Prepared in cooperation with Spokane County 

Hydrogeology of the Little Spokane River Basin, Spokane, 

Stevens, and Pend Oreille Counties, Washington

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2013–5124
Cover: Photograph of area north of Spokane near Chattaroy, Washington, looking 

approximately northeast, autumn 2011. Photograph taken by Karen Payne, U.S. 

Geological Survey.
Hydrogeology of the Little Spokane River 

Basin, Spokane, Stevens, and Pend Oreille 

Counties, Washington

By Sue C. Kahle, Theresa D. Olsen, and Elisabeth T. Fasser

Prepared in cooperation with Spokane County

Scientific Investigations Report 2013–5124

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director 

U.S. Geological Survey, Reston, Virginia: 2013

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Suggested citation:

Kahle, S.C., Olsen, T.D., and Fasser, E.T., 2013, Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and 

Pend Oreille Counties, Washington: U.S. Geological Survey Scientific Investigations Report 2013–5124, 52 p., http://

pubs.usgs.gov/sir/2013/5124/
iii

Contents

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

Introduction.....................................................................................................................................................2

Purpose and Scope .............................................................................................................................4

Description of Study Area ...................................................................................................................4

Previous Investigations........................................................................................................................4

Methods of Investigation..............................................................................................................................6

Well Data................................................................................................................................................6

Geology...................................................................................................................................................6

Hydrogeology.........................................................................................................................................6

Horizontal Hydraulic Conductivity.............................................................................................7

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

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

Pre-Tertiary Geology ...................................................................................................................8

Tertiary Geology ...........................................................................................................................8

Quaternary Geology ....................................................................................................................9

Pleistocene ..........................................................................................................................9

Holocene ............................................................................................................................13

Geologic Units ............................................................................................................................13

Hydrogeologic Units...........................................................................................................................14

Bedrock Unit...............................................................................................................................17

Basin Fill ......................................................................................................................................17

Upper Aquifer....................................................................................................................17

Upper Confining Unit ........................................................................................................17

Lower Aquifers..................................................................................................................21

Lower Confining Unit........................................................................................................21

Wanapum Basalt Unit ......................................................................................................21

Latah Unit ...........................................................................................................................21

Grande Ronde Basalt Unit...............................................................................................23

Occurrence and Movement of Groundwater.................................................................................23

Groundwater Occurrence ........................................................................................................23

Groundwater Movement ..........................................................................................................23

Boundary Conditions.................................................................................................................25

Long-Term Water-Level Data...................................................................................................25

Data Needs ...................................................................................................................................................29

Summary........................................................................................................................................................31

Acknowledgments.......................................................................................................................................32

References Cited..........................................................................................................................................32

Glossary.........................................................................................................................................................49
iv

Plates

In pocket

1. Geologic map and location of project wells in the Little Spokane River Basin study

area, Spokane, Stevens, and Pend Oreille Counties, Washington

2. Hydrogeologic unit map, unit of open interval of project wells, and hydrogeologic

sections, Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, 

Washington

Figures

1. Map showing location of the Little Spokane River Basin study area, Spokane,

Stevens, and Pend Oreille Counties, Washington ..................................................................3

2. Map showing physiographic regions of Washington.............................................................5

3. Map showing extent of glacial ice and glacial lakes in northern Washington, 

Idaho, and parts of Montana ....................................................................................................10

4. Conceptual model of the hydrogeologic system in the Little Spokane River 

Basin, Spokane, Stevens, and Pend Oreille Counties, Washington...................................15

5. Map showing estimated altitude of the top of the bedrock in the Little Spokane

River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington ........................18

6. Map showing thickness of basin fill over bedrock in the Little Spokane River 

Basin, Spokane, Stevens, and Pend Oreille Counties, Washington...................................19

7. Map showing thickness and areal extent, and water-level altitudes and inferred

directions of groundwater flow of the Upper aquifer (UA) in the Little Spokane 

River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington ........................20

8. Map showing thickness and areal extent, and water-level altitudes of the 

Lower aquifers (LA) in the Little Spokane River Basin, Spokane, Stevens, and 

Pend Oreille Counties, Washington.........................................................................................22

9. Map showing thickness and extent, and water-level altitudes and inferred

directions of groundwater flow of the Grande Ronde basalt unit (B2) in the 

Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, 

Washington..................................................................................................................................24

10. Map showing water-level altitudes and inferred directions of groundwater flow 

in the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties,

Washington .................................................................................................................................26

11. Map showing locations of wells with long-term water level measurements in the

Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties,

Washington..................................................................................................................................27

12. Map showing Water Resource Inventory Area 55 in the Little Spokane River 

Basin, Spokane, Stevens, and Pend Oreille Counties, Washington...................................30
v

Conversion Factors, Datums, Abbreviations and Acronyms, 

and Well Numbering System

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2)

Volume

gallon (gal) 3.785 liter (L)

gallon (gal) 0.003785 cubic meter (m3)

million gallons (Mgal) 3,785 cubic meter (m3)

cubic mile (mi3) 4.168 cubic kilometer (km3)

Flow rate

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

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)

gallon per minute (gal/min) 0.06309 liter per second (L/s)

Hydraulic gradient

foot per mile (ft/mi) 0.1894 meter per kilometer

Transmissivity*

square foot per day (ft2/d) 0.09290 square meter per day (m2/d)

Tables

1. Geologic timescale with simplified geology of the Little Spokane River Basin 

study area, Spokane, Stevens, and Pend Oreille Counties, Washington. ........................12

2. Lithologic and hydrologic characteristics of the hydrogeologic units in the Little

Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington........16

3. Wells with long-term water level measurements in the Little Spokane River 

Basin, Spokane, Stevens, and Pend Oreille Counties, Washington...................................28

4. Selected physical and hydrologic data for the project wells in or near the Little

Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington........36
vi

Conversion Factors, Datums, Abbreviations and Acronyms, 

and Well Numbering System

Conversion Factors

SI to Inch/Pound

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

°F=(1.8×°C)+32

*Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times 

foot of aquifer thickness [(ft3/d)/ft2]ft. In this report, the mathematically reduced form, foot 

squared per day (ft2/d), is used for convenience.

Datums

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

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

Altitude, as used in this report, refers to distance above the vertical datum.

Abbreviations and Acronyms 

BR Bedrock unit

B1 Wanapum Basalt unit

B2 Grande Ronde Basalt unit

LA Lower aquifers unit

LC Lower confining unit

LT Latah unit

NED National Elevation Dataset

UA Upper aquifer

UC Upper confining unit

USGS U.S. Geological Survey

Multiply By To obtain

Area

square meter (m2) 0.0002471 acre 
vii

Well Numbering System

In Washington, wells are assigned numbers that identify their location in a township, range, 

section, and 40-acre tract. For example, well number 28N/41E-14A05D1 indicates that the well is 

in township 28 north of the Willamette Base Line, and range 41 east of the Willamette Meridian. 

The numbers immediately following the hyphen indicate the section (14) in the township, and 

the letter following the section (A) gives the 40-acre tract of the section. The two-digit sequence 

number (05) following the letter indicates that the well was the fifth one inventoried in that 

40-acre tract. The "D" following the sequence number indicates that the well has been deepened. 

In the illustrations of this report, wells are identified individually using only the section and 

40-acre tract, such as 14A05D1. The townships and ranges are shown on the map borders.

Conversion Factors, Datums, Abbreviations and Acronyms, 

and Well Numbering System

Willamette Meridian

Willamette Base Line

SECTION 14

28N/41E-14A05D1

ABCD

E F G H

JKLM

N P Q R

R. 41 E.

T.

28

 N.

123456

7 12

18 14 13

19 24

30 25

31 32 33 34 35 36

W A S H I N G T O N

Well numbering system in Washington.
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Hydrogeology of the Little Spokane River Basin, Spokane, 

Stevens, and Pend Oreille Counties, Washington

By Sue C. Kahle, Theresa D. Olsen, and Elisabeth T. Fasser

Abstract

A study of the hydrogeologic framework of the 

Little Spokane River Basin was conducted to identify and 

describe the principal hydrogeologic units in the study 

area, their hydraulic characteristics, and general directions 

of groundwater movement. The Little Spokane River 

Basin includes an area of 679 square miles in northeastern 

Washington State covering parts of Spokane, Stevens, and 

Pend Oreille Counties. The groundwater system consists of 

unconsolidated sedimentary deposits and isolated, remnant 

basalt layers overlying crystalline bedrock. In 1976, a water 

resources program for the Little Spokane River was adopted 

into rule by the State of Washington, setting instream flows 

for the river and closing its tributaries to further uses. Spokane 

County representatives are concerned about the effects that 

additional groundwater development within the basin might 

have on the Little Spokane River and on existing groundwater 

resources. Information provided by this study will be used 

in future investigations to evaluate the effects of potential 

increases in groundwater withdrawals on groundwater and 

surface-water resources in the basin.

The hydrogeologic framework consists of eight 

hydrogeologic units: the Upper aquifer, Upper confining unit, 

Lower aquifers, Lower confining unit, Wanapum basalt unit, 

Latah unit, Grande Ronde basalt unit, and Bedrock. The Upper 

aquifer is composed mostly of sand and gravel and varies in 

thickness from 4 to 360 ft, with an average thickness of 70 ft. 

The aquifer is generally finer grained in areas farther from 

main outwash channels. The estimated horizontal hydraulic 

conductivity ranges from 4.4 to 410,000 feet per day (ft/d), 

with a median hydraulic conductivity of 900 ft/d. The Upper 

confining unit is a low-permeability unit consisting mostly 

of silt and clay, and varies in thickness from 5 to 400 ft, with 

an average thickness of 100 ft. The estimated horizontal 

hydraulic conductivity ranges from 0.5 to 5,600 ft/d, with 

a median hydraulic conductivity of 8.2 ft/d. The Lower 

aquifers unit consists of localized confined aquifers or lenses 

consisting mostly of sand that occur at depth in various places 

in the basin; thickness of the unit ranges from 8 to 150 ft, 

with an average thickness of 50 ft. The Lower confining unit 

is a low-permeability unit consisting mostly of silt and clay; 

thickness of the unit ranges from 35 to 310 ft, with an average 

thickness of 130 ft. 

The Wanapum basalt unit includes the Wanapum Basalt 

of the Columbia River Basalt Group, thin sedimentary 

interbeds, and, in some places, overlying loess. The unit 

occurs as isolated remnants on the basalt bluffs in the study 

area and ranges in thickness from 7 to 140 ft, with an average 

thickness of 60 ft. The Latah unit is a mostly low-permeability 

unit consisting of silt, clay, and sand that underlies and is 

interbedded with the basalt units. The Latah unit ranges in 

thickness from 10 to 700 ft, with an average thickness of 

250 ft. The estimated horizontal hydraulic conductivity ranges 

from 0.19 to 15 ft/d, with a median hydraulic conductivity of 

0.56 ft/d. The Grande Ronde unit includes the Grande Ronde 

Basalt of the Columbia River Basalt Group and sedimentary 

interbeds. Unit thickness ranges from 30 to 260 ft, with an 

average thickness of 140 ft. The estimated horizontal hydraulic 

conductivity ranges from 0.03 to 13 ft/d, with a median 

hydraulic conductivity of 2.9 ft/d. 

The Bedrock unit is the only available source of 

groundwater where overlying sediments are absent or 

insufficiently saturated. The estimated horizontal hydraulic 

conductivity ranges from 0.01 to 5,000 ft/d, with a median 

hydraulic conductivity of 1.4 ft/d. The altitude of the buried 

bedrock surface ranges from about 2,200 ft to about 1,200 ft. 

Groundwater movement in the Little Spokane River 

Basin mimics the surface-water drainage pattern of the basin, 

moving from the topographically high tributary-basin areas 

toward the topographically lower valley floors. Water-level 

altitudes range from more than 2,700 ft to about 1,500 ft near 

the basin’s outlet. 
2 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

Introduction

The Little Spokane River Basin, also referred to as 

the Little Spokane Water Resources Inventory Area 55 

(WRIA 55), includes an area of 679 mi2 in northeastern 

Washington State covering parts of Spokane, Stevens, and 

Pend Oreille Counties (fig. 1). Streams originate in the 

northern part of the basin and contribute flow to the Little 

Spokane River, which flows southward about 49 mi from 

just south of Newport, Washington, to its confluence with 

the Spokane River, about 5 mi northwest of the City of 

Spokane. Mean annual flow in the Little Spokane River at 

Dartford (U.S. Geological Survey (USGS) streamgaging 

station No. 12431000; fig. 1) is 299 ft3/s (U.S. Geological 

Survey, 2009).

Important aquifers in the basin occur primarily within 

unconsolidated sediments that include glacial flood deposits 

and recent alluvium. Basalt aquifers also contribute water to 

some wells in the southern part of the basin where the basalt 

underlies the unconsolidated sediment or occurs at land 

surface in remnant basalt mesas. Crystalline basement rocks 

provide generally limited quantities of water in the higher 

elevation areas of the basin where the other more-productive 

units do not occur. The Spokane Valley–Rathdrum Prairie 

aquifer, a large regional groundwater system described by 

Kahle and Bartolino (2007) and Hsieh and others (2007), 

occupies a small area of the southern part of the basin (fig. 1).

Precipitation in the Little Spokane River Basin is 

relatively low, particularly during summer and early 

autumn. The annual precipitation in the basin ranges from 

17 in/yr at its confluence with the Spokane River to 40 in/yr 

in the higher altitude areas (Washington State Department of 

Ecology, 2012); average precipitation at Deer Park is 22 in. 

(Chung, 1975). The basin relies on spring snowmelt from the 

higher altitude areas of the basin and groundwater discharge 

to the river to maintain streamflows during the drier months, 

typically July through October. 

In 1976, a water resources program for the Little Spokane 

River was adopted into rule, setting instream flows for the 

river and closing its tributaries, as well as natural lakes, to 

further uses (Washington State Department of Ecology, 1988). 

Instream flow rules establish a water right and priority date 

for the river to protect instream uses like fish habitat, water 

quality, recreation, and navigation. The rule only affects those 

who apply for new water rights after the rule was adopted. 

These “junior” water rights can be shut off when the flow in 

the river is less than required flows. Currently, the streamgage 

at Dartford is used to manage all junior water rights in the 

Little Spokane River; when summer flow at Dartford is less 

than the minimum 115 ft3

/s, all junior water rights holders in 

the basin receive notice to stop withdrawals (Spokane County, 

2006). Residents on the Little Spokane River have been 

advised to conserve water in 9 of the last 10 years when late 

summer flows have diminished enough to restrict junior 

water-right holders and other users from taking water from 

the river. Specifically, about 150 junior water-right holders 

and other residents along the Little Spokane River have been 

asked to curtail their irrigation or other use of river water 

during summer low flows to ensure that water is available for 

instream resources and senior water-right holders. 

Although parts of the hydrogeologic framework 

had been studied prior to this investigation (Cline, 1969; 

EMCON, 1992; Dames and Moore, Inc., 1995; Boese, 1996; 

and Golder Assoc., Inc., 2003), the nature and extent of the 

unconsolidated sediments and basalt throughout the basin 

were not well defined. Additionally, Golder Assoc., Inc. (2003) 

observed that the Diamond Lake area in the northeastern 

part of the basin might be a conduit for groundwater flow 

from the Pend Oreille River Basin into the headwaters of the 

Little Spokane River. An assessment of the hydrogeologic 

framework of the entire basin was needed, prior to and 

as a basis for developing a groundwater flow model that 

could in turn quantify the effects of groundwater use on the 

groundwater and surface-water system.

Spokane County representatives are concerned about 

the effects of potential future groundwater development 

throughout the basin. With increased subdivision and 

development, an increase in exempt groundwater use is 

expected to continue, but the potential effects of this growth 

on the Little Spokane River and the basin’s aquifers are 

not known. 

To obtain information necessary to evaluate these 

concerns, Spokane County requested that the USGS conduct 

this initial study with the primary goal of describing the 

hydrogeologic framework of the Little Spokane River Basin. 

This work is intended to be followed by subsequent studies 

that would provide the remaining information needed for 

the eventual construction and calibration of a numerical 

groundwater flow model. Such a model then could be used by 

the county to evaluate the possible regional effects of different 

groundwater-use and climate scenarios on the groundwater 

and surface-water system of the basin.
Introduction 3

tac13-0812_fig 01

395

395

2

2

2

3

90

211

292

291

291

20

90

Deer

Lake

Loon 

Lake

Newman 

Lake

Eloika 

Lake

Diamond 

Lake

Sacheen 

Lake

Horseshoe 

Lake

Deer Cr

Dragoon

Cr

Spokane

River

Long Lake

Beaver Cr

West Branch

Little Spokane R

Little Spokane River

Little Deep Cr

Deadman CreekDeadman Creek

Peone Cr

Deep Cr

Coulee Cr

Pend Oreille R

Grouse Creek

Brickel Cr

WASHINGTON

Study

area

STEVENS

PEND OREILLE

SPOKANE

IDAHO

Spokane

Dartford

Chattaroy

Spokane Valley

Deer Park

Newport

Peone Prairie

Half Moon Prairie

Fivemile

Prairie

Orchard

Bluff

Green Bluff

12431500

Little

Spokane

River at

Dartford

12431000

12427000

12429500

12395500

Little Spokane Water Resources Inventory Area 55

Spokane Valley-Rathdrum Prairie aquifer

EXPLANATION

12431500

U.S. Geological Survey

streamgaging site

117°40' 117°20'

48°

10'

48°

47°

50'

0 5 10 MILES

0 5 10 KILOMETERS

Base modified from U.S. Geological Survey data, USGS National Elevation Data (2000), 

30 foot resolution DEM and other digital sources. Projection: UTM, Zone 11N, North 

American Datum 1983, Scale factor= 0.9996, False easting = 500,000, False northing = 0.

Figure 1. Location of the Little Spokane River Basin study area, Spokane, Stevens, and Pend Oreille Counties, Washington.
4 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

Purpose and Scope 

This report describes the development of a hydrogeologic 

framework of the Little Spokane River Basin, focusing on the 

area upstream of the Little Spokane River at Dartford (USGS 

Station No. 12431000). The framework is based on a review 

and interpretation of available drillers’ logs for wells in the 

basin, existing geologic maps, previous investigations, and 

data collected at field-located wells. The description of the 

framework includes: 

1. An updated and compiled digital geologic map for the 

entire basin, 

2. A map and sections of the major hydrogeologic units, 

3. Estimates of horizontal hydraulic conductivity by 

hydrogeologic unit, 

4. Thickness and extent maps of principal water-bearing 

units, 

5. A map of the approximate bedrock surface that marks the 

lower boundary of the basin’s aquifer system,

6. Maps of water-level altitudes based on measurements 

made from November through December 2011 with 

inferred directions of groundwater movement, and 

7. A map and table of long-term water-level measurement 

sites in the basin. 

The report also includes a brief description of the regional 

and local geologic history of the Little Spokane River Basin. 

A glossary is included with definitions for selected technical 

terms contained in the report. 

Description of Study Area

The Little Spokane River Basin is in the Okanogan 

Highlands East, a physiographic region east of the Columbia 

River and Franklin D. Roosevelt Lake, and north of the 

Columbia Plateau (fig. 2). This area is characterized by 

north-south trending mountain ranges reaching altitudes of 

8,000 ft separated by valleys. Rock types in the study area 

include the oldest sedimentary and metamorphic rocks in 

Washington State (Lasmanis, 1991), younger granites, and 

even younger basalt. Today, remaining basalt in the study 

area forms mesas in the southern part of the Little Spokane 

River Basin. 

The major tributaries to the Little Spokane River are 

Deadman, Deer, Dragoon, and Little Deep Creeks, as well as 

the West Branch of the Little Spokane River; the largest lakes 

include Diamond, Eloika, Horseshoe, and Sacheen, which are 

all located in the northern part of the basin (fig. 1). Altitudes 

range from more than 5,300 ft in the northeast side of the 

basin to about 1,540 ft at the confluence of the Little Spokane 

and Spokane Rivers. 

Evergreen forests are the primary land cover in the 

mountainous northern and eastern parts of the basin. 

Agricultural lands are interspersed throughout the basin, but 

most are in the lower-elevation, southeastern parts of the 

basin. Urban areas are most prominent in the southern part 

of the basin and include the northern extent of the City of 

Spokane. Smaller cities in the basin include Deer Park and 

Newport (fig. 1). Numerous vacation or seasonal properties are 

located near the many lakes in the study area.

Previous Investigations

Numerous documents describe previous investigations 

that have contributed to the understanding of the 

hydrogeologic framework in all, or parts, of the Little 

Spokane River Basin. These documents are listed below, in 

chronological order.

Cline (1969) studied the groundwater resources and 

related geology of an area covering 450 mi2 in north-central 

Spokane and southeastern Steven Counties. The report 

includes descriptions of geologic units and their water-bearing 

properties and groundwater recharge, discharge, availability, 

chemical quality, and use.

