Hydrologic and Water-Quality Conditions During 

Restoration of the Wood River Wetland, 

Upper Klamath River Basin, Oregon, 2003–05

Scientific Investigations Report 2009-5004

Prepared in cooperation with the Bureau of Land Management and the

U.S. Fish and Wildlife Service

U.S. Department of the Interior

U.S. Geological Survey
Front Cover: Aerial view of the lower Wood River Valley showing the Wood River 

Wetland (center), Sevenmile Canal, Wood River, and Agency Lake. (Photograph 

courtesy of Trisha Roninger, U.S. Fish and Wildlife Service.)

Back Cover: Wood River Wetland (looking east). Photograph taken by Kurt Carpenter, 

U.S. Geological Survey, January 2003.
Hydrologic and Water-Quality Conditions During 

Restoration of the Wood River Wetland, 

Upper Klamath River Basin, Oregon, 2003–05

By Kurt D. Carpenter, Daniel T. Snyder, John H. Duff, Frank J. Triska, Karl K. Lee, 

Ronald J. Avanzino, and Steven Sobieszczyk

Prepared in cooperation with the Bureau of Land Management and the

U.S. Fish and Wildlife Service

Scientific Investigations Report 2009–5004

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Carpenter, K.D., Snyder, D.T., Duff, J.H., Triska, F.J., Lee, K.K., Avanzino, R.J., and Sobieszczyk, Steven, 2009, 

Hydrologic and water-quality conditions during restoration of the Wood River Wetland, upper Klamath River basin, 

Oregon, 2003–05: U.S. Geological Survey Scientific Investigations Report 2009-5004, 66 p. 

(Available at http://pubs.usgs.gov/sir/2009/5004)
iii

Contents

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

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

Description of Wood River Wetland ...........................................................................................................4

Origin of Wood River Wetland ...........................................................................................................4

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

Geology and Soils .................................................................................................................................6

Vegetation and Other Biota.................................................................................................................6

Climate and Water Availability ...........................................................................................................7

Hydrology ...............................................................................................................................................7

Historical and Current Water Management.....................................................................................7

Study Design and Methods........................................................................................................................10

Field Methods......................................................................................................................................10

Laboratory Methods...........................................................................................................................14

Water Budget ......................................................................................................................................14

Inflows .........................................................................................................................................15

Precipitation ......................................................................................................................15

Ground Water....................................................................................................................16

Regional Discharge .................................................................................................16

Seepage through Dikes ..........................................................................................16

Discharge from Artesian Wells .............................................................................17

Applied Flood Irrigation ...................................................................................................17

Outflows.......................................................................................................................................18

Evaporation of Open Water.............................................................................................18

Evapotranspiration from Emergent Vegetation............................................................19

Changes in storage....................................................................................................................19

Standing Surface-Water Level and Volume.................................................................19

Ground-Water Storage ....................................................................................................21

Soil-Moisture Storage......................................................................................................21

Calculation of Standing Nutrient Masses.......................................................................................21

Results ...........................................................................................................................................................22

Hydrologic Conditions During 2003–05............................................................................................22

Surface Water and Ground Water..........................................................................................22

Water Budget .............................................................................................................................23

Inflows ................................................................................................................................23

Outflows..............................................................................................................................23

Changes in Storage ..........................................................................................................28

Water-Budget Residual....................................................................................................28

Surface-Water Quality .......................................................................................................................29

Seasonal Patterns in Standing Nutrient Masses ..........................................................................41

Trace Metals........................................................................................................................................41

Ground-Water Quality ........................................................................................................................46

Biogeochemistry Experiments..........................................................................................................46
iv

Figures

Figure 1. Map of study area showing location of the Wood River Wetland, upper

Klamath River basin, Oregon ............................................................... 3

Figure 2. Map showing Wood River Wetland and locations of sampling sites, upper

Klamath River basin, Oregon ............................................................... 5

Figure 3. Maps showing observed and modeled extent of inundation and depth to

water at the Wood River Wetland, Oregon, April–August 2004 ........................ 8

Figure 4. Graphs showing stage, volume, and area relations for the North Unit, South

Unit, and North and South Units of the Wood River Wetland, Oregon ............... 9

Figure 5. Graphs showing daily water-surface elevations and standing volumes in the

North Unit and South Unit of the Wood River Wetland, upper Klamath River

basin, Oregon, 2003–05 ..................................................................... 22

Figure 6. Graphs showing ground-water elevations in wells and surface-water

elevations from staff gages in the North Unit and South Unit of the Wood

River Wetland, upper Klamath River basin, Oregon, 2003-05........................... 24

Figure 7. Graphs showing monthly water-budget components inflows,

outflows, observed changes in storage, and residuals, Wood River Wetland,

upper Klamath River basin, May 2003 through September 2005 ..................... 26

Figure 8. Graphs showing median values for water-quality variables grouped by site

type, Wood River Wetland, upper Klamath River basin, Oregon, 2003-05 ............ 30

Figure 9. Graphs showing trends in water-quality variables in the North Unit and South

Unit, Wood River Wetland, upper Klamath River basin, Oregon, 2003–05 ............ 39

Figure 10. Graphs showing median concentrations of bioavailable and total forms of 

nitrogen and phosphorus in the North and South Units, Wood River Wetland, 

upper Klamath River basin, Oregon, 2003–05. .......................................... 41

Contents—Continued

Discussion.....................................................................................................................................................51

Water-Quality ......................................................................................................................................51

Legacy Effect of Wetland Drainage and Land Management ......................................................51

Biogeochemical Processes and Nutrient Transformation...........................................................54

Potential Management Strategies............................................................................................................54

Water-Quality Management..............................................................................................................54

Water-Level Management.................................................................................................................55

Capping Artesian Wells .....................................................................................................................57

Potential Future Studies..............................................................................................................................57

Comparing Managed Wetlands........................................................................................................57

Plant Physiology Studies ...................................................................................................................57

Potential Effects of Dissolved Organic Carbon Export from Restored Wetlands.....................57

Summary........................................................................................................................................................58

Acknowledgments.......................................................................................................................................60

References Cited..........................................................................................................................................60

Appendix A. Water-Quality Data, Wood River Wetland, Oregon, 2003–05.........................................65
v

Figures—Continued

Figure 11. Graphs showing relation between dissolved chloride and specific

conductance in the North Unit and South Unit of the Wood River Wetland,

upper Klamath River basin, Oregon, 2003–05............................................. 42

Figure 12. Graphs showing ratios of nutrients to specific conductance for the North

and South Units, Wood River Wetland, upper Klamath River basin, Oregon,

2003–05 ....................................................................................... 43

Figure 13. Graphs showing trends in standing nutrient masses (nitrogen, phosphorus,

and carbon) in the North and South Units, Wood River Wetland, upper

Klamath River basin, Oregon, 2003–05 ................................................... 44

Figure 14. Graphs showing relations between dissolved oxygen and soluble reactive

phosphorus and dissolved iron and manganese, at surface water sites in 

and around the Wood River Wetland, upper Klamath River basin, 

Oregon, May 2003 ........................................................................... 45

Figure 15. Graphs showing soluble reactive phosphorus and specific conductance in

wells and piezometers in the North Unit and South Unit of the Wood River

Wetland, upper Klamath River basin, Oregon, 2003–05 ................................. 47

Figure 16. Graphs showing seasonal patterns in nutrients and dissolved oxygen

concentrations in wells at the Wood River Wetland, upper Klamath River

basin, Oregon, 2003–05 ..................................................................... 48

Figure 17. Graphs showing results of nutrient flux chamber experiments showing

concentrations of dissolved ammonium, soluble reactive phosphorus, and

dissolved oxygen in the South Unit of the Wood River Wetland, upper

Klamath River basin, Oregon, June 2005 ................................................ 49

Figure 18. Graphs showing effect of nitrate addition, glucose plus nitrate addition, and

no addition on nitrogen concentrations during in-situ chamber experiments

conducted in the South Unit of the Wood River Wetland, upper Klamath River

basin, Oregon, August 2005 ............................................................... 50

Figure 19. Graph showing annual loads of total Kjeldahl nitrogen and total phosphorus

discharged from the Wood River Wetland, upper Klamath River basin,

Oregon, 1975–2005........................................................................... 55

Figure 20. Graphs showing effect of water depth (stage) on formation and size of

ponded areas (polygons) in theNorth Unit and South Unit of the Wood River

Wetland, upper Klamath River basin, Oregon .......................................... 56
vi

Tables

Table 1. Water-quality sampling sites, Wood River Wetland, upper Klamath River

basin, Oregon, 2003–05 ..................................................................... 10

Table 2. Piezometers installed at the Wood River Wetland, upper Klamath River basin,

Oregon, July 2003 ........................................................................... 13

Table 3. Artesian wells at Wood River Wetland, upper Klamath River basin, Oregon. ...... 17

Table 4. Estimated monthly evaporation from open water and evapotranspiration

from emergent vegetation, Wood River Wetland, upper Klamath River basin,

Oregon, October 2003–September 2005................................................... 19

Table 5. Water budget summary for the North Unit, South Unit, and total for the Wood

River Wetland, upper Klamath River basin, Oregon, October 2003–September

2005 .......................................................................................... 25

Table 6. Summary of field parameter surface-water data for Wood River Wetland,

adjacent streams, and ground-water sites, upper Klamath River basin,

Oregon, 2003–05 ........................................................................... 31

Table 7. Summary of seasonal field parameter data for the North Unit and South Unit,

Wood River Wetland, upper Klamath River basin, Oregon, 2003–05 .................. 32

Table 8. Summary of nutrients, major ions, and dissolved organic carbon data for

adjacent streams, wetland surface water, and ground-water sites, Wood

River Wetland, upper Klamath River basin, Oregon, 2003–05 ........................ 34

Table 9. Summary of seasonal nutrients, major ions, and dissolved organic carbon

data for the North Unit and South Unit, Wood River Wetland, upper Klamath

River basin, Oregon, 2003–05............................................................... 36

Table 10. Trace metals and other selected water-quality variables from the Wood River

Wetland and Agency Lake, upper Klamath River basin, Oregon, May 2003 ......... 45

Table 11. Changes in peat thickness and nutrient content in soil cores collected from

Wood River Wetland, upper Klamath River basin, Oregon ........................... 52

Table 12. Losses of carbon, nitrogen, and phosphorus from soil cores, and comparison

to Redfield ratio factors, Wood River Wetland, upper Klamath River basin,

Oregon ....................................................................................... 53
vii

Conversion Factors and Datums

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 0.4047 hectare (ha)

Volume

acre-foot (acre-ft) 1,233 cubic meter (m3

)

Flow rate

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

foot per year (ft/yr) 0.3048 meter per year (m/yr)

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

mile per hour (mi/h) 1.609 kilometer per hour (km/h) 

Energy

calorie (cal) 4.184 joule (J)

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Volume

liter (L) 0.2642 gallon (gal)

Flow rate

meter per second (m/s) 3.281 foot per second (ft/s) 

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound avoirdupois (lb)

Pressure

kilopascal (kPa) 0.01 bar

kilopascal (kPa) 0.1450 pound-force per square inch (lb/in2

)
viii

Conversion Factors and Datums—Continued

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

°F=(1.8×°C)+32.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25°C).

