined aquifer. The 

potentiometric surface fluctuates in response to changes in 

recharge and discharge, however, unlike the water table, the 

potentiometric surface is higher in altitude than the top of the 

confined aquifer. 

Glacial deposits generally are heterogeneous, and 

although a glacial aquifer may be composed primarily of sand 

or gravel, it may locally contain varying amounts of clay or 

silt. Conversely, a confining layer composed predominantly 

of silt or clay may contain local lenses of coarse material. 

These small-scale variations in lithology may influence the 

occurrence and movement of groundwater at a scale that likely 

is too small to be adequately represented by the hydrogeologic 

framework constructed for this study. In the Puget Lowland, 

aquifers consist primarily of glacial outwash but also may 

include coarse-grained interglacial deposits. The confining 

units consist primarily of fine-grained interglacial deposits 

but also may include glacial till or glaciolacustrine deposits. 

Unconsolidated glacial and interglacial aquifer and confining 

units are underlain by low-permeability Tertiary bedrock units, 

described as the basement confining unit in Jones (1999). 

Eleven hydrogeologic units are recognized in the study 

area (table 1 and pl. 2) and their lithologic and hydrologic 

characteristics are described below.

AL alluvial valley aquifer.—The AL alluvial valley 

aquifer is present throughout the Puyallup, Carbon, and 

Nisqually River valleys and along Ohop Creek (fig. 3), and 

includes alluvial (Qal and Qa), mudflow (Qvl (e)), and tide flat 

and artificial fill (Qp and af) deposits. This hydrogeologic unit 

primarily consists of alluvial silt, sand, and gravel deposits 

that closely follow Holocene river valleys. Because of the 

spatial variability of stream sediments and inclusion of some 

mudflow and lahar deposits, the lithologic character of this 

unit is quite heterogeneous and varies greatly with depth. The 

unit generally is less than 100 ft thick along the Nisqually 

River, Ohop Creek, and Carbon River, but exceeds 250 ft 

along the Puyallup River as it nears Commencement Bay. 

Groundwater in this aquifer generally is unconfined; however, 

confined conditions may occur locally beneath mudflow 

deposits. 

A1 aquifer.—The A1 aquifer is present at land surface 

throughout much of the study area (pl.2) and primarily is 

composed of Vashon recessional outwash (Qvr) deposits of 

the Fraser Glaciation. These deposits consist of stratified 

silt, sand, and gravel deposited by large meltwater streams 

formed during the northward retreat of the Puget Lobe. A 

subdivision of Qvr deposits known as the Steilacoom Gravels 

(Qvs) are found in successive outwash channels formed by 

streamflow originating from proglacial Lake Puyallup (Walters 

and Kimmel, 1968). These gravels are characterized by their 

consistency and coarseness over a large part of the study area. 

Several other geologic units, including wetland (Qw), peat 

(Qp), Osceola mudflow (Qvl(o)), and undifferentiated Vashon 

drift (Qv) deposits, were included in the A1 aquifer unit 

because of their limited areal extent and/or close proximity 

to other recessional deposits. Some alluvial deposits (Qa and 

Qal) that were not connected with river valleys also were 

grouped with the A1 aquifer unit. The thickness of the A1 

aquifer typically ranges from a thin veneer of less than 35 ft to 

about 150 ft, but can locally exceed 200 ft where underlying 

units are not present (fig. 4). Groundwater generally is 

unconfined in this aquifer.

A2 confining unit.—The A2 confining unit is 

present at land surface throughout the study area (pl. 2) 

and is composed primarily of Vashon till (Qvt) and 

lesser amounts of ice-contact (Qvi), moraine (Qgm), and 

fine‐grained glaciolacustrine (Qvrl and Qgl) deposits. This 

low‐permeability unit consists of various proportions of clay, 

silt, sand, and gravel, with locally occurring sand and gravel 

lenses capable of providing water for domestic use. The 

thickness of the A2 confining unit averages about 60 ft but 

varies spatially from a thin veneer to about 150 ft (fig. 5). In a 

few small areas, the thickness exceeds 200 ft.
10 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

tac09-9722-0409 CCCW_Fig 03

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

0 5 10 15 KILOMETERS

0 5 10 15 MILES

Extent and thickness of

 AL alluvial valley aquifer, in feet

0 – 70

71 – 125

126 – 175

176 – 250

251 – 425

Boundary of study area

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

Well used to determine extent and

 thickness of AL alluvial valley 

 aquifer—See plate 1

EXPLANATION

Bedrock outcrop

SR

7

SR

161

SR

512

I-5

I-5

SR

16

Figure 3. Extent and thickness of AL alluvial valley aquifer in Chambers-Clover Creek Watershed and vicinity, Washington.
Hydrogeologic Framework 11

tac09-9722-0409 CCCW_Fig 04

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

0 5 10 15 KILOMETERS

0 5 10 15 MILES

Approximate extent and thickness

 of the A1 aquifer, in feet

0 – 35

36 – 75

 76 – 150

151 – 300

301 – 535

Boundary of study area

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

Well used to determine extent and

 thickness of A1 aquifer—See plate 1

EXPLANATION

Bedrock outcrop

SR

7

SR

161

SR

512

I-5

I-5

SR

16

Figure 4. Extent and thickness of A1 aquifer in Chambers-Clover Creek Watershed and vicinity, Washington.
12 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

tac09-9722-0409 CCCW_Fig 05

0 5 10 15 KILOMETERS

0 5 10 15 MILES Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

Approximate extent and thickness

 of the A2 confining unit, in feet

0 – 40

41 – 70

 71 – 100

101 – 160

161 – 378

Boundary of study area

Well used to determine extent and thickness

 of A2 confining unit—See plate 1

EXPLANATION

Bedrock outcrop

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

Figure 5. Extent and thickness of A2 confining unit in Chambers-Clover Creek Watershed and vicinity, Washington.
Hydrogeologic Framework 13

A3 aquifer.—The A3 aquifer is present in the subsurface 

throughout most of the study area (fig. 6), with surface 

exposures limited to a few steep slopes and along the walls of 

deeply incised stream valleys and coastal bluffs (pl. 2). The 

unit primarily is composed of Vashon advance outwash (Qva) 

and small amounts of Pre-Fraser coarse-grained non-glacial 

deposits (Qpfc), and consists of well-sorted sand or sand and 

gravel, with lenses of silt and clay. The average thickness 

of the A3 aquifer is 75 ft, but locally exceeds 160 ft (fig. 6). 

Groundwater in this aquifer generally is confined by the 

overlying Vashon till; however, unconfined conditions may 

occur locally where it is not fully saturated or is exposed at 

land surface. 

B confining unit.—The B confining unit is present in the 

subsurface throughout central and northern parts of the study 

area (fig. 7) with surface exposures limited to areas along 

coastal bluffs (pl. 2). This low-permeability unit primarily is 

composed of fine-grained silts and clays (Olympia beds–Qob) 

deposited during the Olympia interglacial and glaciolacustrine 

clays deposited during early Vashon (Lawton clay–Qvlc). The 

B confining unit also includes several additional geologic units 

(table 1) that are laterally continuous with the Qob and Qvlc 

deposits and/or have similar lithologic characteristics. The 

average thickness of the B confining unit is about 55 ft, but 

locally exceeds 200 ft (fig. 7).

C aquifer.—The C aquifer, often referred to as the 

sea‐level aquifer because of its coincident altitude, is present 

in the subsurface throughout central and northern parts of the 

study area (fig. 8), with surface exposures limited to a few 

steep slopes and along the walls of deeply incised stream 

valleys (pl. 2). The unit primarily is composed of pre-Olympia 

glacial drift deposits locally referred to as the Salmon Springs 

Drift (Walters and Kimmel, 1968) and consists of sand and 

gravel, with minor lenses of silt, clay, and till. The average 

thickness of the C aquifer unit is about 105 ft, but locally 

exceeds 200 ft (fig. 8). Groundwater in this aquifer generally 

is confined by the overlying B confining unit. However, 

unconfined conditions may occur locally where no overlying 

confining unit is present (figs. 5 and 7), or in places where the 

unconfined unit is not fully saturated.

D confining unit.—The D confining unit is present in the 

subsurface throughout central and northern parts of the study 

area (fig. 9); is not present at land surface in the study area, 

except under Puget Sound (pl. 2); and is recognized only in 

drillers’ logs. This low-permeability unit most likely correlates 

with deposits from the Puyallup Interglacial and consists 

of alluvial and lacustrine sand, silt, and clay deposits, and 

occasional deposits of volcanic ash. The average thickness of 

the D confining unit is about 100 ft, but locally exceeds 200 ft 

(fig. 9). Most notably, an area of significant thickness occurs 

along the western edge of the study area south of Chambers 

Creek where unit D is present in place of Units C or E (or 

both). Brown and Caldwell (1985) and Noble (1990) describe 

this feature as being a probable ancestral Narrows channel that 

was filled in with fine-grained lacustrine deposits.

E aquifer.—The E aquifer is present in the subsurface 

throughout central and northern parts of the study area 

(fig. 10); is not present at land surface in the study area, except 

under Puget Sound (pl. 2); and is recognized only in drillers’ 

logs. This unit most likely correlates with deposits of the 

Stuck Drift; the third recognized glaciation of the southern 

Puget Sound area (Walters and Kimmel, 1968), and consists 

primarily of silt, sand, and gravel, with discontinuous till and 

lacustrine deposits. The thickness of the E aquifer typically 

ranges from a thin veneer to about 120 ft but exceeds 200 ft 

in places where underlying units are not present (fig. 10). 

Groundwater in this aquifer is confined by the overlying D 

confining unit.

F confining unit.—The F confining unit is present in the 

subsurface throughout central and northern parts of the study 

area (fig. 11); is not present at land surface in the study area, 

except under Puget Sound (pl. 2); and is recognized only in 

drillers’ logs. This low-permeability unit most likely correlates 

with deposits of the Alderton Formation and primarily consists 

of silt and clay, with minor lenses of sand and gravel. Limited 

well data indicate that thicknesses typically range from 50 to 

200 ft; however, thicknesses exceed 300 ft in places (fig. 11).

G undifferentiated deposits.—The undifferentiated 

deposits assigned to unit G primarily consist of stratified sand 

and gravel, with discontinuous layers of till. Few wells in the 

study area fully penetrate these unconsolidated deposits down 

to the bedrock surface, and little is known about the spatial 

distribution of water-bearing and non-water-bearing sediments 

in the deeper parts of the unconsolidated sequence (Brown 

and Caldwell, 1985). The uppermost part of unit G likely 

correlates to the Orting drift, the oldest identified Pleistocene 

glaciation in the Puget Sound area (Walters and Kimmel, 

1968). Several public water-supply systems in the study area 

withdraw water from the upper part of the unit. Thickness 

estimates for this unit (fig. 12) were computed by subtracting 

the top of bedrock from the top of unit G.