The Washington State Department of Ecology outlined 

management policies in the Little Spokane River Basin 

in Chung (1975). The policies in the document provided 

a process for making water-allocation and water-use 

decisions within the basin. The program established base 

flows necessary for preserving in-stream values, declared 

beneficial use priorities, closed certain surface-water bodies 

to further appropriation, allocated public water, and set forth 

water-resources administrative procedures.

Landau Associates (1991) characterized the 

hydrogeologic conditions and contaminant distribution at the 

Colbert Landfill, an inactive 40-acre municipal solid waste 

landfill located about 15 mi north of Spokane, Washington. 

Their activities were conducted in order to obtain design 

information needed to design a groundwater pump and treat 

system for the site.

EMCON (1992) described geologic, hydrogeologic, and 

groundwater quality information for the Deer Park Basin, an 

area of about 46 mi2

, in northern Spokane County. Topics in 

the report include geologic history, geologic units, occurrence 

and movement of groundwater, water rights, nitrates in 

groundwater, stream gaging, and a hydrologic budget for 

the area.

Dames and Moore, Inc. (1995) assessed the status of the 

surface and groundwater resources in the Little Spokane River 

Basin (WRIA 55) in support of regulatory concerns and water 

management decisions. Based on available data, hydrologic 

assessments were made that included water quantity, 

hydrogeology, water demand, water quality, and status of 

aquatic habitat and fish stocks.
Introduction 5

tac13-0812_fig 02

Columbia River

Columbia River

Franklin D. Roosevelt Lake

Columbia River

Spokane

River

Olympic

Moutains

Columbia Plateau

Cascades North

Cascades South

Willapa

Hills

Puget

Lowlands

Okanogan

Highlands

West

Okanogan

Highlands

East

Little Spokane

River Basin

Blue

Moutains

0 50 100 MILES

0 50 100 KILOMETERS

122° 120° 118°

49°

124°

48°

47°

46°

Figure 2. Physiographic regions of Washington. (Modified from Lasmanis, 1991.)

Ader (1996) examined the spatial distribution of wells 

and constructed a conceptual hydrogeologic model of the 

4-mi2 Green Bluff Plateau in response to reported water-level 

declines and well interference issues. The study, conducted 

by the Washington State Department of Ecology, was done 

in support of an evaluation of water rights applications on 

the plateau.

Boese (1996) completed a Master’s thesis on aquifer 

delineation and baseline groundwater quality in a 230-mi2 area 

covering most of the southern half of the Little Spokane River 

Basin. The thesis includes descriptions of the geologic and 

hydrogeologic setting and water quality sampling, methods, 

and results. 

Boleneus and Derkey (1996) described the geohydrology 

of a 12-mi2 area of Peone Prairie based on drilling and 

geophysical tests made in the late 1970s as part of a mineral 

exploration venture. Their work includes descriptions of 

aquifers and confining units found during the explorations.

Golder Assoc., Inc. (2003) described the surface water, 

groundwater, water quality, water rights, and water use in the 

Little Spokane (WRIA 55) and Middle Spokane (WRIA 57) 

basins as part of watershed planning efforts. The combined 

area includes 960 mi2

, 675 mi2 in the Little Spokane River 

Basin, and 285 mi2 in the Middle Spokane Basin. Based on 

the data compilation and analysis effort, Golder Assoc., Inc. 

(2004) constructed a watershed simulation model for the 

combined Little and Middle Spokane watershed.

The southernmost part of the Little Spokane River Basin, 

near north Spokane, overlaps with a small part of the Spokane 

Valley–Rathdrum Prairie aquifer, which was described in a 

series of reports including Campbell (2005), Kahle and others 

(2005), Kahle and Bartolino (2007), Bartolino (2007), and 

Hsieh and others (2007). These reports include descriptions of 

the hydrogeologic framework, water-level maps, water budget 

components, and a computer flow model of the aquifer to be 

used in the management of the Spokane Valley–Rathdrum 

Prairie aquifer.
6 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

Spokane County Water Resources has produced several 

documents that describe groundwater inventory and mapping 

in the Little Spokane River Basin (Spokane County, 2009), 

residential water use in Spokane County (2010a), and 

groundwater altitude and stream flow monitoring in the Little 

Spokane River Basin (2010b, 2011). The Spokane County 

Conservation District (2010) produced a stream-gage report 

for Deadman and Dragoon Creeks and the west branch of the 

Little Spokane River. As of 2012, streamflow measurements in 

the basin are made by USGS, Spokane Conservation District, 

and Spokane Community College.

Methods of Investigation

Collecting the basic data required to characterize the 

hydrogeologic framework and estimate the direction of 

groundwater movement in the Little Spokane River Basin 

involved a field inventory of wells, measurement of water 

levels in wells, and construction of hydrogeologic sections, 

hydrogeologic unit maps, and water-level maps.

Well Data

Between November and December 2011, 317 wells 

throughout the study area were field located to acquire 

lithologic data and to measure the depth to water in wells. 

Criteria for site selection included availability of a driller’s 

report and lithologic information (obtained from well records 

at the USGS Washington Water Science Center and the 

Washington State Department of Ecology), location and depth 

of the well, and the ease of access to the well. The intent was 

to collect data from wells evenly distributed throughout the 

study area. This was not possible in all areas because of lack 

of development in much of the basin, or lack of permission to 

access some wells. 

To further augment the project data set, 95 non-fieldlocated wells were assigned approximate locations (latitude 

and longitude coordinates) using public land survey locations 

(township, range, section, and quarter-quarter section), well 

addresses, and (or) parcel numbers for each well included 

on drillers’ logs. To the extent possible, paper maps (USGS 

7 1⁄2-minute quadrangles and City or County road maps) and 

on-line maps (GoogleTMEarth, 2011; Pend Oreille County 

Assessor, 2011; Spokane County Assessor, 2011; and Stevens 

County Assessor, 2011) were used to verify drillers’ locations 

and to estimate latitude and longitude for the non-field-located 

wells. Locations of all 412 project wells are shown on plate 1, 

and selected physical and hydrologic data for the wells are 

provided in table 4 (at back of report).

Information gathered at project wells included site 

location and well-construction details. Depth to water (water 

level) was measured in most wells using an electric tape or 

graduated steel tape, both with accuracy to 0.01 ft. In some 

cases, water levels were not measured because a well was 

difficult to access. Out of the 317 field inventoried wells, 220 

wells had a measurable water level. One well was observed 

as flowing, meaning the water level was above the land 

surface altitude. Latitude and longitude were obtained for 

field-located wells using a Global Positioning System receiver 

with a horizontal accuracy of one-tenth of a second (about 10 

ft). Land-surface altitude for each project well was obtained 

from a digital elevation model with 10-m square cells using 

the latitude and longitude for each well. All water-level 

measurements were made by USGS personnel according 

to standardized techniques of the USGS (Drost, 2005). 

Information for all project wells was entered into the USGS 

National Water Information System database. 

Geology

The geologic map of the study area (pl. 1) was compiled 

and simplified from several sources, including the digital 

geologic map database (1:100,000 scale) for Washington 

(Washington Division of Geology and Earth Resources, 

2005), a spatial database for the geology of the Northern 

Rocky Mountains developed by Zientek and others (2005), the 

surficial geologic map of the Chewelah 1:100,000 quadrangle 

(Carrara and others, 1995), and the reconnaissance geologic 

map of the north-central Spokane and southeastern Stevens 

Counties (Cline, 1969). In some areas, modifications were 

made to existing maps based on field visits or stratigraphic 

evidence obtained during this investigation, primarily from 

drillers’ logs for field-located water wells.

Hydrogeology

Lithologic data from the field-inventoried wells were 

entered into the Rockworks 2006® software, a stratigraphic 

analysis package. Nine hydrogeologic sections were 

constructed using Rockworks to identify and correlate eight 

hydrogeologic units, primarily on the basis of grain size and 

stratigraphic position. Thickness and extent-of-unit maps 

were manually drawn for three units using information from 

the hydrogeologic sections and data from the remaining 

project wells. 
Methods of Investigation 7

Horizontal Hydraulic Conductivity

Hydraulic conductivity is a measure of a material’s ability 

to transmit water. Horizontal hydraulic conductivity was 

estimated for the hydrogeologic units using the drawdown/

discharge relation reported on drillers’ logs that reported pump 

testing wells for 1–29 hours. Only data from those wells with 

a driller’s log containing discharge rate, duration of pumping, 

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

lithologic log were used. Estimates of horizontal hydraulic 

conductivity for this study area are presented in the section 

“Hydrogeologic Units.” Estimates made for neighboring 

basins and for similar units, using the same methods described 

here, are available in Kahle and others, 2003, 2010.

Two methods were used to estimate hydraulic 

conductivity, depending on well construction. For data from 

wells with a screened or perforated 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 hydrogeologic unit supplying water to 

the well. 

The modified equation is

s Q

T

Tt

r s = 4

2 25

2 π ln . (1)

where

s = drawdown in the well, in feet;

Q = discharge, or pumping rate, of the well, 

 in cubic feet per day;

T = transmissivity of the hydrogeologic unit, in

 square feet per day;

t = length of time the well was pumped, in 

 days;

r = radius of the well, in feet; and

S = storage coefficient, a dimensionless

 number, assumed to be 0.0001 for

 confined units and 0.1 for unconfined

 units.

Assumptions for using equation 1 are that aquifers are 

homogeneous, isotropic, and infinite in extent; wells are 

fully penetrating; flow to the well is horizontal; and 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 

many of the assumptions are not precisely met, the field 

conditions in the study area approximate most of the 

assumptions.

A computer program was used to solve equation 1 for 

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

and others, 1969). The calculated transmissivity values 

were not sensitive to assumed storage coefficient values; the 

difference in computed transmissivity between using 0.1 and 

0.0001 for the storage coefficient is a factor of only about 2. 

The following equation was used to calculate horizontal 

hydraulic conductivity from the calculated transmissivity:

K T

b h = (2)

where

Kh = horizontal hydraulic conductivity of the 

 geologic material near the well opening,

 in feet per day; and

b = thickness, in feet, approximated using the

 length of the open interval as reported in

 the driller’s report.

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

overestimates values of Kh because the equations assume that 

all the water flows horizontally within a layer of this thickness. 

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

amount may be relatively small because in most sedimentary 

deposits, vertical flow is inhibited by layering.

For data from wells having only an open-ended casing 

(no perforations), 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

K Q

sr

h = 4π

(3)

Equation 3 is based on the assumption that horizontal and 

vertical hydraulic conductivities are equal, which is not likely 

for the deposits in the study area. The result of violating this 

assumption is underestimating Kh by an unknown amount.

The resulting estimates of hydraulic conductivity 

using the methods described above are presented in the 

Hydrogeologic Units section. The median values of estimated 

hydraulic conductivities for the aquifers are similar in 

magnitude to values reported by Freeze and Cherry (1979, 

p. 29) for similar materials. It is recognized that the estimates 

are biased toward the more productive zones in these 

units and may not be representative of the entire unit. The 

minimum hydraulic conductivities for the hydrogeologic 

units illustrate that there are zones of low hydraulic 

conductivity in most units. Additionally, the range of hydraulic 

conductivities is at least three orders of magnitude for most 

units, indicating substantial heterogeneity and inherent 

uncertainty in estimating hydraulic conductivity. Although 

many uncertainties are in the estimated values of hydraulic 

conductivity, these estimates provide an initial assessment 

of the relative differences in hydraulic conductivity between 

the different hydrogeologic units. These relative differences 

provide the basis for an initial conceptual model of hydraulic 

conductivity values to be used in future computer modeling. 
8 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

Hydrogeologic Framework

This section describes the geologic and hydrogeologic 

framework, including the physical, lithologic, and hydrologic 

characteristics of the hydrogeologic units that compose the 

groundwater system of the Little Spokane River Basin. An 

understanding of the geologic setting and relation of geologic 

units is required to understand the hydrogeologic framework 

and describe the occurrence and availability of groundwater 

within the watershed.

Geologic Setting

A description of the geologic events that have defined 

the geologic framework in the study area is provided in the 

following section. Although descriptions of the region’s 

geologic history are available at various levels of detail in 

numerous documents, the summary that follows is based 

in part on descriptions contained in Cline (1969), Carrara 

and others (1995, 1996), Boese (1996), Kiver and Stradling 

(2001), Kahle and Bartolino (2007), and Bjornstad and 

Kiver (2012). 

The geologic history presented in this report describes 

three major time periods: the pre-Tertiary, the Tertiary, and 

the Quaternary. An expanded description of the geologic 

history for each of these time periods is presented below. A 

simplified geologic time scale (table 1) is provided to aid the 

reader in understanding the sequence of geologic events and 

the magnitude of geologic time during which they occurred. 

Eleven geologic map units occur in the Little Spokane River 

Basin; they are described below and are shown on plate 1. 

Pre-Tertiary Geology

The oldest rocks in the region surrounding and 

underlying the study area are metamorphosed, fine-grained 

sediments that originally were deposited in a large, shallow 

north-south-trending marine basin during the Precambrian 

(table 1). These rocks are present in outcrop today as 

low-grade metasedimentary rocks, including argillite, 

siltite, and quartzite, which grade locally into more highly 

metamorphosed schists and gneisses. In the study area, these 

rocks occur in the headwater areas of the Little Spokane River 

Basin northwest of Eloika Lake, as well as forming an eastwest-trending ridge of mountains (Bare and Lone Mountains 

and Mt. Pisgah) between Diamond Lake to the north, and 

Chain Lakes and Elk to the south (pЄm, pl. 1).

Following deposition and metamorphism, as much as 

20,000 ft of the Precambrian rocks were eroded before the 

Paleozoic Era began (Conners, 1976). During the Paleozoic, 

additional sedimentation occurred in shallow seas that resulted 

in shale, limestone, and sandstone being deposited over 

the Precambrian rocks. However, from near the end of the 

Paleozoic to the present, the region mostly has been emergent, 

and much of the post-Cambrian sediments have been eroded 

from the area leaving few surface exposures. Small outcrops 

occur just outside the Little Spokane River Basin northwest of 

Loon and Deer Lakes.

Emplacement of various granitic intrusive bodies, along 

with associated metamorphism and deformation, occurred 

during a long period of time between the Jurassic and Tertiary. 

The largest volume of granitic rocks was emplaced during the 

Cretaceous and includes biotite-muscovite (two-mica) granite 

that forms Dunns and Lookout Mountains on the southwest 

part of the study area and the southern end of the Selkirk 

Mountains, including Mt. Spokane, on the eastern side of 

the basin (Stoffel and others, 1991). Much smaller outcrops 

of Cretaceous biotite granite form Dart Hill and the northern 

side of Fivemile Prairie (Boese, 1996). Younger granitic rocks 

(hornblende-biotite monzogranite and granodiorite), emplaced 

during the Eocene, occur in the north part of the study area 

in the Diamond and Sacheen Lake areas, and on the western 

margin of the basin south of Loon Lake (Miller, 2000). 

All granitic rocks that occur in the study area are included 

in one geologic map unit, TKg (pl. 1). This unit occurs at land 

surface throughout much of the study area and comprises 

most of the highland areas along the perimeter of the basin. 

Numerous water wells are completed in granite where it 

occurs at land surface, or where overlying units are thin and 

(or) poorly saturated. 

Tertiary Geology

During the Miocene Epoch, basalt lava flowed from 

fissures and vents in eastern Washington, northeastern 

Oregon, and western Idaho, mantling much of the pre-existing 

landscape and filling in low-lying areas. By the end of the 

Miocene, five formations of the Columbia River Basalt Group 

covered much of eastern Washington, west-central Idaho, 

and northeastern Oregon. Burns and others (2011) estimated 

that more than 42,000 mi2

 were covered with a volume 

of about 34,000 mi3 of basalt and associated sedimentary 

interbeds. Because the study area is on the northeastern edge 

of the Columbia Plateau (fig. 2), only a few flows of two 

formations of the Columbia River Basalt Group reached the 

area. The oldest flows in the area are part of the Grande Ronde 

Formation. The stratigraphically higher and younger flows are 

part of the Wanapum Formation (pl. 1).

The Grande Ronde Basalt underlies Wild Rose and Half 

Moon Prairies, and other areas west of the Little Spokane 

River (pl. 1; pl. 2, sections C-C', D-D', and E-E'). Boese 

(1996) identified a thin layer of Grande Ronde Basalt in one 

deep well in section 19 of T. 27 N., R 44 E. near the western 

edge of Green Bluff. Other deep wells on Green Bluff, 

however, did not encounter Grande Ronde Basalt (Boese, 
Hydrogeologic Framework 9

1996). The Wanapum Formation has fewer occurrences in 

the study area than the Grande Ronde because much of it has 

been eroded away. Where it remains, it forms basalt mesas or 

bluffs including Green Bluff, Orchard Bluff, Pleasant Prairie, 

Orchard Prairie, and Fivemile Prairie. 

During the Miocene, as lava flows entered the area, basalt 

blocked existing drainages to the southwest and caused the 

formation of lakes and swamps that covered the lowlands of 

large areas surrounding the basalt flows (Boese, 1996). During 

pauses in the eruption and flow of basalt, great thicknesses 

of sand, silt, and clay were deposited in large basalt-dammed 

lakes along the perimeter of the flows. In the study area, the 

resulting deposits are known as the Latah Formation. Repeated 

cycles of basalt flows and continued damming of the stream 

network resulted in interlayered sediment and basalt.

Following the eruption history of the Columbia River 

Basalt Group, and emplacement of numerous flows and the 

Latah Formation, a period of slow downcutting from the 

Late Miocene to the Early Pleistocene removed as much as 

590 ft of Latah Formation from the region (Anderson, 1927). 

Streams in the redeveloping drainages eroded much of the 

exposed Latah Formation and some of the younger basalt near 

their margin. Accurate estimates of the thickness and extent 

of the remaining Latah Formation sediments are difficult 

to determine because of the cover of Pleistocene drift and 

the difficulty in distinguishing it from younger glacial lake 

sediment. Surface exposures of deeply weathered, yellow 

to orange silt and clay of the Latah Formation can be found 

below the basalt cap on Fivemile and Orchard Prairies, and 

Green Bluff and Orchard Bluff (Ml, pl. 1). 

Quaternary Geology

Pleistocene

During the Pleistocene Epoch, the study area was 

subjected repeatedly to the erosional and depositional 

processes associated with glacial and interglacial periods 

(Kiver and Stradling, 1982, 2001; Kiver and others, 1989). 

A map of the extent of late-glacial ice and glacial lakes in 

northern Washington, Idaho, and northwestern Montana is 

shown in figure 3. At the maximum extent of the most recent 

Pleistocene glaciation (about 15,000 years before present), 

much of northern Washington, Idaho, and westernmost 

Montana was covered by lobes of the Cordilleran ice sheet 

(fig. 3). The large ice sheet formed in the mountains of British 

Columbia and flowed south, filling valleys and overriding 

low mountain ranges. For thousands of years, lobes of the 

Cordilleran ice sheet modified the pre-existing landscape 

through direct ice scour, and through erosion and deposition 

related to glacial and melt water action. Pre-existing river 

or melt water drainages were redirected or even blocked, 

creating ice-age lakes that covered large areas of the inland 

northwest and resulted in thick accumulations of sediment. 

Higher energy environments included glacial outburst 

flooding and glacial meltwater that deposited vast amounts of 

sediment along channels and plains. The resulting assemblage 

of unconsolidated sediment overlies bedrock in much of the 

study area. 

When the Purcell Trench lobe in northern Idaho blocked 

the drainage of the ancestral Clark Fork in northwestern 

Montana, Glacial Lake Missoula was created (fig. 3). The 

lake was about 500 mi3 in volume and reached a maximum 

depth of 2,200 ft (Waitt, 1980). Enormous catastrophic floods 

occurred over a 2,000-year period when the ice dam of the 

Purcell Trench lobe periodically failed, sending floodwaters 

to the west and southwest. The largest of the Missoula floods, 

many of which probably occurred relatively early in the 

lake‐filling and flooding cycle, overwhelmed local drainages 

and topped the 2,400-ft divide west of Spokane, spilling south 

towards Cheney and beyond, and creating the Channeled 

Scablands (fig. 3). When glaciers were at their maximum 

extent, Missoula outburst floods were mostly routed through 

the Spokane Valley, then north through the Hillyard trough to 

the southern portion of the Little Spokane River Basin, and 

then west through the Long Lake area. 

The Pend Oreille River lobe occupied the Pend Oreille 

River valley and reached its most recent southernmost extent 

near the northeast extent of the Little Spokane Basin (fig. 3) 

(Carrara and others, 1995). The terminal area was swept by 

Lake Missoula floodwaters that followed more northern flood 

routes (Carrara and others, 1995). After deflecting off of the 

northern ice lobes, Missoula floodwaters were redirected south 

through a network of channels south and west of Newport, 

including Scotia and Camden Gaps (Bjornstad and Kiver, 

2012), before eventually emptying into the Deer Park area and 

the Little Spokane River (pl. 1). Most of the deposits from the 

catastrophic floods are along the channel of the Little Spokane 

River, where depositional bars and terraces of sand and gravel 

hundreds of feet thick were deposited (Boese, 1996).

