Estimates of Ground-Water Recharge to the 

Yakima River Basin Aquifer System, Washington, for 

Predevelopment and Current Land-Use and 

Land-Cover Conditions

Scientific Investigations Report 2007–5007

Version 1.2, April 2009

Prepared in cooperation with the 

Bureau of Reclamation, 

Yakama Nation, and the 

Washington State Department of Ecology 

U.S. Department of the Interior

U.S. Geological Survey
Cover: Photograph of Clark Well No. 1, located on the north side of the Moxee Valley in North Yakima, 

Washington. The well is located in township 12 north, range 20 east, section 6. The well was drilled 

to a depth of 940 feet into an artesian zone of the Ellensburg Formation, and completed in 1897 at a 

cost of $2,000. The original flow from the well was estimated at about 600 gallons per minute, and 

was used to irrigate 250 acres in 1900 and supplied water to 8 small ranches with an additional 47 

acres of irrigation. (Photograph was taken by E.E. James in 1897, and was printed in 1901 in the U.S. 

Geological Survey Water-Supply and Irrigation Paper 55.)
Estimates of Ground-Water Recharge to the 

Yakima River Basin Aquifer System, 

Washington, for Predevelopment and 

Current Land-Use and Land-Cover 

Conditions

By J.J. Vaccaro and T.D. Olsen

Prepared in cooperation with the 

Bureau of Reclamation,

Yakama Nation, and

Washington State Department of Ecology

Scientific Investigations Report 2007–5007

Version 1.2, April 2009

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Suggested citation:

Vaccaro J.J., and Olsen, T.D., 2007, Estimates of ground-water recharge to the Yakima River Basin aquifer system, 

Washington, for predevelopment and current land-use and land-cover conditions: U.S. Geological Survey Scientific 

Investigations Report 2007-5007, 30 p.
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................3

Previous Estimates of Recharge ........................................................................................................3

Description of Study Area ............................................................................................................................3

Location and Setting ............................................................................................................................4

Development of Water Resources.....................................................................................................4

Overview of the Geology......................................................................................................................6

Methods Used to Estimate Ground-Water Recharge..............................................................................9

Overview of the Two Models Used to Estimate Recharge.............................................................9

Data Used in Models..........................................................................................................................10

Landscape Characteristics ......................................................................................................10

Weather Information .................................................................................................................10

Soil Information..........................................................................................................................12

Land Use and Land Cover.........................................................................................................13

Irrigation Application Rates .....................................................................................................13

Assumptions and Considerations in Estimating Recharge..........................................................15

Modeled Areas.............................................................................................................................................16

Estimates of Ground-Water Recharge .....................................................................................................18

Factors Controlling Recharge....................................................................................................................24

Potential Sources of Error in Recharge Estimates.................................................................................26

Summary and Conclusions.........................................................................................................................27

Acknowledgments.......................................................................................................................................28

References Cited..........................................................................................................................................28
iv

Figures

Figure 1. Map showing the Yakima River Basin, Washington .................................... 2

Figure 2. Map showing land use and land cover, Yakima River Basin, 

Washington, 1999 ........................................................................... 5

Figure 3. Schematic diagram showing selected tributaries, diversion canals, 

return flows, and stream-gaging stations, Yakima River Basin, 

Washington ................................................................................. 7

Figure 4. Map showing simplified surficial geology of the Yakima River Basin, 

Washington ................................................................................. 8

Figure 5. Map showing location of weather-data sites and distribution of mean annual 

precipitation, Yakima River Basin, Washington.......................................... 11

Figure 6. Map showing surface-water irrigation districts, Yakima River Basin, 

Washington ................................................................................. 14

Figure 7. Map showing areas modeled to estimate recharge for predevelopment 

conditions, Yakima River Basin, Washington............................................. 16

Figure 8. Map showing areas modeled to estimate recharge for current conditions, 

Yakima River Basin, Washington ......................................................... 17

Figure 9. Map showing spatial distribution of mean annual recharge for predevelopment 

conditions,Yakima River Basin, Washington ............................................. 18

Figure 10. Map showing spatial distribution of mean annual recharge for current 

conditions, Yakima River Basin, Washington............................................. 21

Figure 11. Map showing spatial distribution of mean annual recharge for predevelopment 

conditions in the Ahtanum area, Yakima River Basin, Washington .................. 22

Figure 12. Map showing spatial distribution of mean annual recharge for current 

conditions in the Ahtanum area, Yakima River Basin, Washington .................. 23

Figure 13. Graph showing calculated annual values of selected water-budget 

components for the lower Naches area ................................................ 24

Figure 14. Graph showing relation between mean annual recharge and the mean 

annual total water input (precipitation or precipitation plus irrigation) for the 

modeled areas for predevelopment and current conditions ........................... 25

Figure 15. Graph showing relation between mean annual recharge and the ratio of the 

total quantity of water that can be stored in the root zone to the total water 

input for the areas modeled using the Deep Percolation Model for 

predevelopment and current conditions ................................................ 25

Figure 16. Graph showing annual precipitation and estimated predevelopment 

recharge for the Prosser area, Yakima River Basin, Washington ..................... 25

Tables

Table 1. Characteristics of the modeled areas, Yakima River Basin, Washington ............ 12

Table 2. Summary of estimates of mean annual recharge for the modeled areas, Yakima River 

Basin, Washington ........................................................................ 19
v

Conversion Factors, Datums, and Abbreviations and 

Acronyms

Conversion Factors

Multiply By To obtain

acre 4,047 square meter 

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

cubic foot (ft3

) 0.02832 cubic meter

cubic foot per second (ft3

/s) 0.02832 cubic meter per second

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

inch (in.) 2.54 centimeter

inch (in.) 25.4 millimeter 

inch per year (in/yr) 2.54 centimeter per year

foot (ft) 0.3048 meter 

mile (mi) 1.609 kilometer

million gallons per day (Mgal/d) 0.04381 cubic meter per second

section (640 acres or 1 square mile) 259.0 square hectometer

square foot (ft2

) 0.09290 square meter 

square inch (in2

) 6.452 square centimeter

square mile (mi2

) 2.590 square kilometer 

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

°F=(1.8×°C)+32.

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

°C=(°F-32)/1.8.

Datums

Vertical coordinate information is referenced to the 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. 
vi

Conversion Factors, Datums, and Abbreviations and 

Acronyms—Continued 

Abbreviations or Acronyms

Abbreviation and Acronym Meaning

AET actual evapotranspiration

CRBG Columbia River Basalt Group

DEM digital elevation model

DOA Washington State Department of Agriculture

DPM Deep Percolation Model

GIS Geographic Information System

HRU Hydrologic Response Unit

I/P ratio of irrigation to precipitation

km kilometer

LULC land use and land cover

m meter

MMS Modular Modeling System

PRMS Precipitation-Runoff Modeling System

PWS public water supply

R/P ratio of recharge to precipitation

R/T ratio of recharge to total water input

Reclamation Bureau of Reclamation

S quantity of water that root/soil zone can hold

SAT quantity of water above TWAC

SOAC Systems Operations Advisory Committee

T total water input: precipitation plus irrigation

TAWC total available water capacity

TWSA total water supply available

USGS U.S. Geological Survey

WaDOE Washington State Department of Ecology

WRIA Washington State Water Resource Inventory Area

WY water year

YN Yakama Nation
Abstract

Two models were used to estimate ground-water recharge 

to the Yakima River Basin aquifer system, Washington for 

predevelopment (estimate of natural conditions) and current 

(a multi-year, 1995–2004, composite) land-use and landcover conditions. The models were the Precipitation-Runoff 

Modeling System (PRMS) and the Deep Percolation Model 

(DPM) that are contained in the U.S. Geological Survey’s 

Modular Modeling System. Daily values of recharge were 

estimated for water years 1950–98 using previously developed 

PRMS-watershed models for four mainly forested upland 

areas, and for water years 1950–2003 using DPM applied to 

17 semiarid to arid areas in the basin.

The mean annual recharge under predevelopment 

conditions was estimated to be about 11.9 in. or 5,450 ft3/s 

(about 3.9 million acre-ft) for the 6,207 mi2 in the modeled 

area. In the modeled areas, recharge ranged from 0.08 in. 

(1.2 ft3/s) to 34 in. (2,825 ft3/s). About 97 percent of the 

recharge occurred in the 3,667 mi2 area included in the uplandarea models, but much of this quantity is not available to 

recharge the bedrock hydrogeologic units. Only about 1.0 in., 

or 187 ft3/s (about 0.14 million acre-ft), was estimated to occur 

in the 2,540 mi2 area included in the semiarid to arid lowland 

modeled areas.

The mean annual recharge to the aquifer system under 

current conditions was estimated to be about 15.6 in., or 

7,149 ft3/s (about 5.2 million acre-ft). The increase in recharge 

is due to the application of irrigation water to croplands. The 

annual quantity of irrigation was more than five times the 

annual precipitation for some of the modeled areas. Mean 

annual actual evapotranspiration was estimated to have 

increased from predevelopment conditions by more than 

1,700 ft3/s (about 1.2 million acre-ft) due to irrigation.

Introduction

Surface water in the Yakima River Basin, in south-central 

Washington (fig. 1) is under adjudication and the amount 

of surface water available for appropriation is unknown, 

but there are increasing demands for water for municipal, 

fisheries, agricultural, industrial, and recreational uses. These 

demands must be met by ground-water withdrawals and/or 

by changes in the way water resources are allocated and used. 

On-going activities in the basin for enhancement of fisheries 

and obtaining additional water for agriculture may be affected 

by ground-water withdrawals and by rules implemented under 

the Endangered Species Act for salmonids that have been 

either listed or were proposed for listing in the late 1990s. An 

integrated understanding of the ground-water flow system and 

its relation to the surface-water resources is needed in order to 

implement effective water-resources management strategies 

in the basin. In order to develop this understanding, a study of 

the Yakima River Basin aquifer system began in June 2000. 

The study is a cooperative effort of the U.S. Geological 

Survey (USGS), Bureau of Reclamation (Reclamation), the 

Yakama Nation (YN), and the Washington State Department 

of Ecology (WaDOE).

The overall objectives of the study are to fully describe 

the ground-water flow system and its interaction with and 

relation to surface water, and to provide baseline information 

for a management tool—a numerical model. The conceptual 

model of the flow system and the results of the study can 

be used to guide and support actions taken by management 

agencies with respect to ground-water availability and to 

provide information to other stakeholders and interested 

parties. The numerical model will be developed as an 

integrated tool to assess short-term to long-term management 

activities, including the testing of potential management 

strategies.

Estimates of Ground-Water Recharge to the Yakima River 

Basin Aquifer System, Washington, for Predevelopment and 

Current Land-Use and Land-Cover Conditions

By J.J. Vaccaro and T.D. Olsen
82 

22

22

97 

97

97

12

12

82

82

240

24

410

240

90 

90 

90 

24

410

12

97

12 

241

82 

82 12 

KITTITAS COUNTY 

YAKIMA COUNTY 

COUNTY 

BENTON COUNTY

KLICKITAT

COUNTY

YAKIMA

EXPLANATION

BOUNDARY OF YAKIMA

 RIVER BASIN

Canal

Roza

Sunnyside Canal

Main Canal

Extension

Kennewick

Main Canal

Marion Drain

North 

Branch 

Canal 

Kittitas Main Canal

Bumping 

Lake N Fk 

S Fk

S Fk 

N Fk 

S Fk 

N Fk 

N Fk 

Cle Elum River

Swauk Creek

Caribou Cr

Coleman Cr

Naneum Cr

Cooke Cr

Crow Creek

Bumping River

American River

Rattlesnake Cr

Little Rattlesnake Cr

Nile Creek

Manastash

Badger Creek

Lmuma Cr

Ahtanum Creek 

Oak Creek

Tieton River

Wide Hollow Cr

Wenas Creek

Selah Creek

North Fork

Dry Creek

Simcoe Creek

Agency Creek

Creek

Toppenish

Corral Cr

RIVER

Spring Cr

Logy

Creek

Satus

Creek

Mule Dry

Creek

Cle 

Elum 

Lake 

Rimrock 

Lake 

Kachess Lake 

Keechelus Lake 

Lake 

Wallula 

Priest 

Rapids 

Lake 

Teanaway River Reecer Cr

Wilson Creek

Park Cr

Taneum Creek

Umtanum Creek

Little Naches River

Cr

Cowiche Creek

Cowiche Creek

River

Naches

Snipes Cr

Sulphur Cr Wasteway

Cherry 

Cr 

S Fk

N Fk

YAKIMA

YAKIMA

RIVER

Cle Elum 

Parker 

Wapato 

Ellensburg

Umtanum 

Kittitas

Thrall 

Toppenish 

Moxee City Union Gap 

Yakima 

Selah 

Naches 

Sunnyside Richland 

Kiona 

Kennewick Prosser 

Grandview 

Mabton 

Satus 

Zillah 

Granger 

Roza 

Easton 

Teanaway 

Tieton Rimrock 

Snoqualmie

Pass

Van Epps 

Pass 

Esmeralda

Peaks

K I T T I T A S

V A L L E Y

M A N A S T A S H

KACHESS RIDGE

R I D G E

UNION GAP

CLEMAN 

MOUNTAIN 

TEANAWAY

NORTH RIDGE

U M T A N U M

R I D G E

Deception

Pass

Y A K I M A 

 V A L L E Y 

AHTANUM RIDGE

COWICHE MTN

AMERICAN RIDGE

CLE ELUM

RIDGE

RIDGE

TOPPENISH RIDGE

R A T T L E S N A K E H I L L S

Y A K I M A R I D G E

H O R S E

H E A V E N

H I L L S

C

A

S C A

D E R

A

N

G

E

W E N AT C H E E

M O U N TA I N S

Gilbert

Peak

121°

47°

47°

30'

46° 

121°30' 120°30' 120° 119°30'

46°

30'

0 5 10 20 30 40 MILES 

0 5 10 20 30 40 50 60 KILOMETERS 

Yakima

River

Basin

WASHINGTON

Figure 1. The Yakima River Basin, Washington.