Concentrations of chemical constituents in water are given in milligrams per liter (mg/L) or 

micrograms per liter (μg/L).

Datums

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

(NGVD29). For the purpose of this publication, the term sea level is used to represent the 0-foot 

altitude as referenced to NGVD29. The conversion between NGVD29 and the commonly used 

North American Vertical Datum of 1988 (NAVD88) varies spatially; for conversions the reader is 

directed to either the National Geodetic Survey website for VERTCON at http://www.ngs.noaa.

gov/TOOLS/Vertcon/vertcon.html or the U.S. Army Corps of Engineers website for Corpscon at 

http://crunch.tec.army.mil/software/corpscon/corpscon.html.

Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD27). 

The conversion between NAD27 and the commonly used North American Datum of 1983 

(NAD83) varies spatially; for conversions, the reader is directed to either the National Geodetic 

Survey website for NADCON at http://www.ngs.noaa.gov/TOOLS/Nadcon/Nadcon.html or the U.S. 

Army Corps of Engineers website for Corpscon at http://crunch.tec.army.mil/software/corpscon/

corpscon.html.

Elevation, as used in this report, refers to distance above the vertical datum. Vertical coordinate 

information for historical data collected and stored as NAVD88 have been converted to NGVD29 

for this publication. Horizontal coordinate information for historical data collected and stored as 

NAD83 have been converted to NAD27 for this publication.

A local vertical datum, called the Upper Klamath Lake Vertical Datum (UKLVD), established by 

the Bureau of Reclamation, is often used for reporting elevation, especially with regard to the 

stage of Upper Klamath Lake. The conversions from UKLVD to the national datums NAVD88 and 

NGVD29 vary spatially and are presently not well defined for much of the Wood River Valley. For 

the purpose of this publication, the conversion used is UKLVD – 1.78 = NGVD29 (all values are in 

feet) (Source: William Wood, Bureau of Reclamation, written commun., 2007).
ix

Abbreviations and Acronyms

AGKO Agency Lake AgriMet station

BLM Bureau of Land Management

CH

4 methane

Cl chloride

CO

2 carbon dioxide

DBP disinfection by-products

DEM digital elevation models

DIN dissolved inorganic nitrogen

DKN dissolved Kjeldahl nitrogen

DNRA dissimilatory nitrate reduction to ammonium

DO dissolved oxygen

DOC dissolved organic carbon

ET evapotranspiration

GF/F glass fiber filter

HAA haloacetic acid

HCl hydrochloric acid H2S hydrogen sulfide H2

SO

4 sulfuric acid

KFLO Klamath Falls, Oregon AgriMet station

LiDAR Light Detection and Ranging

mg-C/L milligrams of carbon per liter

mg-N/L/m

2

/h milligrams of nitrogen per liter per square meter per hour

N

2 nitrogen gas

NH

3 un-ionized ammonia

NH

4

+ ammonium

NO nitric oxide N2O nitrous oxide

NO

2

+NO

3 nitrite-plus-nitrate

NO

3 nitrate

O

2 oxygen

PAR photosynthetically active radiation

SC specific conductance

SRP soluble reactive phosphorus

TKN total Kjeldahl nitrogen

TN total nitrogen

TNC The Nature Conservancy

TP total phosphorus

μg-C/L micrograms of carbon per liter

μg-Cl/L micrograms of chloride per liter

μg-Fe/L micrograms of iron per liter

μg-N/L micrograms of nitrogen per liter

μg-P/L micrograms of phosphorus per liter

μg-Mn/L micrograms of manganese per liter

μL microliter

USEPA U.S. Environmental Protection Agency

USFWS U.S. Fish and Wildlife Service

USGS U.S. Geological Survey

Ws wind speed
x

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Abstract

Restoring previously drained wetlands is a strategy 

currently being used to improve water quality and decrease 

nutrient loading into Upper Klamath Lake, Oregon. In 

this 2003–05 study, ground- and surface-water quality 

and hydrologic conditions were characterized in the Wood 

River Wetland. Nitrogen and phosphorus levels, primarily 

as dissolved organic nitrogen and ammonium (NH4) and 

soluble reactive phosphorus (SRP), were high in surface 

waters. Dissolved organic carbon concentrations also were 

elevated in surface water, with median concentrations of 44 

and 99 milligrams of carbon per liter (mg-C/L) in the North 

and South Units of the Wood River Wetland, respectively, 

reaching a maximum of 270 mg-C/L in the South Unit in 

late autumn. Artesian well water produced NH4 and SRP 

concentrations of about 6,000 micrograms per liter (μg/L), 

and concentrations of 36,500 μg-N/L NH4 and 4,110 μg-P/L 

SRP in one 26–28 ft deep piezometer well. Despite the high 

ammonium concentrations, the nitrate levels were moderate to 

low in wetland surface and ground waters. 

The surface-water concentrations of NH4 and SRP 

increased in spring and summer, outpacing those for chloride 

(a conservative tracer), indicative of evapoconcentration. 

In-situ chamber experiments conducted in June and August 

2005 indicated a positive flux of NH4 and SRP from the 

wetland sediments. Potential sources of NH4 and SRP include 

diffusion of nutrients from decomposed peat, decomposing 

aquatic vegetation, or upwelling ground water. In addition to 

these inputs, evapoconcentration raised surface-water solute 

concentrations to exceedingly high values by the end of 

summer. The increase was most pronounced in the South Unit, 

where specific conductance reached 2,500 μS/cm and median 

concentrations of total nitrogen and total phosphorus reached 

18,000–36,500 μg-N/L and about 18,000–26,000 μg-P/L, 

respectively. Water-column SRP and total phosphorus levels 

decreased during autumn and winter following inputs of 

irrigation water and precipitation, which have lower nutrient 

concentrations. The SRP concentrations, however, decreased 

faster than the dilution rate alone, possibly due to precipitation 

of phosphorus with iron, manganese, or calcium.

The high concentrations of dissolved nitrogen and 

phosphorus during the growing season give rise to a rich 

plant community in the wetland consisting of emergent and 

submergent macrophytes and algae including phytoplankton 

and benthic and epiphytic algae that have pronounced effects 

on dissolved oxygen (DO) and pH. Midday readings of 

surface-water DO during summer often were supersaturated 

(as much as 310 percent saturation) with elevated pH (as much 

as 9.2 units), indicative of high rates of photosynthesis. 

Minimum DO concentrations in the shallow groundwater piezometer wells were 0.4 mg/L in the North Unit and 

0.8 mg/L in the South Unit during summer, which is probably 

low enough to support microbial denitrification. Denitrification 

was confirmed during in-situ experiments conducted at the 

sediment-water interface, but rates were low due to low 

background nitrate (NO3). Nevertheless, denitrification (and 

plant uptake) likely contribute to low nitrate levels. Another 

possible cause of low nitrate levels is dissimilatory nitrate 

reduction to ammonia (DNRA), a microbial process that 

converts and decreases nitrate to ammonia. DNRA explains 

the excess ammonia production measured in the chambers 

treated with nitrate.

Surface-water levels and standing surface-water 

volume in the Wood River Wetland reached a maximum 

in early spring, inundating 80–90 percent of the wetland. 

Surface- water levels and standing volume then declined 

reaching a minimum in August through November, when the 

South Unit was only 10 percent inundated and the North Unit 

was nearly dry. The shallow ground-water levels followed a 

trend similar to surface-water levels and indicated a strong 

upward gradient.

Hydrologic and Water-Quality Conditions During 

Restoration of the Wood River Wetland, 

Upper Klamath River Basin, Oregon, 2003–05

By Kurt D. Carpenter, Daniel T. Snyder, John H. Duff, Frank J. Triska, Karl K. Lee, Ronald J. Avanzino, and 

Steven Sobieszczyk
2 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

A monthly water budget was developed individually 

for the North and South Units of the Wood River Wetland 

and then summed to produce a budget over 2 water years 

(2004 and 2005). Inflows for the entire wetland consisted of 

precipitation (43 percent), regional ground-water discharge 

(40 percent), applied water for irrigation from adjacent 

surface-water bodies (12 percent), ground-water seepage 

through dikes (4 percent), and discharge from artesian wells 

(1 percent). Outflows consisted of open-water evaporation 

(64 percent) and evapotranspiration from emergent vegetation 

(36 percent). Outflows exceeded inflows by about 22 percent 

over the 2-year period. Changes in surface- and groundwater storage during this period amounted to losses of 1 and 

2 percent relative to the total inflow, respectively. A waterbudget residual consisting of the errors in measurement of all 

water-budget components and the sum of any unaccounted for 

components indicated a deficit of water of 19 percent relative 

to the total inflow. The monthly patterns in water-budget 

residuals closely resembled the pattern expected for soilmoisture storage, which was not estimated, but indicated that 

soil moisture could represent a significant part of the water 

budget for the wetland.