The Okanogan and Columbia River lobes affected the 

study area by blocking westward drainage of the ancestral 

Columbia and Spokane Rivers and creating vast ice-age lakes 

that resulted in thick accumulations of clay and silt (Waitt and 

Thorson, 1983). Glacial Lake Columbia, impounded by the 

Okanogan lobe, was the largest glacial lake in the path 

of the Missoula floods (fig. 3). This lake was long-lived 

(2,000–3,000 years) and had various surface altitudes 

depending largely on the degree of blockage by the Okanogan 

lobe and timing of Lake Missoula outburst floods that brought 

additional water into the lake. The typical surface altitude of 

Lake Columbia was about 1,640 ft, but the altitude reached 

2,350 ft during maximum blockage by the Okanogan lobe 

and was as high as about 2,460 ft during the Missoula floods 

(Atwater, 1986). The higher levels of Glacial Lake Columbia 

probably occurred early, whereas the lower and more typical 

level of the lake occurred in later glacial time (Richmond and 

others, 1965; Waitt and Thorson, 1983; and Atwater, 1986). 
10 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

Figure 3. Extent of glacial ice and glacial lakes in northern Washington, Idaho, and parts of Montana. (Modified from U.S. Forest 

Service, 2010.)

tac13-0812_fig 03A
Hydrogeologic Framework 11

Figure 3.—Continued

tac13-0812_fig 03B

LITTLE SPOKANE 

RIVER BASIN

R I V E R L O B E

P E N D O R E I L L E 
12 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

Table 1. Geologic timescale with simplified geology of the Little Spokane River Basin study area, Spokane, Stevens, and Pend Oreille 

Counties, Washington. 

[Modified from U.S. Geological Survey Geologic Names Committee (2010). Abbreviations: Mya, million years ago; ya, years ago; –, indicates a gap in the 

geologic record resulting from erosion and (or) nondeposition]

Eon Era Period, Subperiod Epoch Geologic unit; 

Map symbol

Phanerozoic

(542 Mya to present)

Cenozoic

(66 Mya to present)

Quaternary

(2.6 Mya to present)

Holocene

(11,700 ya to present)

Stream deposits; Qs

Mass - wasting deposits; Qmw

Eolian deposits, Qe

Pleistocene

(2.6 Ma to 11,700 ya)

Fine grained glacial deposits; Qgf

Coarse grained glacial deposits; Qgc

Glacial till, Qgt

Tertiary

(66 to 2.6 Mya)

Pliocene

(5.3 to 2.6 Mya)

–

Miocene

(23 to 5.3 Mya)

Wanapum Basalt; Mw

Grande Ronde Basalt; Mgr

Latah Formation; Ml

Oligocene

(34 to 23 Mya)

–

Eocene

(56 to 34 Mya)

Intrusive igneous

rocks; TKg

Paleocene

(66 to 56 Mya)

Mesozoic

(251 to 65 Mya)

Cretaceous

(146 to 65 Mya)

Jurassic

(200 to 146 Mya)

–

Triassic

(251 to 200 Mya)

Paleozoic

(542 to 251 Mya)

Permian

(299 to 251 Mya)

–

Pennsylvanian

(318 to 299 Mya)

Mississippian

(359 to 318 Mya)

Devonian

(416 to 359 Mya)

Silurian

(444 to 416 Mya)

Ordovician

(488 to 444 Mya)

Cambrian

(542 to 488 Mya)

Proterozoic

(2,500 to 542 Mya)

Neoproterozoic

(1,000 to 542 Mya)

Metasedimentary

rocks; pЄm

Mesoproterozoic

(1,600 to 1,000 Mya)

Paleoproterozoic

(2,500 to 1,600 Mya)
Hydrogeologic Framework 13

At the higher level of Glacial Lake Columbia (2,350 ft), the 

glacial lake would have flooded most of the Little Spokane 

River Basin covering what is now Deer Park and extending 

to near the top of the basalt bluffs in the southern part of 

the basin (pl. 1). The long-lived and sediment-rich nature of 

glacial lakes in the region led to vast thicknesses of mostly 

fine-grained material being deposited throughout much of the 

region’s lower altitude areas.

Downwind from the ice front, wind-blown sediments 

were deposited over much of the Columbia Plateau during 

the Pleistocene (McDonald and Busacca, 1992). This eolian 

material is informally known as the Palouse loess and consists 

of angular fragments that are fine sand to silt sized particles 

of mostly quartz, feldspar, and mica (McDonald and Busacca, 

1992). The Little Spokane River Basin is at the northern edge 

of the Palouse deposition area, so thicknesses generally are 

less than 25 ft (Boese, 1996). In the southern part of the basin, 

the unit mantles the basalt bluffs and occurs locally overlying 

the bedrock.

Holocene

Following the Pleistocene, rivers and streams have 

eroded the glacial deposits in many places as well as 

depositing alluvium along their flood plains. Sand deposited 

by wind also covers parts of the western side of Peone Prairie 

and areas around Mead (Boese, 1996). 

Geologic Units

The geology of the study area consists of 11 geologic 

units (pl. 1).

Recent non-glacial sediment (Qs): This unit includes 

channel, overbank, and alluvial-fan deposits of rivers and 

streams, and peat in low-lying and poorly drained areas. Unit 

consists mostly of stratified silt and sand with some gravel and 

minor amounts of clay deposited by flowing water. 

Mass-wasting deposits (Qmw): Includes poorly sorted 

angular rock fragments deposited as talus at the base of 

steep slopes and heterogeneous mixtures of unconsolidated 

surficial material and rock fragments deposited by landslides. 

Commonly occurs at the base of the basalt uplands where 

the unit is composed mostly of Latah Formation and 

basalt fragments.

Eolian deposits (Qe): Unit includes loess—wind-blown 

silt and fine sand, with minor amounts of clay, blanketing 

basalt uplands, and dune sand overlying glacial outburst flood 

deposits in north Spokane and Mead.

Fine-grained glacial deposits (Qgf): Unit includes clay, 

silt, and sand lake sediments deposited in ice-marginal lakes 

and sand and silt outwash and distal outburst flood deposits. 

Unit includes coarse-grained lenses in places.

Coarse-grained glacial deposits (Qgc): Unit includes 

glacial-outburst flood deposits that consist of sand with gravel, 

cobbles, and boulders deposited by catastrophic draining 

of Glacial Lake Missoula and reworked outwash and till 

deposited by the Pend Oreille lobe. Unit includes localized 

areas and lenses of fine-grained material.

Glacial till (Qgt): Unit includes mostly poorly sorted and 

unstratified clay, silt, sand, and gravel deposited by the Pend 

Oreille River lobe. In the study area, the unit occurs only near 

Newport, where the unit includes the terminal moraine of the 

Pend Oreille River lobe.

Wanapum Basalt (Mw): Unit includes the Wanapum 

Basalt, Priest Rapids Member, of the Columbia River Basalt 

Group. Unit is composed of fine- to coarse-grained basalt 

flows with olivine and plagioclase phenocrysts. The unit 

overlies the Grande Ronde Basalt and, when present, the 

Latah Formation. The Priest Rapids Member is also invasive 

into Latah Formation. Forms prominent rim rock and steep 

cliffs (Greenbluff and Fivemile Prairie), commonly with 

well-developed columnar jointing.

Grande Ronde Basalt (Mgr): Unit includes the Grande 

Ronde Basalt of the Columbia River Basalt Group. Unit is 

composed of black to dark gray, fine-grained, dense to slightly 

vesicular flows composed of dark-brown glass, plagioclase, 

pyroxene, and minor olivine. Flows are commonly pillowed, 

indicating the basalt flowed into water. Overlies or is invasive 

into the Latah Formation; where Latah Formation is absent, 

the Grande Ronde overlies older crystalline rocks.

Latah Formation (Ml): Unit includes lacustrine and 

fluvial deposits of gray to tan to yellow orange siltstone, 

claystone, and minor sandstone that underlie and are 

interbedded with the Grande Ronde Basalt and Priest Rapids 

Member of the Wanapum Basalt in the Spokane area. The unit 

locally contains fossil leaves and carbonized logs.

Intrusive igneous rocks (TKg): Unit is generally 

described as granite and includes fine- to coarse-grained, 

equigranular to porphyritic, muscovite-biotite granite, 

hornblende-biotite granite, granodiorite, and quartz monzonite. 

Metamorphic rocks (pЄm): Unit includes strongly 

foliated and layered, fine- to coarse-grained gneiss, schist, and 

quartzite; minor amphibolite and hornfels; meta-argillite and 

metasiltite, and metadolomite.
14 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

Hydrogeologic Units

The geologic units and the deposits at depth were 

differentiated into aquifers and confining beds on the basis 

of areal extent and general water-bearing characteristics. 

An aquifer is saturated geologic material that is sufficiently 

permeable to yield water in significant quantities to a well 

or spring, whereas a confining bed has lower permeability 

that restricts the movement of groundwater and limits 

the usefulness of the unit as a source of groundwater. 

Generally, well-sorted, coarse-grained deposits have greater 

permeabilities than do fine-grained or poorly sorted deposits. 

In the Little Spokane River Basin, saturated glacial outwash 

or other coarse-grained deposits form the primary aquifers, 

whereas deposits such as lacustrine or glaciolacustrine 

deposits form the confining beds. The aquifers and confining 

beds identified herein are referred to as hydrogeologic 

units because the differentiation takes into account both the 

geologic and hydraulic characteristics of the units. Eight 

hydrogeologic units were identified in the study area, based on 

their areal extent and general water-yielding properties:

• Upper aquifer (UA);

• Upper confining unit (UC);

• Lower aquifers (LA);

• Lower confining unit (LC);

• Wanapum basalt unit (B1);

• Latah unit (LT);

• Grande Ronde basalt unit (B2); and

• Bedrock (BR).

A simplified conceptual model of the hydrologic 

system of the Little Spokane River Basin (fig. 4) illustrates 

a series of unconsolidated sedimentary deposits and basalt 

layers (together referred to as basin fill) overlying the 

“basin” of crystalline bedrock. Figure 4 is representative of 

approximately the southern half of the Little Spokane River 

Basin where basin-fill deposits are composed mostly of low 

permeability fine-grained material overlain or interbedded 

with coarse-grained material (sand and gravel) or basalt, in 

places. Farther north in the basin, the basin-fill deposits are 

generally thinner and the basalt does not extend beyond the 

Eloika Lake area (fig. 1).

The lithologic and hydrologic characteristics of the 

hydrogeologic units are summarized in a table that includes 

the range of thicknesses for each unit, based on data from the 

inventoried wells, and the number of inventoried wells open 

to each unit (table 2). Wells open to more than one unit are 

not included in the chart, but are indicated in table 4. Project 

well locations are shown on plate 2 and are color coded 

based on the hydrogeologic unit that the wells are open to; 

wells completed in multiple units, exploratory bore holes, 

and wells without available drillers’ logs are designated as 

Other and are shown as gray dots; wells open to the Spokane 

Valley–Rathrum Prairie aquifer are shown as black dots. The 

thickness and areal extent of the units are shown on nine 

hydrogeologic sections and exhibit considerable variation 

(pl. 2). Adequate data were available to map the approximate 

thickness and extent of the Upper aquifer, the Lower aquifers, 

and the Grande Ronde basalt unit. The hydrogeologic units 

are commonly heterogeneous and locally discontinuous; 

therefore, correlations are tentative in many places. The Upper 

confining unit, Lower confining unit, and the Latah unit are 

virtually indistinguishable in drillers’ descriptions of material 

detected during well construction. Generally, the first or upper 

confining material detected during drilling was considered 

part of the Upper confining unit. If a deeper confining unit 

was detected below a lower aquifer, it was considered part 

of the Lower confining unit. Confining beds (with or without 

associated sandy zones) either below or associated with basalt 

were considered part of the Latah unit. Along much of the 

Little Spokane River valley floor, the depth to bedrock, and 

therefore the total thickness of the unconsolidated deposits, 

is not well known. Generally, the deeper the units, the less 

certain are the correlations. 

A summary of well yields, as reported on drillers’ logs 

used during this investigation, is also shown on table 2 by 

hydrogeologic unit. Well-yield testing is done to determine 

if an adequate and sustainable yield is available from a well. 

Driller-reported well yields are not only dependent on the 

productivity of the unit to which the well is open, but also 

is a function of the design and purpose of the well. During 

well-yield testing, a municipal well likely would be pumped 

at a higher rate and have a larger diameter casing and a longer 

open interval than one intended for single-family use, thereby 

having an apparent greater yield than that for the single-family 

well. Despite the fact that yields often are estimates, they are 

useful in comparing the general productivity of hydrogeologic 

units; they also illustrate the variability within a single unit. 

Based on the available driller-reported yields from 353 of the 

project wells, yields ranged overall from 0 to 5,000 gal/min, 

with a median yield of 15 gal/min. 

A summary of specific capacity information, derived 

from driller-reported yield divided by the drawdown measured 

in the well during pumping, is also provided, by hydrogeologic 

unit (table 2). Specific capacity often is used to describe the 

productivity of a hydrogeologic unit and is expected to be 

smaller for confined aquifers than unconfined aquifers (Freeze 

and Cherry, 1979). Based on the available driller-reported 

yields and drawdowns of 20 of the project wells, the median 

specific capacity overall, ranged from 0.7 to 300 (gal/min)/ft, 

with a median of 84 (gal/min)/ft. 
Hydrogeologic Framework 15

tac13-0812_fig4 conceptual 01

WEST EAST

Bedrock

uplands Basalt mesa Little Spokane River

Sand, gravel

Silt, clay

Basalt

Bedrock

Approximate direction of groundwater 

flow

EXPLANATION

Spring

Figure 4. Conceptual model of the hydrogeologic system in the Little Spokane River Basin, Spokane, Stevens, and 

Pend Oreille Counties, Washington.
16 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington Hydrogeologic unit [unit label] Range of thick- ness [average thick- ness] (ft) Lithologic and hydrologic characteristics Number of project wells open to unit Estimated hydraulic conductivity [min, median, max] (ft/d) Yield [min, median, max] (gal/min) Specific capacity [min, median, max] ([gal/min]/ft) Upper aquifer [UA] 4–360 [70] Generally an unconfined sand and gravel aquifer with some fine-grained lenses. Most of the unit is composed of glacial outwash, outburst flood deposits, and stream deposits. Unit consists of sand, gravel, and cobbles along the Little Spokane River and in much of the Diamond Lake area; unit is generally finer grained, consisting mostly of sand, in the Deer Park area. Unit is thickest along former outwash channels including that now occupied by the Little Spokane River. Where unit is thin and insufficiently saturated, wells penetrate UA and are completed in deeper units. 57 [4.4, 900, 410,000] {21} [1.0, 20, 1300] {51}

[300] 

{1}

Upper

confining

unit

[UC]

5–400

[100]

Low-permeability unit consisting mostly of silt and clay with some sand. Contains coarse grained 

material in places. Unit is composed mostly of glaciolacustrine material deposited in ice dammed lakes and the distal and fine-grained part of Missoula flood deposits. Unit contains mass-wasting deposits at the base of steep slopes and bluffs. Unit may contain lithologically similar but older deposits of the Latah Formation.

36 [0.5, 8.2, 5600] 15} [2.5, 15, 75] {30}

[2.4] 

{1}

Lower

aquifers

[LA]

8–150

[50]

Localized confined aquifers consisting of sand and some gravel. Unit occurs at depth in various 

places in the basin but appears to be fairly continuous at depth below the lower reaches of the Little Spokane River. Unit is commonly overlain by UC; unit is underlain by other low permeability sedimentary units (LC, LT), basalt, or bedrock. 

36 [8.2, 340, 8700] {12} [7.5, 26, 5000] {35} [2.5, 100, 280] {4}

Lower

confining

unit

[LC]

35–310

[130]

Low-permeability unit consisting mostly of silt and clay that, in places, underlies the Lower 

aquifers (see sections B-B' and F-F'). Unit may be composed of glaciolacustrine sediment and (or) older Latah Formation sediment. 1 [0.2] {1}

[6] 

{1} –

Wanapum

basalt 

unit

[B1]

7–140

[60]

Unit includes the Wanapum Basalt of the Columbia River Basalt Group; includes thin 

sedimentary interbeds in places and overlying loess. Unit occurs on Green Bluff and Orchard Bluff in the southeastern part of the study area. Generally not a reliable water-bearing unit. 2 [2.4] {1}

[19] 

{1} –

Latah

unit

[LT]

10–700

[250]

Mostly low-permeability unit consisting of the Latah Formation silt, clay, and sand that underlies 

and is interbedded with the Grande Ronde and Wanapum Basalts. Includes thin or broken basalt and coarse grained lenses. The sandy or gravelly parts of this unit can provide sufficient water for domestic use. Unit may contain lithologically similar but younger glaciolacustrine deposits.

34 [0.19, 0.56, 15] {3} [3.0, 20, 100] {35} –

Grande

Ronde

basalt unit

[B2]

30–260

[140]

Unit includes the Grande Ronde Basalt of the Columbia River Basalt Group and sedimentary 

interbeds in places. Provides sufficient water to numerous domestic wells in the west central part of the study area from Half Moon Prairie to several miles north of Deer Park. 35 [0.03, 2.9, 13] {3} [0.25, 27, 200] {33}

[0.7] 

{1}

Bedrock

unit

[BR]

Not

applicable

Unit includes granite, quartzite, schist, and gneiss. Locally yields usable quantities of water 

where rocks are fractured. Yields are generally small; some abandoned wells due to low yields.

141 [0.01, 1.4, 5000] {9} [0, 4.3, 60] {127} –

Table 2. Lithologic and hydrologic characteristics of the hydrogeologic units in the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington.[Values in braces { } indicate number of values. Hydrogeologic unit: UA, Upper aquifer; UC, upper confining unit; LA, Lower aquifers; LC, Lower confining unit; B1, 

Wanapum basalt unit; LT, Latah unit; 

B2, Grande Ronde basalt unit; BR, Bedrock unit. Abbreviations: SVRP, Spokane Valley–Rathdrum Prairie aquifer; ft, foot; ft/d, foot per day; gal/min, gallon per minute; (gal/min)/ft, gallon per minute per foot; min, minimum; max, maximum; –, no data available]
Hydrogeologic Framework 17

Bedrock Unit

The Bedrock unit underlies the entire basin and occurs at 

land surface on about 44 percent of the basin’s surface area, 

including most of the higher altitudes areas (pl. 2). Rock types 

included in this unit are granite, quartzite, schist, and gneiss; 

these rocks yield usable quantities of water where rocks are 

fractured. Although this unit generally yields only small 

quantities of water, it is the only available source of water 

where overlying saturated sediments are absent. Roughly 

one-third of the project wells (141 wells) are completed 

in the Bedrock unit (pl. 2). The depths of the project wells 

completed in the Bedrock unit range from 52 to 800 ft, 

with a median depth of 320 ft. The estimated horizontal 

hydraulic conductivity ranges from 0.01 to 5,000 ft/d, with 

a median hydraulic conductivity of 1.4 ft/d (table 2). The 

driller-reported yields for Bedrock unit wells ranged from 

0 (those noted as ‘dry’) to 60 gal/min, with a median yield of 

4.3 gal/min (table 2). Several of the project wells completed in 

the Bedrock unit are unused due to insufficient yields.

The approximate altitude of the top of the bedrock, or 

pre-Tertiary basement, is shown in figure 5. This contour 

map is based on information from the geologic map, well 

logs for project wells, the hydrogeologic sections, and a 

bedrock elevation map developed by Boese (1996) for the 

southern part of the basin. Contours for the buried bedrock 

surface were manually drawn in 200-ft intervals and lie 

within the extent of the Little Spokane River Basin. Along 

the bedrock’s outcrop area, subsurface contours were tied to 

DEM-derived land-surface contours, also in 200-ft intervals. 

The altitude of the bedrock is about 2,200 ft near Diamond 

Lake, about 1,200 ft beneath Peone Prairie, and about 1,600 ft 

near the Little Spokane River at Dartford (USGS Station 

No. 12431000; fig. 1).

Basin Fill

The long and varied geologic history of the Little 

Spokane River Basin has led to varying thickness of basin fill 

overlying bedrock. To estimate and illustrate the thickness 

of basin fill, which includes all of the hydrogeologic units 

described in this report—except the Bedrock unit—a 10-m 

Digital Elevation Model of land surface was used along with 

the altitude of bedrock to subtract the first from the latter in 

order to get approximate thickness of basin fill. Basin fill is 

greatest in Peone Prairie, Half Moon Prairie, Orchard Bluff, 

and Green Bluff (figs. 1 and 6).

Upper Aquifer

The Upper aquifer is composed mostly of sand and 

gravel, with some fine-grained lenses, and includes material 

deposited by glacial meltwater, glacial outburst floods, and 

streams. The Upper aquifer consists of sand, gravel, and 

cobbles along the Little Spokane River and in much of the 

Diamond Lake area. The aquifer is generally finer grained, 

consisting mostly of sand, in the Deer Park area, and in areas 

farther from main outwash channels. Where the unit is thin 

and insufficiently saturated, wells penetrate the Upper aquifer 

and are completed in deeper units (hydrogeologic sections, 

pl. 2). 