2 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
The study includes three phases. The first phase includes 

(1) project planning and coordination, (2) compiling, 

documenting, and assessing available data, and (3) initial data 

collection. The second phase consists of data collection to 

support the following Phase 2 work elements: (1) mapping of 

hydrogeologic units, (2) estimating ground-water pumpage, 

(3) developing estimates of ground-water recharge, (4) 

assessing ground water-surface water interchanges, and 

(5) constructing maps of ground-water levels. Together, these 

five elements provide the information needed to describe the 

ground-water flow system, develop the conceptual model, and 

provide the building blocks for the hydrogeologic framework. 

In the third phase, six structural basin models and one regional 

model of the ground-water flow system will be constructed 

in order to integrate the available information. The numerical 

models will be used to gain a further understanding of the 

flow system and its relation to surface water, and to test 

management strategies.

The results from selected work elements will be 

described in a series of reports. This report describes the 

estimates of ground-water recharge to the Yakima River Basin 

aquifer system, a Phase 2 work element. Recharge is a major 

control on the flow of ground-water in the aquifer system 

and on water availability. The estimates of recharge provide 

information on a little known, but important, water-budget 

component in the study area. Spatial and temporal estimates 

of recharge also are needed as input to the ground-water flow 

models being constructed as part of this study.

Purpose and Scope

This report presents estimates of mean annual groundwater recharge to the Yakima River Basin aquifer system for 

predevelopment and current land-use and land-cover (LULC) 

conditions. Predevelopment conditions are an estimate of 

LULC conditions prior to any human activities in the basin, 

and current conditions are representative of a recent multi-year 

(1995–2004) composite.

The report describes the data and methods used to 

estimate recharge, the factors controlling recharge, and the 

potential sources of error in the estimates. For this report, 

recharge is defined as deep percolation past the bottom of 

the root zone, or in the case of bare soils as deep percolation 

through the bottom of the mapped soil depth, herein called 

the soil zone. Recharge is derived from snowmelt, incident 

rain on the land surface (including throughfall), irrigation of 

croplands, and septic-system drainfields.

Hydrologic models have proved to be efficient tools 

for estimating long-term daily average recharge to an 

aquifer system under predevelopment and current LULC 

conditions. Recharge to the Yakima River Basin aquifer 

system was calculated using two different models for the 

complete system (18 areas or watersheds covering 6,207 mi2) 

for predevelopment LULC conditions. Predevelopment 

conditions were estimated by changing the LULC with 

large human influences to a LULC of sagebrush. Currentcondition recharge was modeled for 16 areas with large 

human influences, such as irrigated agriculture, highdensity commercial or residential use, and urban land. 

Thirteen of these 16 areas were the same areas modeled for 

predevelopment conditions.

Four previously developed watershed models (Mastin 

and Vaccaro, 2002a) were used to calculate daily values of 

recharge for upland areas for water years (WY) 1950–98. 

A soil water-budget model was used to calculate recharge 

for WYs 1950–2003 for lowland areas with large human 

influences. The daily values were then aggregated to calculate 

monthly, annual, mean monthly, and mean annual values. This 

report principally describes the mean annual values.

Previous Estimates of Recharge

The most comprehensive previous estimates of recharge 

to the Yakima River Basin system were made by Bauer and 

Vaccaro (1990) for the parts of the study area underlain by 

the Columbia River Basalt Group using the Deep Percolation 

Model (DPM) (Bauer and Vaccaro, 1987). The DPM was 

applied to 15 areas or watersheds in the basin, which included 

most of the irrigated lands in the basin. These areas were 

generally divided into 1-mi square cells for model simulations. 

Recharge was estimated for both predevelopment and 

current LULC conditions for climatic conditions during the 

period 1956–77. Mean annual recharge for predevelopment 

conditions was estimated to range from about 0.23 to 10.65 in. 

for the 15 areas. For current conditions, mean annual recharge 

was estimated to have increased by more than 15 in. in some 

of the areas irrigated by surface water.

Description of Study Area

The location and setting of the study area, the 

development of water resources in the basin, and an overview 

of the geology are presented to provide a general background 

for understanding the study area.

Description of Study Area 3
Location and Setting

The Yakima River Basin aquifer system underlies about 

6,200 mi2 in south-central Washington (fig. 1). The Yakima 

River Basin produces a mean annual unregulated streamflow 

(adjusted for regulation and without diversions or returns) of 

about 5,600 ft3/s (about 4.1 million acre-ft) and a regulated 

streamflow of about 3,600 ft3/s (about 2.6 million acre-ft). 

The basin includes three Washington State Water Resource 

Inventory Areas (WRIA—numbers 37, 38, and 39), part of 

the Yakama Nation lands, and three ecoregions (Cascades, 

Eastern Cascades, and Columbia Basin—Omernik, 1987; 

Cuffney and others, 1997). The basin encompasses parts of 

four counties (Klickitat, Kittitas, Yakima, and Benton). Almost 

all of Yakima County, more than 80 percent of Kittitas County, 

and about 50 percent of the Benton County is in the basin. 

Less than 1 percent of the basin, principally in an unpopulated 

upland area, lies in Klickitat County.

The headwaters of the basin are on the upper, humid 

east slope of the Cascade Range, where the mean annual 

precipitation is more than 100 in. The basin terminates at the 

confluence of the Yakima and Columbia Rivers in a low-lying, 

arid area that receives about 6 in. of precipitation per year. 

Altitudes in the basin range from 400 to nearly 8,000 ft. Eight 

major rivers and numerous smaller streams are tributary to 

the Yakima River (fig. 1); the largest tributary is the Naches 

River. Most of the precipitation in the basin falls during the 

winter months as snow in the mountains. The mean annual 

precipitation over the entire basin is about 27 in. (about 

12,300 ft3/s or 8.9 million acre-ft). The spatial pattern of 

mean annual precipitation resembles the pattern of the basin’s 

highly variable topography. The difference between the mean 

annual precipitation and mean annual unregulated streamflow 

is 6,400 ft3/s (about 4.6 million acre-ft); about 53 percent of 

the precipitation is lost to evapotranspiration under natural 

conditions.

The basin is separated into several broad valleys by large 

east-west trending anticlinal ridges. The valley floors are flat 

and slope gently towards the Yakima River. Few perennial 

tributary streams traverse these valleys. Most of the population 

and economic activity occurs in these valleys.

Agriculture is the principal economic activity in the 

Yakima River Basin. The average annual surface-water 

demand met by the Reclamation’s Yakima Project is about 

2.5 million acre-ft; an additional 336,000 acre-ft of demand 

in the lower river basin is separate from the demand met by 

the project. Additional surface-water demand that is not met 

by Reclamation occurs in smaller tributaries and on the large 

rivers; this demand is based on State appropriated water. 

More than 95 percent of the demand is for irrigation of about 

500,000 acres in the low-lying semiarid to arid parts of the 

basin (fig. 2). The demand is partly met by storage of nearly 

1.1 million acre-ft of water in five Reclamation reservoirs. The 

major management point for Reclamation is the streamflow 

gaging station at the Yakima River near Parker. Just upstream 

of this site, at Union Gap, is the location that is considered the 

dividing line between the upper (mean annual precipitation 

of 7 to 125 in.) and lower (mean annual precipitation of 6 to 

45 in.) parts of the Yakima River Basin. About 45 percent 

of the water diverted for irrigation is eventually returned to 

the river system as surface-water inflows and ground-water 

discharge, but at varying time-lags (Bureau of Reclamation, 

1999). During the low-flow period, these return flows, on 

average, account for about 75 percent of the streamflow 

below the streamflow gaging station near Parker. Much of 

the surface-water demand in the basin below Parker is met 

by these return flows and not by release of water from the 

reservoirs. As a result of water use in the basin, the difference 

between mean annual unregulated and regulated streamflow in 

the basin is about 2,000 ft3/s, suggesting that some 1.4 million 

acre-ft of water, or about 17 percent of the precipitation in the 

basin, is consumptively used—principally by irrigated crops 

through evapotranspiration.

Development of Water Resources

Missionaries arrived in the basin in 1848 and established 

a mission in 1852 on Atanum (now Ahtanum) Creek. They 

were some of the first non-Indian settlers to use irrigation on 

a small scale. Miners and cattlemen immigrated to the basin 

in the 1850s and 1860s, which resulted in a new demand for 

water. With increased settlement in the mid-1860s, irrigation 

of the fertile valley bottoms began and the outlying areas were 

extensively used for stock rearing. One of the first known 

non-Indian irrigation ditches was constructed in 1867 and 

diverted water from the Naches River (Parker and Storey, 

1913; Flaherty, 1975). Private companies later delivered 

water through canal systems built between 1880 and 1904 

for the irrigation of large areas. The development of irrigated 

agriculture was made more attractive by the construction 

of the Northern Pacific Railway, which reached Yakima in 

December 1884 and provided a means to transport agricultural 

goods to markets; two years later, the completion of the 

railway to the Pacific coast provided new and easily accessible 

markets for agricultural products. The State of Washington 

was created in 1889, spurring further growth in the basin, 

especially because the cities of Ellensburg and Yakima were 

in contention for being the State capital. By 1902 there were 

about 120,000 acres under mostly surface-water irrigation in 

the basin (Parker and Storey, 1913; Bureau of Reclamation, 

1999).

4 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
Richland

Yakima

EXPLANATION

SIMPLIFIED LAND COVER

BOUNDARY OF

 AGRICULTURAL AREA

FOREST (33%)

RANGE (36%)

CITIES AND TOWNS (2%)

AGRICULTURE (28%)

Hops

Irrigated hay

Mixed row crops

Orchards

Orchards and grapes

Undifferentated agriculture

LAKES AND RESERVOIRS (1%)

121°

47°

47°

30'

46°

121°30' 120°30' 120° 119°30'

46°

30'

KITTITAS COUNTY

YAKIMA COUNTY

COUNTY

BENTON COUNTY

KLICKITAT

COUNTY

YAKIMA

0 5 10 20 30 40 MILES

0 5 10 20 30 40 50 60 KILOMETERS

YAKIMA RIVER

 YAKIMA

RIVER

Figure 2. Land use and land cover, Yakima River Basin, Washington, 1999. From Fuhrer and others, 2004.

Description of Study Area 5
The Federal Reclamation Act was enacted in 1902 

to enable the construction of Federal water projects in the 

western United States in order to expand the development 

of the West. In 1905, the Washington State Legislature 

passed the Reclamation Enabling Act, and the Yakima 

Federal Reclamation Project was authorized to construct 

facilities to irrigate about 500,000 acres. As part of the 1905 

authorization and extensions, all forms of further appropriation 

of unappropriated water in the basin were withdrawn (Parker 

and Storey, 1913). Six dams were constructed as part of the 

Yakima Project: Bumping Dam in 1910, Kachess Dam in 

1912, Clear Creek Dam in 1914, Keechelus Dam in 1917, 

Tieton Dam (Rimrock Lake) in 1925, and Cle Elum Dam 

in 1933. The construction of the dams and other irrigation 

facilities resulted in an extremely complicated surface-water 

system (fig. 3). These Federal reservoirs provide water 

storage to meet irrigation requirements of the major irrigation 

districts at the time of year when the natural streamflow from 

unregulated streams can no longer meet demands; this time 

is referred to as the ‘storage control’ date. Several of the 

reservoirs also provide instream flows during the winter for 

the incubation of salmon eggs in the salmon redds (gravel 

spawning nests).

Legal challenges to water rights resulted in the 1945 

Consent Decree (U.S. District Court, 1945) that established 

the framework of how Reclamation operates the Yakima 

Project to meet water demands. The Decree determined 

two classes of rights—nonproratable and proratable. When 

the total water supply available (TWSA, defined as current 

available storage in the reservoirs, estimates of unregulated 

flow, and other sources that are principally return flows) is 

not sufficient to meet both classes of rights, the proratable 

(junior) rights are decreased according to the quantity of water 

available defined by the TWSA. This legally mandated method 

generally performs well in most years, but is dependent on the 

accuracy of the TWSA estimate. In some years, for example 

1977, problems have arisen because of errors in the TWSA 

estimate (Kratz, 1978; Glantz, 1982). System management 

also accounts for defined instream flows at selected target 

points on the river, and for suggested changes in storage 

releases recommended by the Systems Operations Advisory 

Committee (SOAC)—the advisory board of fishery biologists 

representing the different stakeholders (Systems Operations 

Advisory Committee, 1999).

The drilling of numerous wells for irrigation was spurred 

by new (post-1945) well-drilling technologies, legal rulings, 

and the onset of a multi-year dry period in 1977 (Vaccaro, 

1995). Population growth in the basin was, and still is, the 

driving force behind the increased drilling of shallow domestic 

wells and deeper public water supply wells. Currently, there 

are more than 20,000 wells in the basin. More than 70 percent 

of these wells are shallow, 10–250 ft deep, domestic wells. 

Based on the digital water-rights database provided by 

WaDOE (R. Dixon, Washington State Department of Ecology, 

written commun., 2001) and other information, there are at 

least 2,874 active ground-water rights associated with the 

wells in the basin that can collectively withdraw an annual 

quantity of about 529,231 acre-ft during dry years. The 

irrigation rights are for the irrigation of about 129,570 acres. 

There are about 16,600 ground-water claims in the basin; these 

claims are for some 270,000 acre-ft of ground water (J. Kirk, 

Washington State Department of Ecology, written commun., 

1998). ‘A water right claim is a statement of claim to water 

use that began before the state Water Codes were adopted, 

and is not covered by a water right permit or certificate. A 

water right claim does not establish a water right, but only 

provides documentation of one if it legally exists. Ultimately, 

the validity of claimed water rights would be determined 

through general water right adjudications’ (Washington State 

Department of Ecology, 1998). A ground-water claim means 

a user claims that they were using ground water continuously, 

prior to 1945, when the State legislature enacted the Ground 

Water Code, for a particular use.