Bedrock unit.—The bedrock unit crops out in the 

foothills along the southern and southeastern margin of the 

study area. This low-permeability unit consists of sedimentary 

claystone, siltstone, sandstone, beds of coal, and volcanic 

rocks. Alpine glacial deposits (primarily clay and silt) also 

were included in this unit where they are laterally continuous 

with and have similar lithologies to bedrock.
14 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

tac09-9722-0409 CCCW_Fig 06

Approximate extent and thickness

 of the A3 aquifer, in feet

0 – 40

41 – 75

 76 – 110

111 – 160

161 – 360

Boundary of study area

Well used to determine extent and

 thickness of A3 aquifer—See plate 1

EXPLANATION

Bedrock outcrop

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

0 5 10 15 KILOMETERS

0 5 10 15 MILES

Figure 6. Extent and thickness of A3 aquifer in Chambers-Clover Creek Watershed and vicinity, Washington.
Hydrogeologic Framework 15

tac09-9722-0409 CCCW_Fig 07

Approximate extent and thickness

 of the B confining unit, in feet

0 – 35

36 – 70

71 – 110

111 – 165

166 – 349

Well used to determine extent and thickness

 of B confining unit—See plate 1

Boundary of study area

EXPLANATION

Bedrock outcrop

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83) 0 5 10 15 KILOMETERS

0 5 10 15 MILES

Figure 7. Extent and thickness of B confining unit in Chambers-Clover Creek Watershed and vicinity, Washington.
16 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

tac09-9722-0409 CCCWFig 08

Approximate extent and thickness

 of the C aquifer, in feet

0 – 70

71 – 130

131 – 180

181 – 300

301 – 451 Well used to determine extent and thickness

of C aquifer—See plate 1

Boundary of study area

EXPLANATION

Bedrock outcrop

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83) 0 5 10 15 KILOMETERS

0 5 10 15 MILES

Figure 8. Extent and thickness of C aquifer in Chambers-Clover Creek Watershed and vicinity, Washington.
Hydrogeologic Framework 17

tac09-9722-0409 CCCW_Fig 09

Approximate extent and thickness

 of the D confining unit, in feet

0 – 70

70 – 110

110 – 160

160 – 230

230 – 427

Well used to determine extent and thickness

 of D confining unit—See plate 1

Boundary of study area

EXPLANATION

Bedrock outcrop

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

0 5 10 15 KILOMETERS

0 5 10 15 MILES

Figue 9. Extent and thickness of D confining unit in Chambers-Clover Creek Watershed and vicinity, Washington.
18 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

tac09-9722-0409 CCCW_Fig 10

Approximate extent and thickness

 of the E aquifer, in feet

0 – 75

76 – 120

121 – 170

171 – 240

241 – 500 Well used to determine extent and thickness

 of E aquifer—See plate 1

Boundary of study area

EXPLANATION

Bedrock outcrop

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

0 5 10 15 KILOMETERS

0 5 10 15 MILES

Figure 10. Extent and thickness of E aquifer in Chambers-Clover Creek Watershed and vicinity, Washington.
Hydrogeologic Framework 19

tac09-9722-0409 CCCW_Fig 11

Approximate extent and thickness

 of the F confining unit, in feet

0 – 60

61 – 120

121 – 190

191 – 285

286 – 615 Well used to determine extent and thickness

 of F confining unit—See plate 1

Boundary of study area

EXPLANATION

Bedrock outcrop

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

0 5 10 15 KILOMETERS

0 5 10 15 MILES

Figure 11. Extent and thickness of F confining unit in Chambers-Clover Creek Watershed and vicinity, Washington.
20 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

tac09-9722-0409 CCCW_Fig 12

Approximate extent and thickness of the

 G undifferentiated deposits, in feet

0 – 200

201 – 400

401 – 600

601 – 1,100

1,101 – 1,583

Well used to determine extent and thickness

 of G undifferentiated deposits—See plate 1

Boundary of study area

EXPLANATION

Bedrock outcrop

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

0 5 10 15 KILOMETERS

0 5 10 15 MILES

Figure 12. Extent and thickness of G undifferentiated deposits in Chambers-Clover Creek Watershed and vicinity, 

Washington.
Hydrogeologic Framework 21

Hydraulic Conductivity

Hydraulic conductivity is a measure of a material’s 

ability to transmit water, and in unconsolidated sediment, 

it is dependent on the size, shape, distribution, and packing 

of the particles. Because these physical characteristics vary 

greatly within the glacial deposits of the study area, hydraulic 

conductivity values also are highly variable. Estimates of the 

magnitude and distribution of hydraulic conductivity were 

used to develop an understanding of groundwater movement 

and availability in the hydrogeologic units.

Horizontal hydraulic conductivity was estimated for 

the hydrogeologic units using specific-capacity data from 

drillers’ logs, and results of aquifer tests conducted by 

Robinson & Noble Inc. (Burt Clothier, written commun., 

2009) and Carr/Associates Inc. (1988). Specific-capacity data 

(water-level drawdown measured after pumping a well for 

a specified period of time) were compiled and analyzed for 

wells that had a drillers’ log containing discharge rate, time of 

pumping, drawdown, static water level, well-construction data, 

and lithologic descriptions. Wells that met the above criterion 

included 142 wells constructed with a screened or perforated 

open interval and 18 wells constructed with an open-ended 

well casing. Aquifer tests results were available for 43 public 

water-supply wells.

Two sets of equations were used to estimate hydraulic 

conductivity from specific-capacity data, depending on well 

construction. For data from wells with a screened or perforated 

open interval, the modified Theis equation (Ferris and others, 

1962) was first used to estimate transmissivity of the pumped 

interval. Transmissivity is the product of horizontal hydraulic 

conductivity and thickness of the part of the hydrogeologic 

unit supplying water to the well. The modified equation is

2

2.25 ln , 4

where

is drawdown in the well, in feet;

is discharge, or pumping rate, of the well, in

cubic feet per day;

is transmissivity of the hydrogeologic unit, in

days;

is length of time the w

Q Tt

s

T r S

s

Q

T

t

= π

ell was pumped, in days;

is radius of well, in feet; and

is storage coefficient, a dimensionless number,

assumed to be 0.0001 for confined units and

0.1 for unconfined units.

r

S

(1)

Assumptions for using equation 1 are that (1) aquifers 

are homogeneous, isotropic, and infinite in extent; (2) wells 

fully penetrate the aquifer; (3) flow to the well is horizontal; 

and (4) water is released from storage instantaneously. 

Additionally, for unconfined aquifers, drawdown is assumed 

to be small in relation to the saturated thickness of the aquifer. 

Although most of the assumptions are not precisely met, the 

field conditions in the study area approximate most of the 

assumptions and the calculated hydraulic conductivities are 

reasonable estimates.

A computer program was used to solve equation 1 for 

transmissivity (T) using Newton’s iterative method (Carnahan 

and others, 1969). The difference in computed transmissivity 

between using storage coefficient values of 0.1 and 0.0001 is a 

factor of only about 2. Next, the following equation was used 

to calculate horizontal hydraulic conductivity:

,

where

is horizontal hydraulic conductivity of the

geologic material in the vicinity of the

well opening, in feet per day; and

is thickness of the geologic material, in feet,

approximated using the

h

h

T K

b

K

b

=

 length of the open

interval as reported in the drillers' report.

(2)

The use of the length of a well’s open interval for b may 

overestimate values of Kh because the equations assume that 

all water flows horizontally within a layer of this thickness. 

Although some of the flow will be outside this region, the 

amount can be expected to be small (for short-duration 

pumping events) because in most sedimentary deposits, 

vertical flow is inhibited by layering.

For data from wells having only an open-ended well 

casing rather than a screened or perforated interval, a second 

equation was used to estimate hydraulic conductivities. Bear 

(1979) provides an equation for hemispherical flow to an 

open-ended well just penetrating a hydrogeologic unit. When 

modified for spherical flow to an open-ended well within a 

unit, the equation becomes 

. 4 h

Q K

sr = π

(3)

This equation is based on the assumption that horizontal 

and vertical hydraulic conductivities are equal, which is not 

likely for the deposits in the study area. Because vertical 

conductivities generally are lower than horizontal in these 

deposits, the result of violating this assumption is an 

underestimate of Kh by an unknown amount.

Horizontal hydraulic conductivities were calculated for 

wells with available specific-capacity data, and statistical 

summaries were prepared by hydrogeologic unit (table 3). 

Horizontal hydraulic conductivity was not calculated for 

the bedrock unit because of a lack of available data. Median 

values of estimated hydraulic conductivity for the aquifers 

(AL, 328 ft/d; A1, 933 ft/d; A3, 122 ft/d; C, 96 ft/d: E, 57 ft/d; 

and G, 33 ft/d) are similar in magnitude to values compiled by 
22 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

Vaccaro and others (1998) for the Puget Sound lowlands and 

reported by Freeze and Cherry (1979) for similar materials. 

Median values of estimated hydraulic conductivities for the 

confining units (A2, 18 ft/d; B, 21 ft/d; D, 29 ft/d; and F, 

131 ft/d) are higher than is typical for most of the material in 

these units because data for confining units usually are from 

wells that are preferentially open to lenses of coarse material. 

As a result, the data are biased toward the more productive 

zones in these units and are not representative of the entire 

unit. 

Estimates of horizontal hydraulic conductivity also were 

compiled from aquifer tests conducted by environmental 

consulting firms, and statistical summaries of these data were 

prepared by hydrogeologic unit (table 3). Aquifer tests data 

were available for public-supply wells only and are biased 

toward the major water-producing aquifers in the study area. 

Aquifer tests data were not available for the AL and A1 

aquifers, or for any of the confining units.

Groundwater Movement

This section describes the movement of groundwater in 

the aquifer system in the study area, and includes discussions 

of groundwater recharge, flow direction, discharge to surface 

water, exchange of water between the aquifer system and 

streams, and temporal fluctuations in groundwater levels. 

These processes occur within the physical domain described 

by the hydrogeologic framework and are influenced by the 

hydrogeologic characteristics of the aquifer system in which 

they occur, and by other factors, including streamflow and the 

spatial distribution of precipitation and land cover. 

Recharge 

Precipitation is the dominant source of water recharging 

the groundwater-flow system in the study area, and it is 

reasonable to expect groundwater recharge to vary with 

precipitation. Factors such as the permeability of surficial 

hydrogeologic units and land-cover characteristics also 

affect recharge; therefore, the relation between precipitation 

and recharge also is likely to depend on hydrogeologic and 

land-cover characteristics. The distribution of recharge from 

precipitation in the water-budget area was estimated by 

applying precipitation-recharge relations based on regression 

equations developed for areas in Washington State by Bidlake 

and Payne (2001) that incorporate the effects of surficial 

characteristics. 

Mean annual precipitation totals were calculated from 

daily values for the study monitoring period (September 

1, 2006, to August 31, 2008) and were obtained from the 

National Climate Data Center (NCDC) (www.ncdc.noaa.gov) 

for four active National Weather Service (NWS) stations in the 

vicinity of the study area: McMillin Reservoir (NWS station 

455224), Tacoma #1 (NWS station 458278), Olympia Airport 

(NWS station 456114), and Fort Lewis Golf Course (NWS 

station 452952). These point data were extrapolated across the 

study area (fig. 13) based on the spatial distribution of normal 

precipitation (average annual precipitation for 1971–2000) 

generated from the computer program Parameter-elevation 

Regressions on Independent Slopes Model (PRISM) (Daly 

and others, 1994; Oregon State University, 2009) The PRISM 

model estimates the distribution of normal precipitation based 

on a statistical method that takes into account land-surface 

altitude and spatial variation.

Normal precipitation at each NWS station was obtained 

by sampling the PRISM distribution at the four station 

locations, allowing the PRISM distribution to be scaled for 

extrapolation. The normal precipitation was compared to the 

annual precipitation at the NWS stations and a regression 

equation was developed for the four points:

Pactual = 10.23 in/yr + 0.808 × Pnormal (4)

Table 3. Summary of hydraulic conductivity values estimated 

from specific-capacity data and aquifers tests, by hydrogeologic 

unit, Chambers-Clover Creek Watershed and vicinity, Washington.