The distribution of inflow between the North and 

South Units generally was proportional to their area, with 

the primary exception being applied irrigation water, which 

entered entirely into the North Unit. Because of the larger area 

of open water in the South Unit, the proportion of the outflow 

from open-water evaporation was greater than from the North 

Unit.

Introduction

Since about 1890, many marshlands have been drained in 

the upper Klamath River basin in southern Oregon, including 

31,000 acres adjacent to Agency and Upper Klamath Lakes 

(Snyder and Morace, 1997). Although the undrained areas 

provide high quality habitat and food resources for diverse 

wildlife communities, 69 percent of the original within-lake 

wetlands have been drained. Effects of drainage include loss 

of marsh habitat and lake storage capacity, and altered soil 

biogeochemistry, including oxidation of peat soils, reduction 

in bulk mass, and release of carbon, nutrients, and minerals. 

Wetlands in the upper Klamath River basin were drained 

for cattle grazing and crop cultivation including hay, barley, 

wheat, and potatoes. Draining lowered the water table and 

allowed oxygen to penetrate organic-rich peat soils, which 

promoted decomposition and release of nutrients and minerals 

that had accumulated over several thousand years (Snyder and 

Morace, 1997). The decreased nutrient content and greater 

bulk density of drained wetland soils manifested itself as land 

subsidence of as much as 13 ft in some wetlands adjacent 

to Upper Klamath Lake. Subsiding wetlands may release 

large quantities of carbon, nitrogen, and phosphorus when 

they are flooded. Subsequent pumping of standing water 

delivers great quantities of nutrients and carbon into Upper 

Klamath and Agency Lakes. Additional nutrient inputs from 

tributaries and internal loading fuel massive blooms of bluegreen algae (Aphanizomenon flos-aquae) that cause periods 

of poor water quality. The annual growth and decomposition 

of dense algal blooms produce high pH (9–10 units), widely 

variable dissolved oxygen (anoxic to supersaturated), and 

high ammonia concentrations (nearly 0.3 mg-N/L, un-ionized) 

(Wood and others, 2006). Episodes of poor water quality 

have been associated with large kills of sucker fish species, 

including the Lost River sucker (Deltistes luxatus) and 

the shortnose sucker (Chasmistes brevirostris), which are 

protected under the Endangered Species Act (U.S. Fish and 

Wildlife Service, 1988).

Efforts to regain wetland function, increase water 

availability, decrease nutrient loading, and improve water 

quality and habitat have been initiated by several private 

landowners, organizations, and government agencies including 

the Klamath Basin Ecosystem Restoration Office (a division of 

the U.S. Fish and Wildlife Service), The Nature Conservancy, 

the Bureau of Land Management (BLM), and the Running 

Y Ranch Resort (MacLaren and Geiger, 2001). In 1994, 

the BLM completed acquisition of the Wood River Ranch, 

a 3,200-acre cattle ranch along the north shore of Agency 

Lake (fig. 1) that was drained and converted to pastureland 

in the 1950s and 1960s. Prior to 1994, this property was 

managed as irrigated pasture for beef production (Bureau of 

Land Management, 2006). This area is now referred to as the 

“Wood River Wetland” and currently is managed as an Area 

of Critical Environmental Concern to improve water quality, 

increase water availability, and provide wildlife and fish 

habitat (Bureau of Land Management, 1995, 1996, 2006). In 

2003, the U.S. Geological Survey (USGS), in cooperation with 

BLM and with subsequent support from the U.S. Fish and 

Wildlife Service, began a study to characterize the hydrologic 

and water-quality conditions within the Wood River Wetland 

to help address questions regarding possible consequences of 

future management options.
Introduction 3

Figure 1. Location of the Wood River Wetland, upper Klamath River basin, Oregon.

tac08-0249_Figure 01 

122°10' 122°00' 121°50' 121°40' 121°30'

42°30'

42°60'

42°50'

42°40'

42°20'

42°10'

0 20 KILOMETERS

0 20 MILES

JACKSON CO

KLAMATH CO

Crater

Lake

Agency

Lake

Klamath Marsh

National Wildlife

Refuge

Wood River

Valley

Upper Klamath

National Wildlife

Refuge

Lower Klamath

National Wildlife

Refuge

Upper

 Klamath

 Lake

Wood River

Wetland

Klamath

Falls

Chiloquin

Fort

Klamath

Willia

mson 

River

Klamath 

Sprague

River

River

Williamso

n

River

97

66

62

39

70

140

140

Lost River

Base modified from USGS digital data, various scales, variously dated

Projection: UTM, Zone 10, North American Datum 1927.

Wocus

Marsh

The Nature 

Conservancy 

Williamson 

River Delta 

Preserve

OREGON

Upper

Klamath

Lake

Agency

Lake

Wood River

Wetland

KFLO

AGKO

!
4 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Description of Wood River Wetland

Origin of Wood River Wetland 

The wetlands surrounding Upper Klamath and Agency 

Lakes (fig. 1), were formed 10,000–12,000 years ago 

following recession of an expansive Pleistocene water body 

filled from melting of glacial ice (Dicken, 1980). This great 

water body, called Modoc Lake, extended 75 mi from Fort 

Klamath in southern Oregon, to south of Tule Lake in northern 

California. Modoc Lake deposited lacustrine clays typically 

to depths between 2.5 and 12 ft (Snyder and Morace, 1997), 

but occasionally deeper. Such clays can confine groundwater movement, especially where the layers remain intact. 

Canal digging and dike building possibly breached some clay 

layers in wetlands around Upper Klamath Lake, including the 

Wood River Wetland, altering ground-water flow paths. Atop 

these clay layers, peat soils developed to varying degrees, 

storing partly decomposed remnants of annual vegetation and 

associated nutrients. Under the clay are alternating layers of 

organic and inorganic sediments that probably were deposited 

over the 1 million years before the clay layer. Sediment cores 

from Wocus Marsh near the southwestern part of Upper 

Klamath Lake (fig. 1) contained peat deposits at about 85 ft 

depth that may be as old as 400,000 years (Adam and others, 

1994).

Study Area Description

The Wood River Wetland is bordered by North Canal 

to the northwest, Sevenmile Canal to the southwest, Wood 

River to the northeast, and Agency Lake to the south (fig. 2). 

The property was diked and drained in two stages—the 

higher, drier, northern parcel in 1948 and the lower, wetter 

southern parcel in 1957. A central levee maintains the two 

parcels, a seasonally inundated 1,600-acre North Unit and 

a more developed wetland, the deeper 1,200-acre South 

Unit. The Wood River Wetland and the Wood River to the 

northeast have undergone extensive restoration during the past 

decade. Restoration included improving water management 

options, blocking certain canals in the Wood River Wetland to 

encourage water flow through the historical drainage system, 

and adding meanders to the Wood River channel (Bureau of 

Land Management, 2006). 

Wood River Wetland (looking east northeast). Photograph taken by 

Kurt Carpenter, U.S. Geological Survey, October 2003.

Wood River Wetland (looking east). Photograph taken by Kurt 

Carpenter, U.S. Geological Survey, December 2004.
Description of Wood River Wetland 5

Figure 2. Wood River Wetland and locations of sampling sites, upper Klamath River basin, Oregon.

tac08-0249_Figure 02

Sevenmile Canal

Sevenmile Canal

water control 

structure

Dike Road

ART-1

ART-4

ART-3

ART-2

ART-5

PZ-AGDK

PZ-WRDK

PZ-SU1, 

PZ-SU2, 

PZ-SU3

PZ-NU1,

PZ-NU2,

PZ-NU3

A g e n c y

L a k e

Wood

 River

N O R T H

U N I T

A g e n c y

L a k e

R a n c h

S O U T H

U N I T

North Dike Road

North Canal

SMDK WRDK

SMIN

NCANAL

NCANAL4

NCANAL5

NCANALP

121°59' 121°58' 121°57'

42°34'

42°35'

42°36'

42°37'

Surface-water inflow

Surface-water inflow sampling site

Wetland surface-water sampling site

Ground-water piezometer sampling site

Adjacent stream sampling site

Staff plate

Pump station

Artesian well

Road

EXPLANATION

Base modified from USGS digital data, various scales.

Projection UTM, Zone 10, NAD27, NGVD1929.

Elevation, in feet

Less than 4,132

4,133

4,134

4,135

4,136

4,137

4,138

4,139

4,140

4,141

4,142

Greater than 4,142

0 1 MILE

0 1 KILOMETER

Upper

Klamath

Lake

Agency

Lake

Wood River

Wetland

OREGON

AGKO AgriMet weather station

NU-NW

SU-NW

SU-SW

SU-SE

SU-NE

SU-NC

SU-S-C

SU-SE-C

SU-SW-C

NU-WC

NU-Cu

NU-Cd

NU-EC NU-SE

NU-S
6 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Geology and Soils

Upper Klamath and Agency Lakes are in a large, deep 

basin filled with layers of volcanic and alluvial sediments, 

lake clays, and peat soils (Leonard and Harris, 1974). Rocks 

in the area are predominantly unconsolidated and consolidated 

volcanic materials (Leonard and Harris, 1974). Large 

quantities of ash, pumice, and lacustrine deposits of diatoms 

and peat are hundreds of feet thick (Dicken and Dicken, 

1985). Alluvial floodplain deposits consist of volcanic ash-rich 

clays, silts, sands, along with peat, and other organic materials 

(Cahoon, 1985; Bureau of Land Management, 1996). 

Thin horizontal layers of coarse volcanic pumice underlie 

the Wood River Wetland, which may facilitate lateral water 

movement along preferential flow paths through the layers. 