Overview of the Geology

The Columbia Plateau has been informally divided 

into three physiographic subprovinces (Meyers and Price, 

1979). The western margin of the Columbia Plateau contains 

the Yakima Fold Belt subprovince and includes the Yakima 

River Basin. The Yakima Fold Belt is a highly folded and 

faulted region, and within the study area it is underlain by 

various consolidated rocks ranging in age from Precambrian 

to Tertiary, and unconsolidated materials and volcanic rocks 

of Quaternary age (fig. 4). In the Yakima River Basin, the 

headwater areas in the Cascade Range include metamorphic, 

sedimentary, and intrusive and extrusive igneous rocks. The 

central, eastern, and southwestern parts of the basin are 

composed of basalt lava flows of the Columbia River Basalt 

Group (CRBG) with some intercalated sediments that are 

discontinuous and weakly consolidated. The lowlands are 

underlain by unconsolidated and weakly consolidated valley 

fill comprising glacial, glacio-fluvial, lacustrine, and alluvium 

deposits that in places exceed 1,000 ft in thickness (Drost and 

others, 1990). Wind-blown deposits, called loess, occur locally 

along the lower valley.

6 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
CITY OF YAKIMA 

RM 115.9 

RM 113.3 

RM 111.0 

RM 107.4 

RM 106.9 

RM 106.7 

RM 103.8 

RM 89.2 

RM 86.0 

RM 83.2 

RM 82.8 

RM 82.8 

RM 82.6 

RM 80.4 

RM 77.0 

RM 69.6 

RM 69.3 

RM 65.1 

RM 35.5 

RM 47.1 

RM 46.5 

RM 41.8 

RM 41.8 

RM 35.8 

RM 35.8 

RM 34.9 

RM 28.6 

RM 18.0 

Mouth of 

Yakima River 

RM 0.0 

RM 18.0 

RM 107.3 

12500450

RM 116.3 

RM 29.9 

12510500

RM 55.0 

12509050

RM 103.7 

12505000

RM 61.0 

COLUMBIA RIVER 

Kiona Canal

Benton City STP

Columbia Canal

Richland Canal

Corral Canyon Creek

Chandler Canal

Prosser STP

Spring Creek

Snipes Creek

Chandler Canal

Kennewick Canal

Satus Drain 303

Mabton STP

Continued at top of next column 

RM 203.5 

RM 202.5 

RM 183.1 

RM 179.6 

RM 176.1 

RM 173.9 

RM 169.9 

RM 166.1 

RM 166.1 

RM 161.3 

RM 160.3 

RM 156.3 

RM 154.5 

RM 151.5 

RM 147.0 

RM 139.8 

RM 127.9 

RM 123.7 

RM 123.6 

RM 122.4 

RM 117.0 

RM 185.6 

RM 202.0 

12477000

RM 214.4 

12474500

RM 182.9 

12479500

RM 140.4 

12484500

RM 16.8 

12494000

RM 12.6 

RM 9.7 

RM 9.7 

RM 8.5 

RM 3.6 

RM 17.5 

RM 17.1 

YAKIMA RIVER

Moxee Canal

Roza Power Plant Return Flow 

Yakima STP 

Wide Hollow Creek 

Moxee Drain 

Moxee City STP 

North Fork 

Ahtanum Creek Ahtanum Creek 

South Fork 

Ahtanum Creek Wapato Canal

Sunnyside Canal

Zillah STP 

Toppenish STP 

East Toppenish Drain 

Sub-Drain No. 35 

Granger STP 

Toppenish Creek Coulee Drain

Satus Creek 

South Drain

DID No. 7

RM 60.2 

RM 59.5 

12506000

RM 

23.1 

RM 5.3 

12500500

Sunnyside STP

Sulphur Creek

RM 0.8 

12508850

YAKIMA 

RIVER 

Kachess Kachess River 

Lake 

Kittitas Main Canal

Cle Elum WTP

Cle Elum STP

Teanaway River 

Kittitas Main Canal Return Flow 

Swauk Creek 

Taneum Creek 

West Side Ditch

Town Canal

Cascade Canal

Ellensburg Power Canal Outfall 

Manastash Creek 

Ellensburg STP 

Wilson Creek 

Naneum Creek 

Cherry 

Creek 

RM 

1.1 

RM 

20.0 

RM 0.6 

12476000 

RM 

0.9 

(Dam) 

RM 

8.2 

(Dam) 

RM 214.5 

(Dam) 

Cle Elum 

Lake 

RM 7.9 Cle Elum River 12479000

RM 3.7 

12480500

RM 5.5 

12483800

Keechelus 

Lake 

Union and Fruitvale Canals

NACHES RIVER Cowiche Creek 

Granger Drain 

Wapato STP Harrah STP 

Marion Drain

Simcoe Creek 

Umtanum Creek 

Roza Canal

Selah Creek 

Selah-Moxee Canal

Wenas Creek 

Selah STP 

Little Naches River 

American River 

Bumping River 

Rattlesnake Creek 

Naches-Selah Canal

Tieton Canal

Tieton River 

Wapatox Canal

Naches STP 

Wapatox Power Plant Return Flow 

Yakima WTP

Congdon Ditch

Naches-Cowiche Canal

Continued from bottom of previous column 

Rimrock 

Reservoir 

RM 21.3 

(Dam) 

RM 0.6 

12499000

RM 0.5 12488500

RM 16.6 

12488000

RM 19.4 

12489500

RM 20.9 

12491500

RM 14.2 

12492500

RM 44.6 

RM 27.8 

RM 18.4 

RM 13.9 

12506500

RM 4.0 

12501000

RM 2.7 

RM 2.7 

RM 

3.5 

DID No. 3

NACHES RIVER 

RM 44.2 

YAKIMA RIVER 

EXPLANATION

OUTFLOW FROM MAIN STEM

INFLOW TO MAIN STEM

GAGING STATION AND NO.

RIVER MILE

SEWAGE-TREATMENT PLANT

WATER-TREATMENT PLANT

DRAINAGE IRRIGATION DISTRICT

WTP

DID

STP

RM 140.4

12484500

Figure 3. Selected tributaries, diversion canals, return flows, and stream-gaging stations, Yakima River Basin, Washington.

Description of Study Area 7
Kiona

Naches

Yakima

Wapato

Prosser

Cle Elum

Sunnyside Richland

Union Gap

Ellensburg

Toppenish

121°

47°

47°

30'

46°

121°30' 120°30' 120° 119°30'

46°

30'

0 5 10 20 30 40 MILES

0 5 10 20 30 40 50 60 KILOMETERS

EXPLANATION

SIMPLIFIED SURFICIAL GEOLOGY

Quaternary flood deposits

Quaternary deposits, loess

Quaternary and Pliocene volcanic rock

Columbia River Basalt Group rock

Miocene and older volcanic rock

Tertiary granitic and intermediate intrusive rock

Non-marine sedimentary rock

Marine sedimentary rock

Pre-Tertiary metamorphic and intrusive rock

Figure 4. Simplified surficial geology of the Yakima River Basin, Washington. From Fuhrer and others, 1994.

8 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
Valley-fill deposits and basalt lava flows are important 

for ground-water occurrence in the study area. The basalt 

consists of a series of flows erupted during various stages 

of the Miocene Age, from 17 to 6 million years ago. Basalt 

erupted from fissures in the eastern part of the Columbia 

Plateau and individual flows range in thickness from a few 

feet to more than 100 ft. The total thickness in the central 

part of the plateau is estimated to be greater than 10,000 ft 

(Drost and others, 1990) with a maximum thickness of more 

than 8,000 ft in the study area. Unlike most of the Columbia 

Plateau, the CRBG in the Yakima Fold Belt is underlain by 

sedimentary rocks. The valley-fill deposits were eroded from 

the Cascade Range and from the east-west-trending anticlinal 

ridges that were formed by the buckling of the basalt sequence 

during mid- to late-Miocene time. Much of these deposits are 

part of the Ellensburg Formation. This formation underlies, 

intercalates, and overlies the basalts along the western edge, 

and comprises most of the thickness of the unconsolidated 

deposits (informally called the overburden; Drost and others, 

1990) in the basinal areas. The basins are narrow to large open 

synclinal valleys between the numerous anticlinal ridges.

The deposition of a thick, upper sequence of sand, gravel, 

and some fine-grained material is the result of erosion by 

glacial ice and transport by meltwater streams. Damming of 

large lakes by glacial ice during the Pleistocene epoch resulted 

in the deposition of silt and clay beds in parts of the uplands. 

When the lakes drained, the fine sediments were exposed, 

subsequently eroded by wind, and deposited over the lower, 

eastern parts of the study area. Thus, the unconsolidated 

materials in the basinal areas that are abutting and interbedded 

with the basalts range in age from Miocene to Holocene.

Methods Used to Estimate 

Ground-Water Recharge

Overview of the Two Models Used to 

Estimate Recharge

Two models in the USGS’s Modular Modeling System 

(MMS; Leavesley and others, 1996) were used to estimate 

recharge for the entire aquifer system: Precipitation-Runoff 

Modeling System (PRMS; Leavesley and others, 1983) 

and DPM (Vaccaro, 2007). Both models are extensively 

documented and will not be described in detail here.

The models are driven by daily values for precipitation 

and for maximum and minimum air temperatures, and 

partition precipitation into either rain or snow. The models 

simulate snow accumulation and ablation, plant interception, 

evapotranspiration, surface runoff, infiltration, water storage in 

the root or soil zone, and recharge (deep percolation through 

the bottom of the root or soils zone). The models have similar 

required input parameters and calculate water balances on 

the basis of user-defined Hydrologic Response Units (HRUs) 

into which a watershed or an area is subdivided for model 

calculations.

PRMS was used to estimate recharge for four, generally 

wetter, forested upland areas where there are few human 

activities; these estimates were assumed to be the same for 

predevelopment and current LULC conditions. PRMS is a 

physically-based rainfall-runoff watershed model that is fully 

described and documented in Leavesley and others (1983). 

The PRMS models were previously constructed (Mastin and 

Vaccaro, 2002a) as part of the joint USGS and Reclamation 

Watershed and River System Management Program (U.S. 

Geological Survey, 1998), and modifications to PRMS for 

application to the Yakima River Basin are documented in 

Mastin and Vaccaro (2002b). The models simulate streamflow 

for estimated unregulated conditions for use in reservoir and 

river management by Reclamation.

DPM was used to estimate predevelopment and 

current recharge in 17 areas with extensive human 

activities, principally agricultural and urban areas. DPM 

was originally developed by Bauer and Vaccaro (1987) as 

a tool for estimating daily ground-water recharge over a 

broad array of landscapes and spatiotemporal scales for the 

purpose of providing an independent estimate of recharge 

for ground-water flow models. DPM was later modified by 

Bauer and Mastin (1997). As part of this study, DPM was 

modularized and incorporated into MMS (Vaccaro, 2007); the 

modularization included some modifications. Unlike PRMS, 

DPM simulates only the land-surface processes and does not 

simulate the movement of deep percolation below the root or 

soil zone.

For consistency in calculating recharge between PRMS 

and DPM, PRMS-recharge was defined as the excess 

water (deep percolation) leaving the root or soil zone after 

abstractions by surface runoff and evapotranspiration. The 

total amount of water that can be stored in the root or soil 

zone before recharge occurs in both PRMS and DPM is the 

total available water capacity (TAWC), which is the amount 

of water that can be stored in the soil column before gravity 

drainage occurs. TAWC approximates the total unsaturated 

storage capacity of the root or soil zone because it does not 

account for the volume of water stored below the wilting 

point.

The root or soil zone in PRMS is modeled as a single 

water-storage unit that has an upper part, where both 

evaporation and transpiration can occur, and a lower part, 

where only transpiration occurs. The depth of the root or 

soil zone is determined by the LULC for a HRU. Four 

LULCs are used in PRMS (bare soils, grasses, shrubs, and 

trees) and a fifth (water) was added by Mastin and Vaccaro 

(2002b). A water land cover does not have a root zone, and 

recharge is assumed to be zero for HRUs with that land cover; 

Methods Used to Estimate Ground-Water Recharge 9
moisture additions to water HRUs are due to precipitation and 

abstractions are due to evaporation. For barren land, the root 

zone is the soil zone and is that upper part of the soil column 

where bare-soil evaporation occurs (Leavesley and others, 

1983).

The root zone in DPM is the depth of the roots for the 

LULC of a HRU and for bare soils it is the soil zone, which 

is the depth of the mapped soil column. DPM currently has 

31 LULCs that include a variety of crops, such as beans, 

grapes, orchards, corn, and hops. Recharge is assumed to be 

zero for land covers of water and impervious areas (barren 

rocks and built-up areas—urban areas and high-density 

commercial or residential). The root zone has a temporally 

constant depth for such covers as forests, orchards, and 

sagebrush, and expands with plant growth for such covers 

as beans or corn. The depth of the root zone is limited by 

the depth to bedrock for shallow soils, and thus may be less 

than a particular plant’s root depth. All plant types in DPM 

have a default value for the maximum root depth, maximum 

interception capacity, and maximum foliar cover. Interception 

capacity is the amount of water that a plant can store on its 

foliage and it varies greatly by plant type and for some plants, 

by growth stage. Foliar cover is similar to a leaf area index, 

and is the percent of shading the plant’s foliage provides 

to the ground; it is used in throughfall and soil evaporation 

calculations. Users can define these three plant parameters for 

any plant type contained in DPM because a parameter, such 

as root depth, can vary depending on a plant’s genetic stock, 

soils, and climatic setting. For some plant types, these three 

parameters are adjusted daily using a calculated daily plant 

growth stage.