[–, no data; ft/d, feet per day]

Hydrogeologic 

unit

Number 

of wells

Horizontal hydraulic 

conductivity (ft/d)

Minimum Median Maximum

Estimated from specific-capacity data

AL alluvial valley 

aquifer

10 36 328 3,779

A1 aquifer 4 62 933 5,065

A2 confining unit 5 1 18 144

A3 aquifer 34 1 122 15,137

B confining unit 5 4 21 120

C aquifer 59 3 96 12,753

D confining unit 3 18 29 32

E aquifer 22 11 57 1,317

F confining unit 1 – 131 –

G undifferentiated 

deposits

17 7 33 936

Estimated from aquifer tests

A3 aquifer 9 229 588 3,228

C aquifer 13 21 198 1,337

E aquifer 15 12 214 1,519

G undifferentiated 

deposits

6 11 39 163
Groundwater Movement 23

tac09-9722-0409 CCCW_Fig 13

SR

7

SR

161

SR

512

I-5

I-5

SR

16

50

48

50

48

46

46

44

75

65

70

65

60

60

55

42

44

55

50

48

46

44

44

46

44

50

48

50

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

0 5 10 15 KILOMETERS

Base from U.S. Geological Survey and/or 0 5 10 15 MILES

National Land-Cover Database, 2001

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

EXPLANATION

Less than 50 percent

More than 50 percent More than 50 percent

Line of equal average annual precipitation—

 Interval is 2 and 5 inches

Boundary of study area

Canopy cover, in percent Impervious surface, in percent

Less than 50 percent

60

Boundary of water-budget area

Figure 13. Average annual precipitation, canopy cover, and impervious surface across the Chambers-Clover Creek 

Watershed and vicinity, Washington, September 2006–August 2008.
24 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

This relation has a correlation coefficient of 

0.96 and was used to estimate the distribution 

of mean annual precipitation for the study 

monitoring period (September 1, 2006, to 

August 31, 2008) throughout the study area 

(fig. 13), based on the PRISM distribution of 

normal precipitation. The study area received 

an average (September 1, 2006, to August 31, 

2008) of about 1,025,000 acre-ft or about 

45 in/yr of precipitation a year.

The effects of surficial hydrogeology 

on recharge from precipitation (fig. 14) were 

estimated using regression equations developed 

by Bidlake and Payne (2001) for soils in 

western Washington. Recharge estimates for 

aquifer units (outwash and alluvium) exposed 

at land surface in the study area were calculated 

using regression equation developed for 

soils formed on glacial outwash and alluvial 

sediments. Recharge estimates for confining 

units (till and lacustrine) were calculated using 

regression equation developed for soils formed 

on glacial till and fine-grained sediments.

The effect of evaporative loss on recharge 

from the interception of precipitation by tree 

canopy was estimated for aquifers using 

equations from Bidlake and Payne (2001). Tree 

canopy distribution data were obtained from the 

National Land Cover Database (NLCD) (2001). 

Interception loss was applied only to areas with 

more than 50 percent tree canopy (fig. 13). 

Urban centers in the study area manage 

stormwater by discharging runoff either to dry 

wells that promote the infiltration of this water 

into the groundwater-flow system or to streams 

in areas where soils are incapable of receiving 

the extra water. Therefore, recharge through confining units 

(such as A2 and B) at the ground surface was reduced by 

one-half according to the method of Bidlake and Payne (2001) 

where the percentage of impervious surface was greater than 

50 percent (fig. 13) as derived from the National Land Cover 

Database (2001). No direct recharge from precipitation was 

assumed for areas covered by lakes.

GIS techniques were used to combine the data coverages 

described in the previous paragraphs and calculate the 

distribution of groundwater recharge from precipitation 

in the water-budget area (fig. 15). Recharge rates ranged 

from about 6 in/yr in urban areas (greater than 50 percent 

impervious surface) underlain by confining units to about 

30 in/yr in areas underlain by permeable aquifer deposits 

with less than 50 percent tree canopy in the eastern-central 

part of the area where precipitation locally exceeds 48 in/yr. 

Summing the recharge areas shown in figure 15 indicates that 

the groundwater-flow system within the water-budget area 

receives about 455,000 acre-ft or about 20 in. of recharge from 

precipitation during an average year (September 1, 2006, to 

August 31, 2008). 

Figure 14. Precipitation-recharge relations used in this study, 

Chambers-Clover Creek Watershed and vicinity, Washington.

tac09-0409_Fig 14

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40 45 50 55 60

GROUNDWATER RECHARGE, IN INCHES PER YEAR

PRECIPITATION, IN INCHES PER YEAR

Groundwater recharge as a function of

 surficial hydrogeology and land cover

Without trees

Aquifers receiving recharge—AL, A1, A3, C

With trees

With and without trees

Urban areas

Confining units receiving recharge—A2, B

Both the spatial distribution and the annual amounts 

of recharge estimated for this study are similar to estimates 

made by Vaccaro and others (1998) in an assessment of 

the Puget Sound Regional Aquifer System. However, the 

recharge estimates for confining units (till and lacustrine 

deposits) used in this study (generally 5 to 15 in/yr 

depending on land cover) are substantially greater than 

the 2.6 in/yr average value estimated by Mastin (1996) 

and Bauer and Mastin (1997) for till-mantled areas in 

Clover Creek basin. The 2.6 in/yr estimate primarily was 

derived from site-scale measurements, and the successful 

incorporation of the estimate into the Clover Creek basin 

model (Mastin, 1996) required including poorly constrained 

assumptions about groundwater flow out of the modeling 

domain. Recharge estimates used in other investigations for 

till-mantled areas in the Puget Sound region (Turney and 

others, 1995; Drost and others, 1999; van Heeswijk and 

Smith, 2002) are similar to the estimates used in this study. 
Groundwater Movement 25

tac09-9722-0409 CCCW_Fig 15

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

0 5 10 15 KILOMETERS

0 5 10 15 MILES

EXPLANATION

Estimated recharge, in inches per year Boundary of study area

Boundary of water-budget area

Water (no recharge)

5 – 10

11 – 15

16 – 20

21 – 25

26 – 30

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

Figure 15. Distribution of average annual groundwater recharge from precipitation in Chambers-Clover Creek Watershed 

and vicinity, Washington, September 2006–August 2008.
26 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

 In addition to groundwater recharge from precipitation, 

groundwater recharge from streams also occurs in the 

study area along losing stream reaches. The total amount of 

groundwater recharge from streams is not quantified here, but 

is reflected in the computation of the total net groundwater 

discharge to streams presented in the water budget.

Groundwater-Flow Directions

The generalized direction of horizontal groundwater 

movement was inferred from maps of water-level altitude 

contours. Groundwater generally moves from areas 

of recharge to areas of discharge in the direction of 

decreasing water-level altitudes and is perpendicular to the 

water-level altitude contours. Groundwater levels measured 

during operation of the monthly monitoring network 

(March 2007 – September 2008) were used to evaluate 

groundwater-flow directions in aquifers within the study 

area (figs. 16 through 21). The mean water-level value for 

the period of record was used to represent the water-level 

altitude at monthly monitoring wells for this analysis. 

Synoptic measurements of groundwater levels made during 

the field inventory (September–December 2006) were 

used only in areas where monthly water-level data were 

not available, and, in places, field inventory values do not 

correlate well with water-level altitude contours based on 

monthly data. Water‐level contours for most aquifer units 

are based on limited water-level data and are subject to some 

uncertainty. For the same reason, the illustrated groundwaterflow directions for the uppermost units in particular are 

generalized and do not reflect local flow characteristics, 

such as groundwater discharge to or recharge from streams. 

Water‐level contours were not drawn for large parts of aquifer 

units E and G because of a lack of data. A numerical flow 

model of the groundwater-flow system in the study area, 

currently under development, should provide additional 

insight into groundwater-flow directions. 

In the northeastern part of the study area, groundwater 

flow in the AL alluvial valley aquifer beneath the Puyallup 

River valley is towards the northwest in the down-valley 

direction of the river, towards Puget Sound (fig. 16). A 

northwest down-valley groundwater flow direction also is 

likely in the AL alluvial valley aquifer beneath the Nisqually 

River valley in the southern part of the area (inset, fig. 16) 

although no data were collected from the aquifer in this area.

Groundwater flow in the A1 and A3 aquifers generally 

is towards the northwest (figs. 17 and 18, respectively). 

North and northeastward groundwater flows in the A1 

aquifer are inferred from widely spaced water-level data in 

the northeastern part of the area (fig. 17). Water-level data 

in this area suggest the presence of a groundwater divide 

that separates flow towards the Puyallup River valley and 

groundwater movement towards Puget Sound. A similar 

divergence of groundwater flow (northeast and northwest 

flow directions) in the A3 aquifer is indicated by water-level 

data in the central part of the study area (fig. 18) and suggests 

that northeast flow occurs over a larger part of the A3 aquifer 

than the A1 aquifer. Large areas of low permeability glacial 

till (B confining unit) separate the A1 aquifer to the south and 

Puyallup River valley to the north, and likely are barriers to 

groundwater flow.

Groundwater flow in the C aquifer diverges to the 

northwest and northeast along a complex, groundwater divide 

(fig. 19). Water-level data in the northwestern part of the 

C aquifer in the study area indicate localized groundwater 

flow towards the west in the direction of the Puget Sound. 

Northwest to northeast groundwater flow in the E aquifer is 

inferred from widely spaced water-level data in the northern 

part of the study area (fig. 20). Water-level data from 

three wells in the G undifferentiated deposits suggest that 

northwestward groundwater flow is likely in the northwestern 

part of the study area (fig. 21).

The potential for vertical flow between aquifers is 

difficult to determine because extents and thicknesses of 

hydrogeologic units vary considerably throughout the study 

area, the presence of confining layers within and between 

aquifers is highly variable, and the data available for 

comparing water levels between adjacent units are widely 

spaced. Small water-level differences between the A1 and 

A3 aquifers in the north-central part of the study area, 

where sufficient contoured data were available to make a 

comparison, suggest little in the way of vertical flow potential 

between the aquifers (figs. 17 and 18). Downward vertical 

flow from the A1 to A3 aquifers may occur in an area of 

widely spaced water levels in the northeastern part of the area, 

but the discontinuous nature of the A1 aquifer makes direct 

comparison difficult. Water-level differences between the A3 

and C aquifers show the potential for downward vertical flow 

in western (vicinity of American, Gravelly, and Steilacoom 

Lakes) and eastern (along the bluffs of the Puyallup River 

valley) parts of the study area (figs. 18 and 19). 

The potential for upward groundwater flow is indicated 

by the presence of flowing wells at several locations in the 

aquifer units. Confining clays within the AL alluvial valley 

aquifer likely produce flowing conditions observed at four 

wells in the Puyallup River valley (fig. 16), and an upward 

vertical gradient in this area is supported by water levels in 

nearby non-flowing wells in the AL alluvial valley aquifer. 

The potential for upward flow in the C aquifer is indicated by 

the presence of a flowing well in the Puyallup River valley 

in the northern part of the study area (fig. 19), and an upward 

vertical gradient in this area is supported by water levels in the 

overlying AL alluvial valley aquifer.
Groundwater Movement 27

tac09-9722-0409 CCCW_Fig 16

SR

512

I-5

I-5

SR

16

122°20' 122°10'

R. 3 E. R. 4 E. R. 5 E.

47°10'

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

0

2 4 6 8 MILES

2 4 6 8 KILOMETERS

0

31P03

192

25

50

100

150

38P01

38K01

31C01

36H04

35A03

27B01

25M01

20E06

19Q01

19K04

13C02

06M04

06A02

36A02

25G02

01J04

01A02

36H03

19F03

74

25

79

80

76

77

67 76

44

69

84

86

79

171

156

17 F

24 F

29 F

28

36A02

171

51J01

36R02

27J01

11L01

31P03

36A01

13B01

63

78

11

192

168

106

56 F

AL alluvial valley aquifer

Inferred direction of groundwater flow

Boundary of study area

EXPLANATION

Approximate water-level contour—Shows altitude of 

 water level in alluvial valley aquifer, October 2006–

 September 2008. Contour interval, 25 and 50 feet. 