The volcanic pumice was deposited about 7,600 years ago, 

when a massive eruption from Mount Mazama formed the 

current Crater Lake (Hallett and others, 1997). Pumice and 

volcanic ash were deposited or washed down-valley near 

the Wood River Wetland (Williams, 1965). This and other 

eruptions during the Holocene epoch produced layers of 

pumice and ash that underlie the present wetlands in the upper 

Klamath River basin (Smith, 1988). In the Wood River Valley, 

south of Crater Lake, a 6-in. thick layer of pumice tapers off to 

the south (Walker, 1951; Williams, 1965). This layer is visible 

in the soil cores collected by Snyder and Morace (1997).

Three major types of peat soils occur around Upper 

Klamath Lake: hemic peat, hemic/sapric peat, and sapric peat 

(Snyder and Morace, 1997). Hemic peat is undecomposed 

to moderately decomposed peat; hemic/sapric peat is 

intermediately decomposed peat; sapric peat is the most 

decomposed. Peat color indicates the degree of decomposition 

(Cameron, 1973; 1975). Hemic peat, either newly exposed or 

well protected from air, is generally light yellow or brown. 

Partially decomposed hemic or hemic/sapric peat is brown to 

dark brown; well-decomposed sapric peat is black. Wetland 

soils are of the Lather-Histosols type, formed from organic 

matter, and characterized as poorly drained mucks (Cahoon, 

1985). Climate, topography, and changes in water table depth 

are the primary drivers in the formation and preservation of 

peat deposits (Cameron and others, 1989). Draining the Wood 

River Wetland has resulted in the decomposition of peat soils, 

which is evident in the various occurrences of sapric peat, land 

subsidence, and loss of mineral and nutrient content in soil 

cores (Snyder and Morace, 1997).

Vegetation and Other Biota

Vegetation in the Wood River Wetland includes willow 

thickets and obligate wetland species such as cattail (Typha 

latifolia), giant bur-reed (Sparganium eurycarpum), and 

spikerush (Eleocharis macrostachya) that also are scattered 

throughout the mostly flooded South Unit, in shallow areas 

unaffected by the canals. The plant communities at the 

wetland were similar to those reported at the Twitchell Island 

restoration wetlands in the Sacramento-San Joaquin River 

Delta, California (Miller and others, 2008), and include nearly 

150 species (Bureau of Land Management, 2006). The plant 

community is in a dynamic state of change characterized 

by a general shift from grazing resistant, edge, and upland 

plants toward obligate wetland species (Bureau of Land 

Management, 2006). High nutrient concentrations provide for 

enhanced growth of numerous species, including submerged 

macrophytes such as coontail (Ceratophyllum demersum), 

Canadian waterweed (Elodea canadensis), and curly 

pondweed (Potomogeton crispus). A variety of filamentous 

green algae, duckweed, and other plants occur in the openwater areas, canals, and in shallow ponds during summer. 

Around the wetland fringe, particularly in the South Unit, 

shallow margin areas teem with aquatic life including diving 

beetles and zooplankton, which feed a diversity of bird life. 

Nearly 200 bird species have been identified in the area, with 

waterfowl counts of 25,000–80,000 during peak use periods in 

spring and autumn (Bureau of Land Management, 2006).

Vegetation at the Wood River Wetland. Photograph taken by Kurt Carpenter, 

U.S. Geolgocial Survey, July 2005.

Waterfowl at the Wood River Wetland. Photograph taken by John Duff, 

U.S. Geological Survey, August 2004.
Description of Wood River Wetland 7

Climate and Water Availability

The semiarid climate in the upper Klamath River basin is 

characterized by hot, dry summers and moderately wet winters 

with moderate to low temperatures. Most precipitation occurs 

between October and March, producing marked seasonal 

fluctuations in water levels. During winter, precipitation often 

is in the form of snow, and ice often forms on the surface of 

the wetland (Bureau of Land Management, 2006). During 

high snowpack years, high-quality meltwater infiltrates and 

recharges the ground-water system while surface runoff pulses 

down the stream network in the Wood River Valley and is used 

for flood irrigation of pastures. Subirrigation, the irrigation 

of plants by water delivered to the roots from shallow ground 

water, also occurs in the Wood River Valley when groundwater levels are sufficiently high (Graham Matthews and 

Associates, 2005). 

Large seasonal temperature changes in the upper Klamath 

River basin are due to the semiarid climate and high elevation 

(more than 4,000 ft). Summer months are dry, hot, and often 

windy. Solar intensity, which is higher at this elevation, adds 

heat that contributes to high rates of evapotranspiration (ET)—

the loss of water from evaporation and plant transpiration.

Hydrology

The wetland is isolated from adjacent surface-water 

bodies and adjoining property by levees, and water control 

structures are located at key sites throughout the wetland to 

manage water levels. The inflow of surface water for irrigation 

is controlled and generally enters the wetland by first passing 

into North Canal, on the north side of North Dike Road 

(fig. 2). North Canal is filled with water from Sevenmile Canal 

during flood irrigation, and from overland and subsurface 

drainage from the adjoining property upgradient (north) of 

the wetland. Although water from Wood River can be used, 

Sevenmile Canal is the primary water source during flood 

irrigation because the inlet structure includes a fish screen. 

Water from North Canal is routed into the North Unit through 

control structures along the North Dike Road, at the north 

end of the north-south trending canals. Although separate, 

the two parcels that compose the wetland may be partly 

hydrologically connected by ground-water transport through 

the horizontal pumice sand and gravel layers. Minor surfacewater movements primarily are in the upland North Unit, 

from the northwest corner to the southeast, following canals 

and parts of a former natural channel toward the Wood River 

pump station (fig. 2). Water accumulated in the southeast 

corner of the North Unit can be pumped into Wood River or 

passed into the South Unit through a water control structure 

near the pump station, and gates can be managed for draining 

units independently. A second pump station in the southwest 

corner of the South Unit can be used to discharge water to 

the lower reaches of Sevenmile Canal. However, during this 

investigation (2003–05) only a negligible amount of pumping 

took place from either pump station for pump maintenance.

Additional sources of water inflow include direct 

precipitation, regional ground-water discharge, seepage 

through the dikes, and discharge from five flowing artesian 

wells on the wetland. The only significant outflow of water 

from the wetland during the study period was evaporation 

from areas of open water and evapotranspiration from plants.

Historical and Current Water Management

From 1985 through 1994, the Wood River Wetland 

was managed for beef cattle production (Bureau of Land 

Management, 2005). Prior to 1995, water accumulated during 

winter was pumped off in February or March through May, 

until surface water was confined to the drainage canals. About 

1,300 cow-calf pairs grazed the wetland from about April 

through November. The pasture was flood irrigated with about 

3,000–6,000 acre-ft about once per month during summer. 

Under this management scenario, open water occurred only 

from December through April, and grasses, sedges, and weeds 

provided forage for waterfowl and other wildlife.

From 1995 through 2005, water that accumulated during 

winter was not pumped off, allowing full inundation of the 

South Unit, and seasonal inundation of the North Unit. As 

the dry summer season progressed, water levels declined and 

much of the wetland went dry or moist, especially in the North 

Unit, but also partially in the South Unit. Flood irrigation was 

limited to one watering per year in September and October, 

when about 1,000 acre-ft of water was added from Sevenmile 

Canal to the North Unit to provide additional habitat for 

migrating and resident waterfowl. Under this management 

scenario, an annual cycle of drying and wetting occurred in the 

North Unit during moderate to dry years, while relatively deep 

water (4–6 ft) persisted in the South Unit canals during spring 

and early summer. Water depth in the non-canal areas of the 

South Unit ranged from a few inches to more than 6 ft. The 

seasonal extent of water inundation is shown in figure 3. Both 

wetland units combined hold about 16,700 acre-ft of water at a 

water-surface elevation of 4,142 ft (National Geodetic Vertical 

Datum of 1929 [NGVD29]). The largest rate of increase in 

the inundated area occurs between water-surface elevations of 

4,135 and 4,138 ft (fig. 4).
8 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Figure 3. Observed and modeled extent of inundation and depth to water at the Wood River Wetland, Oregon, April–August 

2004. (Observed inundation [insets] obtained from Landsat 7 imagery for the specified date using false color to emphasize 

inundation. Modeled inundation derived from a digital elevation model based on LiDAR [Light Detection And Ranging] data.)

tac08-0249_Figure 03 

122°00’ 121°59' 121°58' 121°57' 121°56'

42°37'

42°36'

42°35'

42°34'

122°00’ 121°59' 121°58' 121°57' 121°56'

42°37'

42°36'

42°35'

42°34'

122°00’ 121°59' 121°58' 121°57' 121°56'

42°37'

42°36'

42°35'

42°34'

122°00’ 121°59' 121°58' 121°57' 121°56'

42°37'

42°36'

42°35'

42°34'

0 1 KILOMETER

0 1 MILE

0 1 KILOMETER

0 1 MILE

0 1 KILOMETER

0 1 MILE

0 1 KILOMETER

0 1 MILE

April 22, 2004 June 25, 2004

July 27, 2004 August 28, 2004

Base from U.S. Geological Survey digital data, 2004

UTM projection, Zone 10, North American Datum 1927

National Geodetic Vertical Datum of 1929

North Unit (4137.50 ft)

South Unit (4136.50 ft)

Depth

Min: 0.1 ft

Max: 6.6 ft

Inundation Elevation

North Unit (4136.80 ft)

South Unit (4135.80 ft)

Depth

Min: 0.1 ft

Max: 6.6 ft

Inundation Elevation

North Unit (4135.50 ft)

South Unit (4134.70 ft)

Depth

Min: 0.1 ft

Max: 6.6 ft

Inundation Elevation

North Unit (4136.10 ft)

South Unit (4135.20 ft)

Depth

Min: 0.1 ft

Max: 6.6 ft

Inundation Elevation
Description of Wood River Wetland 9

Figure 4. Stage, volume, and area relations for the (A) North Unit, (B) South Unit, 

and (C) North and South Units of the Wood River Wetland, Oregon.

tac08-0249_Figure 04

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

0

500

1,000

1,500

2,000

2,500

3,000

3,500

A. North Unit 

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

0

500

1,000

1,500

2,000

2,500

3,000

3,500

B. South Unit 

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,130 4,132 4,134 4,136 4,138 4,140 4,142 4,144 4,146 4,148 4,150

WATER SURFACE ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

C. North and South Units 

Area, in acres 

Volume, in acre-feet 

AREA, IN ACRES 

VOLUME, IN ACRE-FEET 
10 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Study Design and Methods

Surface- and ground-water quality was evaluated at 

several sites in each unit in 2003–05. Adjacent streams, Wood 

River and Sevenmile Canal (table 1, fig. 2), also were sampled 

for comparison. Sampling was concentrated during the 

growing season (approximately monthly May/June through 

September) with a few winter and early spring samples 

collected to characterize the non-growing season. Samples 

of flood-irrigation water were collected over a 3-day period 

in September 2003, when water from the adjacent property 

to the north was let on to the wetland. In 2005, samples were 

collected monthly from June to September. 