Data Used in Models

Landscape Characteristics

PRMS and DPM require landscape characteristics as 

input parameters for each HRU. These characteristics are the 

average altitude, slope and aspect, the area, and the x- and 

y-locations of the centroid of the HRU. For the PRMS models, 

a digital elevation model (DEM) with a 208-ft grid-cell size of 

the basin was used by a GIS (Geographic Information System) 

interface, termed the GIS Weasel (Leavesley and others, 

1997; Viger and others, 1997), to calculate HRU values for 

these characteristics (Mastin and Vaccaro, 2002a). The GIS 

Weasel is part of MMS and facilitates model development. 

For the DPM models, 10-m DEMs (U.S. Geological Survey, 

2000) were mosaicked and the landscape characteristics for 

each HRU in each modeled area were calculated using a 

DPM ‘plug-in’ for the GIS Weasel (R. Viger, U.S. Geological 

Survey, written commun., 2005).

Weather Information

Daily values of precipitation and maximum and minimum 

air temperatures for 36 sites were previously compiled in the 

MMS-input format for WYs 1950–96 (Mastin and Vaccaro, 

2002a). There were 17 National Weather Service sites, 

12 Natural Resources and Conservation Service SNOTEL 

sites, and 7 Reclamation sites. Data from these sites were 

interpolated by PRMS to the HRUs using a distance-weighted 

scheme. Daily values from these sites for WYs 1997–98 were 

later compiled by Mastin (U.S. Geological Survey, written 

commun., 2002). To develop input for the DPM models, 

records from 13 sites (fig. 5) were either compiled or extended 

for WYs 1999-2003. These 13 sites did not include the wetter, 

high-elevation sites because of their distance from the areas 

being modeled using DPM.

Mean annual precipitation at the 36 sites ranges from 

about 7 to 128 in. and annual values ranged from about 3 in. 

to more than 140 in. The large differences in mean annual 

precipitation between weather sites are clearly indicated by 

the spatial distribution of mean annual precipitation (Daly 

and Taylor, 1998) (fig. 5). The daily precipitation has ranged 

from zero to more than 7 in. Mean annual minimum air 

temperatures were as low as about 20°F and mean annual 

maximum temperatures were as high as 70°F. Daily minimum 

air temperatures were as low as -30°F and daily maximum air 

temperatures were as high as 110°F.

Adjustments to daily precipitation interpolated from 

weather sites to a HRU use the ratios of the mean monthly 

precipitation of the HRU to those at the weather site. Mean 

monthly precipitation at the weather sites was calculated 

for the period of record. The mean monthly precipitation 

at a HRU was calculated using the GIS Weasel ‘plug-in’ 

from information of Daly and Taylor (1998), which is the 

mean monthly precipitation values for 4- by 4-km grid cells. 

The size of the cells results in large changes across cell 

boundaries, especially where there are large gradients in 

monthly precipitation. In turn, there are similar changes in the 

interpolated precipitation values at the HRUs that are near the 

grid cell boundaries.

Monthly minimum and maximum lapse rates 

(temperature change per 1,000 ft change in elevation) for both 

minimum and maximum air temperatures were calculated 

from the daily temperature data. These monthly values are 

based on lapse-rate calculations between all sites for each day 

for each month for the period 1950–98.

10 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
wa19-0052_fig05 46°00' N 46°30' N 47°00' N 47°30' N

121°30' W 121°00' W 120°30' W 120°00' W 119°30' W 119°00' W

0 10 Miles 20

0 2010 Kilometers

Prosser

4 NE (ARS)

Richland

Kennewick

Easton

Teanaway

Cle Elum

Naches 10 NW

Tieton

Headworks

Intake Moxee

City 10 E Yakima WSO AP

Wapato

Ellensburg

Naches River

Yakima River

Columbia

River

Easton

Teanaway

Cle Elum

Naches 10 NW

Tieton

Headworks

Intake Moxee

City 10 E Yakima WSO AP

Wapato

Sunnyside

Ellensburg

Naches River

Yakima River

Kennewick

Prosser

4 NE (ARS)

American R.American R.

EXPLANATION

Mean annual precipitation,

in inches

Weather site

6 – 10

10.1 – 20

20.1 – 30

30.1 – 40

40.1 – 50

50.1 – 60

60.1 – 70

70.1 – 80

80.1 – 90

90.1 – 128

Figure 5. Location of weather-data sites and distribution of mean annual precipitation, Yakima River Basin, 

Washington.

Methods Used to Estimate Ground-Water Recharge 11
Soil Information

Three soil databases were used in this study. The 

STATSGO database (U. S. Department of Agriculture, 1994) 

was used to define the soil properties for the PRMS models 

and for three of the DPM models; these latter three models 

were for parts of the upper basin where data from the other 

databases were unavailable (table 1). For all but two of 

the remaining DPM models, the SSURGO database (Soil 

Survey Staff, undated) was used. The remaining two models 

(for the Yakama Nation irrigated lands) used a SSURGOformatted database (S. Wangemann, Bureau of Indian Affairs, 

written commun., 2002; table 1). The SSURGO data include 

information from several survey areas because of the large size 

of the study area.

The PRMS soil parameters were calculated from the 

STATSGO database using the GIS Weasel. These parameters 

include such information as the TAWC, soil depth, the TAWC 

in the upper part of the root zone where soil evaporation 

can occur, and soil texture. For the DPM models, soil types 

were first determined for the three databases. A specified soil 

type has similar soil attributes throughout and carries these 

attributes as model input parameters. Thirty-three soil types 

were defined for the STATSGO database and 119 soil types 

Name

Identification 

No.

Model

Hydrologic Response Unit

Area

(mi2

)

Capacity (inches) Precipitation

(inches)

Temperature

(oF)

Irrigation

(inches)

Soil 

dataNo. base

Size

TAWC SAT Total

(feet) (acres)

Selah Creek 1 DPM 5,294 800 14.7 116.5 5.68 7.04 12.72 9.7 47.1 2.1 1

Selah-Wenas 2 DPM 2,980 500 5.7 25.2 3.8 9.81 13.61 9.9 49.5 24.4 1

Cold-Dry 3 DPM 9,254 1,000 23.0 321.3 3.0 7.62 10.62 8.4 50.0 2.4 1

Cle Elum 4 DPM 758 1,500 51.7 49.9 7.47 9.25 16.73 27.4 45.4 15.0 2

Kittitas 5 DPM 536 5,280 640.0 459.8 4.56 10.18 14.74 16.0 44.9 0.0 2

Ellensburg 6 DPM 2,123 2,000 91.8 284.2 4.99 9.92 14.91 13.6 46.2 28.8 2

Kiona 7 DPM 6,145 1,000 23.0 211.0 3.98 9.41 13.39 7.7 52.3 13.7 1

Satus 8 DPM 5,711 800 14.7 123.6 4.93 8.25 13.22 8.1 51.8 17.6 1

lower Naches 9 DPM 7,264 600 8.3 90.4 3.39 10.69 14.08 14.3 48.2 25.8 1

Prosser 10 DPM 3,007 1,000 23.0 99.9 4.18 8.80 12.98 7.9 51.8 44.9 1

Roza-Sunny 11 DPM 4,920 1,200 33.1 242.4 4.61 10.74 15.35 7.3 51.5 42.5 1

Rattle east 12 DPM 3,798 1,000 23.0 129.4 4.45 8.40 12.85 9.6 48.6 10.2 1

Toppenish 13 DPM 8,730 1,000 23.0 301.1 4.76 4.73 9.49 8.2 51.6 32.0 1

Moxee 14 DPM 6,898 800 14.7 153.0 3.5 8.14 11.64 8.3 48.6 12.7 1

Ahtanum 15 DPM 7,060 800 14.7 156.1 4.4 9.01 13.41 14.4 48.2 15.9 1

Rattle west 16 DPM 3,380 1,000 23.0 110.4 2.15 7.47 9.62 8.3 49.1 5.0 1

Wenas 17 DPM 2,807 500 5.7 23.9 3.45 9.64 13.09 12.4 49.2 21.0 1

Naches 18 PRMS 363 Varies Varies 1,107 3.47 9.49 12.96 43.0 39.1 0.0 2

upper Yakima 19 PRMS 404 Varies Varies 1,127 3.91 9.80 13.71 53.0 41.1 0.0 2

ToppSatus 20 PRMS 242 Varies Varies 1,027 3.48 9.49 12.97 17.0 46.2 0.0 2

Yak Canyon 21 PRMS 101 Varies Varies 406.1 2.79 7.54 10.33 21.0 44.5 0.0 2

Table 1. Characteristics of the modeled areas, Yakima River Basin, Washington.

[Values will not sum due to rounding. Identification No.: Location of area shown on figures 7 and 8. Model: DPM, Deep Percolation Model; PRMS, 

Precipitation-Runoff Modeling System. Hydrologic Response Unit: (HRU), each area is subdivided by HRUs for calculating water budgets. SIZE: square 

HRUs were used for the subdivisions in the DPM models and they would not be squares where the boundary of the model area intersected the boundary HRUs. 

SIZE in feet represents the length of a side of a complete square and SIZE in acres represents the amount of acreage in a complete square. Number of HRUs 

multiplied by the area of the square HRU will not equal the modeld area (Area). Capacity: TAWC, total available water capacity is the amount of water that 

can be stored in the root zone between the wilting point and field capacity; SAT, saturated capacity; Total, total water capacity. SAT and Total for Naches, upper 

Yakima, ToppSatus, and Yak Canyon modeled areas estimated from information for the remaining areas. Soil database: 1 is the SSURGO database and 2 is the 

STATSGO database. Abbreviations: oF, degrees Fahrenheit; mi2

, square miles]

12 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
were defined for the combined SSURGO databases. For each 

soil type, the soil depth, the number of 6-in. soil layers, and 

the depth-weighted average of the TAWC were calculated. 

On the basis of the calculated TAWC, the soil attributes of 

soil texture, saturated water capacity (the amount of available 

water storage in excess of TAWC to bring the soils to full 

saturation—the specific yield), and the lateral hydraulic 

conductivity were estimated.

Land Use and Land Cover

A USGS national database (Loveland and others, 1991) 

was used to estimate a dominant LULC for the HRUs in the 

previously developed PRMS models. The PRMS models 

include most of the forested lands in the study area, and land 

covers of shrub or grass occur mainly in two of the modeled 

areas. The LULC for a HRU was assumed to be applicable for 

both predevelopment and current conditions in the four areas 

modeled with PRMS.

Several LULC databases were used to estimate the 

dominant current LULC condition for the HRUs in the DPM 

models, which differentiate among different crop types. 

Reclamation (E. Young, Bureau of Reclamation, written 

commun., 2003) provided (1) a GIS database for the basin 

that identified irrigated lands, but not crop type; and (2) 

databases for crop types for several smaller areas. The Kittitas 

Conservation District provided a crop-type distribution for 

most of Kittitas County (Kittitas Conservation District, written 

commun., 2003) and the South Yakima Conservation District 

provided information for Roza and Sunnyside Valley Irrigation 

Districts (fig. 6) (South Yakima Conservation District, written 

commun., 2004). A LULC for the basin was obtained from the 

USGS national database (Homer and others, 2004), and this 

database also provided information on the location of urbanto-low-density residential areas. Detailed crop-type coverage 

for a small subbasin was developed by the USGS as part of 

their National Water Quality Assessment Program. A field 

survey was conducted for the Wapato Irrigation Project (fig. 6) 

to identify fields planted in orchards, vineyards, and hops. 

Additional field surveys were conducted in some areas that 

were identified as irrigated lands from either the Reclamation 

or the USGS data, but the crop types were not known. Lastly, 

a 2004 geodatabase was obtained from Washington State 

Department of Agriculture (DOA), Pesticide Management 

Division (T. Maxwell, Washington State Department of 

Agriculture, written commun., 2005). This geodatabase 

contained information on size of irrigated fields and crop 

types, aggregated to the section level; thus, the field location 

within the section could not be determined. This database 

provided information on the dominant crop type in areas 

where the LULC was identified as irrigated croplands but the 

crop type was not known. Most of the crop types in these areas 

were small grains, hay, pasture, and row crops. Excluding the 

DOA database, the LULC information was combined into a 

single spatial database (starting with the least detailed data 

and substituting in the more detailed data sets) for developing 

LULC identification numbers for the DPM models.

The database represents a multi-year (approximately 

1995–2004) composite LULC that was assumed to be 

constant for the period of recharge calculations. Information 

on temporal changes in crop distributions and types and in 

the distribution of built-up areas was generally not available, 

especially for years prior to the 1990s, and it would not be 

computationally feasible to include such information. The 

LULC in the models, however, allows potential future use of 

the models to be representative of existing conditions. The 

potential error in recharge due to using the composite LULC is 

described in a subsequent section.

An estimated distribution of the natural (predevelopment) 

vegetative cover was needed to calculate predevelopment 

recharge using DPM. Most of the areas with human activities 

within the DPM models are in the semiarid to arid parts of 

the basin, where a typical native-plant community consists 

of intermixed sagebrush and grasses; thus the HRUs with 

human influences were set to a predevelopment cover type of 

sagebrush.

Irrigation Application Rates

In DPM, the HRUs with irrigated croplands require as 

an input the annual application rate of water. Application 

rates were calculated using two different methods, depending 

on whether the crops were irrigated with surface-water 

(principally located within an irrigation district) or with 

ground water. For surface-water irrigated crops, it was first 

determined which district a HRU was in. The boundaries of 

the irrigation districts (fig. 6) in the study area were obtained 

from Reclamation (E. Young, Bureau of Reclamation, written 

commun., 2002) and are based on 1974 maps that show 

irrigation districts in Washington State. The maps included 

information on the average on-farm deliveries of water (in/yr) 

and the effective canal losses (in/yr) for a district as a whole. 