The Upper aquifer occurs on about 32 percent of the 

surface area of the basin (pl. 2) and varies in thickness from 

4 to 360 ft, with an average thickness of 70 ft (table 2). The 

unit is thickest along former outwash channels, including the 

channel now occupied by the Little Spokane River, and in the 

Diamond Lake area (fig. 7).

Fifty-seven of the project wells are completed in the unit; 

the locations of which are shown on plate 2. The depths of 

the project wells completed in this aquifer range from 29 to 

243 ft, with a median depth of 88 ft. The estimated horizontal 

hydraulic conductivity ranges from 4.4 to 410,000 ft/d, with 

a median hydraulic conductivity of 900 ft/d (table 2). Landau 

(1991) and Boese (1996) reported hydraulic conductivity 

values of about 500–600 ft/d for the Upper aquifer. Median 

values of hydraulic conductivity for similar aquifers in 

neighboring Colville and Chamokane valleys were 84 and 

540 ft/d, respectively (Kahle and others, 2003 and 2010). 

The driller-reported yields for the Upper aquifer wells ranged 

from 1.0 to 1,300 gal/min, with a median yield of 20 gal/min 

(table 2). Data were available for only one specific capacity 

estimate—300 (gal/min)/ft (table 2). For the most part, 

the aquifer is under unconfined or water table conditions, 

except where less permeable material may cause confined 

conditions locally. 

Upper Confining Unit

The Upper confining unit is a low-permeability 

unit consisting mostly of silt and clay with some sand; 

coarse-grained lenses occur locally (pl. 2, sections A-A′ 

and E-E′). The unit is composed mostly of glaciolacustrine 

material deposited in ice-dammed lakes and the distal and 

fine-grained part of Missoula flood deposits. In places, the 

unit contains mass-wasting deposits at the base of steep 

slopes, and lithologically similar but older deposits of the 

Latah Formation. The Upper confining unit occurs on about 

20 percent of the surface area of the basin (pl. 2) and varies in 

thickness from 5 to 400 ft, with an average thickness of 100 ft 

(table 2). The lateral extent of the unit is difficult to determine 

due to similar lithologic properties with the Latah unit and 

Lower confining unit (pl. 2, sections B-B′ and C-C′).
18 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

tac13-0812_fig 05

Deer

Lake

Loon 

Lake

Newman 

Lake

Eloika 

Lake

Diamond 

Lake Sacheen 

Lake

Horseshoe 

Lake

Deer Cr

Dragoon

Cr

Spokane

R

Long Lake

Beaver Cr

West Branch

Little Spokane R

Little Spokane R

Little Deep Cr

Deadman CrDeadman Cr

Peone Cr

Deep Cr

Coulee Cr

Pend Oreille R

Grouse Cr

Brickel Cr

Base modified from U.S. Geological Survey data, USGS National Elevation Data (2000), 

30 foot resolution DEM and other digital sources. Projection: UTM, Zone 11N, North 

American Datum 1983, Scale factor= 0.9996, False easting = 500,000, False northing = 0.

STEVENS

PEND OREILLE

SPOKANE

IDAHO

Spokane Spokane Valley

Deer Park

Newport

2,800

2,600

2,600

2,400

2,400

2,200

2,200

2,000

2,400

2,200

2,400

2,400

2,400

2,200

2,200

2,200

2,200

2,200

2,000

2,000

2,000

2,000

2,000

2,000

2,200

2,200

2,400

2,600

2,000

2,000

2,000

2,000

2,200

2,000

1,800

1,800

1,800

1,800

1,600

1,600

1,400

1,400

1,200

2,200

2,000

1,800

EXPLANATION

Estimated top of bedrock,

 in feet above NAVD 88

Bedrock well

Bedrock contour below land surface

2,200

2,000

1,800

1,600

1,400

1,200

2,600

2,800

2,400 2,933

1,112

Little Spokane Water

 Resources Inventory

 Area 55

Bedrock at land surface

117°40' 117°20'

48°

10'

48°

47°

50'

0 5 10 MILES

0 5 10 KILOMETERS

Figure 5. Estimated altitude of the top of the bedrock in the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille 

Counties, Washington.
Hydrogeologic Framework 19

tac13-0812_fig 06

0 to 100

100.1 to 300

300.1 to 500

500.1 to 828

Deer

Lake

Loon 

Lake

Newman 

Lake

Eloika 

Lake

Diamond 

Lake Sacheen 

Lake

Horseshoe 

Lake

Deer Cr

Dragoon

Cr

Spokane

River

Long Lake

Beaver Cr

West Branch

Little Spokane R

Little Spokane River

Little Deep Cr

Deadman CreekDeadman Creek

Peone Cr

Deep Cr

Coulee Cr

Pend Oreille R

Grouse Creek

Brickel Cr

Base modified from U.S. Geological Survey data, USGS National Elevation Data (2000), 

30 foot resolution DEM and other digital sources. Projection: UTM, Zone 11N, North 

American Datum 1983, Scale factor= 0.9996, False easting = 500,000, False northing = 0.

STEVENS

PEND OREILLE

SPOKANE

IDAHO

Spokane Spokane Valley

Deer Park

Newport

Extent and thickness of basin fill, in feet

Bedrock well

EXPLANATION

Little Spokane Water Resources

Inventory Area 55

Bedrock at land surface

117°40' 117°20'

48°

10'

48°

47°

50'

0 5 10 MILES

0 5 10 KILOMETERS

Figure 6. Thickness of basin fill over bedrock in the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille 

Counties, Washington. 
20 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

tac13-0812_fig 07

T26N

T25N

T27N

T30N

T28N

T29N

T31N

R41E R42E R43E 2R44E R45E R46E

Deer

Lake

Loon 

Lake

Newman 

Lake

Eloika 

Lake

Diamond 

Lake Sacheen 

Lake

Horseshoe 

Lake

Deer Cr

Dragoon

Cr

Spokane

River

Long Lake

Beaver Cr

West Branch

Little Spokane R

Little Spokane River

Little Deep Cr

Deadman CreekDeadman Creek

Peone Cr

Deep Cr

Coulee Cr

Pend Oreille R

Grouse Creek

Brickel Cr

26D01 29F01

27J01

34G02 05A01

03A01

01P01

12A01

16E01 15N01

13P01

35L01 35R01

02Q04

11N02

13P01 20H03

29N02

14A03

23C06

27R03

27R04

09C01

10J01D1

24B01

16E01

10E02

23C02

06G01

STEVENS

PEND OREILLE

SPOKANE

IDAHO

Spokane Spokane Valley

Deer Park

Newport

Little Spokane Water Resources Inventory Area 55

1,750 to 1,577

1,800 to 1,751

1,900 to 1,801

1,950 to 1,901

2,000 to 1,951

2,050 to 2,001

2,100 to 2,051

2,150 to 2,101

2,200 to 2,151

2,250 to 2,201

2,300 to 2,251

2,391 to 2,301

Well in unit UA; waterlevel altitude, in feet 

above NAVD 88

Well identification No. 

EXPLANATION

Less than 100

101 to 200

201 to 300

Greater than 300

Extent and thickness of UA, in feet Spokane Valley Rathdrum Prairie aquifer

Approximate direction of 

groundwater movement

10E02

EXPLANATION

117°40' 117°20'

48°

10'

48°

47°

50'

0 5 10 MILES

0 5 10 KILOMETERS

Base modified from U.S. Geological Survey data, USGS National Elevation Data (2000), 

30 foot resolution DEM and other digital sources. Projection: UTM, Zone 11N, North 

American Datum 1983, Scale factor= 0.9996, False easting = 500,000, False northing = 0.

Figure 7. Thickness and areal extent, and water-level altitudes and inferred directions of groundwater flow of the Upper 

aquifer (UA) in the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington. 
Hydrogeologic Framework 21

Thirty-six of the project wells are completed in the 

Upper confining unit (pl. 2). The depths of the project 

wells completed in this unit range from 18 to 470 ft, with a 

median depth of 95 ft. The estimated horizontal hydraulic 

conductivity ranges from 0.5 to 5,600 ft/d, with a median 

hydraulic conductivity of 8.2 ft/d (table 2). The median value 

of hydraulic conductivity for a confining unit of the same 

origin (glacial lake sediment) in neighboring Chamokane 

valley was 10 ft/d, (Kahle and others, 2010). The driller 

reported yields for the Upper confining unit ranged from 

2.5 to 75 gal/min, with a median yield of 15 gal/min (table 2). 

Data are available for only one specific capacity estimate—

2.4 (gal/min)/ft (table 2).

Lower Aquifers

This unit consists of localized confined aquifers 

consisting of sand and some gravel that occurs at depth in 

various places in the basin but appears to be fairly continuous 

at depth below the lower reaches of the Little Spokane River 

(section F-F′, pl. 2; fig. 8). The unit is overlain by the Upper 

confining unit and underlain by other low-permeability 

sedimentary units (Lower confining unit, Latah unit), basalt, 

or bedrock.

Thirty-six of the project wells are completed in the Lower 

aquifers (pl. 2). The depths of the project wells completed 

in this unit range from 102 to 435 ft, with a median depth of 

178 ft. Based on data from the project wells, the thickness of 

the unit ranges from 8 to 150 ft, with an average thickness of 

50 ft. The estimated horizontal hydraulic conductivity ranges 

from 8.2 to 8,700 ft/d, with a median hydraulic conductivity 

of 340 ft/d (table 2). Landau (1991) and Boese (1996) reported 

hydraulic conductivity values of about 100–200 ft/d for the 

Lower aquifers. Median values of hydraulic conductivity 

for similar aquifers in neighboring Colville and Chamokane 

valleys were 50 and 20 ft/d, respectively (Kahle and others, 

2003 and 2010). The driller-reported yields for wells in 

the Lower aquifers ranged from 7.5 to 5,000 gal/min, with 

a median yield of 26 gal/min (table 2). Specific capacity 

estimates ranged from 2.5 to 280 (gal/min)/ft, with a median 

of 100 (gal/min)/ft (table 2). 

Lower Confining Unit

The Lower confining unit is a low-permeability unit 

consisting mostly of silt and clay that, in places, underlies 

the Lower aquifers (pl. 2, see sections B-B' and F-F'). The 

unit may be composed of glaciolacustrine sediment and (or) 

older Latah Formation sediment. The thickness of the unit 

ranges from 35 to 310 ft, with an average thickness of 130 ft. 

Although several wells penetrate the Lower confining unit, 

only one of the project wells, 27N/43E-35E02, is open to 

it; the location of which is shown on plate 2 (section F-F′). 

The depth of well 27N/43E-35E02 is 570 ft; the estimated 

hydraulic conductivity is 0.2 ft/d, and the driller-reported yield 

is 6 gal/min.

Wanapum Basalt Unit

The Wanapum basalt unit includes the Wanapum Basalt 

of the Columbia River Basalt Group, thin sedimentary 

interbeds, and in places, overlying loess. The unit occurs 

as isolated remnants on Green Bluff, Orchard Bluff, Peone 

Prairie, and Fivemile Prairie. Ader (1996) reported that the 

Green Bluff basalt aquifer is spatially isolated from sources of 

regional groundwater recharge and that water-level declines 

(as of 1992) in the aquifer were due to losses (pumping from 

wells and spring discharge) exceeding recharge to the aquifer. 

Based on data from project wells, the unit ranges in 

thickness from 7 to 140 ft, with an average thickness of 

60 ft. Only two of the project wells, 26N/43E-23C03 and 

28N/44E-07L01 are completed in the Wanapum basalt unit 

(pl. 2). The depths of the wells are 144 and 73 ft, respectively. 

Well 26N/43E-23C03 has an estimated hydraulic conductivity 

of 2.4 ft/d and driller-reported yield of 19 gal/min. For 

comparison, the median horizontal hydraulic conductivity for 

the Columbia River basalts (Saddle Mountains, Wanapum, and 

Grande Ronde units combined) was 70 ft/d based on data from 

573 wells (Kahle and others, 2011).

Latah Unit

The Latah unit is a mostly low-permeability unit 

consisting of the Latah Formation silt, clay, and sand that 

underlies and is interbedded with the Grande Ronde and 

Wanapum Basalts. The unit includes thin or broken basalt 

and coarse-grained lenses in places. The unit may also 

contain lithologically similar but younger glaciolacustrine 

deposits. The sandy zones of this unit can provide sufficient 

water for domestic use. Based on data from project wells, the 

unit ranges in thickness from 10 to 700 ft, with an average 

thickness of 250 ft; it is important to note, however, that 

generally only the coarser zones of this unit provide sufficient 

water for modest use. 

Numerous project wells were open to the Latah unit as 

illustrated on sections A-A′ through E-E′ (pl. 2). The Latah 

unit is commonly hundreds of feet thick in the southern part 

of the basin beneath the basalt bluffs and Peone Prairie. On 

Green Bluff, in well 27N/44E-20K02, 595 ft of clay and silt 

was drilled through (pl. 2, section A-A′); on Orchard Bluff, in 

well 28N/43E-36P02, 511 ft of clay was drilled through (pl. 2, 

section C-C'). The Latah unit thins to the north and is about 

100 ft thick near Deer Park (pl. 2, section E-E′).

Thirty-four of the project wells are completed in the 

Latah unit (pl. 2). The depths of the project wells completed 

in this unit range from 79 to 660 ft, with a median depth of 

292 ft. The estimated horizontal hydraulic conductivity ranges 

from 0.19 to 15 ft/d, with a median hydraulic conductivity of 

0.56 ft/d (table 2). The driller reported yields for the Latah unit 

wells ranged from 3.0 to 100 gal/min, with a median yield of 

20 gal/min (table 2). 
22 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

tac13-0812_fig 08

T26N

T25N

T27N

T30N

T28N

T29N

T31N

R41E R42E R43E R44E R45E R46E

Deer

Lake

Loon 

Lake

Newman 

Lake

Eloika 

Lake

Diamond 

Lake

Sacheen 

Lake

Horseshoe 

Lake

Deer Cr

Dragoon

Cr

Spokane

River

Long Lake

Beaver Cr

West Branch

Little Spokane R

Little Spokane River

Little Deep Cr

Deadman CreekDeadman Creek

Peone Cr

Deep Cr

Coulee Cr

Pend Oreille R

Grouse Creek

Brickel Cr

Base modified from U.S. Geological Survey data, USGS National Elevation Data (2000), 

30 foot resolution DEM and other digital sources. Projection: UTM, Zone 11N, North 

American Datum 1983, Scale factor= 0.9996, False easting = 500,000, False northing = 0.

STEVENS

PEND OREILLE

SPOKANE

IDAHO

Spokane Spokane Valley

Deer Park

Newport

Little Spokane Water Resources

Inventory Area 55

Less than 50

51 to 100

Greater than 100

Extent and thickness of 

LA, in feet Spokane Valley Rathdrum Prairie aquifer

EXPLANATION

1,700 to 1,680

1,800 to 1,701

1,900 to 1,801

1,950 to 1,901

2,000 to 1,951

2,050 to 2,001

2,100 to 2,051

2,150 to 2,101

2,200 to 2,151

2,250 to 2,201

2,346 to 2,251

Well in unit LA; waterlevel altitude, in feet 

above NAVD 88

Well identification No. 

EXPLANATION

15F05

117°40' 117°20'

48°

10'

48°

47°

50'

0 5 10 MILES

0 5 10 KILOMETERS

24B01

02E01

02M01

14L01

31N01

03L01

01J01

24B02

Flowing

26L02

15F05

14R01

10K01

Figure 8. Thickness and areal extent, and water-level altitudes of the Lower aquifers (LA) in the Little Spokane River Basin, 

Spokane, Stevens, and Pend Oreille Counties, Washington. 
Hydrogeologic Framework 23

Grande Ronde Basalt Unit

The Grande Ronde unit includes the Grande Ronde 

Basalt of the Columbia River Basalt Group and sedimentary 

interbeds, in places. This unit provides sufficient water to 

numerous domestic wells in the west-central part of the 

study area from Half Moon Prairie to several miles north of 

Deer Park (pl. 2, section D-D′). The approximate extent and 

thickness of the Grande Ronde unit is shown in figure 9. 

Thirty-five of the project wells are completed in the 

Grande Ronde basalt unit (pl. 2). Based on data from the 

project wells, the thickness of the unit ranges from 30 to 

260 ft, with an average thickness of 140 ft (table 2). The 

depths of the project wells completed in this unit range from 

66 to 460 ft, with a median depth of 180 ft. The estimated 

horizontal hydraulic conductivity ranges from 0.03 to 13 ft/d, 

with a median hydraulic conductivity of 2.9 ft/d (table 2). 

The driller-reported yields for the Grande Ronde unit ranged 

from 0.25 to 200 gal/min, with a median yield of 27 gal/min 

(table 2). Data are available for only one specific capacity 

estimate—0.7 (gal/min)/ft (table 2).

Occurrence and Movement of Groundwater

A general description of the occurrence and movement 

of groundwater in the Little Spokane River Basin is provided 

below. It is based largely on the previously described 

hydrogeologic framework and on water-level measurements 

made during this investigation from November through 

December 2011. 

Groundwater Occurrence

Groundwater in the unconsolidated deposits occurs in the 

pore spaces of the sediment where the sediment is saturated. 

In the Upper and Lower aquifers, the saturated sediment (sand, 

gravel) can transmit significant quantities of water, whereas 

in the Upper and Lower confining units and the Latah unit, 

the saturated sediment (clay, silt) generally does not transmit 

significant quantities of water except where sand and gravel 

lenses occur. Groundwater in the Wanapum and Grande 

Ronde basalt units occurs in joints, vesicles, fractures, and 

in the pore spaces of sedimentary interbeds. In the Bedrock 

unit, groundwater occurs within weathered or fractured zones, 

and depending on the permeability of the weathered zones 

and degree of connectedness of the fractures, can transmit 

usable (for domestic purposes), but generally small, quantities 

of water. It is important to note that not all units are fully 

saturated throughout their extent, and in the case of the basin 

fill units, many are ‘bypassed’ during drilling, and wells are 

completed in bedrock.

Groundwater Movement

Groundwater flow generally is from areas of recharge 

to areas of discharge, in the direction of decreasing waterlevel altitudes. Recharge from downward percolation of rain 

and snowmelt can occur at land surface throughout much of 

the basin, but may be greatest in higher altitude areas where 

precipitation is greatest and in areas where coarse deposits 

occur at land surface. Direct precipitation recharges the Upper 

aquifer over its extent, and streamflow may recharge the 

aquifer if losing stream reaches directly overlie the aquifer. 

Groundwater and surface-water relations are uncertain, 

however, and were not within the scope of this investigation. 

Significant recharge also may occur along the perimeter of 

the Upper aquifer, where it is in contact with coarse-grained 

lenses or landslide deposits within the Upper confining unit. 

Relatively small amounts of recharge may occur where the 

Upper aquifer is in contact with springs discharging from 

productive zones in the basalt or fractured zones within the 

bedrock. Recharge to the Lower aquifers probably occurs 

along the valley walls where talus slopes and landslide 

deposits along basalt bluffs or glacial outwash fans overlie and 

interfinger with the otherwise continuous confining material. 

Vertical downward flow through coarse areas of confining 

units also recharges the Lower aquifers, in places. 

Discharge from the groundwater system in the Little 

Spokane River Basin occurs as pumping from wells, discharge 

from flowing wells, discharge at springs and seeps, and 

discharge to the Little Spokane River and its tributaries if 

groundwater heads are greater than stream stage. Chung 

(1975) reported that the main stem of the Little Spokane 

River receives a large amount of groundwater discharge from 

springs and subsurface seepage, especially along the stream 

reach between 3 mi north of Chattaroy to 4 mi downstream 

of Dartford.

Water-level altitudes for the Upper aquifer, Lower 

aquifers, and Grande Ronde basalt unit are included in 

figures 7–9, respectively, along with generalized directions 

of groundwater movement. Directions of vertical flow were 

inferred from water-level altitudes in the Upper aquifer and 

the Lower aquifers where the units overlie one another. 

Water-level altitudes in closely spaced wells were reviewed 

to assess if vertical gradients could be determined. In wells 

27N/43E-10B02 and -10B03 near the Colbert Landfill (pl. 1), 

the difference in water levels was almost 100 ft, with a 

downward gradient from the Upper aquifer to the underlying 

Lower aquifers. 
24 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

tac13-0812_fig 09

T26N

T25N

T27N

T30N

T28N

T29N

T31N

R41E R42E R43E 2R44E R45E R46E

Deer

Lake

Loon 

Lake

Newman 

Lake

Eloika 

Lake

Diamond 

Lake Sacheen 

Lake

Horseshoe 

Lake

Deer Cr

Dragoon

Cr

Spokane

River

Long Lake

Beaver Cr

West Branch

Little Spokane R

Little Spokane River

Little Deep Cr

Deadman CreekDeadman Creek

Peone Cr

Deep Cr

Coulee Cr

Pend Oreille R

Grouse Creek

Brickel Cr

Base modified from U.S. Geological Survey data, USGS National Elevation Data (2000), 

30 foot resolution DEM and other digital sources. Projection: UTM, Zone 11N, North 

American Datum 1983, Scale factor= 0.9996, False easting = 500,000, False northing = 0.