A hydrologic budget for the Wood River Wetland was 

developed by collecting information on inflows, outflows, 

and changes in water storage for the wetland. Water-budget 

components were determined through measurement or 

estimation. Results of the water-budget analysis were used 

to calculate standing surface-water volume on each sampling 

date to quantify changes in water quality over time.

Field Methods

Water samples—Water samples were collected 

from adjacent streams at the Dike Road bridges (for 

Sevenmile Canal and Wood River) or at the Sevenmile 

Canal water control structure at the inlet to the wetland (fig. 

2). Surface-water sites in the wetland were accessed by 

canoe or by wading. Discrete water samples were collected 

about 10–20 cm below the water surface. Although wind 

occasionally mixes the surface water, temperature stratification 

was sometimes observed, especially in the South Unit. 

Therefore, the discrete water samples may not fully represent 

the water quality throughout the water column.

In the North Unit, sampling started at the northwest 

corner and progressed toward the southeast corner pump 

station. In the South Unit, sampling order varied depending 

on water level, wind, and other conditions. Surface water 

was collected using a battery-operated peristaltic pump 

(Geopump®) with Masterflex® tubing. Occasionally, water 

samples were collected in 2-L amber polyethylene bottles and 

processed off site. 

Site code Site name

Adjacent streams

SMIN Sevenmile Canal at Wood River Wetland inlet upstream of 

fish screen

SMDK Sevenmile Canal Bridge at Dike Road near mouth

WRDK Wood River Bridge at Dike Road near mouth

Wood River Wetland surface water1

NU-NW North Unit - NW northwest

NU-WC North Unit - WC west central

NU-Cu North Unit - Cu - center upstream of artestian well # 4

NU-Cd North Unit - Cd - center downstream of artesian well # 4

NU-EC North Unit - EC - east central

NU-SE North Unit - SE - east

NU-S North Unit - south central

SU-NW South Unit - NW - northwest

SU-NC South Unit - NC - north central

SU-NE South Unit - NE - northeast

SU-SW South Unit - SW - southwest

SU-SW-C South Unit - SW-C - southwest central

SU-S-C South Unit - S-C - south central

SU-SE-C South Unit - SE-C - southeast central

SU-SE South Unit - SE - southeast

 Table 1. Water-quality sampling sites, Wood River Wetland, upper Klamath River basin, Oregon, 2003–05. 

[Site code: Locations of sampling sites shown in figure 2, and (or) the online database. Abbreviations: WRW, Wood River Wetland; ft, foot]

Site code Site name

Wood River Wetland ground water

 PZ-NU1 NU Piezometer 59588 (shallow 3–5 ft)

 PZ-NU2 NU Piezometer 59589 (intermediate 10–12 ft)

 PZ-NU3 NU Piezometer 59590 (deepest 26–28 ft)

 PZ-SU1 SU Piezometer 59591 (shallow 5–6 ft) 

 PZ-SU2 SU Piezometer 59592 (intermediate 10–12 ft)

 PZ-SU3 SU Piezometer 59593 (deepest 30–32 ft) artesian

 PZ-WRDK Dike Road (Wood River) Piezometer 59594 (depth 8–10 ft)

 PZ-AGDK Dike Road (Agency Lake) Piezometer 59595 

(depth 14–16 ft)

 ART-1 Artesian well #1 at upper northeastern corral (depth 208 ft)

 ART-3 Artesian well #3 (near the North Unit pump station) (depth 

219 ft)

GW-AG pore Agency Lake pore water along shore near Wood River 

Wetland

North Canal (irrigation canal)

NCANAL Wood River Wetland inlet and fish screen

NCANAL4 Water control structure 4

NCANAL5 Water control structure 5

NCANALP North levy pond inflow

Agency and Upper Klamath Lakes

AGENCY shore Agency Lake along shore near Wood River Wetland

AGENCY straits Agency Straits adjacent to The Nature Conservancy parcel

AGENCY Lake Upper Agency Lake

UKL outlet Upper Klamath Lake outlet at Klamath Falls, Oregon

1

 Although differentiated according to general location (for example, Wood River Wetland North Unit - NW - northwest), multiple sampling locations in 

each wetland unit were analyzed together to produce medians and other statistical summaries for each sampling date used in the analyses. Data for individual 

locations are given in appendix A.
Study Design and Methods 11

Accessing canals for sampling at the Wood River Wetland (looking 

southeast). Photograph taken by John Duff, U.S. Geological Survey, 

August 2004.

light or photosynthetically active radiation (PAR) available for 

photosynthesis in the water column and to calculate the light 

extinction depth (where PAR is zero).

Ground-water piezometers—Eight piezometers 

(wells used to measure ground-water pressure head or to 

sample water quality at a point or specific depth range in 

the subsurface) were installed at four sites in July 2003 

(fig. 2, table 2), according to the Oregon Water Resources 

Department guidelines for monitoring wells (Oregon Water 

Resources Department, 2001). Two nests consisting of three 

wells each (shallow, intermediate, and deep) were installed 

in the North and South Units, and two individual wells were 

drilled along the East and South Dike Roads (fig. 2). Slug 

tests were performed according to USGS protocols (Halford 

and Kuniansky, 2002) in the two dike road piezometers, 

PZ-WRDK, on the dike adjacent to Wood River, and 

PZ-AGDK, on the dike adjacent to Agency Lake. The slug 

tests were conducted to determine the hydraulic properties of 

the wetland soils and dike materials, and to estimate the rate 

of water flow through the dike materials and ground-water 

seepage through the wetland soils.

Construction of ground-water piezometers in the North Unit of the 

Wood River Wetland (looking north). Photograph taken by Charley 

Palmer, U.S. Geological Survey, August 2003.

Water samples also were collected from eight groundwater piezometers (fig. 2) using a peristaltic pump and 

weighted Masterflex® tubing. Wells were purged for at least 

10 minutes (or until dry) by pumping approximately three 

water volumes from each well. Water samples were collected 

12–24 hours after purging to allow fresh water to recharge 

wells. Prior to initial purging, water levels were measured with 

a calibrated electronic E-tape.

Water samples were analyzed for filtered and unfiltered 

(total) nutrients on 15 occasions. Dissolved organic carbon 

(DOC), select metals, and chloride (Cl) were analyzed less 

frequently. Bulk samples were shaken and subsampled into 

125-mL bottles for total phosphorus (TP) and total Kjeldahl 

nitrogen (TKN). Samples for dissolved constituents, including 

ammonium (NH4), nitrite plus nitrate (NO2+NO3), hereafter 

referred to as nitrate (NO3), and dissolved Kjeldahl nitrogen 

(DKN) were filtered into 60-mL sample bottles (for NH4, 

NO3, and SRP), or a 125-mL bottle (for DKN). Filtered 

samples were processed through 0.45-μm filtration capsules 

attached directly to the peristaltic tubing or collected into 

a 60-mL syringe and filtered through 0.45-μm Acrodisk®

filters. DOC samples were filtered through combusted 0.7 μm 

GF/F filters (Whatman®). Total nutrient samples (TKN and 

TP) were acidified with 1 mL sulfuric acid (H2SO4), and NH4

and SRP samples were preserved with 100 μL concentrated 

hydrochloric acid (HCl) per 60-mL sample. Samples were 

packed on ice and shipped to the laboratories for analyses.

Field parameters—In-situ water temperature, specific 

conductance (SC), dissolved oxygen (DO), and pH were 

measured at most sites using a calibrated Hydrolab H20 or YSI 

6600 multi-parameter probe, or an equivalent single-parameter 

meter. Readings occasionally were taken below the water 

surface and just off the bottom, but most readings were taken 

about 10–20 cm below the water surface. Vertical profiles of 

light intensity occasionally were collected to determine the 
12 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Material collected during well drilling included a wide 

range of coarse sediments (pumice pebbles and sand), silty 

loams, clays, peat, and a small amount of volcanic ash. The 

North Unit piezometers (PZ-NU1, PZ-NU2, and PZ-NU3) 

were installed in the northern corner of the wetland near an old 

corral. The shallow well (PZ-NU1) in this nest was completed 

in a pumice horizon at 3–5 ft overlain by sapric peat. The 

open interval of the intermediate-depth well (PZ-NU2) was 

installed in a deeper pumice horizon at 10–12 ft. The deep 

well (PZ-NU3), was completed at 26–28 ft in a mixed media 

bed consisting of inorganic sand and loam. The South Unit 

piezometers (PZ-SU1, PZ-SU2, and PZ-SU3) were installed 

along the central-eastern margin of the South Unit. The 

shallow well (PZ-SU1) in the South Unit piezometer nest was 

open to a depth of 5–6 ft in decomposed to partly decomposed 

sapric and sapric-hemic peat. The intermediate-depth well 

(PZ-SU2) was open at 15–17 ft in a pumice horizon with some 

silt and clay. The deep well (PZ-SU3) was open at 30–32 ft in 

a layer of medium-sized and well-sorted flowing sands, and 

was artesian with a hydraulic head several feet above land 

surface. The wells along the Wood River and Agency Lake 

dikes were open to a layer of decomposed peat at 8–10 and 

14–16 ft, respectively (fig. 2). Piezometers were sampled for 

nutrients on most sampling trips, whereas field parameters 

were collected less frequently, often limited by the amount of 

recoverable water.