Together, these values were assumed to be the application rate, 

and provided a consistent and uniform method to estimate 

rates. For the irrigation districts, the total application rates 

varied from 32.4 to 86.4 in/yr, with 22 districts having rates 

of 36 in/yr and higher, and 16 districts having rates of 42 in/yr 

and higher. Although the actual water applied may be less than 

the allowable/estimated rate, Washington State’s water law has 

a ‘use-it or lose-it’ (relinquishment) provision. Thus, irrigation 

water above the amount needed for a particular crop type may 

be diverted for on-farm use but may not be applied to a field, 

and is instead discharged to a farm drain or wasteway. It was 

beyond the scope of this study to estimate how much water 

is actually applied to the more than 500,000 acres of surfacewater irrigated croplands; a simplified method to indirectly 

account for potentially unused (not applied) water is described 

in the following section.

Methods Used to Estimate Ground-Water Recharge 13
Figure 6. Surface-water irrigation districts, Yakima River Basin, Washington.

14 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington

Kennewick Irrigation District

Irrigation districts in the Yakima River Basin

Kittitas Reclamation District

Roza Irrigation District

Sunnyside Valley Irrigation District

Yakima-Tieton Irrigation District

Wapato Irrigation Project

All other irrigation districts

KITTITAS COUNTY

YAKIMA COUNTY

COUNTY

BENTON COUNTY

KLICKITAT

COUNTY

YAKIMA

Bumping

Lake

Cle Elum River

Bumping River

Ahtanum Creek

Tieton River

Wenas Creek

North Fork

Dry Creek

RIVER

YAKIMA

Satus

Creek

Cle

Elum

Lake

Rimrock

Lake

Kachess Lake

Keechelus Lake

Lake

Wallula

Teanaway River

Umtanum Creek

Little Naches River

Cowiche Creek

North Fork

River

Naches

RIVER

YAKIMA

RIVER

YAKIMA

Cle Elum

Parker

Wapato

Ellensburg

Umtanum

Kittitas

Thrall

Toppenish

Moxee City Union Gap

Yakima

Selah

Naches

Sunnyside Richland

Kiona

Kennewick

Prosser

Grandview

Mabton

Satus

Zillah

Granger

Roza

Easton

Teanaway

Tieton Rimrock

Snoqualmie

Pass

Van Epps

Pass

Esmeralda

Peaks

K I T T I T A S

V A L L E Y

M A N A S T A S H

KACHESS RIDGE

R I D G E

UNION GAP

CLEMAN

MOUNTAIN

TEANAWAY

NORTH RIDGE

U M T A N U M

R I D G E

Deception

Pass

Y A K I M A

 V A L L E Y

AHTANUM RIDGE

COWICHE MTN

AMERICAN RIDGE

CLE ELUM

RIDGE

RIDGE

TOPPENISH RIDGE

R A T T L E S N A K E H I L L S

Y A K I M A R I D G E

H O R S E

H E A V E N

H I L L S

C

A

S C A

D E R

A

N

G

E

W E N AT C H E E

M O U N TA I N S

Gilbert

Peak

121°

47°

47°

30'

46°

121°30' 120°30' 120° 119°30'

46°

30'

0 5 10 20 30 40 MILES

0 5 10 20 30 40 KILOMETERS

EXPLANATION

T.

24

N.

T.

22

N.

T.

20

N.

T.

18

N.

T.

16

N.

T.

14

N.

T.

12

N.

T.

10

N.

T.

8

N.

T.

6

N.

R.10E. R.12E. R.14E. R.16E. R.18E. R.20E. R.22E. R.24E. R.26E. R.28E.

wa19-0052_fig06
The application rates input to the model for groundwater irrigated crops were estimated on the basis of the 

dominant crop type for a HRU (a model input parameter) and 

the estimated long-term average potential water use of that 

crop. The average potential water use for each crop type was 

estimated by operating DPM for WYs 1950–2003 for each 

crop type and averaging the daily values of potential plantwater use (soil moisture non-limiting). These average values 

were originally calculated by Vaccaro and Sumioka (2006) 

as part of estimating ground-water pumpage from the aquifer 

system. The estimated application rates for the ground-water 

irrigated crops ranged from 15.0 to 38.9 in/yr.

Assumptions and Considerations in Estimating 

Recharge

Built-up areas were assumed to be represented by 

an impervious LULC; accounting for lawn and landscape 

irrigation in these areas and subsequent recharge of excess 

applied water was beyond the scope of this study.

A source of recharge that was not simulated by the 

models is that from septic-system drainfields. Vaccaro and 

Sumioka (2006) estimated ground-water pumpage from the 

aquifer system for the Public Water Supply (PWS) systems 

and for self-supplied domestic households, which was 

aggregated by the 2000 census blocks of the U.S. Census 

Bureau (2004). These estimates were annual values for 

pumpage by the PWS systems, beginning in 1960, or later if 

the system was established after 1960, and the values were 

for 5-year increments, beginning in 1960 for the domestic 

pumpage. Vaccaro and Sumioka (2006) also estimated the 

monthly distribution of the PWS and domestic pumpage 

based on a percentage of the annual value; the percentages 

were calculated using all available data. The months with the 

lowest percentage of annual pumpage were November through 

February, and the values ranged from 4.8 to 5.4 percent. The 

percentage for March, when outdoor use of water starts, was 

5.9. Based on the percentages for November through February 

and assuming that there is a base-level percentage of 5.5 for 

the months of March through October, about 63 percent of the 

annual pumpage is for indoor use. About 90 percent (Solley 

and others, 1988, 1993) of this value was assumed to be the 

base-level, non-consumptive use of water that was returned 

to the ground through septic systems; thus about 57 percent 

of the annual pumpage becomes septic-system recharge. 

Multiplication of the annual pumpage data by this value 

gave a distribution of septic-system recharge from 1960 to 

2000 by 5-year increments. Values, including PWS, between 

the 5-year increments, such as 1961–64, were assumed to 

be constant from the start of the interval, in this case 1960, 

until the beginning of the next increment, in this case 1965. 

Census blocks with 1 acre-ft or less of annual pumpage or that 

were in the PRMS modeled areas were not included in the 

calculations. It was assumed that from 1950 to 1960 there was 

no change in the amount of septic-system recharge. During 

this period, more that 85 percent of the population growth 

in the basin occurred in municipalities that do not use septic 

systems. The basin-wide septic-system recharge from selfsupplied domestic pumpage and PWS (non-sewered) in 1960 

was only about 7,000 acre-ft and 2,700 acre-ft, respectively, 

and a small change from 1950 to 1960 is negligible compared 

to changes in the other components of recharge. The estimates 

of septic-system recharge for 2000 were a reasonable 

approximation for 2001 through 2003. The resulting mean 

annual distribution of septic-system recharge was added to the 

mean annual recharge values calculated by DPM.

The three-county (Yakima, Kittitas, and Benton) area that 

makes up most of the study area contains about 9,500 irrigated 

fields with different crop types and irrigation methods 

(T. Maxwell, written commun., 2005). The amount of water 

actually applied to the fields in surface-water irrigated areas 

is not known, especially on an annual basis during WYs 

1950–2003. In addition, the relinquishment provision in State 

law and the implementation of Best Management Practices in 

the basin suggests that the water application rate input to the 

models may be too large. To reduce the total amount of water 

that can become recharge, a simplified method was employed 

in which the application of water to the surface-water irrigated 

croplands was defined in DPM as being supplied to the crops 

from above their foliage (sprinkler, center pivot, or wheel 

line). This allows for more evaporation of the applied water 

from the intercepted water on the plant foliage, and, in effect, 

reduces the application rate and ultimately the amount of 

recharge. Depending on crop type, evaporation can be as much 

as 10 in/yr. In addition, the application rate was identified in 

DPM to be constant over the irrigation season and was not 

based on crop growth, which also reduced calculated recharge.

Irrigation of croplands and other human activities occur 

in some of the areas modeled using PRMS. For two areas with 

the most human influences (Cle Elum and Wenas, table 1), 

boundaries were digitized to define model areas, and DPM 

models were constructed to estimate recharge for current 

conditions. The recharge simulated in these models was 

substituted in place of the recharge calculated by PRMS to 

estimate the distribution of current-condition recharge.

Methods Used to Estimate Ground-Water Recharge 15
Modeled Areas

The four areas modeled with PRMS include about 

3,667 mi2 (about 59 percent of the study area). Most of 

the upland areas in the basin, which produce more than 

95 percent of the natural runoff (Mastin and Vaccaro, 2002a), 

are included in the upper Yakima, Naches, Yak Canyon, and 

ToppSatus areas (fig. 7 and table 1; also U.S. Geological 

Survey [1998]). The PRMS areas were divided into a total 

of 1,110 HRUs based on several factors (mean annual 

precipitation, elevation, soil properties, and left or right stream 

bank contributing area), and the HRUs vary in size and shape 

(Mastin and Vaccaro, 2002a).

EXPLANATION

Precipitation-Runoff

 Modeling System

Deep Percolation Model

Predevelopment model

 boundaries

10 Identification number, table 1

19

21 18

20

Model

12

10 7

9 2 1

14

16 11

3

8

15

13

5

Sunnyside

Ellensburg

Cle Elum

Pasco

Richland

Yakima

Kennewick

American R.

Naches River

Yakima River

Columbia

River

Priest

Rapids

Dam

46°00' N 46°30' N 47°00' N 47°30' N 48°00' N

121°30' W 121°00' W 120°30' W 120°00' W 119°30' W 119°00' W

Figure 7. Areas modeled to estimate recharge for predevelopment conditions, Yakima River Basin, Washington.

16 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
Fourteen DPM models were constructed to calculate 

predevelopment recharge, principally in the areas not included 

in the PRMS models. The 14 areas (fig. 7) include about 

2,554 mi2, and were subdivided into a total of 74,978 square 

HRUs (table 1). Note that because of the irregular-shaped 

boundaries for the modeled areas, the HRUs at the boundaries 

are not complete squares. Thirteen of these areas also were 

modeled using DPM to estimate current-condition recharge. 

In addition, as described above, two other areas with extensive 

irrigated agriculture and development included in the PRMS 

models were modeled using DPM (Wenas and Cle Elum, 

fig. 8, table 1). One predevelopment area (Kittitas, fig. 7 and 

table 1) was further refined (Ellensburg, fig. 8 and table 1) to 

include mainly irrigated croplands and cities for estimating 

recharge for current conditions. The 16 current-condition 

models have a total of 80,130 HRUs and include an area of 

2,438 mi2. The weather information for input to the DPM 

models was obtained from the weather sites shown on figure 5.

Predevelopment model results

assumed to be applicable for

current conditions

0 10 20 Miles

0 2010 Kilometers

EXPLANATION

4

6

17

9

15

2 1

14

3

16

13 11

8

10

12

7

10

Current condition model boundaries

Identification number, table 1

46°00' N 46°30' N 47°00' N 47°30' N

121°30' W 121°00' W 120°30' W 120°00' W 119°30' W 119°00' W

American R.

Naches River

Yakima River

Sunnyside

Ellensburg

Cle

Elum

Pasco

Richland

Columbia

River

Priest

Rapids

Dam

Yakima

Kennewick

Figure 8. Areas modeled to estimate recharge for current conditions, Yakima River Basin, Washington.

Modeled Areas 17
Estimates of Ground-Water Recharge

The estimated mean annual recharge for predevelopment 

conditions (fig. 9) clearly shows large spatial variations in 

recharge, from more than 50 in. in the wet uplands to zero 

in the arid lowlands. The average predevelopment recharge 

for the entire 6,207 mi2 that was modeled for the Yakima 

River Basin aquifer system was estimated to be about 11.9 in. 

or 5,450 ft3/s (about 3.9 million acre-ft), which is about 

44 percent of the total precipitation. About 97 percent of the 

recharge occurred in the upland parts of the 3,667 mi2 area 

included in the PRMS models, and nearly 90 percent of the 

total was in the upper Yakima and Naches modeled areas, 

herein called the ‘humid’ areas (fig. 7, tables 1 and 2). 

Mean annual recharge, in inches

0 - 0.1

0.11 - 0.5

0.51 - 2.0

2.1 - 5.0

5.1 - 10.0

10.1 - 20.0

20.1 - 50.0

> 50

EXPLANATION

Boundaries of Yakima

River basin and model

shown in figures 10–11

46°00' N 46°30' N 47°00' N 47°30' N

121°30' W 121°00' W 120°30' W 120°00' W 119°30' W 119°00' W

0 10 Miles 20

0 2010 Kilometers

Figure 9. Spatial distribution of mean annual recharge for predevelopment conditions, Yakima River 

Basin, Washington.

18 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
Table 2. Summary of estimates of mean annual recharge for the modeled areas, Yakima River Basin, Washington.

[Conversions and ratios will not be exact due to rounding. Identification No.: Location of area shown on figures 7 and 8. Condition: P, predevelopment; C, 

current. Irrrigation: the sum of irrigation application rate and canal/lateral losses. Septic: recharge estimate from septic-system drainfields. AET: modelcalculated actual evapotranspiration and includes evaporation of intercepted water, snow sublimation, soil evaporation, and plant transpiration. I/P: ratio of 

irrigation to precipitation—no irrigation for predevelopment conditions. R/T: ratio of recharge to total water input—precipitation for predevelopment conditions 

and precipitation plus irrigation for current conditions. R/P: ratio of recharge to precipitation. R/AET: ratio of recharge to evapotranspiration. Abbreviations:

R, recharge; P, precipitation; I, irrigation; T, total water input; in., inch; ft3/s, cubic foot per second; NA, not applicable]

Name

Identification 

No.

Condition

Precipitation 

(in.)

Irrigation 

(in.)

Recharge

(in.)

Septic

(in.)

AET

(in.)