15D02 13H03

23E01

25H01

35C04

01P01 03C03

11L04

08R01

12R03

19D01

23Q05 28Q02

33D02

17M09

07C01

10Q02

09N03

16D04 16D03

18D02

17Q01

28Q01

14A05D1

33G01

STEVENS

PEND OREILLE

SPOKANE

IDAHO

Spokane Spokane Valley

Deer Park

Newport

Well in unit B2; waterlevel altitude, in feet

 above NAVD 88

Well identification No.

EXPLANATION

2,207 to 2,201

2,200 to 2,176

2,175 to 2,151

2,150 to 2,126

2,125 to 2,101

2,100 to 2,076

2,075 to 2,051

2,050 to 2,026

2,025 to 2,001

2,000 to 1,976

1,975 to 1,951

1,950 to 1,925

17M09

Little Spokane Water Resources Inventory Area 55 Less than 100

101 to 200

Greater than 200

Extent and thickness of 

Spokane Valley-Rathdrum Prairie aquifer B2, in feet

Approximate direction of groundwater movement

EXPLANATION

117°40' 117°20'

48°

10'

48°

47°

50'

0 5 10 MILES

0 5 10 KILOMETERS

Figure 9. Thickness and extent, and water-level altitudes and inferred directions of groundwater flow of the Grande Ronde 

basalt unit (B2) in the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington.
Hydrogeologic Framework 25

Generalized water-level altitudes of the entire Little 

Spokane River Basin groundwater system, including all 

water levels measured during November–December 2011, 

are shown in figure 10. Although the general direction of 

regional groundwater movement can be inferred from these 

maps of water-level altitudes, it is important to note that these 

water-level maps are general in nature and indicate regional 

groundwater conditions and directions of flow. Small-scale 

local flow patterns may vary greatly, but were not within the 

scope of this study to define and map. Previous analysis of 

local groundwater flow patterns is available for some of the 

subareas within the Little Spokane River Basin in reports 

discussed in section, Previous Investigations. 

Groundwater movement in the Little Spokane River 

Basin generally mimics the surface-water drainage pattern 

and topography of the basin. Groundwater flow moves from 

the topographically high tributary-basin areas toward the 

topographically lower valley floors (fig. 10). Over the entire 

basin, water-level altitudes range from more than 2,700 ft 

to about 1,580 ft near the Little Spokane River at Dartford 

(USGS streamgage 12431000). Groundwater flow directions 

near Newport are less certain, but available data indicate a 

groundwater divide west of Newport with water on one side 

moving southwest into the Little Spokane River Basin, and 

water on the other side moving northeast into the Pend Oreille 

River Basin.

Boundary Conditions

The groundwater system of the Little Spokane River 

Basin is bounded laterally and at depth by dense crystalline 

bedrock. Although the bedrock can supply water from 

weathered and fractured zones, the unit is expected to 

be significantly less permeable with depth. In the upper 

unconfined aquifer, the water table represents an upper 

boundary. The Lower aquifers are bound by overlying 

low-permeability sediment and underlying low-permeability 

sediment, basalt, or bedrock. The rivers and lakes in the basin 

also act as local boundaries, as zones of discharge or recharge 

to or from the groundwater system. The lower discharge point 

of the ground- and surface-water system of the Little Spokane 

River Basin likely coincides with the location of the USGS 

Dartford streamgage (12431000) where bedrock crops out at 

land surface. 

Long-Term Water-Level Data

Although it was outside the scope of this investigation 

to analyze long-term water-level data, this study provided an 

opportunity to review 32 long-term water level measurement 

sites in the Little Spokane River Basin. Future water-use 

planning and forecasting efforts will rely in part on the use of 

available long-term data and the understanding of long-term 

water level patterns. Each site listed in table 3 and shown in 

figure 11 was field visited to determine the condition of the 

well, obtain accurate location information, and measure depth 

to water if possible. Dates of measurements and the name of 

the agency responsible for those measurements are indicated 

in table 3. As of 2012, there are 10 continuous monitoring 

sites in the basin (fig. 11), which use pressure transducers and 

data loggers to record the depth to water in each well on a 

continuous basis. Six wells were destroyed and were no longer 

measurable (table 3). The wells with the longest period of 

record (1978–2012) are 28N/43E-16E01 and 29N/42E-33G01 

(fig. 11, table 3).
26 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

tac13-0812_fig 10

T26N

T25N

T27N

T30N

T28N

T29N

T31N

R41E R42E R43E 2R44E R45E R46E

Deer

Lake

Loon 

Lake

Newman 

Lake

Eloika 

Lake

Diamond 

Lake Sacheen 

Lake

Horseshoe 

Lake

Deer Cr

Dragoon

Cr

Spokane

River

Long Lake

Beaver Cr

West Branch

Little Spokane R

Little Spokane River

Little Deep Cr

Deadman CreekDeadman Creek

Peone Cr

Deep Cr

Coulee Cr

Pend Oreille R

Grouse Creek

Brickel Cr

Base modified from U.S. Geological Survey data, USGS National Elevation Data (2000), 

30 foot resolution DEM and other digital sources. Projection: UTM, Zone 11N, North 

American Datum 1983, Scale factor= 0.9996, False easting = 500,000, False northing = 0.

STEVENS

PEND OREILLE

SPOKANE

IDAHO

Spokane Spokane Valley

Deer Park

Newport

Well; water-level altitude, 

in feet above NAVD 88

EXPLANATION

2,787 - 2,701

2,700 - 2,601

2,600 - 2,501

2,500 - 2,401

2,400 - 2,301

2,300 - 2,201

2,200 - 2,101

2,100 - 2,001

2,000 - 1,901

1,900 - 1,801

1,800 - 1,701

1,700 - 1,556

Little Spokane Water Resources Inventory Area 55

Spokane Valley-Rathdrum Prairie aquifer

Approximate direction of groundwater movement

EXPLANATION

117°40' 117°20'

48°

10'

48°

47°

50'

0 5 10 MILES

0 5 10 KILOMETERS

Figure 10. Water-level altitudes and inferred directions of groundwater flow in the Little Spokane River Basin, Spokane, 

Stevens, and Pend Oreille Counties, Washington.
Hydrogeologic Framework 27

tac13-0812_fig 11

T26N

T25N

T27N

T30N

T28N

T29N

T31N

R41E R42E R43E 2R44E R45E R46E

Deer

Lake

Loon 

Lake

Newman 

Lake

Eloika 

Lake

Diamond 

Lake Sacheen 

Lake

Horseshoe 

Lake

Deer Cr

Dragoon

Cr

Spokane

River

Long Lake

Beaver Cr

West Branch

Little Spokane R

Little Spokane River

Little Deep Cr

Deadman CreekDeadman Creek

Peone Cr

Deep Cr

Coulee Cr

Pend Oreille R

Grouse Creek

Brickel Cr

Base modified from U.S. Geological Survey data, USGS National Elevation Data (2000), 

30 foot resolution DEM and other digital sources. Projection: UTM, Zone 11N, North 

American Datum 1983, Scale factor= 0.9996, False easting = 500,000, False northing = 0.

20B01

03H01

20H01

33G01

16E01

24D01

19P01

08H01 10E02

19H01

19J01 20N01

32J02

06G01

03N01 09D03 07Q01

16D01

19A01 21E02

30H01 21Q02

27J01 31A01

34P01

20J01

22D01 22B01

23C02 22R01

22R02

33G02

USGS

12427000

12431000

12431500

USGS

12429500

STEVENS

PEND OREILLE

SPOKANE

IDAHO

Spokane Spokane Valley

Deer Park

Newport

Well

Well with transducer

EXPLANATION

16E01

06G01

Little Spokane Water Resources

Inventory Area 55

Spokane Valley-Rathdrum Prairie aquifer 12431000 U.S. Geological Survey

streamgaging site

117°40' 117°20'

48°

10'

48°

47°

50'

0 5 10 MILES

0 5 10 KILOMETERS

Figure 11. Locations of wells with long-term water level measurements in the Little Spokane River Basin, Spokane, 

Stevens, and Pend Oreille Counties, Washington.
28 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington Table 3.

Wells with long-term water level measurements in the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington.

[Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; B1, Wanapum basalt unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; UNK, unknown. Abbreviations: ft, foot; USGS, U.S. Geological Survey; NWIS, National Water Information System; WDOE, Washington State Department of Ecology] 

USGS station No. USGS well No. Other identifier or comment Depth of well (ft) Hydrogeologic unit Number of water levels in USGS NWIS

Period of record

USGS measurements WDOE measurements WDOE transducer data Spokane County transducer data

474622117304701 26N/42E-09D03 Rutter Parkway 422 SVRPA 1 2011 2007–12

474623117220001 26N/43E-03N01 180 SVRPA 10 1977–78, 2004, 2012

474658117245601 26N/43E-06G01 Rivilla 30 UA 7 1977–78 2009–12474532117251701 26N/43E-07Q01 Destroyed 88 SVRPA 152 1942–53, 1963

474519117231001 26N/43E-16D01 247 SVRPA 510 1943–55,1977–78, 2004

474436117245501 26N/43E-19A01 163 SVRPA 1,684 1930–81, 2012

474418117231001 26N/43E-21E02 246 SVRPA 10 1977–78, 2004, 2012

474348117223901 26N/43E-21Q02 Crestline and Lincoln 410 SVRPA 1 2011 2009–12

474307117204601 26N/43E-27J01 225 UNK 9 1977–78, 2004, 

474326117244901 26N/43E-30H01 310 SVRPA 14 1975, 1977–78, 2004, 2012

474242117244901 26N/43E-31A01 270 SVRPA 42 1959–60, 1977–78, 2012

474208117213901 26N/43E-34P01 210 SVRPA 563 1928–53

475112117311501 27N/42E-08H01 Destroyed 30 UA 168 1947–73

475123117214701 27N/43E-10E02 Colbert North Glen 44 UA 1 2011 2009–12474935117244201 27N/43E-19H01 41 UNK 12 1962–63

474915117244001 27N/43E-19J01 North Mtn View 90 UC 8 1964–65 2009–12474726117233201 27N/43E-32J02 Pine River Park 208 LA 2 1963, 2011 2009–12

474745117223801 27N/43E-33G02 Shady Slope 182 BR 2 2000–2011 2009–12474940117161201 27N/44E-20B01 50

M 26 1962–65, 2012

474911117165101 27N/44E-20N01 28 UNK 26 1962–65, 2012

475458117270601 28N/42E-24D01 Destroyed 49 UA 25 1962–65

475546117234101 28N/43E-16E01 Chattaroy/Perry Road 242 UA 1 2011 1978–2012 2005–12475502117212001 28N/43E-22B01 Destroyed 100 UC 64 1964–73

475505117220101 28N/43E-22D01 Destroyed 268 UC 17 1962–64

475424117210301 28N/43E-22R01 Destroyed 44 UA 25 1962–65

475417117210501 28N/43E-22R02 Destroyed 157 UA 80 1962–73

475459117201701 28N/43E-23C02 River Estates 88 UA 1 2011 2009–12

475414117173501 28N/44E-19P01 44 UC 25 1962–65, 2012

475941117313401 29N/42E-20J01 18 UC 25 1963–65, 2012

475806117302601 29N/42E-33G01 Deer Park Hwy 395 350 B2 1 2011 1978–2008 2009–12480223117205501 29N/43E-03H01 Destroyed 52 BR 24 1963–65

475946117154301 29N/44E-20H01 28 UC 34 1965–69
Data Needs 29

Data Needs

During the course of this investigation, several data needs 

were identified that, if filled, would provide a more complete 

understanding of the hydrogeologic framework of the Little 

Spokane River Basin. Completion of these tasks could aid in 

the eventual development of a groundwater surface-water flow 

model to estimates effects of groundwater use on streamflow 

and provide managers with a tool to evaluate various 

groundwater-use scenarios in the basin. Data needs for future 

research identified during this study are listed below, in no 

particular order of importance.

• A comparison of the boundary of the Little Spokane 

Water Resources Inventory Area (WRIA) 55 with 

the boundary of the Little Spokane River Basin as 

delineated in the National Watershed Boundary Dataset 

(U.S. Department of Agriculture, 2012), and an 

evaluation of possible groundwater and surface-water 

inputs from the larger area that is not included in 

WRIA 55 (fig. 12).

• An enhanced definition of the inferred groundwater 

divide near Newport would provide a better 

understanding of the boundary conditions at the 

northeastern extent of the basin. 

• A review of existing water-level and streamflow 

monitoring networks for adequacy of data 

collection would assure a robust data set for future 

modeling efforts. 

• Measurement of stream discharge throughout the 

basin during low-flow conditions would help identify 

gaining and losing stream reaches, and further the 

understanding of groundwater and surface-water 

interactions in the basin. 

• A compilation and review of available estimates of 

water use, including Spokane County (2010b), in the 

basin and further refinements or updates, also will be 

needed for future modeling and analysis. 

• Development of a groundwater budget of the basin 

would provide water users with a better understanding 

of this important resource. 

• Acquire deep borehole information in areas where they 

are currently not available, particularly near the outlet 

of the basin east of Dart Hill. 
30 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

tac13-0812_fig 12

Deer

Lake

Loon 

Lake

Eloika 

Lake

Diamond 

Lake

Sacheen 

Lake

Horseshoe 

Lake

Deer Cr

Dragoon

Cr

Spokane

River

Long Lake

Beaver Cr

West Branch

Little Spokane R

Little Spokane River

Little Deep Cr

Deadman Creek

Peone Cr

Deep Cr

Coulee Cr

Pend Oreille R

Grouse Creek

Brickel Cr

Newman 

Lake

Liberty

Lake

Calispell

Lake

Marshall

Lake

Base modified from U.S. Geological Survey data, USGS National Elevation Data (2000), 

30 foot resolution DEM and other digital sources. Projection: UTM, Zone 11N, North 

American Datum 1983, Scale factor= 0.9996, False easting = 500,000, False northing = 0.

12429500

12395500

12431500

Little

Spokane

River at

Dartford

12431000

12427000

STEVENS

PEND OREILLE

SPOKANE

IDAHO

Spokane Spokane

Deer Park

Chewelah

Newport

Valley

EXPLANATION

Little Spokane Water Resources Inventory Area 55

Spokane Valley-Rathdrum Prairie aquifer

Little Spokane River Basin from National Watershed Boundary Dataset

12431000 U.S. Geological Survey

streamgaging site

117°40' 117°20'

48°

10'

48°

47°

50'

47°

40'

0 5 10 MILES

0 5 10 KILOMETERS

117°

Figure 12. Water Resource Inventory Area 55 in the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille 

Counties, Washington. (HUC, hydrologic unit code.)
Summary 31

Summary

The Little Spokane River Basin includes an area of 

679 square miles in northeastern Washington State covering 

parts of Spokane, Stevens, and Pend Oreille Counties. Streams 

originate in the northern part of the basin and contribute flow 

to the Little Spokane River which flows about 49 miles from 

just south of Newport, Washington, to its confluence with 

the Spokane River, about 5 miles northwest of the City of 

Spokane. Precipitation in the Little Spokane River Basin is 

relatively low, particularly during summer and early autumn. 

The basin relies on spring snowmelt from the higher elevation 

areas of the basin and groundwater discharge to the river to 

maintain streamflows during the drier months. 

In 1976, a water resources program for the Little 

Spokane River was adopted into rule, setting instream 

flows for the river and closing its tributaries to further 

uses. Groundwater is an important resource for domestic, 

commercial, and agricultural use in the Little Spokane River 

Basin, and groundwater discharge helps maintain streamflow 

in area streams. The quantity of usable groundwater, and the 

potential effects of changes in climate or human activities 

on groundwater resources, as well as potential affects to 

streamflow, is poorly understood. 

An assessment of the hydrogeologic framework of 

the entire basin was conducted, as a basis for developing 

an eventual groundwater-flow model that could in turn 

be used to quantify the effects of groundwater use on the 

groundwater and surface-water system. Existing geologic and 

hydrogeologic information was obtained and used to evaluate 

the hydrogeologic framework of the Little Spokane River 

Basin. Between November and December 2011, 317 wells 

throughout the study area were field located to acquire 

lithologic data and to measure the depth to water in wells; 

water levels were measurable in 220 wells. 

The pre-Tertiary geology includes mostly Precambrian 

sedimentary rocks that have been metamorphosed and 

disrupted in places by igneous intrusions. The Tertiary geology 

includes the remnant Columbia River basalts and interbedded 

lacustrine deposits of the Latah Formation. The Quaternary 

geology includes lake, stream, glacial, and catastrophic flood 

deposits of varying grain size that overlie the older rocks. 

A digital geologic map compiled for the entire study area 

includes 11 geologic units—recent non-glacial sediment, 

mass-wasting deposits, eolian deposits, fine-grained glacial 

deposits, coarse-grained glacial deposits, glacial till, Wanapum 

Basalt, Grande Ronde Basalt, Latah Formation, intrusive 

igneous rocks, and metamorphic rocks.

Based on lithology, areal extent, and general wateryielding properties, eight hydrogeologic units were identified 

in the study area—Upper aquifer, Upper confining unit, 

Lower aquifers, Lower confining unit, Wanapum basalt unit, 

Latah unit, Grande Ronde basalt unit, and Bedrock unit. The 

Upper confining unit, Lower confining unit, and the Latah 

unit are lithologically similar and difficult to differentiate. 

Conceptually, the hydrogeologic system of the Little Spokane 

River Basin includes a series of sedimentary deposits and 

basalt layers, together referred to as basin fill, overlying a 

‘basin’ of crystalline bedrock. The basin fill is composed 

mostly of low permeability, fine-grained material overlain or 

interbedded with coarse-grained material (sand and gravel) 

or basalt. 

The Bedrock unit underlies the entire basin, occurs 

at land surface on about 44 percent of the surface area of 

the basin and includes granite, quartzite, schist, and gneiss. 

Although this unit generally yields only small quantities 

of water from fractured and weathered zones, it is the only 

available source of water where overlying sediments are 

absent or insufficiently saturated; 141 of the project wells are 

completed in this unit. The estimated horizontal hydraulic 

conductivity ranges from 0.01 to 5,000 feet per day (ft/d), 

with a median hydraulic conductivity of 1.4 ft/d. The 

driller reported yields for Bedrock unit wells ranged from 

0 (those noted as ‘dry’) to 60 gallons per minute (gal/min), 

with a median yield of 4.3 gal/min. A contour map of the 

approximate altitude of the top of the bedrock indicates that 

the altitude of the buried bedrock surface ranges from about 

2,200 feet to about 1,200 feet. Basin fill is thickest where 

remnant basalt and Latah Formation overlay bedrock.

The Upper aquifer is composed mostly of sand and 

gravel with some fine-grained lenses and includes material 

deposited by glacial meltwater, and glacial outburst floods 

and streams. The unit varies in thickness from 4 to 360 feet, 

with an average thickness of 70 feet, and is thickest along 

former outwash channels, including the channel now occupied 

by the Little Spokane River, as well as in the Diamond Lake 

area. The aquifer generally is finer grained in areas farther 

from main outwash channels. Where the unit is thin and 

insufficiently saturated, wells penetrate the Upper aquifer and 

are completed in deeper units. Fifty-seven of the project wells 

are completed in the unit; the estimated horizontal hydraulic 

conductivity ranges from 4.4 to 410,000 ft/d, with a median 

hydraulic conductivity of 900 ft/d. The driller-reported yields 

for the Upper aquifer wells ranged from 1.0 to 1,300 gal/min, 

with a median yield of 20 gal/min. 

The Upper confining unit is a low-permeability 

unit consisting mostly of silt and clay with some sand; 

coarse-grained lenses occur locally. The unit is composed 

mostly of glaciolacustrine material deposited in ice-dammed 

lakes, and the distal and fine-grained glacial flood deposits. 

In places, the unit contains mass-wasting deposits at the base 

of steep slopes, and lithologically similar but older deposits 

of the Latah Formation. The Upper confining unit varies 

in thickness from 5 to 400 feet, with an average thickness 

of 100 feet. The lateral extent of the unit is difficult to 

determine due to similarities in lithologic properties between 
32 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

the Latah unit and Lower confining unit. Thirty-six of the 

project wells are completed in the Upper confining unit. The 

estimated horizontal hydraulic conductivity ranges from 0.5 to 

5,600 ft/d, with a median hydraulic conductivity of 8.2 ft/d; 

driller-reported yields ranged from 2.5 to 75 gal/min, with a 

median yield of 15 gal/min. 

The Lower aquifers unit is composed of localized 

confined aquifers consisting of sand and some gravel that 

occurs at depth in various places in the basin but appears to be 

fairly continuous at depth below the lower reaches of the Little 

Spokane River. Thirty-six of the project wells are completed in 

this unit. The thickness of the unit ranges from 8 to 150 feet, 

with an average thickness of 50 feet. 