Soil cores—Soil core data collected from the Wood 

River Wetland and used in this report (peat thickness, mass, 

and carbon/nutrient content) were obtained from Snyder and 

Morace (1997).

Ground-water piezometer nest in the South Unit of the Wood River Wetland (looking west southwest). Photograph taken by Kurt Carpenter, 

U.S. Geological Survey, June 2004.
Study Design and Methods 13

Site code Description

Open interval, in 

feet below 

land surface

Open interval material

Completed well depth, 

in feet below 

land surface

 PZ-NU1 North Nest - Shallow 3.4 – 5.4 Pumice under decomposed peat 6.5

 PZ-NU2 North Nest - Intermediate 10.4 – 12.4 Pumice under decomposed peat 13.5

 PZ-NU3 North Nest - Deep 26.2 – 28.2 Inorganic sand and loam under clay 29.3

 PZ-SU1 South Nest - Shallow 5.5 – 6.5 Decomposed peat and ash/clay 6.5

 PZ-SU2 South Nest - Intermediate 15.0 – 17.0 Pumice/silt/clay under decomposed peat 18.0

 PZ-SU3 South Nest - Deep 30.0 – 32.0 Well sorted sand under clay/loam 33.0

 PZ-WRDK Wood River dike 8.0 – 10.0 Decomposed peat 11.0

 PZ-AGDK Agency Lake dike 14.0 – 16.0 Decomposed peat 17.0

Site code

Depth to water 

range, in feet 

below land 

surface 2003–05

Land surface elevation 

from LiDAR, in feet 

above NGVD29

USGS site No.

Oregon Water 

Resources Department 

well log identification 

No.

Station name

 PZ-NU1 0.4 – 5.2 4,139 423548121564703 KLAM-54064 34.00S/07.50E-14BAD03

 PZ-NU2 0.3 – 5.2 4,139 423548121564702 KLAM-54063 34.00S/07.50E-14BAD02

 PZ-NU3 0.3 – 5.2 4,139 423548121564701 KLAM-54062 34.00S/07.50E-14BAD01

 PZ-SU1 0.5 – 4.6 4,137 423656121575903 KLAM-54061 34.00S/07.50E-24CAD03

 PZ-SU2 0.7 – 4.8 4,137 423656121575902 KLAM-54066 34.00S/07.50E-24CAD02

 PZ-SU3 -4.6 – -2.0 4,137 423656121575901 KLAM-54065 34.00S/07.50E-24CAD01

 PZ-WRDK 4.1 – 8.7 4,144 423554121564001 KLAM-54223 34.00S/07.50E-24ACC01

 PZ-AGDK 3.6 – 7.0 4,143 423510121572301 KLAM-54222 34.00S/07.50E-26ADD01

Table 2. Piezometers installed at the Wood River Wetland, upper Klamath River basin, Oregon, July 2003.

[Site code: Locations of sampling sites shown in figure 2. Description: The south nest of wells was heavily damaged by inundation during extraordinarily 

high water levels in the wetland during spring 2006; wells were decommissioned and abandoned. USGS site No.: Additional information may be available for 

these wells on the USGS National Water Information System (http://nwis.waterdata.usgs.gov/nwis/gw) using the Site No. as the Site Identifier. Oregon Water 

Resources Department well log identification No.: Drillers’ logs for these wells are available from the Oregon Water Resources Department (http://apps2.wrd.

state.or.us/apps/gw/well_log/Default.aspx) using the well log identification No. as the Site Identifier. Abbreviations: USGS, U.S. Geological Survey; LiDAR, 

light detection and ranging; NGVD29, National Geodetic Vertical Datum of 1929]

In-situ mesocosm (chamber) experiments—

Ammonium and SRP fluxes from the sediment–water 

interface in the South Unit were examined in June 2005 

using clear polycarbonate dome chambers (volume about 

4 L, with dimensions of 19 cm [diameter] × 21 cm [height]). 

Chambers were inserted into the sediment to a depth of 6 cm, 

and purged of air prior to incubation. Two chambers in each 

site (eight chambers in all) were fitted with combination 

dissolved oxygen (DO)–temperature probes mounted on 

stirring platforms to measure oxygen demand. Water samples 

(60 mL) were drawn at the beginning and end of 19–26 hour 

incubation period by syringe for analysis of ammonium and 

SRP. Water samples were filtered through 0.45-μm membrane 

filters and acidified with 100 μL of ultra pure HCl in 60 mL 

polyethylene bottles. A second chamber study (August 2005) 

examined inorganic nitrogen dynamics. Chambers of varying 

size (0.8–1.85 L) were set into the wetland sediment, filled 

with surface water, and sparged with helium to displace DO 

inside the chambers. The acetylene block method estimated 

denitrification by measuring nitrous oxide (N2O) production 

with and without additions of 0.8 to 2 mg/L NO3 and (or) 

glucose (80 mg/L) at two sites in the southern South Unit. 

Dissolved NH4, NO3, and N2O were measured before and after 

4–5 hours.
14 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Laboratory Methods

Dissolved nutrients (NO3, NH4, and SRP), chloride (Cl), 

and dissolved metals (Fe, Mn, Cd, Co, Cu, Ni, Pb, V, and Zn) 

were analyzed at the USGS National Research Laboratory in 

Menlo Park, California. Metals were analyzed using the U.S. 

Environmental Protection Agency (USEPA) Method 200.8 

(ICP-MS). Dissolved organic carbon (DOC) was analyzed on 

an Oceanography International Model 700 carbon analyzer 

using persulfate oxidation at high temperature at the USGS 

National Research Laboratory in Boulder, Colorado. TKN, 

TP, and DKN were analyzed at the USGS National Water 

Quality Laboratory in Denver, Colorado, using published 

protocols (Patton and Truitt, 1992, 2000). In this report, 

dissolved ammonium includes ionized ammonium (NH4

+

) 

plus un-ionized ammonia (NH3), hereafter referred to as 

ammonium (NH4). Total nitrogen (TN) was calculated as the 

sum of TKN plus nitrate.

Analyses for dissolved inorganic nutrients (NO3

, NH4, 

and SRP) and Cl were performed on a Technicon Auto 

Analyzer II continuous-flow analyzer with colorimetric 

detection. All samples were refiltered immediately before 

analysis using 0.45-μm, 25-mm syringe filters (Pall Life 

Sciences, No. 4497T). When analyzing acidified samples, 

standards were identically acidified with high-purity 

hydrochloric acid. Correction of sample absorbance for 

color was necessary for the dissolved nutrients because 

many samples were highly colored. For each method, special 

reagents were made that omitted one or more, critical, colorforming ingredients. Sample-color absorbance, measured with 

the special reagents, was subtracted from total absorbance 

and measured with the standard reagents to obtain colorcorrected absorbance. Analyte concentrations were calculated 

by interpolation of the color-corrected absorbance on the 

calibration curve. Analyte concentrations greater than the 

range of the methods used required dilution prior to analysis. 

An automated version of the method of Armstrong and others 

(1967), implemented by Technicon as Industrial Method No. 

158-71W (Technicon Industrial Systems, 1972), was used to 

determine NO2+NO3. The critical ingredient omitted for color 

correction was N-1-naphthylethylenediamine dihydrochloride. 

An automated phenol-hypochlorite method (Technicon 

Industrial Method No. 154-71W; Technicon Industrial 

Systems, 1973a) was used to determine ammonium. The 

critical ingredients omitted for color correction were sodium 

nitroferricyanide and sodium hypochlorite. The molybdenumblue method of Murphy and Riley (1962), implemented by 

Technicon as Industrial Method No. 155-71W (Technicon 

Industrial Systems, 1973b), was used to determine SRP. When 

acidified samples were analyzed, sufficient sodium hydroxide 

was added to the surfactant solution reagent to neutralize 

sample acidity. The critical ingredient, ascorbic acid, was 

omitted for color correction. A modified version of the ferric 

thiocyanate method of O’Brien (1962) was used to determine 

chloride. To eliminate color prior to analysis, 0.5 mL of 30 

percent hydrogen peroxide was added to each 30 mL sample. 

Samples in quartz-glass tubes were then irradiated for 75 

minutes with ultraviolet light from a 1200-watt source in a 

La Jolla Scientific Photo-Oxidation Unit (Model PO-14). 

This photo-oxidation treatment destroyed all organic coloring 

matter, but did not oxidize Cl to higher oxidation states. After 

photo-oxidation and refiltration, all samples were clear, so 

sample absorbance did not require color correction. Humic 

associated chloride released by the photo-oxidation process 

was assumed negligible compared to the amount of inorganic 

chloride already present in solution.

Water Budget

A water budget is an accounting of the water stored in 

and water exchanged between the atmosphere, land surface, 

and subsurface. Inflows minus outflows equal the change 

in storage over a specified period of time within a specified 

volume (control volume) (Healy and others, 2007, p. iii–iv and 

p. 6). The water budget for the Wood River Wetland was based 

on observations and estimations of the inflows, outflows, 

and changes in storage of the wetland units. A monthly water 

budget was developed individually for the North and South 

Units of the Wood River Wetland for control volumes. The 

control volumes were laterally bound by the surrounding 

dikes, the upper surface consisted of the land, water, and 

vegetation surfaces, and the lower boundary was the shallow 

subsurface. The water budget was based on estimates of 

inflows from precipitation, ground water, and surface water 

applied for irrigation; outflows to open-water evaporation and 

evapotranspiration due to emergent vegetation; and changes in 

surface-water and ground-water storage (eq. 1).