R

(ft3

/s)

P

(ft3/s) R/P R/AET I/P R/T

Selah Creek 1 P 9.7 0.0 0.46 0.0 9.1 3.9 83.2 0.05 0.05 NA 0.05

Selah Creek 1 C 9.7 2.1 1.35 .055 10.2 11.6 83.2 .14 .13 .22 .11

Selah-Wenas 2 P 9.9 .0 .69 .0 9.1 1.3 18.3 .07 .08 NA .07

Selah-Wenas 2 C 9.9 24.4 11.19 .574 22.9 20.8 18.3 1.13 .49 2.47 .33

Cold-Dry 3 P 8.4 .0 .44 .0 7.9 10.4 199.1 .05 .06 NA .05

Cold-Dry 3 C 8.4 2.4 1.3 .049 9.2 30.8 199.1 .15 .14 .29 .12

Cle Elum 4 C 27.4 15.0 22.45 .029 19.5 82.5 100.7 .82 1.15 .55 .53

Kittitas 5 P 16.0 .0 2.9 .0 12.4 98.2 542.6 .18 .23 NA .18

Ellensburg 6 C 13.6 28.8 20.06 .038 21.8 420.0 285.6 1.47 .92 2.11 .47

Kiona 7 P 7.7 .0 .08 .0 7.5 1.2 119.5 .01 .01 NA .01

Kiona 7 C 7.7 13.7 4.99 .052 16.4 77.6 119.5 .65 .3 1.78 .23

Satus 8 P 8.1 .0 .2 .0 7.9 1.8 73.6 .02 .03 NA .02

Satus 8 C 8.1 17.6 7.47 .028 18.1 68.0 71.1 .96 .41 2.18 .29

lower Naches 9 P 14.3 .0 2.46 .0 11.0 16.4 95.2 .17 .22 NA .17

lower Naches 9 C 14.3 25.8 15.52 .309 23.1 103.4 95.2 1.09 .67 1.80 .39

Prosser 10 P 7.9 .0 .11 .0 7.7 0.8 57.8 .01 .01 NA .01

Prosser 10 C 7.9 44.9 22.5 .082 30.4 165.6 57.8 2.87 .74 5.72 .43

Roza-Sunny 11 P 7.3 .0 .14 .0 7.1 2.5 129.4 .02 .02 NA .02

Roza-Sunny 11 C 7.3 42.5 21.3 .176 28.3 380.3 129.4 2.94 .75 5.86 .43

Rattle east 12 P 9.6 .0 .45 .0 9.1 4.3 91.6 .05 .05 NA .05

Rattle east 12 C 9.6 10.2 6.02 .002 13.5 57.4 91.6 .63 .45 1.06 .30

Toppenish 13 P 8.2 .0 .23 .0 7.9 5.1 180.8 .03 .03 NA .03

Toppenish 13 C 8.2 32.0 13.26 .11 26.7 294.1 180.8 1.63 .5 3.93 .33

Moxee 14 P 8.3 .0 .43 .0 7.8 4.8 93.1 .05 .06 NA .05

Moxee 14 C 8.3 12.7 6.09 .189 14.6 68.7 93.1 .74 .42 1.54 .29

Ahtanum 15 P 14.4 .0 2.67 .0 10.6 30.7 165.8 .19 .25 NA .19

Ahtanum 15 C 14.4 15.9 11.62 .202 18.3 133.6 165.8 .81 .63 1.10 .38

Rattle west 16 P 8.3 .0 .63 .0 7.6 5.1 67.8 .08 .08 NA .08

Rattle west 16 C 8.3 5.0 2.66 .003 10.4 21.6 67.8 .32 .26 .60 .20

Wenas 17 C 12.4 21.0 11.02 .192 22.0 19.4 21.9 .89 .5 1.69 .33

Naches 18 P 43.0 .0 25.3 .0 16.7 2,041.9 3,485 .58 1.51 NA .58

upper Yakima 19 P 53.0 .0 34.0 .0 19.1 2,822.1 4,412 .64 1.78 NA .64

ToppSatus 20 P 17.0 .0 3.72 .0 13.2 281.2 1,286 .22 .28 NA .22

Yak Canyon 21 P 21.0 .0 4.00 .0 17.0 119.7 628 .19 .24 NA .19

Estimates of Ground-Water Recharge 19
Most recharge in the humid areas discharges as shallow 

subsurface flow to support streamflow (Mastin and Vaccaro, 

2002b) rather than entering the bedrock hydrogeologic units 

in the uplands. For example, PRMS calculated mean annual 

inflow to the ground-water reservoirs in the 1,127 mi2 upper 

Yakima area to be about 960 ft3/s (about 34 percent of the 

calculated 2,821 ft3/s of deep percolation), most of which 

provides baseflow to streams above Keechelus, Kachess, 

and Cle Elum Lakes. Inflow to the bedrock units (recharge 

to the aquifers) in the upland areas is limited because the 

units generally have low permeability (Molenaar and others, 

1980) that is much less than the overlying soils and (or) the 

unconsolidated deposits are generally thin or missing in 

these areas (Jones and others, 2006). Estimated mean annual 

predevelopment recharge was only about 1.0 in., or 187 ft3/s 

(about 0.14 million acre-ft) for the 2,540 mi2 in the 14 areas 

modeled with DPM. Recharge in these areas, which is about 

3 percent of the total basin recharge, was about 10 percent of 

the precipitation.

The mean annual predevelopment recharge estimates for 

modeled areas (table 2) vary widely, as do the ratios of recharge 

to precipitation (R/P). The large variations in mean annual 

recharge (0.08 to 33.9 in.) for the areas further highlight the 

spatial variations shown on figure 9. For example, recharge in 

the humid areas was 1 to 2 orders of magnitude larger than that 

in other areas, and R/P was above 0.60. In contrast, R/P ranged 

from 0.01 to 0.19 for the 14 areas modeled with DPM, of which 

11 areas had R/P values of less than 0.10. One of the smallest 

recharge estimates, 0.11 in., was for the Prosser area (fig. 7, 

table 2), where recharge is less than 1 ft3/s (about 585 acreft) and R/P is 0.01. Intermediate amounts of recharge, 2.16 

to 4.00 in., occur in the Ellensburg, ToppSatus, Yak Canyon, 

lower Naches, and Ahtanum areas, where precipitation was 

greater than 14 in. (fig. 7 and table 2), and the R/P values were 

between 0.18 and 0.22.

Except for the humid areas, the ratio of predevelopment 

recharge to model-calculated actual evapotranspiration (AET) 

approximates the R/P values (table 2) because AET accounts 

for most of the incident precipitation. The model-calculated 

potential evapotranspiration for the semiarid to arid areas also 

is much greater than precipitation.

Estimated current recharge increased as a result of human 

activities (fig. 10). Excluding septic-system recharge (discussed 

separately below), mean annual current condition recharge was 

estimated to be 15.6 in., or 7,132 ft3/s (5.2 million acre-ft)—an 

increase of 3.7 in. or 1,682 ft3/s (1.2 million acre-ft) from 

predevelopment conditions. The largest increases in recharge 

were in areas with the most surface-water irrigation; recharge 

in some irrigated arid areas was estimated to be similar to the 

recharge in the humid areas. For example, the Prosser area 

(predevelopment recharge of 0.11 in.) was estimated to receive 

about 22.5 in., or 165.6 ft3/s (about 0.12 million acre-ft) of 

recharge under current conditions (table 2), which is similar to 

the 25.3 in. of recharge for the humid Naches area. Therefore, 

under current LULC conditions, recharge is derived primarily 

from precipitation in the uplands and applied irrigation water in 

the lowlands.

Excluding recharge from septic-system drainfields, 

the 16 DPM-modeled areas with extensive human activities 

(fig. 8) produce about 1,955 ft3

/s of recharge (an increase 

of about 1,769 ft3/s from predevelopment conditions for the 

DPM areas [table 2]). A large part of this quantity, however, 

is expressed as streamflow in drains and wasteways that 

ultimately becomes return flow to the streams. These return 

flows are relied on to meet downstream demands for irrigation 

and instream flows. Septic systems produce only about 17 ft3/s 

(about 12,000 acre-ft) of recharge in these 16 areas, and the 

basin-wide mean annual septic recharge is about 0.04 in. 

(about 0.2 percent of the total basin average current recharge). 

Locally, the septic-system recharge can be much greater 

than precipitation-derived recharge, especially in areas with 

concentrated population and or with low annual precipitation 

quantities. For example, a 4-acre census block in the lower 

Naches area had a population of 293 and a resulting large 

quantity of septic recharge. Also compare predevelopment 

recharge to septic recharge for the Selah-Wenas and Ahtanum 

areas (table 2).

The change in recharge between predevelopment and 

current conditions is most pronounced for the modeled areas 

with the most irrigation, but it is also pronounced for areas 

that are only partly irrigated. For example, LULC for the 

Ahtanum area (fig. 7, table 2) was estimated to be about 

48 percent native sagebrush and grasslands, about 37 percent 

irrigated (surface water and ground water) agriculture, and 

about 12 percent high-density development (urban areas, 

residential, and commercial), with the remaining 3 percent 

of the area containing several other LULCs. Its average 

annual water-application rate, 15.9 in. (about 183 ft3/s), was 

about the median for the 16 areas. The spatial distribution of 

recharge for both LULC conditions (figs. 11–12) indicates 

the magnitude of the effects of human activities. Precipitation 

was about 14.4 in. and, with the 15.9 in. application rate, 

recharge increased by about 9 in. (103 ft3/s). Correspondingly, 

R/T (where T is the total water input—the sum of P and the 

application rate) doubled from 0.19 to 0.38 (table 2). The 

relatively uniform distribution of predevelopment recharge 

(fig. 11) changed dramatically under current conditions 

(fig. 12), and there are both large increases and some decreases 

in the areas with high-density development.

On an annual basis, recharge, and the difference between 

predevelopment and current recharge, vary widely. The annual 

values for the lower Naches area (fig. 13; location shown 

on fig. 8) clearly show large interannual variations (more 

than 5 in.) and the effects of irrigation on model-calculated 

recharge and AET.

The estimated current recharge in the built-up areas was 

zero due to the assumption that these areas are impervious 

LULC. Although this results in areas of no recharge to 

the aquifer system, most of these areas are surrounded by 

extensive irrigated lands, and the ground-water levels in the 

shallow hydrogeologic units would not be representative of 

areas with zero recharge.

20 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
Mean annual recharge, in inches

0 - 0.1

0.11 - 0.5

0.51 - 2.0

2.1 - 5.0

5.1 - 10.0

10.1 - 20.0

20.1 - 50.0

> 50

EXPLANATION

Boundaries of Yakima

River basin and model

shown in figures 11–12

46°00' N 46°30' N 47°00' N 47°30' N

121°30' W 121°00' W 120°30' W 120°00' W 119°30' W 119°00' W

0 10 20 Miles

0 10 20 Kilometers

Figure 10. Spatial distribution of mean annual recharge for current conditions, Yakima River Basin, Washington.

Estimates of Ground-Water Recharge 21
EXPLANATION

Mean annual recharge,

in inches

0 - 0.1

0.11 - 0.5

0.51 - 2.0

2.1 - 5.0

5.1 - 10.0

>10

46°30' N 35' N 40' N 45' N

120°55' W 50' W 45' W 40' W 35' W 120°30' W

0 1 2 3 4 Miles 5

0 1 2 3 4 Kilometers 5

Figure 11. Spatial distribution of mean annual recharge for predevelopment conditions in the Ahtanum area, 

Yakima River Basin, Washington.

22 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
EXPLANATION

Mean annual recharge,

in inches

0 - 0.1

0.11 - 0.5

0.51 - 2.0

2.1 - 5.0

5.1 - 10.0

10.01 - 20

>20

46°30' N 35' N 40' N 45' N

120°55' W 50' W 45' W 40' W 35' W 120°30' W

0 1 2 3 4 Miles 5

0 1 2 3 4 Kilometers 5

Figure 12. Spatial distribution of mean annual recharge for current conditions in the Ahtanum area, Yakima 

River Basin, Washington.

Estimates of Ground-Water Recharge 23
Factors Controlling Recharge

The two dominant factors controlling predevelopment 

ground-water recharge are the quantity and timing of 

precipitation (including snow accumulation and melt) and the 

soil properties. Although recharge is affected by the LULC, 

it is similarly controlled by the quantity of precipitation. 

For current conditions, the irrigation of croplands is an 

additional controlling factor. The daily-to-interannual 

(climate) variability of precipitation, and to some extent air 

temperature, also influences the amount of recharge under 

both predevelopment and current conditions.

The relation between mean annual recharge and total 

water input (R/T, where T is total water input: precipitation for 

predevelopment conditions and precipitation plus irrigation 

for current conditions) clearly shows the control that the 

quantity of water input has on recharge (fig. 14 and table 2). 

Estimated recharge increases nearly linearly from T quantities 

of about 7 to about 40 in. At T values larger than about 40 in., 

the relationship is nonlinear due to the effects of: (1) timing 

of water input, (2) excess water above the amount that can be 

captured by AET, and (3) soil properties. The timing of water 

input is best reflected by estimated current recharge for two 

areas (Prosser and Roza-Sunny areas, tables 1–2) with the 

largest percentage of irrigated lands. These two areas have 

a total water input of about 53 and 50 in., respectively, and 

ratios of irrigation to precipitation (I/P) of more than 5.5; I/P 

ratios ranged from about 0.2 to 4 for the other areas. During 

the growing season, crops in the Prosser and Roza-Sunny 

areas use a larger part of T in comparison to the upper Yakima 

area (which has a similar total water input) because the input 

to the upper Yakima area mainly occurs during the nongrowing season and is not available for AET. This difference 

also reflects the excess water above the amount that can be 

captured by AET; note that the potential evapotranspiration is 

also much lower in the uplands than in the lowlands.