 Datum is North American Vertical Datum of 1988 

 (NAVD 88)

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

Well used to measure water-level altitudes on a monthly basis— The mean water-level altitude for March 2007 through September 

 2008 was used to represent the water-level altitude at each of the 

 wells monitored on a monthly basis. Numbers are well No. (top) 

 and water-level altitude (bottom)

Field inventory well used to measure synoptic water-level altitudes—

 Synoptic water-level altitude for September through December 2006 

 and February through April 2007 was used only in areas where monthly 

 water-level data were not available. Numbers are well No. (top) and 

 water-level altitude (bottom)

Measurement location and water-level altitude, in feet above North 

 American Vertical Datum of 1988 (NAVD 88)

 

F Flowing well

Figure location

Figure 16. Water-level altitudes and direction of groundwater flow in AL alluvial valley aquifer, Chambers-Clover Creek 

Watershed and vicinity, Washington, September 2006–September 2008.
28 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

tac09-9722-0409 CCCW_Fig 17

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

0 5 10 15 KILOMETERS

0 5 10 15 MILES

05Q02

107

04N01

253

R. 3 E.

A1 aquifer

Inferred direction of groundwater flow

EXPLANATION

Approximate water-level contour—Shows altitude of 

 water level in A1 aquifer, September 2006–September 

 2008. Contour interval, 50 feet. Datum is North American 

 Vertical Datum of 1988 (NAVD 88)

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

Well used to measure water-level altitudes on a monthly basis—

 The mean water-level altitude for March 2007 through September 

 2008 was used to represent the water-level altitude at each of the 

 wells monitored on a monthly basis. Numbers are well No. (top) 

 and water-level altitude (bottom)

Field inventory well used to measure synoptic water-level altitudes—

 Synoptic water-level altitude for September through December 2006 

 and February through April 2007 was used only in areas where monthly 

 water-level data were not available. Numbers are well No. (top) and 

 water-level altitude (bottom)

Measurement location and water-level altitude, in feet above North 

 American Vertical Datum of 1988 (NAVD 88)

 

300

250

400

350

200

500

300

200

400

500

450

550

350

36K01

236 12 LT-05

260

13 CW-15

278 42N01

281

24 CW-34D

273 24 DA-2A

266

14 DA-13A

261

19 LF4-MW-02A

225

44 9700-MW-1

270

19 LF4-MW-13A

214

06L01

155

23K01

493

35R03

01N03

27L04

11N04

34D02

275

564

403

395

303

37B03

36C01 21K01

35H02

05L02

04H01

02A02

01B02

24K08D1

226

352 475

396

518

402

461

374

365

Boundary of study area

Figure 17. Water-level altitudes and direction of groundwater 

flow in A1 aquifer, Chambers-Clover Creek Watershed and vicinity, 

Washington, September 2006–September 2008.
Groundwater Movement 29

tac09-9722-0409 CCCW_Fig 18

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

0 5 10 15 KILOMETERS

0 5 10 15 MILES

04N03

410

F R

24Q04

428

Flowing well Recovering well

A3 aquifer

Inferred direction of groundwater flow

Approximate water-level contour—Shows altitude of 

 water level in A3 aquifer, September 2006–September 2008. 

 Contour interval, 50 feet. Datum is North American Vertical 

 Datum of 1988 (NAVD 88)

Well used to measure water-level altitudes on a monthly basis— The mean water-level altitude for March 2007 through September 

 2008 was used to represent the water-level altitude at each of the 

 wells monitored on a monthly basis. Numbers are well No. (top) and 

 water-level altitude (bottom)

Field inventory well used to measure synoptic water-level altitudes— Synoptic water-level altitude for September through December 2006 

 and February through April 2007 was used only in areas where monthly 

 water-level data were not available. Numbers are well No. (top) and 

 water-level altitude (bottom)

Measurement location and water-level altitude, in feet above North 

 American Vertical Datum of 1988 (NAVD 88)

 

EXPLANATION

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

400

300

350

450

250

500

550600

200

650

300

300

500

32K01

14K01

07Q02

23H03

22N04

11R03

09P02

34L03

32G04

32A06

29E02

27A01

21C01

45R01

34R02

22L01

22D05

14L02

48L01

42G01

18N04

27E03

21B02 13E04

24K01

04Q02 14J02

11J01

04N03

22E01

09E01

05B01

25C02D1

07P03D1

19 IH-1C

13 CW-15C

26 LC-149C

19 LF4-MW-13B

19 LF4-MW-02B

12 CW-32A

73

36

227

225

200

205

223

441

374

332

393

255

283

373

265

337

309

305

261

254

276

265

696

653

692

631 688

464

381 402

663

410

331

465

587

298

212

366

230

263

51N01

341

!

!

36H01

07F01

23H08

03E01

31C03

29L03

29C01

24L01

11D01

02B01

27E05

24Q03

12D03

35K01

08J01

02B01

24Q04

23L03

11G01

06Q01

05G03

19A01D1

24R07D1

23B02

14R01

34L02

25C04

14D01

42G02

42A02

21M02

19B02

13R03 13F06

13B06

24Q02

24K02

01R01

22L01

05L01

15R02D1 02D01D1

337

224

204

214

154

345

349

307

163

280

362

349

361

270

283

255

262

694

641

732

468

443

383

374

327

533

663

498

428

383

315

345

493

183 F

476 R

700 R

686 R

443 R

363 R

345 R

583 R

389 R

Boundary of study area

Figure 18. Water-level altitudes and direction of groundwater 

flow in A3 aquifer, Chambers-Clover Creek Watershed and vicinity, 

Washington, September 2006–September 2008.
30 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

tac09-9722-0409 CCCW_Fig 19

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

F Flowing well R Recovering well

600

500 400

350

300

250

200

150

100

150

100

35R02

30F01

41K01

19D01

41Q01

38L01

37K01

33C01

26C02

34L01

20Q02 20F02

20E03

26D01

14R01

11Q01 01C02

33Q01

29J05

22A01

19L04

35D01

03B02

01M04

22P01

24 DA-2D

21 LC-40D

21 LC-21C

14 DA-12D

28 LC-75D

24 CW-34C

30 LC-89D1

21 LC-80D-P1

23 93-LF5-4-SS

26C01

19 LF4-MW-02C

85

99

58

81

44

119 243

211

152

217

219

378

295 282

336

262

262 271

182

270

125

630

648

457

317

452

333

132

240

264

213

246 283

283

171 220

34N01 32C01

20D01

14H01

47Q01

25G06

06Q01

18D03

07G04

21J01

35P03

38R01 03H03D1

29P03

36N01

29E11

14G01

27B01

18B02

21A03

20M01

03A04D1

95 73

84

61

14

260

206

343

293

312

269

241

645

637

645

627

618

453

451

457

286

56 F

30 F

0 5 10 15 KILOMETERS

0 5 10 15 MILES

R. 3 E.

C aquifer

Inferred direction of groundwater flow

EXPLANATION

Approximate water-level contour—Shows altitude of 

 water level in C aquifer, September 2006–September 2008. 

 Contour interval, 50 feet. Datum is North American Vertical 

 Datum of 1988 (NAVD 88)

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

Well used to measure water-level altitudes on a monthly basis— The mean water-level altitude for March 2007 through September 

 2008 was used to represent the water-level altitude at each of the wells 

 monitored on a monthly basis. Numbers are well No. (top) and 

 water-level altitude (bottom)

Field inventory well used to measure synoptic water-level altitudes— Synoptic water-level altitude for September through December 2006 

 and February through April 2007 was used only in areas where monthly 

 water-level data were not available. Numbers are well No. (top) and 

 water-level altitude (bottom)

Measurement location and water-level altitude, in feet above North 

 American Vertical Datum of 1988 (NAVD 88)

 19L04

457

35P03

457

11E01

Boundary of study area

Figure 19. Water-level altitudes and direction of groundwater 

flow in C aquifer, Chambers-Clover Creek Watershed and vicinity, 

Washington, September 2006–September 2008.
Groundwater Movement 31

tac09-9722-0409 CCCW_Fig 20

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

11D02

360

35H04

98

F Flowing well R Recovering well

0 5 10 15 KILOMETERS

0 5 10 15 MILES

R. 3 E.

E aquifer

Inferred direction of groundwater flow

EXPLANATION

Approximate water-level contour—Shows altitude of 

 water level in E aquifer, September 2006–September 2008. 

 Contour interval, 50 and 100 feet. Datum is North American 

 Vertical Datum of 1988 (NAVD 88)

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

Well used to measure water-level altitudes on a monthly basis—

 The mean water-level altitude for March 2007 through September 

 2008 was used to represent the water-level altitude at each of the wells 

 monitored on a monthly basis. Numbers are well No. (top) and 

 water-level altitude (bottom)

Field inventory well used to measure synoptic water-level altitudes— Synoptic water-level altitude for September through December 2006 and

 February through April 2007 was used only in areas where monthly 

 water-level data were not available. Numbers are well No. (top) and 

 water-level altitude (bottom)

Measurement location and water-level altitude, in feet above North 

 American Vertical Datum of 1988 (NAVD 88)

 

350

250

200

200

150

150

35M02

41G01

28A01

11M01

11D02

04B03

13 CW-15D

92

84

127

210

360 259

150

35H04

20D06

98

17 R

Boundary of study area

Figure 20. Water-level altitudes and direction of groundwater 

flow in E aquifer, Chambers-Clover Creek Watershed and vicinity, 

Washington, September 2006–September 2008.
32 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

tac09-9722-0409 CCCW_Fig 21

SR

7

SR

161

SR

512

I-5

I-5

SR

16

122°40' 122°30' 122°20' 122°10'

R. 1 W. R. 1 E. R. 2 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E.

47°

46°50'

47°10'

47°20'

T.

16

N.

T.

15

N.

T.

17

N.

T.

18

N.

T.

19

N.

T.

20

N.

T.

21

N.

41Q02

120

0 5 10 15 KILOMETERS

0 5 10 15 MILES

R. 3 E.

G undifferentiated deposits

Inferred direction of groundwater flow

EXPLANATION

Approximate water-level contour—Shows altitude of 

 water level in G undifferentiated deposits, September 2006–

 September 2008. Contour interval, 50 feet. Datum is North 

 American Vertical Datum of 1988 (NAVD 88)

Base from U.S. Geological Survey and/or

Washington Division of Geology and Earth Resources

digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 10

Horizontal Datum: North American Datum of 1983 (NAD 83)

Well used to measure water-level altitudes on a monthly basis—

 The mean water-level altitude for March 2007 through September 

 2008 was used to represent the water-level altitude at each of the wells 

 monitored on a monthly basis. Numbers are well No. (top) and 

 water-level altitude (bottom)

Measurement location and water-level altitude, in feet above North 

 American Vertical Datum of 1988 (NAVD 88)

 

200

41Q02 150

35P01

12 CW-32C

120

189

234

Boundary of study area

Figure 21. Water-level altitudes and direction of groundwater flow in G undifferentiated deposits, Chambers-Clover Creek 

Watershed and vicinity, Washington, September 2006–September 2008.
Groundwater Movement 33

Discharge

Groundwater in the study area discharges as seepage 

to streams, lakes, springs, marshes, and coastal bluffs; as 

evaporation and transpiration of shallow groundwater; as 

submarine seepage to Puget Sound; and as withdrawals 

from wells. Groundwater discharge sustains the late-summer 

and early-fall flow (baseflow) of streams in the study area. 

Estimates of groundwater discharge to streams in the study 

area were based on synoptic streamflow measurements 

conducted in September 2007 and July 2008 at seven locations 

near the outlets of the major streams draining the study area 

(table 4 and pl. 1), and estimates of evaporative loss from 

groundwater fed lakes within measured reaches (National 

Oceanic and Atmospheric Administration, 1982). Estimates 

of daily evaporative loss from lakes were used to account for 

Table 4. Synoptic streamflow measurements and estimates of evaporative loss from lakes used to 

determine groundwater discharge in the Chambers-Clover Creek Watershed and vicinity, Washington, 

September 2007 and July 2008.