The Lower confining unit is a low-permeability unit 

consisting mostly of silt and clay that, in places, underlies the 

Lower aquifers. The unit may be composed of glaciolacustrine 

sediment and (or) older Latah Formation sediment. The 

thickness of the unit ranges from 35 to 310 feet, with an 

average thickness of 130 feet. 

The Wanapum basalt unit includes the Wanapum Basalt 

of the Columbia River Basalt Group, thin sedimentary 

interbeds, and, in places, overlying loess. The unit occurs 

as isolated remnants on the basalt bluffs in the study area. 

The unit ranges in thickness from 7 to 140 feet, with an 

average thickness of 60 feet. Only two of the project wells are 

completed in the Wanapum basalt unit. 

The Latah unit is a mostly low-permeability unit 

consisting of the Latah Formation silt, clay, and sand that 

underlies and is interbedded with the Grande Ronde and 

Wanapum Basalts. The unit includes thin or broken basalt 

and coarse-grained lenses in places, and also may contain 

lithologically similar but younger glaciolacustrine deposits. 

The sandy zones of this unit can provide sufficient water for 

domestic use. Thirty-four of the project wells are completed 

in this unit. The Latah unit ranges in thickness from 10 to 

700 feet, with an average thickness of 250 feet. The estimated 

horizontal hydraulic conductivity ranges from 0.19 to 

15 ft/d, with a median hydraulic conductivity of 0.56 ft/d; 

driller-reported yields for the unit wells ranged from 3.0 to 

100 gal/min, with a median yield of 20 gal/min. 

The Grande Ronde unit includes the Grande Ronde 

Basalt of the Columbia River Basalt Group and sedimentary 

interbeds, in places. This unit provides sufficient water to 

numerous domestic wells in the west-central part of the 

study area from Half Moon Prairie to several miles north 

of Deer Park. Thirty-five of the project wells are completed 

in the unit. Unit thickness ranges from 30 to 260 feet, with 

an average thickness of 140 feet. The estimated horizontal 

hydraulic conductivity ranges from 0.03 to 13 ft/d, with a 

median hydraulic conductivity of 2.9 ft/d; driller reported 

yields ranged from 0.25 to 200 gal/min, with a median yield of 

27 gal/min. 

Groundwater movement in the Little Spokane River 

Basin generally mimics the surface-water drainage pattern 

of the basin, moving from the topographically high 

tributary-basin areas toward the topographically lower valley 

floors. Over the entire basin, water-level altitudes range 

from more than 2,700 feet to about 1,580 feet near the Little 

Spokane River at Dartford (USGS Station No. 12431000). 

Groundwater flow directions near Newport are less certain, 

but available data indicate a possible groundwater divide west 

of Newport with water on one side moving southwest into the 

Little Spokane River Basin and water on the other side moving 

northeast toward the Pend Oreille River Basin.

The groundwater system of the Little Spokane River 

Basin is bounded laterally and at depth by dense crystalline 

bedrock. The rivers and lakes in the basin also act as local 

boundaries, either as zones of discharge or recharge to or from 

the groundwater system. The lower discharge point of the 

groundwater and surface-water system of the Little Spokane 

River Basin likely coincides with the location of the USGS 

Dartford streamgage (12431000) where bedrock crops out at 

land surface. 

The data needs that were identified during this 

investigation include better definition of the hydrologic 

boundaries at the northeast extent of the basin and at the outlet 

of the basin, a review of existing water-level and streamflow 

monitoring networks, and an analysis of groundwater 

and surface water interactions. Finally, a compilation 

and refinement of available estimates of water use, and 

the development of a groundwater budget could allow a 

better understanding of the movement and availability of 

groundwater in the basin.

Acknowledgments

The USGS gratefully acknowledges the landowners in 

the Little Spokane River Basin who allowed access to their 

land and wells and shared their knowledge about the water 

resources of the area.

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36 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington.

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, 

Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; 

NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

26N/42E-02L02 474636117280601 398 391 SVRPA 474647 1172801 1,845 10-19-90 – – – –

26N/42E-02N07 474636117281601 350 345 SVRPA 474636 1172816 1,770 10-11-01 1.96 – – –

26N/42E-03L03 474636117292201 240 234 SVRPA 474636 1172922 1,714 01-12-95 – – – –

26N/42E-03M01 474643117291401 220 210 SVRPA 474638 1172933 1,705 01-17-95 – – – –

26N/42E-04N03 474629117305101 321 321 SVRPA 474627 1173055 1,712 05-27-92 – 172.55 11-17-11 –

26N/42E-05N03 474623117320301 237 236 SVRPA 474634 1173205 1,742 02-06-78 – – – –

26N/42E-09D01 474611117304201 405 405 SVRPA 474616 1173046 1,762 11-12-66 – – – –

26N/42E-09D03 474622117304701 422 422 SVRPA 474622 1173047 1,769 03-30-07 – 166.3 11-10-11 –

26N/42E-11C02 474614117280501 290 290 SVRPA 474614 1172805 1,761 02-23-00 – – – –

26N/42E-14G02 474512117273701 200 200

M 474512 1172741 2,406 09-06-78 – – – –

26N/42E-23E01 474421117281701 460 460 B2 474421 1172821 2,358 04-16-85 – – – –

26N/43E-02L02 474637117201701 180 173 LA 474637 1172017 1,886 05-28-10 – – – –

26N/43E-03F01 474654117213301 214 175 LA 474654 1172137 1,895 06-08-83 514.3 – – –

26N/43E-03L01 474641117213301 160 154 LA 474641 1172137 1,790 09-16-91 256.3 – – –

26N/43E-03N01 474623117220001 180 180 SVRPA 474623 1172203 1,866 05-29-70 391.3 111.75 04-27-12 –

26N/43E-06G01 474658117245601 30 30 UA 474656 1172501 1,585 07-07-57 6,196 7.81 11-10-11 –

26N/43E-07D02 474617117254501 140 138 SVRPA 474617 1172549 1,571 10-11-84 – – – –

26N/43E-07G02 474610117245401 296 200 SVRPA 474608 1172501 1,819 07-10-79 1,636 – – –

26N/43E-07Q01 474532117251701 88 SVRPA 474546 1172507 1,795 01-01-15 6,409 – – –

26N/43E-08B04 474618117235801 89.5 89.5 SVRPA 474621 1172358 1,786 06-01-59 459.5 – – –

26N/43E-08E03 474604117242901 465 462 SVRPA 474606 1172429 1,788 07-08-96 – – – –

26N/43E-08N02 474538117243601 63 60 SVRPA 474538 1172436 1,782 09-06-73 – 29.04 11-15-11 –

26N/43E-09D01 474618117231501 170 170 SVRPA 474618 1172315 1,825 12-20-95 – – – –

26N/43E-10Q02 474535117213001 405 405 BR 474535 1172124 1,908 05-26-04 – – – –

26N/43E-15H02 474510117204901 340 340 LT 474511 1172052 2,090 09-21-04 – – – –

26N/43E-15N01 474444117215301 300 300 BR 474444 1172153 1,972 10-09-85 – – – –

26N/43E-16D01 474519117231001 247 247 SVRPA 474520 1172310 1,944 – – 160.25 04-20-12 –

26N/43E-16D03 474526117231701 286 SVRPA 474526 1172321 1,942 04-23-51 – – – –

26N/43E-16G01 474512117222701 556 556

M 474512 1172231 1,946 01-01-42 – – – –

26N/43E-18B01 474524117150501 282 282 SVRPA 474518 1172514 1,909 08-21-86 900.6 – – –

26N/43E-19A01 474436117245501 163 163 SVRPA 474436 1172459 1,944 01-01-21 – 137.1 04-26-12 –

26N/43E-19P01 474358117251701 210 210 SVRPA 474359 1172521 1,984 03-26-55 – – – –

26N/43E-20J02 474409117232801 768 SVRPA 474409 1172332 2,015 01-01-62 – – – –
Table 4 37

Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, 

Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

26N/43E-21E02 474418117231001 246 246 SVRPA 474418 1172311 1,995 11-02-51 1,260 181.15 04-24-12 –26N/43E-21Q02 474348117223901 414 410 SVRPA 474348 1172239 2,033 07-25-09 – 193.83 11-10-11 –

26N/43E-22N04 474352117215101 275 254 SVRPA 474347 1172204 2,009 09-01-80 – 182.48 11-14-11 –

26N/43E-23C03 474428117203001 144 144 B1 474428 1172030 2,355 02-12-99 2.35 80.8 11-14-11 –

26N/43E-25P01 474303117190401 500 500 BR 474303 1171904 2,360 07-14-08 – – – –

26N/43E-27J01 474307117204601 – 225 UNK 474308 1172050 2,002 06-01-73 – – – –

26N/43E-30H01 474326117244901 310 310 SVRPA 474327 1172456 2,052 04-19-73 406,700 210 04-20-12

26N/43E-31A01 474242117244901 – 270 SVRPA 474242 1172452 2,068 04-18-60 – 211.83 04-26-12 –

26N/43E-34P01 474208117213901 – 210 SVRPA 474208 1172143 2,040 01-01-28 – – – –

26N/44E-03D01 474704117141001 550 545 LT 474704 1171411 2,403 11-04-10 – – – –

26N/44E-04K01 474638117145301 320 320 LT 474638 1171453 2,016 10-13-04 188.33 11-16-11 –

26N/44E-04L01 474645117150701 138 138 LA 474645 1171507 1,895 05-17-06 31.13 59.87 11-16-11 –

26N/44E-04M01 474644117153201 645 – NA 474644 1171533 1,864 – – – – –

26N/44E-05B01 474703117161601 260 260 LT 474703 1171616 1,905 10-23-06 – – – –

26N/44E-05E01 474652117164401 376.8 – NA 474652 1171644 1,887 – – – – –

26N/44E-05L01 474646117163701 551 – NA 474646 1171637 1,865 – – – – –

26N/44E-05M01 474639117165601 534.2 – NA 474639 1171657 1,864 – – – – –

26N/44E-05R01 474626117155301 700 – NA 474626 1171553 1,864 – – – – –

26N/44E-06A01 474711117171101 310 310 LT 474711 1171711 1,937 05-09-03 0.19 131.71 11-16-11 R

26N/44E-06B01 474702117171401 220 211 LT 474714 1171737 1,897 09-21-90 – – – –26N/44E-06D02 474713117181001 388 – NA 474713 1171810 1,868 – – – – –

26N/44E-06N01 474632117180901 705 – NA 474632 1171809 1,871 – – – – –

26N/44E-07A01 474614117170401 268 – NA 474614 1171704 1,864 – – – – –

26N/44E-07M01 474555117180801 700 700 NA 474555 1171808 1,881 – – – – –

26N/44E-08K02 474551117160801 260 247 LT 474551 1171608 1,884 06-27-08 – – – –

26N/44E-08Q02 474538117160501 760.5 760.5 NA 474538 1171605 1,956 – – – – –

26N/44E-09L01 474545117150801 757.6 – NA 474545 1171508 1,885 – – – – –

26N/44E-09P01 474536117150701 145 145 LA 474536 1171507 1,955 03-03-05 – – – –

26N/44E-09P02 474531117151401 115 115 LA 474531 1171514 1,884 08-28-02 – – – –

26N/44E-11Q04 474537117121301 440 440 BR 474532 1171217 2,368 09-12-94 – 123.4 11-15-11 R

26N/44E-14J01 474459117115301 400 400 M 474459 1171153 2,438 06-26-02 – – – –

26N/44E-14N01D1 474449117125201 580 580 BR 474449 1171253 2,360 03-25-05 – – – –

26N/44E-17N04 474442117165601 180 180 LT 474442 1171656 2,023 06-25-08 – 62.57 11-16-11 –

26N/44E-23H02 474421117120301 240 240 LT 474421 1171203 2,446 12-20-06 – 46.48 11-15-11 –
38 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, 

Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; 

NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

26N/44E-23H03 474424117120401 500 388

M 474425 1171204 2,417 01-31-06 – 66.14 11-15-11 –

27N-42E-02B01 475226117273801 322 322 BR 475226 1172738 1,989 04-21-00 – – – –

27N/42E-02C08 475224117281201 400 400 BR 475224 1172812 2,083 09-13-04 – 78.53 11-17-11 –

27N/42E-08H01 475112117311501 – 30 UA 475121 1173114 2,123 01-01-47 1,002 – – –

27N/42E-08L01 475102117314901 400 400 BR 475102 1173149 2,168 07-07-04 – 39.41 11-16-11 –

27N/42E-09C01 475135117303601 62 55 UA 475135 1173036 2,114 07-23-08 10.82 14.72 11-16-11

27N/42E-12B02 475130117262201 57 57 UA 475134 1172619 2,088 10-31-90 – – – –

27N/42E-13M01 475010117271301 100 100 BR 475010 1172713 2,194 02-01-07 4,990 33.5 11-17-11 –

27N/42E-14R01 474958117271501 205 200 LA 474958 1172715 2,200 09-27-06 9.24 99.98 11-17-11 –

27N/42E-24F01 474932117264601 700 700 BR 474932 1172646 2,109 08-14-03 – 59.9 11-17-11 –

27N/42E-25A02 474849117255801 400 395 BR 474849 1172558 1,982 04-19-05 – – – –

27N/42E-25H01 474837117260201 400 90 BR 474837 1172602 2,027 08-20-04 – 7.6 04-24-12 –

27N/43E-01L01 475155117190201 305 305 BR 475155 1171902 2,070 12-01-05 – – – –

27N/43E-02J03 475156117193401 80 79 LT 475156 1171934 2,041 05-02-95 – 39.46 04-26-12 –

27N/43E-04C06 475217117224701 220 220 LT 475217 1172247 1,822 10-13-11 – 76.83 04-17-12 –

27N/43E-05B01 475227117235401 405 405

M 475227 1172354 2,134 11-12-05 – – – –

27N/43E-06G03 475208117251201 180 180 B2 475208 1172512 2,090 08-04-98 2.88 63.78 04-17-12

R

27N/43E-07M01 475108117255001 130 130 UC 475108 1172550 2,164 07-03-07 71.02 04-17-12

27N/43E-08R03 475047117233101 200 200 B2 475047 1172331 1,911 08-24-99 – – – –

27N/43E-09Q02 475051117224101 229.75 220.75 LT 475051 1172241 1,761 07-12-01 – – – –

27N/43E-10B02 475131117211201 276 272.5 LA 475132 1172112 1,861 01-14-02 – 179.2 04-17-12 –

27N/43E-10B03 475132117211201 100 100 UA 475132 1172112 1,860 01-17-02 – 78.7 04-17-12 –

27N/43E-10E02 475123117214701 45 44 UA 475123 1172147 1,692 – – 8.13 11-10-11 –

27N/43E-11R01 475045117194801 220 200 BR 475045 1171948 1,849 05-19-05 1.09 – – –

27N/43E-12P02 475050117190001 319 316 LA 475055 1171908 1,902 10-9-86 – – – –

27N/43E-13Q01 475003117184201 290 281 LA 475003 1171842 1,947 05-03-99 – 84.2 04-17-12 –

27N/43E-14C03 475033117202701 241 241 LA 475033 1172027 1,854 03-07-03 – 160.7 04-17-12 –

27N/43E-15F05 475024117213201 320 320 LA 475018 1172142 1,844 11-02-92 – 164.31 11-29-11 –

27N/43E-17M09 475017117243801 200 200 B2 475017 1172438 2,054 03-16-06 – 141.98 11-29-11 –

27N/43E-19H01 474935117244201 – 41 UNK 474935 1172432 1,964 01-01-61 – – – –

27N/43E-19J01 474915117244001 90 90 UC 474921 1172443 1,945 01-01-64 4.46 40.42 11-10-11 –

27N/43E-20C07 474947117241701 505 505 BR 474947 1172417 1,964 03-15-04 – 79.43 11-29-11 –

27N/43E-21C01 474945117225001 100 84 UC 474945 1172254 1,694 – – – – –

27N/43E-21C02 474945117224901 195 185 LA 474947 1172251 1,710 03-29-90 – – – –
Table 4 39

Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, 

Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

27N/43E-24K01 474912117190901 360 340 LT 474923 1171839 2,316 09-05-89 – 109.87 04-18-12 –

27N/43E-26M01 474825117203801 264 264 LA 474830 1172032 1,901 02-12-64 8.16 – – –

27N/43E-28R02 474820117221901 183 169 UA 474811 1172213 1,824 05-05-87 – – – –

27N/43E-30M01R1 474823117253202 605 605 BR 474832 1172555 2,078 06-01-77 – 12.95 04-24-12 –

27N/43E-32J02 474726117233201 208 208 LA 474728 1172335 1,623 05-05-61 427 20.51 11-10-11 T

27N/43E-32J05 474738117233401 252 251 LA 474740 1172334 1,641 02-24-05 889 – – –

27N/43E-33A01 474820117214201 470 470 UC 474805 1172223 1,800 11-19-92 – – – –

27N/43E-33G02 474745117223801 182 182 BR 474746 1172238 1,633 10-25-00 – 33.55 11-10-11 –

27N/43E-33G03 474746117223801 130 120 UA 474746 1172238 1,633 01-11-01 116.5 – – –

27N/43E-33M02 474734117230801 236 236 LA 474734 1172308 1,625 05-02-88 640.8 – – –

27N/43E-34H01 474747117210201 440 435 LA 474739 1172058 1,904 01-01-01 – – – –

27N/43E-35E02 474747117203401 570 570 LC 474747 1172041 1,909 10-16-84 0.17 – – –

27N/43E-36A01 474756117182001 202 – NA 474756 1171820 1,909 – – – – –

27N/43E-36C01 474756117191101 569 – NA 474756 1171911 1,908 – – – – –

27N/43E-36P02 474722117185801 160 160 B2 474722 1171858 1,896 10-02-03 – 92.01 04-18-12 –

27N/44E-05P03 475150117164501 325 325 BR 475149 1171634 2,022 07-21-94 – 19.45 04-18-12 R27N/44E-05P04 475148117163001 320 320 BR 475149 1171630 2,025 11-27-07 – 1.06 04-18-12 –

27N/44E-06B01 475221117170201 500 500 BR 475227 1171725 2,336 04-02-92 – – – –

27N/44E-06Q01 475150117170401 300 300 BR 475150 1171708 1,979 04-20-84 – – – –

27N/44E-06R02 475144117171401 760 760 BR 475144 1171715 1,918 05-09-06 – 36.55 04-18-12 –

27N/44E-07P01 475051117174301 85 85 UC 475049 1171744 2,017 10-28-90 – – – –

27N/44E-08N03 475046117165801 120 120 UC 475046 1171658 1,956 05-19-00 2 19.35 04-19-12 –

27N/44E-09B02 475134117145401 700 700 BR 475134 1171454 2,172 09-03-03 – 38.8 04-18-12 –

27N/44E-16L01 475013117150701 225 225 LT 475013 1171507 2,098 05-17-07 – 91.18 04-18-12 –

27N/44E-18G01 475025117172401 440 440 LT 475026 1171727 2,268 06-16-93 – 306.97 11-30-11 –

27N/44E-19R02 474905117171301 440 440 BR 474905 1171713 2,372 08-17-06 – 343.4 04-13-12 –

27N/44E-20B01 474940117161201 – 50 M 474941 1171615 2,346 01-01-50 64.48 -0.4 04-25-12 –

27N/44E-20K02 474922117160601 660 660 LT 474922 1171606 2,323 03-15-06 – 305.4 04-27-12 –

27N/44E-20N01 474911117165101 – 28 UNK 474912 1171658 2,380 01-01-30 – 21.7 04-25-12 –

27N/44E-21G01 474932117144401 400 400 BR 474932 1171444 2,279 01-01-30 – 215.58 12-01-11 –

27N/44E-23L04 474921117124301 525 525 BR 474921 1171243 1,946 01-01-30 – 21.94 12-01-11 –27N/44E-29R01 474819117160001 160 160 LT 474819 1171560 2,351 01-01-30 – – – –

27N/44E-29R02D1 474819117155801 560 560 LT 474819 1171558 2,360 01-01-30 – 356.58 04-19-12 –
40 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, 

Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; 

NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

27N/44E-30Q01 474815117173201 147 146 UC 474815 1171732 1,948 01-01-30 – – – –

27N/44E-31G01D1 474751117172201 440 440 LT 474751 1171722 2,000 01-01-30 – 198.25 12-01-11 –27N/44E-31M01 474740117180601 551 – NA 474740 1171806 1,866 – – – – –

27N/44E-32N02 474727117164101 300 300 LT 474727 1171641 2,023 12-08-00 15.1 – – –

27N/44E-33P01 474721117150801 160 159 LA 474717 1171511 1,842 09-11-92 – – – –28N/41E-01P01 475654117343101 130 130 B2 475654 1173431 2,183 09-19-03 – 24.35 10-31-11 –28N/41E-11E01 475619117362001 393 393 BR 475619 1173620 2,206 11-18-02 – 11.51 10-31-11 –