Precipitation

Irrigation

Predevelopment actual 

 evapotranspiration

Current actual evapotranspiration 

Predevelopment recharge

Current recharge

EXPLANATION

5

10

15

20

25

30

0

RATE, IN INCHES PER YEAR

1950 1960 1970 1980 1990 2000

WATER YEAR

Figure 13. Calculated annual values of selected water-budget components for the lower Naches area.

The control that the soils have on recharge is reflected 

in the relation between mean annual recharge and the ratio of 

the total quantity of water that can be stored in the root or soil 

zone (S) to T (fig. 15). The information for figure 15 is only 

for the areas modeled with DPM, because PRMS does not 

include a saturated soil-moisture storage compartment. 

S is used instead of TAWC because S/T values are larger than 

TAWC/T, and the large amount of irrigation input results 

in saturated soils (one reason for constructing tile drains, 

wasteways, and drainage ditches) that are better accounted 

for by using S. For S/T values greater than one, recharge is 

limited because the mean annual water input is less than the 

total water storage capacity, and for values less than one, the 

estimated recharge sharply increases, especially for values less 

than about 0.6. The estimated average S for the basin is about 

14 in., indicating that, on average, the soils can store about 

14 inches of the precipitation falling in the basin. Indeed, the 

difference between the basin’s mean annual precipitation and 

S is about 12 in., which is nearly equivalent to the estimated 

mean annual predevelopment recharge.

Mean annual recharge is greater than zero for S/T values 

greater than 1.0 because of the temporal variations in the water 

input. For example, the Prosser area (fig. 8) has a S/T value 

of 1.65 and a mean annual predevelopment recharge value of 

0.11 in. (table 2) with a large range in annual predevelopment 

recharge—35 percent of the annual values were zero, 68 percent 

were less than 0.01 in., and 85 percent were less than 0.2 in. 

(fig. 16). These variations are due to both interannual variations 

in precipitation and its timing; if the precipitation quantity is 

large or if it occurs over a short period of time, the TWAC may 

be exceeded, especially during September through March when 

potential evapotranspiration is low. The non-linearity between 

ground-water recharge and daily-to-annual precipitation has 

been described by Rushton and Ward (1979), Stephens and 

Knowlton (1986), Gee and Hillel (1988), and Bauer and 

Vaccaro (1990). The non-linearity was a major factor for using 

daily modeling techniques.

24 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
MEAN ANNUAL RECHARGE, IN INCHES

0

5

10

15

20

25

30

35

5 10 15 20 25 30 35 40 45 50 55

MEAN ANNUAL TOTAL WATER INPUT, IN INCHES

Predevelopment conditions

Current conditions

Figure 14. Relation between mean annual recharge and the 

mean annual total water input (precipitation or precipitation 

plus irrigation) for the modeled areas for predevelopment and 

current conditions.

25

20

15

10

5

0

0.0 0.5 1.0 1.5 2.0 2.5

MEAN ANNUAL RECHARGE, IN INCHES

RATIO OF ROOT ZONE STORAGE TO TOTAL WATER INPUT

Predevelopment conditions

Current conditions

Figure 15. Relation between mean annual recharge and the 

ratio of the total quantity of water that can be stored in the 

root zone to the total water input for the areas modeled using 

the Deep Percolation Model for predevelopment and current 

conditions.

Predevelopment recharge

Annual precipitation

2

4

6

8

10

12

14

16

0

MEAN ANNUAL PRECIPITATION AND RECHARBE, IN INCHES

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

WATER YEAR

Figure 16. Annual precipitation and estimated predevelopment recharge for the Prosser area, Yakima River 

Basin, Washington.

Factors Controlling Recharge 25
Potential Sources of Error in Recharge 

Estimates

Potential sources of error in the estimates of recharge are 

described by following the flux of water through the landsurface system as calculated by the models. This description 

starts with the weather data and ends with the water leaving 

the root or soil zone.

Both errors in the daily weather data and the interpolation 

of weather data to HRUs produce errors in recharge 

calculations (Bauer and Vaccaro, 1990). In the uplands, the 

total annual runoff for a watershed (subbasin) was simulated 

to be lower in some years and higher in others compared to 

the observed/estimated value (Mastin and Vaccaro, 2002a); 

the differences were mainly attributed to the weather data 

and the interpolation of the data to HRUs. Thus recharge was 

either under- or over-estimated for such years. However, the 

simulated and estimated mean annual runoff volume for the 

basin were similar (Mastin and Vaccaro, 2002a) and the mean 

annual water budget under predevelopment conditions was 

reasonable (mean annual recharge was similar to mean annual 

discharge). Mastin and Vaccaro (2002a) used regression 

analysis to estimate that about 165 ft3/s of the mean annual 

streamflow under predevelopment conditions was produced by 

the 14 areas modeled with DPM, which is consistent with the 

mean annual recharge estimate of 187 ft3/s, assuming that most 

of the recharge ultimately becomes streamflow for these areas. 

At shorter time scales (daily to annual), both the spatial and 

temporal distribution of recharge will contain some unknown 

amount of error due to the weather data and its interpolation.

Estimates of irrigation application rates are another 

source of error because their quantities are similar to or 

greater than the precipitation quantities in some areas. The 

I/P ratio ranged from 0.2 to 5.9 and averaged 1.96 for the 

DPM-modeled areas, and only four areas had I/P ratios of 

less than 1.0. Therefore, errors in the estimates of irrigation 

application rates, which averaged about 82 percent of 

irrigation diversions, can have a large effect on the estimated 

recharge. Detailed information on irrigation operations 

(diversion, operational spill, canal/lateral loss, and deliveries) 

was available for several years for one irrigation district, and 

the information indicated that for the later years of simulation 

the effective application rate might be 10 percent too large. If 

application rates were similarly overestimated in other areas, 

the estimated recharge rate for the DPM-modeled areas with 

surface-water irrigation may be more than 1 in. too large. 

The application rates were assumed to be constant over the 

period of simulation and, although this captures the long-term 

mean annual recharge, there will be errors for years when the 

rate was either lower or higher than average. For example, in 

the severe drought of 2001, much less water than usual was 

applied in several of the irrigation districts with junior water 

rights, and thus the recharge estimates would be too large. 

Conversely, the recharge may be too small during the early 

years of simulation (typically prior to 1977) because there was 

a plentiful supply of water for irrigation; differences between 

annual calculated unregulated and regulated streamflow 

increase as the unregulated flow increases, indicating that 

more water is diverted and lost in wet years (Vaccaro, 1986). 

Assuming that the ratio of R/T for an area is applicable if more 

or less water is applied, and adding or subtracting 4 in. (the 

range in the potential crop water use for 1950–2003) to the 

application rate, suggests that using a constant application rate 

can result in errors of about 10 percent in some years if the 

application rate was 4 in. too low or too high. In more extreme 

drought years such as 1992, 1994, and 2001, the recharge 

estimate may be as much 20 percent too high.

The mean monthly precipitation values for the HRUs 

were based on a national database of grids that are 4- by 

4-km cells (PRISM, Daly and others, 1998), leading to large 

differences across the boundaries of those grids in areas with 

large gradients in monthly precipitation. In turn, there are 

similar changes in the interpolated precipitation values at the 

HRUs near the grid boundary. As a result, there are differences 

in calculated recharge values across these boundaries, 

especially for predevelopment estimates of recharge in the 

semiarid to arid parts of the study area (see for example, 

fig. 11). The total estimated mean annual recharge for these 

areas is reasonable but the spatial distribution will be in 

error—some areas have recharge values that are too low and 

other areas have values that are too high. This type of error is a 

discretization problem due to differences in scale.

The next potential source of error in recharge estimates 

is the assignment of the LULC to a HRU. For example, 

under natural conditions, in a typical plant community 

throughout much of the non-forested parts of the study area, 

sagebrush and grasses are generally intermixed, with grasses 

starting to predominate in the forest-transition zone. For 

predevelopment conditions, the DPM HRUs with human 

influences (agriculture, urban areas, etc.) were assigned a 

LULC of sagebrush. Sagebrush, being more deeply rooted 

than grasses, uses more water, and thus, recharge is less. If a 

HRU was predominantly grassland instead of sagebrush, the 

predevelopment recharge estimate would be too small. For 

current conditions, the LULC was based on the composite 

LULC database, and several factors can lead to errors in the 

estimated recharge. Assignment of a low water-use crop type 

in contrast to a high water-use crop (and the opposite) can 

lead to both over-estimated and under-estimated recharge 

and the amount would be dependent on the application rate. 

Although some error is introduced due to assigning a HRU 

the wrong LULC, more error is due to assuming that the 

composite database was valid for all years. The composite 

distribution does not capture the spatial and temporal changes 

in crop types and amount of irrigated lands. The potential error 

would be greater in calculations for the earlier years and less 

for the surface-water irrigated areas established prior to 1950 

and greater for ground-water irrigated areas because of the 

increase in acres irrigated with ground water since 1950.

26 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
After calculating the amount of precipitation and 

irrigation water intercepted by plants, soil column calculations 

are performed on any remaining water (including snowmelt). 

Therefore, the next important source of error is due to the 

soil information for each HRU. The largest potential source 

of error is due to the differences between the generalized 

STATSGO data and the detailed SSURGO data. The SSURGO 

data provides more detail both spatially and with depth. 

STATSGO retains the effective information for the mapped 

soils in the survey areas, but the actual spatial distribution 

is coarse. Thus, the total recharge for the models that used 

the STATSGO data should approximate the actual recharge 

but there would be errors in the spatial distribution; this is 

another discretization problem. Differences in hydrologic 

properties for the same soil-mapping unit occur across some 

of the boundaries of the different SSURGO survey areas. For 

example, the same soil-mapping unit may have a high TAWC 

in one survey area but a low TAWC in the adjacent area, or the 

soil depths may vary; in either case, calculated recharge would 

be different across those boundaries. It was beyond the scope 

of this study to rectify these differences, and thus there are 

differences in calculated recharge across these discontinuities. 

Lastly, to simplify the data management and input for 

estimating recharge for such a large study area, an ‘effective’ 

depth-weighted TAWC was calculated for each soil type. This 

averaging of the TAWC may introduce some error into the 

estimated recharge, especially for predevelopment conditions 

in the semiarid to arid areas. For example, if a clay soil layer 

overlies a sandy soil layer, more water would be retained 

in the upper clay soil and thus more water would be used 

by evapotranspiration than calculated by using an averaged 

value. However, analysis of the layering for selected soil types 

suggests that any error from such averaging is not large.

The amount of water leaving the root or soil zone is a 

function of the vertical infiltration rate below the soils for a 

HRU—the basal (subsoil) rate or infiltration capacity. The rate 

was estimated to be high for soils overlying coarse-grained 

deposits and low for soils overlying bedrock. The rate was 

determined from the depth-to-bedrock information in the 

soil databases. Shallow soils were assigned a low infiltration 

rate and deep soils (typically no bedrock) were assumed 

to overlie deposits with a high infiltration rate. Errors in 

the identification of this HRU parameter can lead to errors 

in recharge. In some areas, deep soils may overlie clayey 

deposits and consequently, the recharge estimate would be 

too high; in other areas soils may overlie bedrock units with 

a high infiltration capacity and the recharge estimate would 

be too low. The potential error in the recharge estimate from 

misidentification of the infiltration rate is not known, but for 

much of the area included in the DPM models, the type of 

underlying deposits is reasonably defined.

Considering all sources of error and the known sensitivity 

of recharge to different factors (Bauer and Vaccaro, 1990), 

the error in the recharge estimates for the modeled areas is 

uncertain. However, mean annual recharge for predevelopment 

conditions is consistent with the information presented in 

Mastin and Vaccaro (2002a), and the error for the basin-wide 

mean annual predevelopment conditions is considered to be on 

the order of 10 percent. The estimated difference between the 

mean annual streamflow leaving the basin for predevelopment 

conditions compared to current conditions is about 

2,000 ft3/s, and the estimated increase in mean annual AET 

from predevelopment to current conditions is about 1,720 ft3/s, 

suggesting about a 15 percent error in the estimated total mean 

annual recharge for current conditions. Area-averaged annual 

recharge values for predevelopment and current conditions 

likely have an error on the order of 25 percent.

The relative error in recharge values increases with an 

increase of spatial and temporal resolution. Although the 

overall spatial distribution of the estimated annual recharge 

in any modeled area is reasonable, the error in the estimated 

recharge for a particular HRU can be quite large. Similarly, 

estimates of daily to monthly recharge likely have larger 

relative errors than estimates of annual recharge.

Summary and Conclusions

Recharge was estimated for 6,207 mi2 of the Yakima 

River Basin aquifer system for predevelopment and current 

land-use and land-cover conditions to help in assessing water 

availability and water management and planning. Recharge 

was estimated using the Precipitation-Runoff Modeling 

System (PRMS) and the Deep Percolation Model (DPM) 

that are contained in the U.S. Geological Survey’s Modular 

Modeling System. The models estimated daily values of 

recharge for water years 1950-98 using four previously 

developed PRMS models for the mostly forested upland parts 

of the study area. Daily values were calculated for water years 

1950-2003, using 14 DPMs applied to the semiarid to arid 

lowlands for predevelopment conditions, and using 16 DPMs 

for current conditions. The daily values of recharge were 

then aggregated to monthly, annual, mean monthly, and mean 

annual values.

The mean annual predevelopment recharge was estimated 

to be about 11.9 in., or 5,450 ft3/s (about 4 million acre-ft). 

About 97 percent of the recharge was calculated to occur in 

the upland areas included in the watershed models, but most 

of this recharge is not available to the bedrock hydrogeologic 

units. Only about 1.0 in., or 187 ft3/s (about 0.14 million 

acre-ft) of the total mean annual recharge was estimated to 

occur in the 2,554 mi2 area included in the deep percolation 

models. Mean annual recharge for all the modeled areas 

ranged from 0.08 in. (1.2 ft3/s) to 34 in. (2,822 ft3/s).