[Discharge rating: Accuracy rating of U.S. Geological Survey measurements: G, good; F, fair; P, poor; –, no rating; estimated 

values are rated poor. Abbreviations: ft3/s, cubic feet per second]

Measurement site name Site No. Date discharge

measured

Discharge 

(ft3

/s)

Discharge 

rating

Swan Creek at Pioneer Way East 12102212 09-11-07 2.75 F

07-10-08 1.81 F

Clear Creek at 31st Ave East 12102175 09-11-07 14.7 F

07-10-08 16.3 F

Clarks Creek at Stewart Ave at railroad bridge 12102060 09-10-07 50.9 F

07-09-08 50.5 F

Chambers Creek upstream of Chambers Bay 12091590 09-10-07 49.0 G

07-09-08 51.3 G

Murray Creek at 41st Division Way (Camp Murray) 12090290 09-10-07 1.21 F

07-10-08 1.85 F

Sequalitchew Creek at Center Drive 12090315 08-09-07 0.00 –

07-10-08 10.00 P

 

Muck Creek at Roy (bridge at Warren Street) 12090200 09-10-07 0.00 –

07-09-08 1.70 G

Evaporative loss from Lake Steilacoom September 2007 21.1

July 2008 22.2

Evaporative loss from Spanaway Lake September 2007 20.9

July 2008 21.7

Total net measured streamflow September 2007 120.6

July 2008 127.4

1

 Estimated by U.S. Geological Survey based on streamflow observation from 2007.

2

 Calculated daily evaporative loss derived from National Oceanic and Atmospheric Administration (1982) annual values.

losses in baseflow during synoptic streamflow measurements 

(September 2007 and July 2008). These estimates were 

based on maps of annual evaporation for shallow lakes in the 

vicinity of the study area (National Oceanic and Atmospheric 

Administration, 1982). Maps were developed using data from 

Class A pan evaporation stations and other spatially distributed 

meteorological data for 1956–1970. The accuracy of the 

maps is a function of the number of nearby data stations and 

their proximity to the area of interest; the closest stations are 

located in the southern Puget Sound area. Estimates of annual 

evaporation assume long-term thermal stability of lake water. 

Daily values of evaporation were estimated using the average 

monthly percentage of annual evaporation derived from Class 

A pan evaporation data (National Oceanic and Atmospheric 

Administration, 1982) for 1956–70.
34 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

Groundwater discharge estimates represent flow from 

contributing areas upstream of the synoptic streamflow 

measurement sites (235.4 mi2 ) and do not include 

contributing areas in downstream portions of the subbasins 

(28.1 mi2). A total net of approximately 120.6 ft3/s 

(87,310 acre-ft/yr) of groundwater discharge to streams 

was measured during September 2007, and approximately 

127.4 ft3/s (92,230 acre-ft/yr) of groundwater discharged to 

streams measured during July 2008 (table 4). These discharge 

estimates should be considered near-minimum values because 

streamflow measurements were made during the dry summer 

period when groundwater levels typically are at annual lows. 

During wetter periods, water levels are usually higher, thus, 

larger quantities of groundwater likely flow to streams. Many 

small streams were not measured, but they may collectively 

receive a large quantity of groundwater discharge at various 

times throughout the year. 

The time-averaged (mean of the September 2007 and 

July 2008 discharge measurements), area-weighted net 

groundwater discharge (excluding groundwater discharge 

to the Puyallup and Nisqually Rivers, which was not 

measured) was estimated to be 126.8 ft3/s (91,800 acre-ft/yr). 

This value includes area-weighted estimates of groundwater 

discharge for portions of stream reaches that were downstream 

of synoptic measurement sites. Area-weighted values 

(measured discharge divided by the contributing area 

upstream of the measurement site) were derived for each 

of the stream basins to better represent spatial variation 

in groundwater-discharge characteristics. The use of a 

time‐averaged groundwater‐discharge estimate, derived 

from measurements made during the dry summer period, 

to compute the area-weighted groundwater discharge in the 

study area may not accurately represent the total annual 

variation in discharge and likely introduces some error into 

this calculation. An estimate of groundwater discharge to the 

Puyallup and Nisqually Rivers, along with submarine seepage 

to Puget Sound, was computed as a residual component (other 

natural discharge) in the water budget presented in this report.

The long-term time-averaged (mean discharge for 

the period of record for all streamflow- gaging stations), 

area‐weighted streamflow for the entire water-budget area 

was estimated to be 217.5 ft3/s (157,500 acre-ft/yr). The 

long-term, time-averaged streamflow estimate incorporates 

surface runoff from precipitation, as well as contributions to 

streamflow from groundwater discharge.

 Groundwater withdrawals from wells in the waterbudget area in 2007 were an estimated 58,500 acre-ft. This 

quantity represents gross withdrawals and does not reflect the 

quantity of water returned to the groundwater system through 

septic tanks or through irrigation return flows to shallow 

aquifers. Groundwater withdrawals for Class A and B public 

water-supply systems (52,200 acre-ft) were estimated using 

typical per capita water use rates of 138 and 109 gallons 

per day, respectively. These typical use rates were based on 

reported withdrawals from several public water suppliers in 

the area, and groundwater withdrawal and use data collected 

by the USGS (Ron Lane, written communication, 2009). 

Public water-supply system service populations were obtained 

from the Washington State Department of Health public water 

system data base (WDOH, 2007). Self-supplied domestic 

groundwater withdrawals (3,000 acre-ft) were estimated 

using a typical per capita water use rate of 104 gallons 

per day (Ron Lane, written communication, 2009), and an 

estimate of the self-supplied population in the area (U.S. 

Department of Commerce, 2007). Groundwater withdrawals 

for the irrigation of golf courses, cemeteries, and agricultural 

crops (3,300 acre-ft) were estimated using an application 

rate of 1.48 acre-ft/yr for golf courses and cemeteries, and an 

application rate of 1.21 acre-ft/yr for crops (Ron Lane, written 

communication, 2009).

Groundwater discharge occurs at numerous springs in 

the study area, and spring locations and discharge have been 

previously reported in several studies (Blair, 1929; Sceva and 

others, 1955; Walters and Kimmel, 1968; Jones and others, 

1999). The total previously reported discharge of springs in 

the area is about 110 ft3/s (80,000 acre-ft/yr). Spring discharge 

values compiled from previous studies span a 70-year time 

period. Spring discharge has varied considerable during 

this period at many locations, and discharge has ceased at 

other locations. The most recently reported discharge was 

used in this compilation for springs with multiple discharge 

measurements, and springs that no longer flow were excluded. 

There are, in addition, many unmeasured springs and the total 

spring discharge in the area is unknown.

Groundwater discharge as evaporation and transpiration 

of shallow groundwater, and as submarine seepage to Puget 

Sound was not directly measured during this study. However, 

estimates for these components were computed as residuals 

during development of the water budget and are described in 

the section, “Water Budget.”

Groundwater and Surface-Water Interactions

The exchange of water between the groundwater-flow 

system and streams in the study area was characterized using 

(1) synoptic streamflow measurements made in September 

2007 and July 2008 at 51 stream locations (table 5 and pl. 1); 

(2) a streamflow measurement for Ponce de Leon Creek made 

in September 2006 by Pierce Conservation District (written 

commun., 2008); and (3) estimates of evaporative loss from 

lakes in measured reaches (National Oceanic and Atmospheric 

Administration, 1982). This information was used to identify 

stream reaches that gain flow and reaches that lose flow to the 

groundwater-flow system. Streamflow measurements were 

made during the low-flow season, usually July–September 

(fig. 22), to capture baseflow conditions. Streamflow in the 

study area remained fairly constant during the September 2007 

and July 2008 measurement periods (figs. 23 and 24). 
Groundwater Movement 35

Table 5. Synoptic streamflow measurements and estimates of gains and losses in the Chambers-Clover Creek Watershed and vicinity, 

Washington, September 2007 and July 2008.

[Site No.: Location of sites shown on plate 1. Discharge rating: Accuracy rating of U.S. Geological Survey measurements: G, good; F, fair; P, poor; –, no 

rating; estimated values are rated poor. Gain or Loss: Uncertainties due to measurement error were too large at some locations to make defensible conclusions 

regarding the characterization of gaining or losing stream reaches and those values are italicized. Abbreviations: ft3/s, cubic feet per second]

Measurement site Site No. Date discharge 

measured

Discharge 

(ft3

/s)

Discharge 

rating

Inflow

(ft3/s)

Gain (+) or 

loss (-) 

(ft3

/s)

Muck Creek at Webster Road 12089980 09-10-07

07-09-08

2.73

2.64

F

F

2.73 

2.64 

Muck Creek at Highway 7 12089990 09-10-07

07-09-08

2.27

2.33

F

F

2.73

2.64

- 0.46

- .31

Muck Creek at 8th Ave East 12090000 09-10-07

07-09-08

1.99

1.65

F

F

2.27

2.33

- .28

- .68

South Creek at 264th Street 12090005 08-13-07

07-09-08

1.10

.50

P

P

.10 

.50

South Creek at Kapowsin Highway 12090015 08-13-07

07-09-08

1.10

1.50

P

P

.10

.50

.00

.00

South Creek at Lebor Devore Street East 12090020 08-13-07

07-09-08

.00

1.50

–

P

.10

.50

- .10

.00

South Creek at Highway 7 12090030 08-13-07

07-09-08

.00

.00

–

–

.00

.50

.00

- .50

South Creek at 304th Street East 12090040 08-13-07

07-09-08

.00

1.50

–

P

.00

.00

.00

.50

South Creek at 8th Ave East (Poleline Road) 12090045 09-10-07

07-09-08

.00

.00

–

–

.00

.50

.00

- .50

Muck Creek at 8th Ave South (Harts Lake Loop Road) 12090050 09-10-07

07-09-08

.00

.00

–

–

1.99

1.65

- 1.99

- 1.65

Muck Creek at Highway 507 12090060 09-10-07

07-09-08

.00

.00

–

–

.00

.00

.00

.00

Lacamas Creek at 288th Street 12090180 08-13-07

07-09-08

1.10

.00

P

–

.10

 

Lacamas Creek at Highway 507 12090190 08-13-07 1.10

2.00

P

–

.10

.00

.00

.00

Muck Creek at Roy (bridge at Warren Street) 12090200 09-10-07

07-09-08

.00

1.70

–

G

.10

.00

- .10

1.70

Murray Creek at 41st Division Way (Camp Murray) 12090290 09-10-07

07-10-08

1.21

1.85

F

F

1.21 

1.85

Sequalitchew Creek at Dupont Steilacoom Road SW 12090310 08-09-07 1.10

3.10

P

P

.10 

.10

Sequalitchew Creek at Center Drive 12090315 08-09-07

07-10-08

.00

3.00

–

–

.10

.10

- .10

- .10

Clover Creek at Canyon Road, near 170th Street East 12090327 09-10-07

07-10-08

1.33

1.38

P

P

1.33

1.38

Clover Creek at Military Road 12090330 09-10-07

07-10-08

1.36

1.31

F

F

1.33

1.38

.03

- .07

Clover Creek at 152nd Street East (John Mahon Road) 12090335 09-10-07

07-10-08

6.17

6.11

F

F

1.36

1.31

4.81

4.80
36 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

Table 5. Synoptic streamflow measurements and estimates of gains and losses in the Chambers-Clover Creek Watershed and vicinity, 

September 2007 and July 2008.—Continued

[Site No.: Location of sites shown on plate 1. Discharge rating: Accuracy rating of U.S. Geological Survey measurements: G, good; F, fair; P, poor; –, no 

rating; estimated values are rated poor. Gain or Loss: Uncertainties due to measurement error were too large at some locations to make defensible conclusions 

regarding the characterization of gaining or losing stream reaches and those values are italicized. Abbreviations: ft3/s, cubic feet per second]

Measurement site Site No. Date discharge 

measured

Discharge 

(ft3

/s)

Discharge 

rating

Inflow

(ft3/s)

Gain (+) or 

loss (-) 

(ft3

/s)