28N/41E-11E02 475619117361901 83 83 UC 475619 1173620 2,206 11-16-98 – – 10-31-11

P

28N/41E-12R03 475555117340601 124 124 B2 475555 1173406 2,154 10-29-04 – 27.55 10-31-11 –28N/41E-13M01 475526117350001 120 117 UC 475526 1173460 2,189 07-10-07 0.5 3.17 10-31-11 –

28N/41E-14A05D1 475554117351401 107 107 B2 475554 1173514 2,184 05-08-06 – 13.47 11-01-11 –

28N/41E-14C01 475551117354501 630 630 BR 475551 1173545 2,193 01-10-05 – 4.89 11-09-11 –

28N/41E-15F02 475537117370901 320 320 BR 475537 1173709 2,262 05-17-06 – 32.73 10-31-11 –28N/41E-25E01 475350117334501 285 285 BR 475357 1173500 2,345 12-21-94 – – – –

28N/41E-25E02 475354117344901 300 300 BR 475354 1173449 2,340 – – 69.4 11-01-11

P

28N/41E-26B01 475411117352801 490 490 BR 475411 1173528 2,526 08-19-04 – 64.22 11-01-11 –

28N/42E-03C01 475732117293001 300 300

M 475731 1172933 2,138 01-01-62 – – – –

28N/42E-03C03 475731117292401 145 145 B2 475731 1172924 2,111 04-25-07 – 20.9 12-23-11

28N/42E-05C02 475734117315601 175 175 B2 475734 1173156 2,146 03-29-96 – – – –

28N/42E-07C01 475644117332701 144 144 B2 475644 1173327 2,140 05-26-05 – 12.11 11-02-11 –

28N/42E-08R01 475600117311901 180 180 B2 475600 1173119 2,128 04-28-11 – 48.01 12-20-11 –

28N/42E-08R02 475556117311701 280 280

M 475556 1173117 2,144 07-14-99 – – – –

28N/42E-09N03 475556117310801 165 165 B2 475557 1173108 2,135 04-13-05 12.66 56.7 12-20-11 –

28N/42E-10Q02 475607117285801 164 164 B2 475607 1172858 2,164 08-24-99 – 76.5 12-20-11 –28N/42E-10Q03 475602117285801 398 398

M 475602 1172858 2,147 08-27-96 – 23.5 12-20-11 –

28N/42E-10Q04 475603117292001 325 320 LT 475602 1172900 2,144 12-03-91 – 35.9 12-20-11 –28N/42E-11L04 475618117280401 170 170 B2 475618 1172804 2,085 09-06-07 – 57.22 12-20-11 –28N/42E-12A07 475631117260501 160 160

M 475639 1172605 2,154 04-23-81 – 37.35 12-20-11 –

28N/42E-12B03 475637117262501 90 90 UA 475637 1172625 2,147 03-05-87 – – – –

28N/42E-13J03 475521117260301 360 360 LT 475521 1172603 2,100 10-03-00 – – – –

28N/42E-14K03 475525117274301 300 292 LT 475529 1172757 2,097 08-31-94 – 36.4 12-21-11 –28N/42E-16D03 475544117311501 185 185 B2 475544 1173115 2,153 07-17-01 – 81.34 12-21-11 –

28N/42E-16D04 475543117311401 290 290 B2 475543 1173115 2,151 07-31-07 – 64.7 12-21-11 –
Table 4 41

Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, 

Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

28N/42E-16K02 475517117302001 300 300 B2 475517 1173020 2,083 06-20-07 – – – –

28N/42E-17Q01 475512117315101 185 185 B2 475512 1173151 2,144 11-05-07 – 30.42 12-22-11 –28N/42E-18D02 475546117333301 253 253 B2 475546 1173333 2,155 10-12-05 – 19.8 11-02-11 –

28N/42E-18N01 475508117333301 51 51 UC 475503 1173335 2,169 05-07-84 – – – –

28N/42E-19D01 475459117334301 140 140 B2 475459 1173343 2,171 04-06-95 – 16.43 11-03-11 –

28N/42E-19D02 475501117333101 160 160 B2 475501 1173331 2,171 07-27-07 – – – –

28N/42E-21G02 475446117302901 320 320 LT 475446 1173029 2,104 04-06-10 – 22.2 12-21-11 R28N/42E-23Q03 475419117274201 197 197 B2 475417 1172751 2,093 03-07-89 – – – –

28N/42E-23Q05 475417117275301 250 250 B2 475417 1172753 2,094 09-07-06 – 80.26 12-23-11 –

28N/42E-24D01 475458117270601 – 49 UA 475458 1172710 1,994 01-01-60 – – – –

28N/42E-24D02 475459117270601 – 66 B2 475459 1172710 1,994 01-01-64 – – – –

28N/42E-25C01 475406117264301 300 290 LT 475401 1172641 2,034 09-24-92 – 83.55 12-21-11 –28N/42E-26H05 475353117274201 375 375 M 475347 1172735 2,093 05-16-90 – – – –

28N/42E-28Q01 475330117301501 200 200 B2 475330 1173015 2,115 07-28-04 – 71 12-21-11 –

28N/42E-28Q02 475331117303001 260 260 B2 475331 1173030 2,124 07-02-10 – 66 12-21-11 –28N/42E-33D02 475315117305401 204 204 B2 475315 1173054 2,127 09-12-05 – 73.9 12-22-11 –28N/42E-35L04 475253117275601 250 250 B2 475253 1172756 2,033 03-22-07 – – – –

28N/42E-36N01 475236117270601 285 275 LT 475237 1172706 2,069 06-13-97 – – – –

28N/43E-02Q01 475650117200601 260 260 BR 475650 1172007 1,801 06-06-07 – – – –

28N/43E-04C01 475732117230101 440 440 BR 475732 1172301 1,994 08-26-03 – – – –

28N/43E-05P01 475658117242301 177 177 UC 475658 1172423 2,155 10-17-05 – 55.95 12-20-11 –28N/43E-07Q03 475606117251901 300 280 LT 475606 1172519 2,114 09-21-00 – 35.1 12-09-11 –

28N/43E-07Q04 475606117252101 – – UNK 475606 1172521 2,118 – – 45.9 12-09-11 –

28N/43E-08H01 475630117233201 280 280 BR 475630 1172336 2,093 03-06-80 – – – –

28N/43E-09J02 475621117221401 160 160 BR 475621 1172214 1,940 06-04-09 – 59.89 12-08-11 –28N/43E-10K05 475617117213001 140 138 LA 475617 1172130 1,926 07-02-03 – – – –

28N/43E-11R01 475557117195001 99 95 UC 475557 1171950 1,729 12-31-09 – 9.5 12-07-11 R28N/43E-13L02 475524117191101 340 340 BR 475524 1171911 1,956 06-26-07 – 84.74 12-07-11 R

28N/43E-14A03 475556117195001 46 45 UA 475556 1171950 1,719 10-11-05 – 11.9 12-07-11 –

28N/43E-16E01 475546117234101 242 242 UA 475545 1172325 1,984 01-23-78 – 34.69 11-10-11 –

28N/43E-17R03 475511117234201 140 140 UC 475511 1172342 2,013 10-07-05 6.49 – – –

28N/43E-19K02 475437117251901 340 340 M 475437 1172519 2,072 05-26-99 – – – –

28N/43E-20A01 475504117233101 265 265 M 475504 1172331 2,023 06-12-95 – 20.85 12-08-11 –
42 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, 

Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; 

NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

28N/43E-22B01 475502117212001 100 100 UC 475459 1172127 1,864 01-01-61 3.02 – – –

28N/43E-22D01 475505117220101 – 268 UC 475504 1172206 1,926 01-01-61 2.92 – – –

28N/43E-22R01 475424117210301 – 44 UA 475424 1172107 1,851 – – – – –

28N/43E-22R02 475417117210501 – 157 UA 475415 1172108 1,844 01-01-61 – – – –

28N/43E-23C02 475459117201701 90 88 UA 475458 1172021 1,704 04-25-62 1,192 19.4 11-10-11

T

28N/43E-23C05 475458117202201 122 121.5 UA 475458 1172022 1,704 06-21-02 – – – –

28N/43E-23C06 475458117201701 65 63 UA 475459 1172017 1,704 10-15-03 1,082 14.96 12-08-11

28N/43E-23C07 475445117194001 90 90 UA 475457 1172021 1,704 08-25-81 – – – –

28N/43E-23J02 475340117191901 332 330 LA 475430 1171947 1,878 07-27-87 – – – –

28N/43E-25L02 475334117185601 620 620 BR 475334 1171856 2,003 01-25-07 – 160.08 12-08-11

R

28N-43E-26L02 475340117201801 279 279 LA 475340 1172018 1,886 11-02-01 – 183.3 12-08-11

28N/43E-27R02 475329117205601 360 360 BR 475329 1172100 1,736 08-22-94 – – – –

28N/43E-27R03 475326117210201 36 36 UA 475326 1172102 1,744 09-02-02 – 15.14 12-09-11

28N/43E-27R04 475326117210101 29 29 UA 475326 1172102 1,744 09-19-08 – 14.92 12-09-11

28N/43E-28P01 475343117225201 150 150 UC 475329 1172250 1,854 03-15-93 8.2 – – –

28N/43E-29C01 475407117240901 210 209 LT 475407 1172413 1,921 04-20-92 – – – –

28N/43E-31B01 475315117250601 355 355

M 475312 1172511 1,936 09-27-94 – – – –

28N/43E-31L01 475245117252701 415 404 LT 475245 1172527 2,020 01-05-07 0.56 – – –

28N/43E-33H01 475307117220701 81 81 UA 475307 1172207 1,714 07-27-09 – – – –

28N/43E-35E01 475302117203601 320 320 UC 475301 1172043 1,876 05-20-86 – – – –

28N/43E-36P02 475235117185901 575 575 LT 475231 1171858 2,384 08-23-90 – – – –

28N/44E-01C01 475723117112401 360 360 BR 475723 1171124 2,616 06-20-06 – 6.45 12-07-11 –

28N/44E-04M01 475703117152401 240 240 BR 475703 1171528 2,214 01-18-95 – – – –

28N/44E-05H02 475720117155001 350 350 BR 475720 1171550 2,180 09-16-04 0.01 49.21 12-06-11

R

28N/44E-07F01 475623117173701 140 140 LT 475623 1171737 2,392 05-10-06 – 54.76 12-06-11

R

28N/44E-07L01 475622117173401 73 73 B1 475621 1171738 2,390 11-05-63 – 30.32 12-06-11 –28N/44E-15C01 475545117135201 550 550 BR 475545 1171352 2,558 11-26-07 – 89.72 12-06-11 –28N/44E-19E02 475427117182101 500 500 BR 475450 1171756 1,949 02-09-94 – – – –

28N/44E-19M04 475432117180701 300 300 LT 475432 1171807 1,946 07-09-09 – – – –

28N/44E-19P01 475414117173501 – 44 UC 475414 1171738 1,936 01-01-59 – 37.5 04-25-12 –

28N/44E-20H01 475446117155401 133 130 UC 475446 1171554 1,997 04-12-01 39.74 90.93 12-06-11 –

28N/44E-21J01 475433117142301 200 200 BR 475433 1171423 2,315 09-19-80 – 12.83 12-05-11 –28N/44E-28C01 475429117150501 160 160 BR 475360 1171511 2,084 06-14-93 – 8.55 12-06-11 –
Table 4 43

Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, 

Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

28N/44E-29Q01 475328117161201 580 580 BR 475328 1171612 2,388 05-18-06 – 284.98 12-06-11 –29N/41E-14R01 480027117352601 85 85 BR 480027 1173526 2,326 05-28-03 – 19.36 11-02-11 –

29N/41E-22P01 475931117371901 448 448 BR 475931 1173719 2,485 09-05-03 – 65.84 11-02-11 –

29N/41E-23B04 480012117354501 425 425 BR 480012 1173545 2,329 08-18-04 – 19.87 11-02-11 –

29N/41E-24M03 475941117351401 225 225 BR 475941 1173514 2,316 09-18-00 – 28.45 11-03-11 R29N/41E-25H01 475909117340501 175 175 BR 475909 1173405 2,235 06-09-06 – 15.25 11-02-11 –

29N/41E-34H01 475825117364401 68 67 UC 475810 1173638 2,246 05-23-85 11.36

29N/41E-34H02 475808117364601 305 305 BR 475808 1173646 2,268 08-23-07 – 36.85 11-02-11 R

29N/41E-35F02 475813117355501 185 185 BR 475813 1173555 2,225 11-08-06 – 15.73 11-03-11 –

29N/42E-02A01 480249117273601 185 185 BR 480249 1172736 2,404 05-03-07 – 17.53 11-16-11 –

29N/42E-04G02 480236117302701 305 305 BR 480236 1173027 2,263 08-11-04 – – – –

29N/42E-07L01 480129117332301 440 440 BR 480129 1173323 2,404 07-27-05 – 162.03 11-01-11 –

29N/42E-13H03 480048117262301 140 140 B2 480048 1172623 2,224 10-06-05 – 21.43 11-14-11 –

29N/42E-15B01 480106117292501 400 400 BR 480106 1172925 2,239 – – 26.69 11-16-11 R29N/42E-15D02 480101117300201 73 73 B2 480101 1173002 2,206 09-26-01 – -2.61 11-14-11 R29N/42E-17Q02 480017117314501 188 188 BR 480017 1173145 2,222 09-26-06 – 7.58 11-16-11 –

29N/42E-20A01 480010117314401 500 500 BR 480010 1173144 2,224 06-29-07 – 17.46 11-15-11 –

29N/42E-20B01 480006117315301 105 102 BR 480006 1173153 2,228 09-26-01 – 37.91 11-15-11 R29N/42E-20J01 475941117313401 – 18 UC 475942 1173138 2,158 01-01-48 – 6.17 04-26-12 –

29N/42E-21N02 475925117312201 175 172 LT 475925 1173122 2,204 07-17-02 – – – –

29N/42E-23E01 475951117283901 125 125 B2 475951 1172839 2,192 07-13-98 – 26.16 11-15-11 –

29N/42E-23E02 475951117284101 – – UC 475951 1172841 2,197 – – 21.06 11-15-11 –

29N/42E-23N02 475926117283801 273 273 M 475926 1172838 2,154 11-13-03 – – – –

29N/42E-25G01 475906117264801 185 185 LT 475906 1172648 2,210 04-24-06 – 34.29 11-15-11 –

29N/42E-25H01 475903117263001 260 260 B2 475903 1172630 2,214 04-25-07 0.02 51.7 11-15-11 –

29N/42E-25K01 475847117264701 176 176 M 475847 1172647 2,209 04-30-07 4.19 46.82 11-15-11 –

29N/42E-26M01 475844117284601 – – UNK 475845 1172846 2,134 – – 4.09 11-15-11 –

29N/42E-31N01 475750117335001 190 185 M 475750 1173350 2,180 04-28-07 – 13.43 11-01-11 R29N/42E-31P02 475745117332501 85 83 UC 475754 1173331 2,192 07-18-86 – 16.25 11-05-11 –

29N/42E-33G01 475806117302601 350 350 B2 475806 1173030 2,184 01-25-78 – 36.9 11-10-11 –

29N/42E-33L01 475755117304801 320 320 LT 475755 1173048 2,164 02-20-04 – 20.92 12-05-11 –

29N/42E-35C04 475822117281001 205 200 B2 475822 1172810 2,168 10-05-06 – 41.95 11-16-11 –

29N/43E-01J01 480212117183201 110 110 LA 480212 1171832 2,065 01-10-02 – 7.63 11-17-11 –
44 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, 

Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; 

NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

29N/43E-02Q04 480203117200601 60 60 UA 480205 1172019 2,123 07-22-92 – 20.98 12-08-11 –29N/43E-03H01 480223117205501 – 52 BR 480224 1172060 2,143 – – – – –

29N/43E-03L01 480221117215701 171 170 LA 480221 1172157 2,135 01-03-01 22.84 70.4 12-07-11 –

29N/43E-06D01 480240117260201 205 205 BR 480241 1172603 2,371 05-04-01 – 75.5 12-06-11 –29N/43E-07B01 480145117252601 300 300 BR 480145 1172526 2,231 05-18-06 – – – –

29N/43E-09D01 480145117232901 400 400 BR 480145 1172329 2,008 11-11-04 – – – –

29N/43E-11N02 480116117204901 99 99 UA 480116 1172049 2,097 06-16-03 – 64.31 12-08-11 –29N/43E-13P01 480018117191301 123 122 UA 480018 1171913 2,027 40-13-06 – 100.12 12-08-11 –

29N/43E-15G02 480040117211901 600 600 BR 480040 1172119 2,004 09-25-06 – 116.4 12-06-11

R

29N/43E-16D01 480058117232501 350 350 BR 480058 1172325 2,039 07-16-04 0.86 – – –

29N/43E-17N01 480018117243501 266 266

M 480018 1172435 2,224 05-26-04 – – – –

29N/43E-17N02 480018117243901 – – UNK 480018 1172439 2,224 – – 88.7 12-09-11 –29N/43E-18H01 480047117250601 325 325

M 480047 1172506 2,234 02-15-07 – – – –

29N/43E-20H03 475953117234901 153 153 UA 475953 1172349 2,237 06-18-07 – 120 12-06-11 –29N/43E-21N01 475933117231001 300 300 BR 475922 1172314 2,226 12-17-80 – 204.1 12-07-11 –29N/43E-22Q03 475929117213401 108 108 UC 475929 1172134 1,964 06-15-05 9.18 – – –

29N/43E-24B02 480006117185501 120 119 LA 480007 1171855 1,964 07-10-08 – – 12-07-11

F

29N/43E-24H01 475957117183401 108 103 UA 475957 1171834 1,997 02-15-07 – – – –

29N/43E-24P02 475927117191001 600 600 BR 475927 1171910 1,932 12-22-05 – 117.9 12-08-11 –29N/43E-26G02 475840117195801 81 81 UC 475855 1172000 1,861 07-27-94 – 41.88 12-07-11 –29N/43E-26H02 475906117195601 762 760 BR 475859 1171954 1,811 08-07-86 – 85.15 12-07-11 –

29N/43E-26R07 475829117195001 510 510 BR 475829 1171950 1,832 09-13-96 – 67.62 12-08-11

R

29N/43E-27A01 475916117210101 320 320 BR 475916 1172101 1,964 09-15-09 – – – –

29N/43E-29N01 475841117243001 202.5 202.5 UA 475840 1172434 2,222 07-01-59 – – – –

29N/43E-29N02 475840117243201 192 183 UA 475839 1172440 2,217 12-01-59 – 88.07 11-29-11 –

29N/43E-32G01 475801117240801 140 140 BR 475813 1172413 2,202 07-22-77 2.17 72.4 12-07-11 –

29N/43E-34L02 475756117214101 117 117 UC 475756 1172141 1,984 04-01-03 5,553 94.15 12-07-11 –

29N/43E-35H02 475802117195601 300 300 BR 475802 1171956 1,771 02-17-09 – – – –

29N/44E-01F01 480220117111801 185 185 UA 480220 1171118 2,307 06-09-03 – – – –

29N/44E-05A02 480240117160101 148 148 BR 480240 1171601 2,267 03-18-03 – – – –

29N/44E-07H05 480134117170401 152 152 BR 480134 1171704 2,154 04-18-07 – – – –

29N/44E-07M03 480119117182101 122 122 LA 480119 1171821 2,043 03-02-88 – – – –

29N/44E-10J01D1 480117117131801 90 90 UA 480117 1171318 2,122 10-07-05 – 23.48 12-08-11 –
Table 4 45

Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, 

Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

29N/44E-11A05 480149117115501 175 175 BR 480149 1171155 2,232 07-30-04 – – – –

29N/44E-14R02 480012117115501 500 500 BR 480012 1171155 2,484 03-15-04 – 139.4 12-09-11 R

29N/44E-15G01D1 480043117134201 315 315 BR 480043 1171342 2,165 04-01-05 – 60.1 12-08-11 –29N/44E-17E03 480039117164401 190 190 BR 480039 1171644 1,904 06-01-07 – – – –

29N/44E-19H06 475953117171001 180 180 BR 475954 1171710 1,842 12-01-06 – – – –

29N/44E-20H01 475946117154301 – 28 UC 475945 1171549 2,024 01-1-45 – – – –

29N/44E-20Q02 475921117160601 245 245 BR 475921 1171606 1,983 10-19-06 – – – –

29N/44E-21F01 475944117151001 550 550 BR 475945 1171510 2,041 10-26-06 – – – –

29N/44E-21M01 475942117154101 95 82 UC 475931 1171544 2,004 07-11-78 – 29.81 12-08-11 –

29N/44E-21N03 475925117153001 77 77 UC 475921 1171544 2,020 07-06-88 – 17.1 12-09-11 –29N/44E-23A02 475959117121001 275 275 BR 475959 1171210 2,420 10-15-97 – – – –

29N/44E-27B01 475905117134601 35 35 M 475905 1171346 2,091 05-06-94 – 7.3 12-09-11 –29N/44E-33C02 475817117152001 80 76 UC 475817 1171520 2,115 09-14-04 – 33.3 12-09-11 –