The mean annual recharge under current land-use and 

land-cover conditions was estimated to be about 15.6 in., 

or 7,132 ft3/s (about 5.2 million acre-ft). Septic-system 

drainfields provide another 17 ft3/s of recharge to the aquifer 

system. The increase in recharge from predevelopment 

Summary and Conclusions 27
conditions was principally due to the application of irrigation 

water to croplands. For some of the modeled areas, the 

irrigation application quantity was more than five times 

larger than the precipitation quantity. As a result, the ratio of 

recharge to total water input increased from less than 0.1 to 

more than 0.5. Actual evapotranspiration was calculated to 

have increased by more than 1,700 ft3/s (about 1.2 million 

acre-ft). Similar to recharge in the humid areas, additional 

recharge under current conditions may not be available to 

deeper aquifers because of shallow sub-surface discharge to 

drains and wasteways.

The main factors that control predevelopment groundwater recharge are the quantity of precipitation and the soil 

properties. For current conditions, the land use and land cover 

and the irrigation of croplands are additional factors. The 

mean annual predevelopment recharge has a potential error of 

about 10 percent, and for current conditions, the mean annual 

recharge error is estimated to be about 15 percent.

Acknowledgments

The authors wish to thank the Bureau of Reclamation, 

Bureau of Indian Affairs, and the Washington State 

Department of Ecology and groups such as conservation 

districts, irrigation districts, and the Yakama Nation that 

provided valuable support and access to their records during 

this study. The authors also thank Steven Wangemann of the 

Bureau of Indian Affairs for developing the soil database for 

the Yakama Nation irrigated lands, and Edward Young of 

the Bureau of Reclamation for providing many Geographic 

Information System databases and for constructing the initial 

land use/land cover database from the numerous data sources.

References Cited

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

precipitation in three small glacial-till-mantled catchments 

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

Survey Water-Resources Investigations Report 96-4219, 

119 p., accessed October, 2006 at http://pubs.er.usgs.gov/

usgspubs/wri/wri964219

Bauer, H.H., and Vaccaro, J.J., 1987, Documentation of a deep 

percolation model for estimating ground-water recharge: 

U.S. Geological Survey Open-File Report 86-536, 180 p., 

accessed October, 2006 at http://pubs.er.usgs.gov/usgspubs/

ofr/ofr86536

Bauer, H.H., and Vaccaro, J.J., 1990, Estimates of groundwater recharge to the Columbia Plateau regional 

aquifer system, Washington, Oregon, and Idaho, for 

predevelopment and current land-use conditions: U.S. 

Geological Survey Water-Resources Investigations Report 

88-4108, 37 p., 2 pls., accessed October, 2006 at http://pubs.

er.usgs.gov/usgspubs/wri/wri884108

Bureau of Reclamation, 1999, Yakima River Basin Water 

Enhancement Project, Washington, Final Programmatic 

Environmental Impact Statement: U.S. Department of 

Interior, Bureau of Reclamation, Pacific Northwest Region, 

Upper Columbia Area Office, Yakima, Washington, 197 p.

Cuffney, T.F., Meador, M.R., Porter, S.D., and Gurtz, M.E, 

1997, Distribution of fish, benthic invertebrate, and 

algal communities in relation to physical and chemical 

conditions, Yakima River Basin, Washington, 1990: U.S. 

Geological Survey Water-Resources Investigations Report 

96-4280, 94 p.

Daly, C. and Taylor, G.H., 1998, 1961-90 mean annual and 

monthly precipitation maps for the conterminous United 

States, Oregon Climate Center, on-line on the World Wide 

Web, May 2000 at http://www.ocs.orst.edu/pub/maps/

Precipitation/prism_ppt.README

Drost, B.W., Whiteman, K.J., and Gonthier, J.B., 1990, The 

geologic framework of the Columbia Plateau regional 

aquifer system, Washington, Oregon, and Idaho: U.S. 

Geological Survey Water-Resources Investigations Report 

87-4238, 10 p., 10 sheets.

Flaherty, N.M., 1975, The Yakima Basin and its water: 

Washington State University, Water Resources Center, 

Pullman, Wash., 29 p.

Fuhrer, G.J., McKenzie, S.W., Rinella, J.F., Sanzolone, R.F., 

and Skach, K.A., 1994, Surface-water assessment of the 

Yakima River Basin in Washington: Analysis of major 

and minor elements in fine-grained-streambed sediment, 

1987, with a section on Geology, by M.W. Gannett: U.S. 

Geological Survey Open-File Report 93-30, 226 p.

Fuhrer, G.J., Morace, J.L., Johnson, H.M., Rinella, J.F., 

Ebbert, J.C., Embrey, S.S., Waite, I.T., Carpenter, K.D., 

Wise, D.R., and Hughes, C.A., 2004, Water quality in 

the Yakima River Basin, Washington, 1999-2000: U.S. 

Geological Survey Circular 1237, 44 p.

Gee, G.W., and Hillel, D., 1988, Groundwater recharge in 

arid regions: Review and critique of estimation methods: 

Hydrologic Processes, v. 2, p. 255-266.

Glantz, M.H., 1982, Consequences and responsibilities in 

drought forecasting: The case of Yakima, 1977: Water 

Resources Research, v. 18, no. 1, p. 3-13.

28 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
Homer, Collin, Huang, Chengquan, Yang, Limin, Wylie Bruce, 

and Coan, Michael, 2004, Development of a 2001 National 

Landcover Database for the United States: Photogrammetric 

Engineering and Remote Sensing, v. 70, no. 7, p. 829-840, 

accessed October, 2002, at http://www.mrlc.gov/mrlc2k_

product_desc.asp

Jones, M.A., Vaccaro, J.J., and Watkins, A.M., 2006, 

Hydrogeologic framework of sedimentary deposits in six 

structural basins, Yakima River Basin, Washington: U.S. 

Geological Survey Scientific Investigations Report 2006-

5116, 24 p., 7 pls. accessed October 2006, at http://pubs.

water.usgs.gov/sir2006-5116

Kratz, M.R., 1978, Dilemmas, disruptions, but no disaster—

drought in the Yakima basin, Washington, 1977: State 

Climatologist for Arizona Climatological Publications, 

Scientific Paper No. 3, 16 p.

Leavesley, G.H., Lichty, R.W., Troutman, B.M., and Saindon, 

L.G., 1983, Precipitation-runoff modeling system—users 

manual: U.S. Geological Survey Water-Resources 

Investigations Report 83-4238, 207 p., accessed October 

2006, at http://pubs.er.usgs.gov/usgspubs/wri/wri834238

Leavesley, G.H., Restrepo, P.J., Markstrom, S.L., Dixon, M., 

and Stannard, L.G., 1996, The modular modeling system 

(MMS)—user’s manual: U.S. Geological Survey Open-File 

Report 96-151, 142 p., accessed October 2006, at http://

pubs.er.usgs.gov/usgspubs/ofr/ofr96151

Leavesley, G.H., Viger, R.J., Markstrom, S.L., and 

Brewer, M.S., 1997, A modular approach to integrating 

environmental modeling and GIS: Berlin, Germany, in

Proceedings of 15th IMACS World Congress on Scientific 

Computation, Modelling, and Applied Mathematics, no 

pagination.

Loveland, T.R., Merchant, J., Ohlen, D.O., and Brown, J., 

1991, Development of a land cover characteristic data 

base for the conterminous United States: Photogrammetric 

Engineering and Remote Sensing, v. 57, no. 11, 

p. 1453-1463.

Mastin, M.C., and Vaccaro J.J., 2002a, Documentation of 

precipitation runoff modeling system modules for the 

modular modeling system modified for the watershed 

and river systems management program: U.S. Geological 

Survey Open-File Report 02-362, accessed December 9, 

2002, at http://pubs.water.usgs.gov/ofr02362/

Mastin, M.C., and Vaccaro, J.J., 2002b, Watershed models for 

decision support in the Yakima River basin, Washington: 

U.S. Geological Survey Open-File Report 02-404, 46 p., 

accessed October 2006, at http://pubs.usgs.gov/of/2002/

ofr02404

Meyers, C.W., and Price, S.M., 1979, Geologic studies of the 

Columbia Plateau, a status report: Rockwell International, 

Rockwell Hanford Operations RHO-BWI-ST-4, 520 p.

Molenaar, Dee, Grimstead, Peder, and Walters, K.L., 

1980, Principal aquifers and well yields in Washington: 

Washington State Department of Ecology, Geohydrologic 

Monograph 5, 1 pl.

Omernik, J.M., 1987, Ecoregions of the conterminous United 

States: Annals of the Association of American Geographers, 

v. 77, no. 1, p. 118-125.

Parker, G.L., and Storey, F.B., 1913, Water powers of the 

Cascade Range, Part III, Yakima River Basin: U.S. 

Geological Survey Water-Supply Paper 369, 169 p., 18 

plates, accessed October 2006, at http://pubs.er.usgs.gov/

usgspubs/wsp/wsp369

Rushton, K.R., and Ward, C., 1979, The estimation of 

groundwater recharge: Journal of Hydrology, v. 41, 

p. 345-361.

Soil Survey Staff, Natural Resources Conservation Service, 

United States Department of Agriculture, undated, Soil 

Survey Geographic (SSURGO) Database for Yakima River 

Basin, Washington; accessed October 2000-December 2004, 

at http://soildatamart.nrcs.usda.gov

Solley, W.B., Merk, C.F., and Pierce, R.R., 1988, Estimated 

water use in the United States in 1985: U.S. Geological 

Survey Circular 1004, 82 p.

Solley, W.B., Pierce, R.R., and Perlman, H.A., 1993, 

Estimated water use in the United States in 1990: U.S. 

Geological Survey Circular 1081, 76 p.

Stephens, D.B., and Knowlton, B., 1986, Soil water movement 

and recharge through sand at a semiarid site in New 

Mexico: Water Resources Research, v. 22, no. 6, 

p. 801-809.

Systems Operations Advisory Committee, 1999, Report 

on biologically based flows for the Yakima River basin: 

Report to The Secretary of the Interior, May 1999, Yakima, 

Washington, Executive Summary, 6 chapters, Appendix A, 

variously paginated.

U.S. Census Bureau, 2004, Census 2000 TIGER/Line Data: 

accessed July 2004 at http://www.census.gov/.

U.S. Department of Agriculture, 1994, State Soil Geographic 

(STATSGO) Data Base: Data Use information, Soil 

Conservation Service, National Cartography and GIS 

Center, Fort Worth, Texas, accessed April, 1997 at http://

dbwww.essc.psu.edu/dbtop/amer_n/us_nw/wa/data/

soilprop/statsgo/doc.html

References Cited 29
U.S. District Court, 1945, Spokane, Washington, Consent 

decree in the District Court of the United States for the 

Eastern District of Washington, Southern Division: Civil 

action No. 21.

U.S. Geological Survey, 1998, Watershed and river systems 

management program: Application to the Yakima River 

basin, Washington: U.S. Geological Survey Fact Sheet FS037-98, 4 p., accessed October 2006, at http://pubs.er.usgs.

gov/usgspubs/fs/fs03798

U.S. Geological Survey, 2000, National Elevation Dataset, 

accessed January 2002, at http://seamless.usgs.gov/website/

seamless/products/3arc.asp

Vaccaro, J.J., 1986, Comparison of unregulated and regulated 

streamflow for the Yakima River at Union Gap and near 

Parker, Washington. U.S. Geological Survey Open-File 

Report 82-646, 54 p., accessed October 2006, at http://pubs.

er.usgs.gov/usgspubs/ofr/ofr82646

Vaccaro, J.J., 1995, Changes in the hydrometeorological 

regime in the Pacific Northwest: Proceedings of the 

Twelfth Annual Pacific Climate Workshop, Asilomar, Cal., 

Technical Report 46 of the Interagency Ecological Program 

for the Sacramento-San Joaquin Estuary, p. 143.

Vaccaro, J.J., 2007, A deep percolation model for estimating 

ground-water recharge: Documentation of modules for the 

modular modeling system of the U.S. Geological Survey: 

U.S. Geological Survey Scientific Investigations Report 

2006-5318, 30 p.

Vaccaro, J.J., and Sumioka, S.S., 2006, Estimates of groundwater pumpage from the Yakima Basin Aquifer System, 

Washington, 1960-2000: U.S. Geological Survey Scientific 

Investigations Report 2006-5205, 56 p.

Viger, R.J., Markstrom, S.L., and Leavesley, G.H., 1997, 

The GIS Weasel – An interface for the treatment of spatial 

information used in watershed modeling and water resource 

management in Proceedings of the First Federal Interagency 

Hydrologic Modeling Conference, April 19-23, 1998, Las 

Vegas, Nevada, v. II, chap. 7, p. 73-80.

Washington State Department of Ecology, 1998, Washington 

State Water Law, A Primer: WR-98-152, accessed October 

2000, at http://www.ecy.wa.gov/pubs/98152

30 Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer, Washington
Manuscript approved for publication, January 10, 2007

Prepared by the USGS Publishing Network, 

Publishing Service Center, Tacoma, Washington

Bill Gibbs 

Chris Janda

Christine Severtson

Bobbie Jo Richey

Sharon L. Wahlstrom

Chet Zenone

For more information concerning the research in this report, contact the 

Director, Washington Water Science Center

U.S. Geological Survey, 934 Broadway — Suite 300

Tacoma, Washington 98402

http://wa.water.usgs.gov
Version 

SIR 2007–5007

1.2,

April 2009

Vaccaro and Olsen

Printed on recycled paper

Estimates of Ground-Water Recharge to the Yakima River Basin Aquifer System, Washington, 

for Predevelopment and Current Land-Use and Land-Cover Conditions