Clover Creek at 25th Ave East 12090355 09-10-07

07-09-08

3.88

5.47

F

F

6.17

6.11

- 2.29

- .64

Clover Creek at 138th Street East 12090360 09-10-07

07-09-08

.25

.00

P

–

3.88

5.47

- 3.63

- 5.47

North Fork Clover Creek at Waller Road East 12090368 08-21-07

07-09-08

.00

2.10

–

P .10

North Fork Clover Creek at 14th Ave East 1209039540 09-10-07

07-09-08

.00

1.10

–

P

.00

.10

.00

.00

North Fork Clover Creek at Golden Given Road East 12090400 09-10-07

07-09-08

4.00

4.00

–

–

.00

.10

.00

- 0.10

Clover Creek at Spanaway Loop Road South 12090430 09-10-07

07-09-08

.00

2.00

–

–

.25

.00

- .25

.00

Spanaway Creek at Spanaway Lake Inlet 12090448 09-10-07

07-09-08

2.10

2.42

F

P

2.10 

2.42

Spanaway Creek at Spanaway Lake Outlet 12090452 09-10-07

07-09-08

4.48

55.38

2.41

54.11

F

F

2.10

2.42

3.28

1.69

Spanaway Creek at Spanaway Loop Road South 12090463 09-10-07

07-09-08

2.32

2.25

F

F

62.76

61.60

- 0.44

.65

Morey Creek at Spanaway Loop Road South 12090478 09-10-07

07-09-08

1.72

.81

F

P

Clover Creek near Tillicum 12090500 09-10-07

07-09-08

 42.50

42.50

F

F

4.04

3.06

- 1.54

- .56

Ponce de Leon Creek at Lake Steilacoom 12090850 09-17-06

07-10-08

 79.00

8.03

F

G

9.00

8.03

Chambers Creek at 88th Street SW 12091000 09-10-07

07-09-08

7.83

88.93

10.4 

812.6

G

G

11.5

10.5

- 2.57

2.10

Chambers Creek near 68th Avenue SW 12091045 09-10-07

07-09-08

26.1

32.2

G

G

18.3

21.8

Flett Creek within Mountain View Memorial Park 12091063 08-03-07 1.50

 3.50

P

P

.50

.50

Flett Creek at Lakewood Drive SW 12091075 08-03-07 1.50

 3.50

P

P

.50

 .50

.00

.00

Flett Creek at Tacoma 12091100 09-10-07

07-09-08

 42.80

 41.90

F

F

.50

.50

2.30

1.40

Leach Creek near Fircrest 12091200 09-10-07

07-09-08

 42.50

 42.10

F

F

2.50

 2.10
Groundwater Movement 37

Table 5. Synoptic streamflow measurements and estimates of gains and losses in the Chambers-Clover Creek Watershed and vicinity, 

September 2007 and July 2008.—Continued

[Site No.: Location of sites shown on plate 1. Discharge rating: Accuracy rating of U.S. Geological Survey measurements: G, good; F, fair; P, poor; –, no 

rating; estimated values are rated poor. Gain or Loss: Uncertainties due to measurement error were too large at some locations to make defensible conclusions 

regarding the characterization of gaining or losing stream reaches and those values are italicized. Abbreviations: ft3/s, cubic feet per second]

Measurement site Site No. Date discharge 

measured

Discharge 

(ft3

/s)

Discharge 

rating

Inflow

(ft3/s)

Gain (+) or 

loss (-) 

(ft3

/s)

Leach Creek at 56th Street 12091250 09-10-07

07-09-08

3.74

3.74

F

F

2.50

2.10

1.24

1.64

Leach Creek at Bridgeport Way bridge 12091300 09-10-07

07-09-08

7.22

7.63

F

F

3.74

3.74

3.48

3.89

Chambers Creek below Leach Creek, near Steilacoom 12091500 09-10-07

07-09-08

440.0

 441.0

F

F

36.1

41.7

3.90

- .70

Peach Creek at Chambers Creek Road West 12091530 08-06-07 1.50 

3.50

P

P

.50 

.50

Chambers Creek upstream of Chambers Bay 12091590 09-10-07

07-09-08 

 49.0

 51.3

G

G

40.5

41.5

8.50

9.80

Clarks Creek at 7th Ave SW 12102010 09-10-07

07-09-08

55.7

54.3

F

F

55.7

54.3

Clarks Creek at Tacoma Road, near Puyallup 12102075 09-10-07

07-10-08

943.0

450.0

P

F

55.7

54.3

- 12.7

- 4.30

West Fork Clarks Creek at Pioneer Way East 12102050 09-10-07

07-09-08

.62

.64

F

F

.62

.64

Clarks Creek at Stewart Ave, at railroad bridge 12102060 09-10-07

07-09-08

50.9

50.5

F

F

43.6

50.6

7.30

- .10

Clear Creek at 31st Ave East 12102175 09-11-07

07-10-08

14.7

 16.3

F

F

14.7

16.3

Swan Creek at 80th Street East 12102190 09-10-07

07-10-08

.00

.00

–

–

Swan Creek at 64th Street East 12102203 09-10-07

07-10-08

.00

.00

–

–

.00

.00

.00

.00

Swan Creek at Pioneer Way East 12102212 09-11-07

07-10-08

2.75

1.81

F

F

.00

.00

2.75

1.81

1

 Estimated by U.S. Geological Survey.

2

 Estimated by U.S. Geological Survey based on discharge measurements from nearby sites.

3

 Estimated by U.S. Geological Survey based on discharge measurements from 2007.

4

 Daily mean streamflow at U.S. Geological Survey stream gage.

5

 Includes measured streamflow plus evaporative loss from Spanaway Lake (table 4)

6

 Includes loss from Spanaway Creek to Morey Creek.

7

 Streamflow measured on September 17, 2006, by Pierce Conservation District (written commun., 2008).

8

 Includes measured streamflow plus evaporative loss from Steilacoom Lake (table 4).

9

 Estimated daily mean streamflow at U.S. Geological Survey stream gage.
38 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

wa19_04090_Fig22 MEAN MONTHLY STREAMFLOW, IN CUBIC FEET PER SECOND

0

40

80

120

160

200

240

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

Mean monthly streamflow

 Clover Creek, 1949–2008 (station No. 12090500)

 Chambers Creek, 1938–2008 (station No. 12091500)

 Clarks Creek, 1995–2008 (station No. 12102075)

EXPLANATION

11 14

SEPTEMBER 2007

5 6 7 8 9 10 12 13 15

DISCHARGE, IN CUBIC FEET PER SECOND

0

5

10

15

20

25

30

35

40

45

50

Chambers Creek (12091500)

Clover Creek (12090500) 

Clarks Creek (12102075)

EXPLANATION

September 2007

synoptic streamflow

measurement period

Figure 22. Mean monthly streamflow at U.S. Geological Survey streamflow-gaging stations for Clover 

Creek (1949–2008), Chambers Creek (1938–2008), and Clarks Creek (1995–2008), Chambers-Clover Creek 

Watershed and vicinity, Washington.

Figure 23. Daily streamflow for U.S. Geological Survey streamflow-gaging stations on Clover Creek

(12090500), Chambers Creek (12091500), and Clarks Creek (12102075), Chambers-Clover Creek Watershed 

and vicinity, Washington, September 5–15, 2007.
Groundwater Movement 39

The results of the synoptic streamflow measurements 

are shown in table 5. Most streamflow measurements were 

rated “fair”; however, 24 measurements were rated “poor” 

because of suboptimal flow conditions (low velocity, shallow 

water depth, or the presence of aquatic vegetation) or the need 

to visually estimate the streamflow value (lack of access to 

stream). Inflow (table 5) is the sum of streamflows measured 

upstream of the measurement site and is used to compute 

the difference between streamflow upstream of the site and 

at the site. The sign of the difference in streamflow (positive 

or negative value) indicates a gaining or losing stream 

reach, respectively. Uncertainties as a result of measurement 

error were too large at some locations to make defensible 

conclusions regarding the characterization of gaining or losing 

stream reaches and those values are italicized in table 5. For 

example, the September 2007 error adjusted minimum and 

maximum values for inflow to Muck Creek at 8th Ave. East 

(12090000), 2.09 and 2.45 ft3/s, respectively, and flow at 

Muck Creek at 8th Ave. East (12090000), 1.83 and 2.15 ft3/s, 

respectively, result in a gain or loss uncertainty range 

(cumulative measurement error) of -0.62 to 0.06 ft3/s. The 

uncertainty range suggests the possibility of either a gaining or 

losing stream reach and does not support the characterization 

of a gaining reach indicated by the unadjusted value of 

-0.28 ft3/s. Conclusions regarding the characterization of 

gaining or losing stream reaches were able to be made at most 

locations (table 5). For example, the July 2008 error adjusted 

minimum and maximum values for inflow to Muck Creek at 

8th Ave. East (12090000), 2.14 and 2.52 ft3/s, respectively, 

and flow at Muck Creek 8th Ave. East (12090000), 1.52 and 

1.78 ft3/s, respectively, result in a gain or loss uncertainty 

range (cumulative measurement error) of -1.00 to -0.36 ft3/s, 

and supports the characterization of a gaining reach indicated 

by the unadjusted value of -0.68 ft3/s. Other potential sources 

of error in the characterization of gaining and losing stream 

reaches include the transient nature of streamflows and 

errors associated with the time lag between upstream and 

downstream measurements and unaccounted for tributary 

inflows within stream reaches.

Streamflow measurements illustrate a complex pattern 

of gains and loses to streamflows that varies throughout 

the study area and seems to be affected in places by local 

topography (pl. 1). The reaches upstream of the uppermost 

measurement sites on all streams except at Swan Creek 

gained flow from groundwater discharge. For example, the 

September 2007 streamflow measurement at Muck Creek at 

Webster Road (12089980) indicates a net gain of 2.73 ft3/s 

from the reach upstream of the measurement site. Intermediate 

reaches of most streams generally were losing or neutral (no 

substantial gain or loss), and the lowermost reaches generally 

were gaining. Substantial groundwater inflows to the lower 

reaches of Chamber, Clear, and Clarks Creeks likely were due 

to significant incision of stream channels as they descend to 

Puget Sound or the Puyallup River valley (pl. 1). Similar gains 

are likely for the lowermost reaches of Sequilitcheu Creek and 

the series of streams draining to the Nisqually River valley, 

although streamflow measurement data are not available.

wa19_0409_Fig24

Chambers Creek (12091500)

Clover Creek (12090500) 

Clarks Creek (12102075)

EXPLANATION

11 14

JULY 2008

54 6 7 8 9 10 12 13

DISCHARGE, IN CUBIC FEET PER SECOND

0

10

20

30

40

50

60

July 2008

synoptic streamflow

measurement period

Figure 24. Daily streamflow for U.S. Geological Survey streamflow-gaging stations on Clover 

Creek (12090500), Chambers Creek (12091500), and Clarks Creek (12102075), Chambers-Clover Creek 

Watershed and vicinity, Washington, July 4-14, 2008.
40 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

Groundwater-Level Fluctuations

Groundwater levels fluctuate over time, both seasonally 

and long term (annually), in response to changing rates of 

groundwater recharge and discharge. When recharge exceeds 

discharge, the amount of water stored in an aquifer increases 

and water levels rise; when discharge exceeds recharge, 

groundwater storage decreases and water levels decline. 

Groundwater levels also may respond to changes in nearby 

stream stage. When stream stage (altitude of the water surface) 

exceeds nearby groundwater levels, streamflow may recharge 

the aquifer, causing a rise in groundwater levels; when 

groundwater levels exceed nearby stream stage, discharge 

from the aquifer to the stream may occur, resulting in a decline 

in groundwater levels. Seasonal changes in groundwater 

levels were observed in many wells in the study area (Justin 

and others, 2009). These observed changes follow a typical 

pattern for shallow wells in western Washington. Water levels 

rose in the autumn and winter when precipitation and river 

stage were high, and declined during spring and summer when 

precipitation and river stage were low (figs. 25 and 26). Also 

typical for western Washington was that the peak groundwater 

levels lagged behind the peak streamflow by a few months, 

reflecting the storage characteristics of the groundwater 

system. 