30N/41E-24N01 480445117350001 525 525 BR 480445 1173460 2,766 05-18-07 – 208.85 11-01-11 –

30N/42E-18B01 480609117331301 552 552 BR 480609 1173313 2,847 06-13-05 – 15.75 11-01-11 R30N/42E-31J01 480311117325501 150 150 BR 480311 1173255 2,414 08-19-02 – 84.99 11-01-11 –

30N/42E-33M01 480307117311801 122 122 BR 480307 1173118 2,411 08-07-03 – 15.14 11-02-11 –30N/42E-35D01 480332117284701 240 240 BR 480332 1172847 2,497 10-25-05 – 49.24 11-01-11 –

30N/43E-02Q01 480718117201601 170 170 BR 480718 1172016 2,466 07-22-03 – 55.28 11-30-11 –

30N/43E-04D01 480756117232801 560 560 BR 480756 1172328 2,283 08-15-08 – 30.71 11-30-11 –

30N/43E-07K01 480630117252501 65 65 UA 480630 1172525 1,989 09-10-07 – – – –

30N/43E-10B01 480658117212401 250 250 BR 480658 1172124 2,460 03-17-05 – 37.1 11-30-11 R30N/43E-15N01 480528117220201 40 39 UA 480528 1172202 2,323 07-12-10 – 14.28 11-30-11 –

30N/43E-19M01 480454117260001 500 500 BR 480454 1172600 2,420 10-03-06 – 4.81 12-01-11 –30N/43E-23D01 480513117204801 425 425 BR 480513 1172048 2,622 10-12-06 – – – –

30N/43E-25C01 480420117191301 400 400 BR 480420 1171913 2,607 05-16-93 – 43.88 11-30-11

30N/43E-26L01 480404117203801 100 100 UA 480404 1172038 2,203 02-03-77 – – – –

30N/43E-27R01 480339117205901 70 64 UA 480339 1172059 2,183 04-28-99 – – – –

30N/43E-27R02 480339117210501 75 53 UA 480339 1172105 2,185 10-04-95 – – – –

30N/43E-29R01 480347117234001 260 240 BR 480347 1172340 2,143 11-03-03 – – – –

30N/43E-33H01 480316117221901 44 44 UA 480316 1172219 2,267 04-19-04 – – – –

30N/43E-33L01 480310117230301 500 500 BR 480310 1172303 2,269 04-23-09 – 124.62 12-01-11 R30N/43E-34H01 480316117205901 400 400 BR 480316 1172059 2,174 05-10-02 – 16.9 04-26-12 –
46 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, 

Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; 

NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

30N/43E-35L01 480306117203001 59 59 UA 480306 1172031 2,175 07-13-98 – 30.98 12-01-11 –30N/43E-35L02 480307117203101 70 70 UA 480307 1172031 2,178 07-20-01 13.88 – – –

30N/43E-35R01 480252117195501 70 70 UC 480252 1171955 2,145 07-28-05 – 4.91 12-01-11 –30N/43E-36J01 480303117182901 120 120 BR 480303 1171829 2,136 01-15-07 – – – –

30N/44E-01P01 480716117112201 180 178 UA 480716 1171122 2,455 06-08-06 114.98 11-15-11 –30N/44E-03A01 480803117131601 110 110 UA 480803 1171316 2,452 06-25-03 219.3 78.48 11-16-11 –

30N/44E-03M01 480735117141701 500 500 BR 480735 1171417 2,367 08-15-05 – – – –

30N/44E-03N01 480707117142301 65 65 UA 480707 1171423 2,382 07-24-92 – – – –

30N/44E-04C01 480805117151001 248 248 BR 480805 1171510 2,471 12-03-03 – 51.14 11-14-11 –

30N/44E-05A01 480811117160301 42 42 UA 480811 1171603 2,425 08-25-00 – 19.32 11-14-11

P

30N/44E-07Q01 480626117173001 123 123 BR 480626 1171730 2,490 06-09-04 – 13.25 11-17-11 –

30N/44E-09K01 480639117150301 248 248 BR 480639 1171503 2,354 09-13-03 – – – –

30N/44E-09R01 480628117144001 40 40 UC 480628 1171440 2,350 08-02-09 81.65 – – –

30N/44E-10D01 480659117142301 45 44 UA 480659 1171423 2,372 05-16-95 – – – –

30N/44E-10K01 480629117134001 180 174 LA 480629 1171340 2,441 07-15-92 – 94.72 11-17-11 –

30N/44E-11D01 480654117124901 150 150 BR 480654 1171249 2,404 01-22-97 0.05 49.72 11-15-11 –

30N/44E-11M01 480630117130001 234 225 UC 480630 1171260 2,496 12-05-04 1.73 – – –

30N/44E-12A01 480658117103801 243 243 UA 480658 1171038 2,450 03-30-98 – 212.6 11-16-11 –

30N/44E-12D01 480659117114501 199 199 UA 480659 1171145 2,473 07-26-02 8,407 – – –

30N/44E-13P01 480523117112001 73 70 UA 480523 1171121 2,303 12-09-10 – 28.45 11-16-11 –30N/44E-13Q01 480524117110801 302 296 BR 480524 1171108 2,222 04-06-04 – 271.4 11-15-11 –30N/44E-14D01 480602117130501 270 270 BR 480603 1171305 2,491 08-07-07 – – – –

30N/44E-14L01 480538117123401 140 138 LA 480538 1171234 2,394 09-07-05 – 70.52 11-17-11 –

30N/44E-15D01 480614117141301 111 111 LA 480614 1171413 2,448 08-21-92 8,667 – – –

30N/44E-16E01 480601117154301 38 35 UA 480601 1171543 2,360 01-15-07 10.17 9.23 11-17-11 –

30N/44E-17D01 480605117165201 150 150 BR 480605 1171652 2,439 05-11-05 – 28.62 11-17-11 –

30N/44E-24B01 480520117105101 230 230 BR 480520 1171051 2,235 08-10-04 17.74 – – –

30N/44E-26F01 480410117123101 198 198 BR 480410 1171231 2,393 10-14-03 – – – –

30N/44E-27E01 480415117142701 250 250 BR 480415 1171427 2,408 08-19-09 – 79.14 12-06-11 –

30N/44E-28P01 480345117151601 300 300 BR 480345 1171516 2,360 05-03-05 – 71.04 11-15-11 –

30N/44E-29J01 480353117154801 597 597 BR 480353 1171548 2,525 09-13-90 – 164.72 11-16-11

R

30N/44E-31N01 480252117181901 102 102 LA 480252 1171819 2,119 12-11-99 – 10.69 11-17-11 –

30N/44E-35C01 480333117123501 42 42 UA 480333 1171235 1,968 08-26-10 – – – –
Table 4 47

Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, 

Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

30N/45E-02E01 480747117050001 160 153 LA 480747 1170460 2,281 12-10-05 1,285 33.52 11-29-11 –

30N/45E-02M01 480734117050501 118 118 LA 480734 1170505 2,264 08-24-06 – 33.05 12-02-11 –30N/45E-04E01 480744117075301 107 107 BR 480744 1170753 2,114 08-30-05 – – – –30N/45E-04F01 480753117073401 275 275 BR 480753 1170734 2,264 07-12-97 44.94 – – –

30N/45E-04K01 480734117071201 216 214 LA 480734 1170712 2,135 07-28-95 – – – –

30N/45E-05D01 480809117085301 340 340 BR 480809 1170853 2,394 07-12-05 – 221.87 11-29-11 P30N/45E-06P01 480721117095401 475 475 BR 480721 1170954 2,393 03-30-06 – – – –

30N/45E-07C01 480702117095601 184 184 UA 480703 1170956 2,403 03-23-04 – – – –

30N/45E-07E01 480646117101201 393 393 BR 480646 1171012 2,402 09-22-83 151.5 11-29-11

30N/45E-08B01 480658117082701 175 175 BR 480658 1170827 2,164 05-16-94 – – – –

30N/45E-10A01 480658117052901 600 600 BR 480658 1170529 2,528 10-30-07 – – – –

30N/45E-11H01 480642117041901 212 212 UC 480642 1170419 2,284 01-17-04 19.87 70.65 11-29-11 –

30N/45E-12D01 480617117035301 200 200 LA 480617 1170353 2,333 08-15-96 – 133.85 11-30-11 –

30N/45E-14N01 480532117050601 450 450 BR 480533 1170506 2,519 07-14-06 – 239.92 11-29-11 –

30N/45E-14P01 480527117045201 125 125 UA 480527 1170453 2,349 06-13-06 6.29 96.42 11-29-11 –

30N/45E-14R01 480530117041101 173 173 UA 480530 1170411 2,364 10-10-09 11.4 128.4 12-02-11 –

30N/45E-18G01 480557117095101 62 62 UA 480557 1170951 2,204 02-28-06 – – – –

30N/45E-18H01 480553117092701 56 56 UA 480553 1170927 2,134 06-05-05 4.45 – – –

30N/45E-31D01 480331117101501 320 320 BR 480331 1171015 2,465 05-25-07 – – – –

31N/43E-24R01 480946117182801 360 360 BR 480946 1171828 2,238 09-12-07 – 4.63 11-09-11 –

31N/43E-26M01 480907117204601 500 500 BR 480907 1172046 2,339 07-06-94 – 40.83 11-08-11 R31N/43E-33R01 480800117223001 173 173 BR 480760 1172230 2,228 09-30-03 – 40.85 11-11-11 R31N/44E-19M01 481015117181801 180 180 BR 481015 1171818 2,304 10-11-04 – 29.23 11-07-11 –

31N/44E-27P01 480910117135301 300 300 BR 480910 1171353 2,578 07-18-07 – 60.78 11-09-11 –

31N/44E-31D01 480902117181201 300 300 BR 480902 1171812 2,299 03-31-98 – 18.5 11-07-11 –

31N/44E-35M01 480840117125801 415 415 BR 480840 1171259 2,567 08-03-06 – 133.6 11-09-11 R31N/45E-13Q01 481103117031801 240 240 BR 481103 1170318 2,188 70-22-07 – 24.08 11-07-11 R31N/45E-14E01 481121117052001 500 500 BR 481121 1170520 2,490 06-27-07 – – – –

31N/45E-15E01 481121117064301 402 402 BR 481121 1170643 2,525 10-13-88 – 122.8 11-07-11 –

31N/45E-19B01 481052117095201 155 155 BR 481052 1170952 2,487 05-20-04 1.39 77 11-07-11 –

31N/45E-21Q01 481004117072001 290 290 BR 481004 1170720 2,458 12-17-03 – 51.34 11-07-11 –

31N/45E-22Q01 481001117055001 800 800 BR 481001 1170550 2,485 09-30-09 – 435.37 12-01-11 –31N/45E-24B01 481044117031401 175 107 UA 481044 1170318 2,159 08-09-73 81.39 45.41 11-08-11 –
48 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington Table 4. Selected physical and hydrologic data for the project wells in or near the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington.—Continued

[USGS well No.: See diagram showing well numbering system for explanation of well-numbering system. Latitude and Longitude are given in degrees, minutes, seconds referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude: Referenced to the North American Vertical Datum of 1988 (NAVD 88). Hydrogeologic unit: SVRPA, Spokane Valley-Rathdrum Prairie aquifer; UA, Upper aquifer; UC, Upper confining unit; LA, Lower aquifers; LC, Lower confining unit, B1, 

Wanapum basalt unit; LT, Latah unit; B2, Grande Ronde basalt unit; BR, Bedrock unit; M, completed in multiple units; 

NA, not applicable—exploratory borehole; UNK, unknown. Status of water level: Minus sign (-) indicates water level above land surface; F, flowing; P, pumping; R, recently pumped; T, nearby recently pumped. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft/d, foot per day; –, no data available]

USGS well No. USGS site identifier Hole depth Well depth Hydrogeologic unit of open interval Latitude Longitude Land- surface altitude (ft) Date of well construction Horizontal hydraulic conductivity (ft/d) Water level (feet below land sur- face) Date of water level Status of water level

31N/45E-26D01 480957117051801 72 72 UA 480957 1170518 2,158 09-23-96 – 43.34 11-09-11 –

31N/45E-27B01 480957117060101 514 514 BR 480957 1170601 2,484 06-18-10 – 161.89 11-08-11

R

31N/45E-27J01 480928117053201 56 56 UA 480928 1170532 2,119 12-04-95 – 22.34 11-08-11 –31N/45E-28L01 480933117072701 500 500 BR 480933 1170727 2,406 07-07-05 – – – –

31N/45E-29F01 480937117090001 48 44 UC 480937 1170900 2,361 06-30-09 – 16.34 11-09-11 –

31N/45E-31H01 480844117092601 100 100 BR 480844 1170926 2,369 05-30-06 – – – –

31N/45E-32G01 480847117082701 123 122 UA 480847 1170827 2,323 05-06-06 – – – –

31N/45E-33B01 480901117071201 475 475 BR 480901 1170712 2,354 03-21-07 – – – –

31N/45E-34G01 480902117060401 208 208 LA 480847 1170554 2,254 11-14-76 71.03 – –

31N/45E-34G02 480854117054901 280 280 LA 480854 1170549 2,288 01-29-96 – 47.18 11-08-11 –

31N/45E-35Q01 480827117043701 520 520 BR 480827 1170437 2,458 08-17-00 – – – –

31N/45E-35R01 480821117041401 400 400 BR 480821 1170414 2,493 04-24-81 – 173.18 11-29-11 –

31N/46E-19M01 481018117023801 170 170 UC 481018 1170238 2,161 09-05-05 30.23 76.25 11-08-11 –

31N/46E-31E01D1 480846117022901 350 350 BR 480846 1170229 2,403 10-12-10 – 186.88 11-09-11 –
Glossary 49

Glossary

Acre-foot (acre-ft): The volume of water 

needed to cover an acre of land to a depth 

of 1 foot (equivalent to 43,560 cubic feet or 

325,851 gallons). 

Alluvium: General term for sediments of 

gravel, sand, silt, clay, or other particulate 

rock material deposited by flowing water, 

usually in the beds of rivers and streams, 

on a flood plain, on a delta, or at the base of 

a mountain. 

Aquifer: A geologic formation, group 

of formations, or part of a formation that 

contains sufficient saturated permeable 

material to yield significant quantities of 

water to springs and wells. 

Bedrock: A general term used for 

solid rock that underlies soils or other 

unconsolidated material. 

Confined aquifer (artesian aquifer): An 

aquifer that is completely filled with water 

under pressure and is overlain by material that 

restricts the movement of water. 

Confining layer: A body of impermeable, or 

distinctly less permeable (see permeability), 

material that is stratigraphically adjacent 

to one or more aquifers that restricts 

the movement of water into and out of 

the aquifers. 

Cubic foot per second (ft3/s, or cfs): Rate 

of water discharge representing a volume 

of 1 cubic foot passing a given point during 

1 second, equivalent to approximately 

7.48 gallons per second or 448.8 gallons per 

minute or 0.02832 cubic meter per second. 

In a stream channel, a discharge of 1 cubic 

foot per second is equal to the discharge at 

a rectangular cross section, 1 foot wide and 

1 foot deep, flowing at an average velocity of 

1 foot per second. 

Discharge: The volume of fluid passing a 

point per unit of time, commonly expressed in 

cubic feet per second, million gallons per day, 

gallons per minute, or seconds per minute 

per day. 

Drainage basin: The land area drained by a 

river or stream. 

Drainage divide: The boundary between 

adjoining drainage basins. 

Drawdown: The difference between the 

water level in a well before pumping and 

the water level in the well during pumping. 

Additionally, for flowing wells, the reduction 

of the pressure head as a result of the 

discharge of water. 

Evaporation: The process by which water is 

changed to gas or vapor; occurs directly from 

water surfaces and from the soil. 

Fluvial deposit: A sedimentary deposit 

consisting of material transported by 

suspension, or laid down by a river or stream. 

Gaging station: A particular site on a stream, 

canal, lake, or reservoir where systematic 

observations of hydrologic data are obtained. 

Glacial: Of or relating to the presence and 

activities of ice or glaciers. 

Glacial drift: A general term for rock 

material transported by glaciers or icebergs 

and deposited directly on land or in the sea. 

Glacial lake: A lake that derives its water, or 

much of its water, from the melting of glacial 

ice; also a lake that occupies a basin produced 

by glacial erosion. 

Glacial outwash: Stratified detritus (chiefly 

sand and gravel) “washed out” from a glacier 

by meltwater streams and deposited in front 

of or beyond the end moraine or the margin of 

an active glacier. 

Granite/Granitic rock: A coarse-grained 

igneous rock. 

Groundwater: In the broadest sense, all 

subsurface water, commonly that part of the 

subsurface water in the saturated zone. 

Groundwater flow system: The underground 

pathway by which groundwater moves from 

areas of recharge to areas of discharge. 
50 Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington

Headwaters: The source and upper part of 

a stream. 

Hydraulic conductivity: The capacity of a 

rock to transmit water. It is expressed as the 

volume of water that will move in unit time 

under a unit hydraulic gradient through a unit 

area measured at right angles to the direction 

of flow. 

Hydraulic head: The height of the free 

surface of a body of water above a given point 

beneath the surface. 

Igneous rocks: Rocks that have solidified 

from molten or partly molten material. 

Infiltration: The downward movement 

of water from the atmosphere into soil or 

porous rock. 

Lacustrine: Pertaining to, produced by, or 

formed in a lake. 

Lake stand: Temporary level of glacial lake 

lasting over a period of years.

Loess: Fine-grained deposit of wind-blown 

and wind-deposited silt and fine sand. 

Long-term monitoring: The collection 

of data over a period of years or 

decades to assess changes in selected 

hydrologic conditions. 

Median: The middle or central value in 

a distribution of data ranked in order of 

magnitude. The median is also known as the 

50th percentile. 

Metamorphic rocks: Rocks derived from 

preexisting rocks by mineralogical, chemical, 

or structural changes (essentially in a solid 

state) in response to marked changes in 

temperature, pressure, shearing stress, 

and chemical environment at depth in the 

Earth’s crust. 

Monitoring: Repeated observation, 

measurement, or sampling at a site, 

on a scheduled or event basis, for a 

particular purpose. 

Moraine: A mound, ridge, or other distinct 

accumulation of unsorted, unstratified glacial 

drift, predominantly till, deposited chiefly by 

direct action of glacier ice. 

Mouth: The place where a stream discharges 

to a larger stream, a lake, or the sea. 

Permeability: The capacity of a rock for 

transmitting a fluid; a measure of the relative 

ease with which a porous medium can 

transmit a liquid. 

Potentiometric surface: An imaginary 

surface that represents the total head in an 

aquifer. It represents the height above a datum 

plane at which the water level stands in tightly 

cased wells that penetrate the aquifer. 

Precipitation: Any or all forms of water 

particles that fall from the atmosphere, such 

as rain, snow, hail, and sleet.

Recharge (groundwater): The process 

involved in the absorption and addition of 

water to the zone of saturation; also, the 

amount of water added. 

Runoff: That part of precipitation or 

snowmelt that appears in streams or surfacewater bodies. 

Sedimentary rocks: Rocks formed by the 

consolidation of loose sediment that has 

accumulated in layers. 

Shale: A fine-grained sedimentary rock 

formed by the consolidation of clay, silt, 

or mud. 

Siltstone: An indurated silt having the 

texture and composition of shale but lacking 

its fine lamination. 

Spring: Place where a concentrated 

discharge of groundwater flows at the 

ground surface. 

Streamflow: The discharge of water in a 

natural channel. 

Surface water: An open body of water such 

as a lake, river, or stream. 

Terminal moraine: The end moraine 

extending across a glacial plain or valley 

as an arcuate or crescent ridge that marks 

the farthest advance or maximum extent of 

a glacier. 

Till: Predominantly unsorted and unstratified 

drift, deposited directly by and underneath 

a glacier without subsequent reworking by 

meltwater, and consisting of a heterogeneous 

mixture of clay, silt, sand, gravel, 

and boulders. 
Glossary 51

Transmissivity: The rate at which water is 

transmitted through a unit width of an aquifer 

under a unit hydraulic gradient. It equals 

the hydraulic conductivity multiplied by the 

aquifer thickness. 

Tributary: A river or stream flowing into a 

larger river, stream, or lake. 

Unconfined aquifer: An aquifer whose 

upper surface is a water table free to fluctuate 

under atmospheric pressure. 

Unconsolidated deposit: Deposit of 

loosely bound sediment that typically fills 

topographically low areas. 

Watershed: See drainage basin. 

Water table: The top water surface of an 

unconfined aquifer at atmospheric pressure. 

Withdrawal Water removed from the 

ground or diverted from a surface-water 

source for use. 
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For more information concerning the research in this report, contact the

 Director, Washington Water Science Center

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934 Broadway, Suite 300

Tacoma, Washington 98402

http://wa.water.usgs.gov
Kahle and others— Hydrogeology of the Little Spokane River Basin, Spokane, Stevens, and Pend Oreille Counties, Washington—Scientific Investigations Report 2013–5124