(P GW SW E ET SW GW SM ) ( ) + + − + in in ( ) = + +

← → ← → ← inflows outflows cha

Δ Δ Δ

nge in storage

where:

is precipitation as rain or snow

→

P

GWi

,

n

in SW

is ground-water inflow volume 

is surface-water inflow

,

 volume 

is open-water evaporation

is evapotranspiration

,

E ,

ET from emergent vegetation 

is change in standing volume

,

ΔSW of surface water

is change in ground-water volume of t

,

ΔGW he 

saturated zone and 

is change in ground-water volum

,

ΔSM e of the

unsaturated zone.

(1)

The estimated error in the total hydrologic budget was 

calculated as the residual of (inflows - outflows) - estimated 

change in storage (Winter, 1981) and represents the sum of 

errors in measurement or estimation of each water budget 

component and the sum of any unestimated components such 
Study Design and Methods 15

as soil-moisture storage. Surface-water inflows were limited 

to small and periodic applications of irrigation water, and 

there were no significant outflows to surface water, pumping, 

or ground water. Insufficient information was available to 

estimate the soil-moisture storage independently.

Inflows

Inflows to the Wood River Wetland consisted of direct 

precipitation on the wetland, ground water, and applied water 

from flood irrigation. Because dikes and canals isolate the 

wetland, there are no significant surface-water inflows. 

Precipitation

Daily precipitation data were acquired from the Agency 

Lake AgriMet station (AGKO), one in a network of satellitebased automated agricultural weather stations operated 

and maintained by the Bureau of Reclamation (Bureau of 

Reclamation, 2008a). The AGKO site is on the northwest 

shore of Agency Lake, 2.5 mi southwest of the Wood River 

Wetland (fig. 1, fig. 2). The precipitation data were used 

without adjustment for distance due to the close proximity of 

the weather station. The precipitation record was complete 

except for 10 days in March and April 2005. Missing values 

were estimated using precipitation records at the Klamath 

Falls, Oregon (KFLO) AgriMet station, about 32 mi south of 

the wetland (fig. 1) (Bureau of Reclamation, 2008b). 

Precipitation at the AGKO site was measured using 

a 12-in. heated tipping-bucket rain and snow gage (Peter 

L. Palmer, Bureau of Reclamation, Boise, Idaho, written 

commun., 2008). The measurement of precipitation using 

rain gages is subject to errors from various sources (Smith, 

1993, p. 3.18–3.19); however, Yang and others (1999, p. 491) 

stated that wind-induced gage undercatch of precipitation is 

the greatest source of bias. This is especially true for solid 

precipitation (snow and ice) measurements (Yang and others, 

1998, p. 241). Unshielded rain gages, which includes the rain 

gage used at the AGKO site (Bureau of Reclamation, 2008c), 

are more susceptible to undercatch than shielded gages. 

Yang and others (1998, p. 243) developed a set of bestfit regression equations to correct wind-induced undercatch 

for unshielded U.S. National Weather Service 8-in. standard 

precipitation gages based on the type of precipitation (rain, 

mixed, or snow) and the wind speed (Ws):

Rain R = exp (4.605 – 0.062 Ws0.58)

Mixed R = 100.77 – 8.34 Ws

Snow R = exp (4.606 – 0.157 Ws1.28)

where:

R is daily catch ratio (percent), and

Ws is daily wind speed at the gage height (m/s).

R, the daily catch ratio, represents the ratio of gage-measured 

precipitation influenced by undercatch due to wind to the 

expected gage-measured precipitation if there was no influence due to wind. These equations produce adjusted precipitation estimates that are similar to those obtained by Larson and 

Peck (1974, fig. 3, p. 859).

Because the precipitation gage and the anemometer (wind 

meter) at the AGKO site are not at the same height above 

land surface, a correction is needed to find the Ws at the gage 

height. The following Ws adjustment was used to find the Ws 

at the gage height based on the wind field profile (Benning and 

Yang, 2005, p. 278):

U h U H

h z

H z

U h

( ) ( )

ln

ln

( )

= ( )

( )

⎡

⎣

⎢

⎢

⎤

⎦

⎥

⎥

0

0

where:

is estimated daily wind speed at the gage 

orifice m s

is measured

Ws

U H

( )

( ) / ,

( ) daily wind speed at the anemometer 

m s

is height of th

( ) / ,

h e gage m

is height of the anemometer m and

is roughn

( )

( )

,

H ,

z0 ess parameter m( ).

(2)

The measured daily wind speed at the anemometer, U(H), was 

recorded by the AGKO AgriMet station. The height of the 

rain gage, h, and anemometer at the AGKO AgriMet site, H, 

are 4.8 and 8.2 ft above land surface, respectively (Peter L. 

Palmer, Bureau of Reclamation, Boise, Idaho, written commun., 2008). The roughness parameter, z0

, was set to 0.01 m 

for a winter snow surface (December through March) and 

0.03 m for short grass (April through November) based on 

values used by Yang and others (1998, p. 247) with seasonal 

adjustments appropriate for the Wood River Valley. The 

precipitation relations are applicable for wind speeds less than 

6.5 m/s; therefore, adjusted wind speeds greater than 6.5 m/s 

(14.5 mi/h) were reset to 6.5 m/s to prevent overestimation 

of precipitation (Yang and others, 1998, p. 247; Benning and 

Yang, 2005, p. 278).

Daily precipitation adjusted for wind was calculated as 

the daily precipitation divided by R. Daily adjusted values of 

precipitation were summed to develop monthly estimates of 

inflow from precipitation. The median values of daily wind 

speed during individual events of rain, mixed precipitation, 

and snow were 6.1, 4.0, and 6.6 mi/h, respectively, for 

May 2003 through September 2005. The median values of 

estimated daily undercatch for individual events of rain, 

mixed precipitation, and snow were 11, 14, and 46 percent 

respectively during this period. Daily adjustment for windinduced undercatch increases the gage-measured precipitation 

by about 19 percent on an annual basis.
16 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Ground Water

Ground-water inflow to the Wood River Wetland takes 

place through numerous possible pathways: regional groundwater discharge through sediments, lateral ground-water 

seepage through dikes, and from direct discharge from flowing 

artesian wells. 

Regional Discharge

The Wood River Wetland is adjacent to Upper Klamath 

and Agency Lakes, which are regional ground-water discharge 

areas (Illian, 1970; Leonard and Harris, 1974; Gannet 

and others, 2007, p. 46-47), and as such receives groundwater discharge from the upward movement of water from 

underlying aquifers. This is indicated by water levels in the 

five artesian wells (heads above land surface) and by the 

artesian water levels in the deepest piezometer (PZ-SU3, 

fig. 2). Preferential ground-water discharge also may occur 

through the natural internal streambeds, and the canal beds 

because of dredging associated with the construction of the 

canals to lower the water table by draining ground water from 

the wetland. During natural stream channel formation or canal 

construction, a significant clay confining layer (occasionally 

observed in soil cores, Rosenbaum and others, 1995, p. 

33-34; Snyder and Morace, 1997, p. 7 and 26) may have been 

breached, providing significantly greater regional groundwater discharge than was calculated for the water budget. 

However, lack of data precluded inclusion of this type of 

discharge in the estimate of regional ground-water discharge.

Regional ground-water discharge was estimated using 

Darcy’s Law, which describes ground-water flow within a 

porous media (Darcy, 1856; Freeze and Cherry, 1979). Darcy’s 

law is expressed as: Q = AiK, where: Q is the volumetric flow 

[length3

/time]; A is the cross-sectional area, perpendicular 

to the flow direction, through which flow occurs [length2]; 

i is the hydraulic gradient [dimensionless], and K is the 

hydraulic conductivity [length/time]. The law predicts that 

the volumetric flow of ground water is directly proportional 

to the hydraulic gradient and hydraulic conductivity of the 

media. The hydraulic gradient is the difference in the height 

of the water surface (that is, head difference) on either side of 

the dike divided by the length of porous media through which 

the head difference is distributed. Hydraulic conductivity is a 

measure of the ability of porous media to transmit water, with 

higher values indicating increased flow.

For diffuse regional ground-water discharge, the crosssectional area perpendicular to ground-water flow was set 

equal to the area of each unit of the Wood River Wetland. 

Daily values of the hydraulic gradient were calculated as the 

daily head difference divided by the soil distance through 

which the head was transmitted. The head difference was 

calculated as the difference between the water level measured 

in the deep piezometer PZ-SU3 and the intermediate-depth 

piezometer PZ-SU2 (South Unit) as measured at least once 

every four months. Linear interpolation of these levels was 

used to calculate the daily head differences. The length 

through which the head difference was distributed was 

estimated as the distance between the centers of the open 

intervals for each piezometer (15 ft). Hydraulic conductivity 

was estimated to be 0.084 ft/d, which was the mean of slug 

tests performed on two piezometers: PZ-WRDK, on the dike 

adjacent to Wood River, and PZ-AGDK, on the dike adjacent 

to Agency Lake (fig. 2, table 2). The open intervals selected 

for these piezometers were representative of the undisturbed 

soils below the dikes. The lithology near the open intervals for 

these piezometers consists of hemic to sapric peat, silty clay 

with sand, and poorly sorted pumice sand and pebbles. The 

hydraulic conductivity estimate is in the high permeability 

range for clays, in the mid- to low range for peat, and in the 

low range for poorly sorted sands (Freeze and Cherry, 1979, 

p. 29; Wolff, 1982, p. 79-84; Fetter, 1994, p. 98). Daily values 

of regional ground-water discharge then were summed by 

month to create monthly estimates of inflow.

Seepage through Dikes

Water levels in the Wood River Wetland are lower than 

the elevation of surrounding surface-water bodies due to land 

subsidence and isolation from Agency Lake and the adjacent 

streams. This produces a head gradient conducive to seepage 

into the wetland, which was estimated using Darcy’s Law. 