The timing and magnitude of seasonal groundwaterlevel fluctuations in an aquifer system are related to (1) the 

hydraulic characteristics of aquifer materials and adjacent 

confining units, (2) the presence of unconfined or confined 

aquifer conditions, (3) the depth to groundwater, (4) the 

proximity to perennial surface-water features, and (5) the 

depth of the well and screened intervals being measured. 

Water levels in deep wells typically respond more slowly 

and with less magnitude than water levels in shallow wells 

because deep wells are farther from the recharge source and 

variability is dampened. Water levels in wells completed in 

the unconsolidated hydrogeologic units exhibited seasonal 

variations ranging from less than 1 to about 50 ft (table 6). The 

largest water-level fluctuation (78 ft) during the monitoring 

period (March 2007–September 2008) was measured in a well 

completed in the bedrock unit. Large water-level fluctuations 

in wells completed in the bedrock unit may be attributed to 

the presence of water-bearing fractures (high conductivity and 

low storage) within local outcrop areas receiving precipitation 

recharge, and the relatively lower (compared to sands and 

gravels) storage capacity (primary porosity) of consolidated 

volcanic and sedimentary units (Freeze and Cherry, 1979; 

Fetter, 1988). Water-level fluctuations measured in the shallow 

and permeable AL alluvial valley unit were muted because of 

proximity to perennial streams and rivers; rising groundwater 

levels in these settings are attenuated by increased discharge 

to surface water, and declining groundwater levels are 

ameliorated by increased recharge from surface water.

0

0.5

1.0

1.5

2.0

2.5

30 3.0

40

50

60

70

80

90

PRECIPITATION, IN INCHES

0

1

2

3

4

5

6

7

8

9

GROUNDWATER LEVEL, IN FEET BELOW LAND SURFACE

STREAM GAGE HEIGHT, IN FEET

SEPT APR MAY JUNE JULY AUG

2007 2008

OCT NOV DEC JAN FEB MAR SEPT

Chambers Creek Gaging Station

 No. 12091500

Monthly precipitation at Tacoma

Well No. 20N/02E-35P01

Figure 25. Water levels in well 20N/02E-35P01, stream stage at U.S. Geological Survey streamflowgaging station on Chambers Creek (12091500), and precipitation at Tacoma, Chambers-Clover Creek 

Watershed and vicinity, Washington, September 2007–September 2008.
Groundwater Movement 41

tac09-0409_Fig 26 PRECIPITATION, IN INCHES

0

1

2

3

4

5

6

7

8

9

GROUNDWATER LEVEL, IN FEET BELOW LAND SURFACE

STREAM GAGE HEIGHT, IN FEET

SEPT APR MAY JUNE JULY AUG

2007 2008

OCT NOV DEC JAN FEB MAR SEPT

Clover Creek Gaging Station

 No. 12090500

Monthly precipitation at Tacoma

Well No. 19N/02E-19FL4 02C

110

111

112

113

114

115

116

117

118

119 12.0

12.5

13.0

13.5

14.0

14.5

15.0

15.5

16.0

16.5

Figure 26. Water levels in well 19N02E-19LF402C, stream stage at U.S. Geological Survey 

streamflow-gaging station on Clover Creek (12090500), and precipitation at Tacoma, Chambers-Clover 

Creek Watershed and vicinity, Washington, September 2007–September 2008.

Table 6. Summary of groundwater-level fluctuations and well depths by hydrogeologic unit, Chambers-Clover Creek Watershed, 

Washington, March 2007 through September 2008.

[–, no data]

Hydrogeologic

unit 

Number 

of wells

Water-level fluctuation (feet) Well depth (feet below land surface)

Minimum Median Maximum Minimum Median Maximum

AL alluvial aquifer 6 2.38 3.11 5.12 82 97 233

A1 aquifer 17 .39 5.43 16.71 19.33 47 234

A2 confining unit 14 1.42 3.89 18.99 27.5 184 509

A3 aquifer 41 .87 6.61 40.16 48 127 395

B confining unit 4 5.78 7.21 10.05 152 300 350

C aquifer 36 1.73 8.07 29.15 85 197 337

D confining unit 1 1.47 1.47 1.47 315 315 315

E aquifer 7 1.59 5.8 50.68 240 280 574

F confining unit 0 – – – – – –

G undifferentiated deposits 3 14.03 14.14 18.62 372 508 768

Bedrock unit 6 6.31 7.78 78.06 62 180 337
42 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

Water Budget

On a long-term basis, a hydrologic system usually is in 

a state of dynamic equilibrium; that is, inflow to the system 

equals outflow from the system, and there is little or no net 

change in the amount of water stored within the system. 

An approximate water budget for an average year of 

precipitation (September 1, 2006, to August 31, 2008) for 

the water-budget area was calculated (table 7). The water 

budget assumes there is little or no net change in the 

amount of water stored within the system (inflow equals 

outflow). For this assumption to be correct, there should 

be an absence of long-term trends in groundwater levels 

in the study area. However, there is no long-term ambient 

groundwater monitoring network in the study area, and data 

from the short-term (March 2007–September 2008) monthly 

monitoring network established for this study are insufficient 

to evaluate water-level trends relating to long-term changes 

in groundwater storage. The Tacoma-Pierce County Health 

Department long-term (1996–2006) groundwater monitoring 

report (2007) identified “possible declining water levels” in 

23 of 70 active public-supply wells in the study area. 

Declining water levels were not observed in the remaining 

47 wells in the network. The possible presence of long-term 

water-level declines indicates a potential decrease in water 

storage and, therefore, suggests the conditions for dynamic 

equilibrium may not be met at some locations in the study 

area.

The data and methods used to estimate values of 

precipitation, groundwater recharge, groundwater discharge to 

streams and springs, and withdrawals from wells are described 

in previous sections of this report along with descriptions 

of the uncertainties associated with the estimates of these 

budget components. These uncertainties arise from the use 

of time-averaged and/or area-weighted approximations 

of precipitation, groundwater discharge, and streamflow; 

groundwater withdrawal estimates that do not account for 

potential return flows; and spring flow estimates that do not 

account for small unreported spring discharges. The water 

budget is intended to provide an initial estimate of budget 

components, and due to the above limitations, should be 

considered an approximation of a complex system.

Surface runoff, including shallow subsurface flow, 

was computed as the quantity of water remaining after 

groundwater discharge to streams was subtracted from total 

measured streamflow. The value for evapotranspiration was 

computed as the quantity remaining after surface runoff plus 

groundwater recharge was subtracted from precipitation. 

Other natural discharge, including unmeasured discharge to 

the Puyallup and Nisqually Rivers and submarine seepage 

to Puget Sound, was computed as the quantity of water 

remaining after groundwater discharge to streams and 

springs plus withdrawals from wells was subtracted from 

groundwater recharge. Precipitation during the study 

period (September 1, 2006, to August 31, 2008) averaged 

an estimated 45 in/yr in the area. About 44 percent of 

precipitation enters the groundwater system as recharge. 

Almost one-half of this recharge (49 percent) discharges to 

the Puyallup and Nisqually Rivers and leaves the groundwater 

system as submarine seepage to Puget Sound. The remaining 

groundwater recharge discharges to streams (20 percent) and 

springs (18 percent), or is withdrawn from wells (13 percent). 

The estimated magnitude of submarine groundwater discharge 

from the area is highly uncertain because it incorporates all 

inaccuracies in the other water-budget component estimates, 

and no attempts have been made to measure it directly. 

Submarine groundwater discharge is a potentially significant 

unknown because it represents a potential groundwater 

resource that could be withdrawn without impact to freshwater 

instream flows.

Summary and Conclusions

In 1998, the Washington State Legislature established 

the Washington State Watershed Management Act (codified 

under RCW 90.82) to address diminishing water availability 

and quality and the loss of critical habitat for fish and wildlife. 

Watershed studies under this Act were started in 1998 in 

the Chambers-Clover Creek Watershed (CCCW) Water 

Resources Inventory Area (WRIA 12) by a group of Initiating 

Governments and local stakeholders (Planning Unit). Upon 

completion of a technical assessment of the watershed, some 

members of the Planning Unit concluded that additional data, 

including development of a numerical groundwater-flow 

model, would contribute to an improved understanding of 

water resources in the CCCW. A study to characterize the 

Table 7. Estimated annual water budget for Chambers-Clover 

Creek Watershed and vicinity, Washington, September 1, 2006, to 

August 31, 2008.

Water-budget component

Quantity

Percent Inches 

per year

Acre-feet 

per year

Precipitation

Fate of precipitation

Surface runoff 3 65,700 7

Evapotranspiration 22 504,300 49

Groundwater recharge 20 455,000 44

Total precipitation 45 1,025,000 100

Fate of recharge

Discharge to streams 4 91,800 20

Discharge to springs 3.5 80,000 18

Other natural discharge 10 224,700 49

Withdrawals from wells 2.5 58,500 13

Total recharge 20 455,000 100
Acknowledgments 43

groundwater-flow system in the Chambers-Clover Creek 

Watershed and vicinity was conducted by the U.S. Geological 

Survey. A second phase of this project will integrate this and 

other information into a numerical groundwater-flow model to 

contribute to an improved understanding of water resources in 

the CCCW.

The study area covers about 706 mi2 in western Pierce 

County, Washington, and extends north to the Puyallup 

River, southwest to the Nisqually River, and is bounded on 

the south and east by foothills of the Cascade Range and to 

the west by the Puget Sound. The Puyallup and Nisqually 

Rivers occupy large, relatively flat alluvial valleys that are 

separated by a broad, poorly drained, upland area that covers 

most of the study area. The northwest-flowing Puyallup River 

receives streamflow from several north-flowing streams 

(Swan, Clear, and Clarks Creeks) that originate in the northern 

uplands. Chambers and Clover Creeks drain much of the 

central uplands and flow westward to Puget Sound. Muck 

and Lacamas Creeks, and several smaller tributaries to the 

northwest-flowing Nisqually River, drain the southern part 

of the study area. Many stream reaches flow year-round; 

however, intermittent and ephemeral flow conditions are 

common, especially during the summer months. Numerous 

springs are present throughout the study area and contribute 

late-summer baseflow to streams and year-round groundwater 

discharge to Puget Sound along shoreline bluffs. The study 

area is underlain by a northwest-thickening sequence of 

unconsolidated glacial (till and outwash) and interglacial 

deposits (fluvial and lacustrine), which overlie sedimentary 

and volcanic bedrock units that crop out in the foothills along 

the southern and southeastern margin of the study area.

Geologic units were grouped into 10 hydrogeologic 

units consisting of aquifers and confining units. A surficial 

hydrogeologic unit map was constructed and used with 

well information from 450 drillers’ logs to produce six 

hydrogeologic sections and unit extent and thickness maps.

Unconsolidated aquifers (AL, A1, A3, C, E, and G) 

typically consist of moderately to well-sorted alluvial and 

glacial outwash deposits of sand, gravel, and cobbles, with 

minor lenses of silt and clay. These units often occur as 

discontinuous or isolated bodies and are of highly variable 

thickness. Unconfined conditions occur in areas where aquifer 

units are at land surface; however, much of the study area 

is mantled by glacial till, and confined aquifer conditions 

are common. Groundwater in the unconsolidated aquifers 

generally flows to the northwest in the direction of Puget 

Sound, and to the north and northeast towards the Puyallup 

River. These generalized flow patterns likely are complicated 

by the presence of low permeability confining units that 

separate discontinuous bodies of aquifer material and act 

as local groundwater-flow barriers. Water-level differences 

between the A3 and C aquifers show the potential for 

downward vertical flow in western and eastern parts of the 

study area. The potential for upward groundwater movement, 

indicated by the presence of flowing wells, was observed at 

several locations within the aquifer units.

Unconsolidated confining units (A2, B, D, and 

F) typically consist of poorly sorted glacial till, and 

glaciolacustrine and interglacial deposits of clay, silt, sand, 

gravel, cobbles, and boulders, with a few locally occurring 

sand and gravel lenses capable of providing water for 

domestic use. Unconsolidated aquifer and confining units 

are underlain by Tertiary bedrock units primarily consisting 

of sedimentary claystone, siltstone, sandstone, beds of coal, 

and volcanic rocks. These units, described as the basement 

confining unit by Jones (1999), are not considered part of the 

active groundwater-flow system.

The largest groundwater-level fluctuation (78 ft) observed 

during the monitoring period (March 2007–September 2008) 

was in a well completed in the bedrock unit. Water levels in 

wells completed in the unconsolidated hydrogeologic units 

showed seasonal variations ranging from less than 1 to about 

50 ft.

Synoptic streamflow measurements made in 

September 2007 and July 2008 indicate a total groundwater 

discharge to streams in the study area of 87,310 and 

92,160 acre-ft/yr, respectively. Streamflow measurements 

indicate a complex pattern of gains and losses to streamflows 

that varies throughout the study area and seems to be affected 

in places by local topography. Groundwater discharge 

occurs at numerous springs in the area, and the total 

previously reported discharge of springs in the area is about 

80,000 acre-ft/yr. There are, in addition, many unmeasured 

springs and the total spring discharge in the area is unknown.

The water-budget area, a subarea of the study area, 

received an average (September 2, 2006, to August 31, 2008) 

of about 1,025,000 acre-ft or about 45 in/yr of precipitation a 

year. About 44 percent of precipitation enters the groundwater 

system as recharge. Almost one-half of this recharge 

(49 percent) discharges to the Puyallup and Nisqually Rivers 

and leaves the groundwater system as submarine groundwater 

discharge to Puget Sound. The remaining groundwater 

recharge discharges to streams (20 percent) and springs 

(18 percent), or is withdrawn from wells (13 percent).

Acknowledgments

The authors wish to thank the many well owners in the 

study area who provided access to their wells. The authors 

also acknowledge the assistance and information provided 

by public water-supply systems and water districts; these 

include Spanaway Water Company, Fruitland Mutual Water 

Company, Parkland Light and Water Company, Summit 

Water and Supply Company, Lakewood Water District, and 

the cities of Tacoma, Milton, and Fife. The authors also 

thank Tacoma-Pierce County Health Department, Pierce 

County Water Utility, and Fort Lewis for providing well data. 

Information used to characterize the groundwater-flow system 

was generously provided by Robinson & Noble Inc., and the 

Pacific Groundwater Group.
44 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

References Cited

Bauer, H.H., and Mastin, M.C., 1997, Recharge from 

precipitation in three small glacial-till-mantled catchments 

in the Puget Sound lowland, Washington: U.S. Geological 

Survey Water-Resources Investigations Report 96-4219, 

119 p. (Also available at http://pubs.er.usgs.gov/usgspubs/

wri/wri964219).

Bear, Jacob, 1979, Hydraulics of groundwater: New York, 

McGraw-Hill, 569 p.

Bidlake, W.R., and Payne, K.L., 2001, Estimating recharge 

to ground water from precipitation at Naval Submarine 

Base Bangor and Vicinity, Kitsap County, Washington: 

U.S. Geological Survey Water- Resources Investigations 

Report 01-4110, 33 p.

Blair, H.O., 1929, Underground water resources in the 

vicinity of Tacoma: Journal of the American Water Works 

Association, v. 21, no. 9, p. 1185-1195.

Borden, R.K., and Troost, K.G., 2001, Late Pleistocene 

stratigraphy in the south-central Puget Lowland, Pierce 

County, Washington: Washington Division of Geology and 

Earth Resources Report of Investigations 33, 34 p.

Brown and Caldwell, 1985, Clover/Chambers Creek 

geohydrologic study for Tacoma-Pierce County Health 

Department: Seattle, WA, Brown and Caldwell, 

unpaginated.

Carnahan, B., Luther, H.A., and Wilkes, J.O., 1969, Applied 

numerical methods: New York, John Wiley and Sons, Inc., 

604 p.

Daly, Christopher, Neilson, R.P., and Phillips, D.L., 1994, A 

statistical-topographic model for mapping climatological 

precipitation over mountainous terrain: Journal of Applied 

Meteorology, v. 33, no. 2, p. 140–158.

Carr/Associates Inc., 1988, Report on the 1987-88 test drilling 

program for the City of Tacoma

Drost, B. W., 2005, Quality-assurance plan for groundwater activities, U.S. Geological Survey, Washington 

Water Science Center: U.S. Geological Survey Open-File 

Report 05-1126, 27 p. (Also available at http://pubs.usgs.

gov/of/2005/1126/.)

Drost, B.W., Ely, D.M., and Lum II, W.E., 1999, Conceptual 

model and numerical simulation of the ground-water-flow 

system in the unconsolidated sediments of Thurston County, 

Washington: U.S. Geological Survey Water-Resources 

Investigations Report 99-4165, 254 p. (Also available at 

http://pubs.usgs.gov/wri/wri994165/).

Ferris, J.G., Knowles, D.B., Brown, R.H., and Stallman, R.W., 

1962, Theory of aquifer tests: U.S. Geological Survey 

Water-Supply Paper 1536-E, 174 p. (Also available at 

http://pubs.usgs.gov/wsp/wsp1536-E/).

Fetter, C.W., 1988, Applied hydrogeology: Columbus, Ohio, 

Merrill Publishing Company, 592 p.

Freeze, R.A., and Cherry, J.A., 1979, Groundwater: 

Englewood Cliffs, N.J., Prentice-Hall, 604 p.

Hutchinson, M.F., 1989, A new method for gridding elevation 

and streamline data with automatic removal of pits: Journal 

of Hydrology, v. 106, p. 211-232.

Jones, M.A., 1999, Geologic framework for the Puget Sound 

aquifer system, Washington and British Columbia: U.S. 

Geological Survey Professional Paper 1424-C, 31 p., 

18 pls., scales 1:500,000 and 1:100,000. (Also available at 

http://pubs.er.usgs.gov/usgspubs/pp/pp1424C).

Jones, M.A., Orr, L.A., Ebbert, J.C., and Sumioka, S.S., 

1999, Ground-water hydrology of the Tacoma-Puyallup 

area, Pierce County, Washington: U.S. Geological Survey 

Water‐Resources Investigations Report 99-4013, 154 p.

Justin, G.B., Julich, R., and Payne, K.L., 2009, Hydrographs 

showing groundwater level changes for selected wells 

in the Chambers-Clover Creek Watershed and vicinity, 

Pierce County, Washington: U.S. Geological Survey Data 

Series 453. (Also available at http://pubs.usgs.gov/ds/453/).

Mastin, M.C., 1996, Surface-water hydrology and runoff 

simulations for three basins in Pierce County, Washington: 

U.S. Geological Survey Water-Resources Investigations 

Report 95-4068, 148 p. (Also available at http://pubs.

er.usgs.gov/usgspubs/wri/wri954068).

National Land Cover Database, 2001: accessed May, 2009, 

http://www.mrlc.gov/multizone_download.php?zone=1.

National Oceanic and Atmospheric Administration, 1982, 

Evaporation atlas for the contiguous 48 United States: 

NOAA Technical Report NWS 33, 27 p., 4 pls.

National Oceanic and Atmospheric Administration, 2007, 

Climatological data, annual summary, Washington, 2007: 

Asheville, N.C., National Climatic Data Center, v.111, 

no. 13, 30 p.

Noble, J.B., 1990, Proposed revision of nomenclature for 

the Pleistocene stratigraphy of coastal Pierce County, 

Washington: Washington Division of Geology and Earth 

Resources Open File Report 90-4, 54 p.

Oregon State University, 2009, PRISM Products: accessed 

May, 2009 at http://www.prism.oregonstate.edu.
References Cited 45

Rantz, S.E., and others, 1982, Measurement and computation 

of streamflow, volume 1—Measurement of stage and 

discharge: U.S. Geological Survey Water-Supply 

Paper 2175, 284 p. (Also available at http://pubs.usgs.gov/

wsp/wsp2175).

Robinson & Noble, Inc., and others, 2003, Chambers-Clover 

Technical Assessment – final report: Tacoma, Washington.

Sceva, J.E., Wegner, D.E., and others, 1955, Records of wells 

and springs, water levels, and quality of ground water in 

central Pierce County, Washington: U.S. Geological Survey 

Open-File Report, 261 p.

Schasse, H.W., compiler, 1987, Geologic map of the Centralia 

quadrangle, Washington: Washington Division of Geology 

and Earth Resources Open File Report 87-11, 28 p., 1 pl., 

scale 1:100,000.

Troost, K.G., in press, Geologic map of the Tacoma South 

7.5-minute quadrangle, Washington: U.S. Geological 

Survey Miscellaneous Field Investigation, scale 1:24,000.

Troost, K.G., in press, Geologic map of the Puyallup 

7.5-minute quadrangle, Washington: U.S. Geological 

Survey Miscellaneous Field Investigation, scale 1:24,000.

Troost, K.G., and Booth, D.B., in press, Geologic map of the 

Tacoma North 7. 5-minute quadrangle, Washington, U.S. 

Geological Survey Miscellaneous Field Investigation, scale 

1:24,000.

Troost, K.G., Booth, D.B., and Borden, R.K., in press, 

Geologic map of the Steilacoom 7.5-minute quadrangle, 

Washington: U.S. Geological Survey Miscellaneous Field 

Investigation, scale 1:24,000.

Troost, K.G., Booth, D.B., and Wells, R.E., in press, Geologic 

map of the Gig Harbor 7.5-minute quadrangle, Washington: 

U.S. Geological Survey Miscellaneous Field Investigation, 

scale 1:24,000.

Turney, G.L., Kahle, S.C., and Dion, N.P., 1995, 

Geohydrology and ground-water quality of east King 

County, Washington: U.S. Geological Survey WaterResources Investigations Report 94-4082, 123 p. (Also 

available at http://pubs.er.usgs.gov/usgspubs/wri/

wri944082).

U.S. Department of Commerce Burea of Census, 2007: 

accessed July, 2007 at http://www.census.gov/popest/

counties/tables/CO-EST2008-01-53.xls.

Vaccaro, J.J., Hansen, A.J., and Jones, M.S., 1998, 

Hydrogeologic framework for the Puget Sound aquifer 

system, Washington and British Columbia: U.S. Geological 

Survey Professional Paper 1424-D, 77 p. (Also available at 

http://pubs.er.usgs.gov/usgspubs/pp/pp1424D).

van Heeswijk, Marijke, and Smith, D.T., 2002, Simulation 

of the ground-water flow system at Naval Submarine Base 

Bangor and vicinity, Kitsap County, Washington: U.S. 

Geological Survey Water-Resources Investigations Report 

02-4261, 142 p. (Also available at http://pubs.usgs.gov/wri/

wri024261/).

Walsh, T.J., 1987, Geologic map of the south half of the 

Tacoma quadrangle, Washington: Washington Division of 

Geology and Earth Resources Open File Report 87-3, 10 p., 

1 pl., scale 1:100,000.

Walters, K.L., and Kimmel, G.E., 1968, Ground-water 

occurrence and stratigraphy of unconsolidated deposits, 

central Pierce County, Washington: Washington State 

Department of Water Resources Water-Supply Bulletin 

no. 22, 428 p.

Washington State Department of Health Office of Drinking 

Water, 2007, public water systems data: accessed March, 

2007 at http://www.doh.wa.gov/ehp/dw/our_main_pages/

data_download.html.
46 Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed, Washington 

This page intentionally left blank.
Publishing support provided by the U.S. Geological Survey

Publishing Network, Tacoma Publishing Service Center

For more information concerning the research in this report, contact the

Director, Washington Water Science Center

U.S. Geological Survey,

934 Broadway –Suite 300

Tacoma, Washington 98402

http://wa.water.usgs.gov/
Savoca and others— Hydrogeologic Framework, Groundwater Movement, Water Budget, Chambers-Clover Creek Watershed, WA —Scientific Investigations Report 2010–5055