Seepage was calculated daily and summarized monthly for 

the exterior dikes adjacent to a surface-water body including 

the Sevenmile Canal, Agency Lake, and Wood River dikes. 

Because sediments in the upper saturated zone consist of 

layers of peat, clay, and pumice (Snyder and Morace, 1997, 

p. 6–7, 25–26), flow through each was calculated separately 

using the thicknesses and hydraulic conductivity for each 

layer. The hydraulic conductivity of the clays, being several 

orders of magnitude less than that of pumice or peat, was 

excluded, as it was assumed to have a negligible contribution.

The cross-sectional area perpendicular to seepage through 

the dikes was calculated as the dike length multiplied by the 

vertical thickness of the pumice or peat layers. A thickness of 

0.5 ft was selected for the pumice layer, and 7.5 ft for the peat 

soil layers, based on soil core data (Snyder and Morace, 1997, 

pl. 1). The thickness of the peat layers was augmented by the 

saturated area of the dike above the preexisting land surface 

as this material was primarily composed of dredged peat soils. 

The augmented thickness ranged from –0.8 to 3.2 ft depending 

on the water stages on either side of the dike.

The head difference was calculated as the daily difference 

between the elevation of Upper Klamath Lake (which adjoins 

Agency Lake) and water-surface elevation in the wetland 

measured at one of several staff gages. The stage of Upper 

Klamath Lake (USGS water-stage station 11507001 http://

waterdata.usgs.gov/or/nwis/uv/?site_no=11507001) was 

selected because it is continually monitored and because the 
Study Design and Methods 17

Site 

code Location USGS site No.

Well depth 

based on 

sounding, in

feet below 

land surface

Depth to 

water, 

in feet below

land surface

Depth to 

water 

measurement 

date

Discharge, in

gallons per 

minute

Discharge

measurement

date

 ART-1 Horse corral 0.25 miles south of northeast corner 423701121575400 208 -6.8 09-28-00 225.5 09-28-00

 ART-2 Wood River dike 0.15 miles west of Crooked 

Creek

423556121565000 149 -3.5 08-17-95 3

2.6 05-24-95

 ART-3 North Unit 0.55 miles west of Wood River pump 

station

423617121575000 219 -8.0 08-17-95 3

5.8 08-17-95

 ART-4 Central North Unit 0.20 miles south of the North 

Canal

423644121585101 –1 -15.4 10-25-00 20.2 10-25-00

 ART-5 South Unit 0.65 miles north of Sevenmile Canal 

pump station

423531121581401 192 -9.9 10-25-00 8.9 10-25-00

1

 Blockage prevented depth sounding.

2

 Previously published measurement by Snyder and Morace (1997, p. 34) did not consider flow from secondary discharge pipe; therefore, that measurement 

was superseded with the more recent measurement presented here.

3

 Previously published measurement by Snyder and Morace (1997, p. 34).

Table 3. Artesian wells at Wood River Wetland, upper Klamath River basin, Oregon.

[Site code: Locations are shown in figure 2. USGS site No.: Additional information is available for these wells on the USGS National Water Information System 

(http://nwis.waterdata.usgs.gov/nwis/gw) using the Site No. as the Site Identifier. Abbreviations: USGS, U.S. Geological Survey; ART, artesian well]

surface-water flow gradients between Upper Klamath and 

Agency Lakes and Agency Lake and its tributaries are so low 

that the monitored stage was assumed representative of all 

adjacent surface-water bodies. The elevation at the selected 

station for Upper Klamath Lake is actually a weighted 

mean elevation determined from three sites measured by the 

USGS. The distance through which the head difference was 

distributed was estimated as the distance across the base of 

the dikes using a detailed map derived from LiDAR (Light 

Detection And Ranging) data with a 1-m lateral resolution (see 

Haluska and Snyder [2007] for a description of the LiDAR 

data). The width of the dikes was set to 100 ft for days when 

wetland water level was above land surface at the base of the 

dikes and to 150 ft for days when water level was below land 

surface. Hydraulic conductivity for the pumice layer was set at 

100 ft/d, based on literature values for sorted sand (Freeze and 

Cherry, 1979, p. 29; Wolff, 1982, p. 84; Fetter, 1994, p. 98). 

Hydraulic conductivity of the peat layer was set at 0.084 ft/d, 

the mean of slug tests performed on piezometers PZ-WRDK 

and PZ-AGDK because peat is the predominant lithology of 

the saturated zone in each piezometer.

Discharge from Artesian Wells

Five artesian wells in the Wood River Wetland 

continuously flow onto the land surface or directly to surface 

waters (fig. 2, table 3). Measurements of hydraulic head 

elevations during this and previous studies (Snyder and 

Morace, 1997; Gannett and others, 2007) ranged from 3.2 

to 15.4 ft above land surface (table 3). Drilling records for 

these wells were unavailable, but soundings from four wells 

indicated depths ranging from 149 to 219 ft (Snyder and 

Morace 1997, p. 34; Gannett and others, 2007). Discharge 

rates from the artesian wells measured in a previous study 

(Snyder and Morace, 1997, p. 12) and as part of this study 

ranged from 2.6 to 20.2 gal/min (table 3). To develop monthly 

estimates of inflow from artesian wells, it was assumed that 

these wells discharged at a continuous rate over the period of 

the study equivalent to the measured values.

Applied Flood Irrigation

From 1999 to 2005, about 1,000 acre-ft of water was 

applied annually to the Wood River Wetland for irrigation, 

typically starting around September 15 and ending around 

October 31 (Bureau of Land Management, 2006, p. 4). The 

quantity of water applied to the wetland was not measured 

and instead was estimated by the approximate area and depth 

of inundation. During 2003, this water was transferred from 

the adjacent private tract located on the northwest side of the 

North Canal to the North Unit, and during 2004–05, the water 

was transferred from the Sevenmile Canal through the water 

control structure to the North Unit (fig. 2). To develop the 

water budget, this water was presumed to enter the wetland at 

a constant rate each year from September 15 through October 

31 and was apportioned by month.
18 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Outflows

Outflows from the Wood River Wetland included 

evaporation of open water and evapotranspiration from 

emergent vegetation. No major pumping of surface water 

took place during this study. No direct outflows from surface 

or ground water took place because of the low surface- and 

ground-water levels in the wetland relative to the area outside 

the wetland.

Daily estimates of evaporation and evapotranspiration 

for the North and South Units were made separately for open 

water and emergent vegetation as a function of the daily 

water-surface elevation, because the ratio of open water to 

emergent vegetation is a function of stage. A similar method 

was used in the Lower Klamath National Wildlife Refuge 

(fig. 1) by Risley and Gannett (2006, p. 5–10) using values for 

the land-cover types at the Wood River Wetland that represent 

open water and emergent vegetation. The ET in areas with 

open water and emergent vegetation was assumed to be 

dominated by the open-water component. The proportion of 

open water was determined daily using the stage–area relation 

previously derived (fig. 4). The remainder of the wetland area 

was assumed to be emergent vegetation.

Evaporation of Open Water

Pan-evaporation data often are used to estimate the rate 

of evaporation for open water. However, daily pan-evaporation 

data were unavailable for the upper Klamath River basin 

for the period of this study. Daily evaporation from the 

open-water areas was estimated as the potential evaporation 

calculated using the empirical Priestley-Taylor equation using 

daily observations of air temperature, water temperature, and 

solar radiation at a nearby weather station. The PriestleyTaylor equation (Winter and others, 1995, p. 984) is defined by 

the equation

( ) ( ) ( )

( )

( )

-1

/ / ,

where:

is potential evaporation (cm/d ); 

is Priestley-Taylor empirically derived 

constant dimensionless ;

/ is parameter derived from the slope of 

saturation vapor pressure-te

PE s s Q Q L n x

PE

s s

= α ∗ + γ ∗ − ⎡ ⎤ ⎣ ⎦

α

+ γ

( )

1

1

-2 1

mperature 

curve at the mean air temperature 

dimensionless ; 

is slope of the saturation vapor pressuretemperature curve (kPa C ), 

is psychrometric constant (kPa C ); 

is net radiation (cal cm d ) n

s

Q

−

−

−

°

γ °

-2 1

-1

; 

is change in heat stored in the water body 

(cal cm d ); and 

is latent heat of vaporization (cal g ).

Qx

L

−

(3)

The widely used Priestley-Taylor equation was selected 

because of its simple form, limited data requirements, and 

proven performance as a reasonable estimate of potential 

evaporation (Winter and others, 1995; Rosenberry and others, 

2004). Values for the terms in the Priestley-Taylor equation 

were obtained as follows: the Priestley-Taylor empirically 

derived constant α was set equal to the commonly used value 

of 1.26, which has been determined to be representative for 

a fully saturated surface (Priestley and Taylor, 1972, p. 87; 

Winter and others, 1995, p. 991). The slope of the saturation 

vapor pressure-temperature curve s and the psychrometric 

constant γ were determined in a manner similar to Allen 

and others (2005, p. 10–11) using values of daily mean 

air temperature and elevation for the AGKO AgriMet site 

(Bureau of Reclamation, 2008a). The net radiation Qn

 also 

was determined in a manner similar to Allen and others (2005, 

p. 11-25) using values of the observation date, daily global 

solar radiation, daily minimum and maximum air temperature, 

mean daily dewpoint temperature, elevation, and latitude for 

the AGKO AgriMet site (Bureau of Reclamation, 2008a) and 

a value of 0.08 (dimensionless) for the albedo of open water 

(Shuttleworth, 1993, p. 4.6). The change in heat stored in the 

water body Qx

 also was determined in a manner similar to 

Shuttleworth (1993, p. 4.10, eqn. 4.2.20) using values of the 

density and specific heat of water, the daily change in water 

volume as determined using daily change in water depth for 

each unit of the Wood River Wetland, and the mean daily 

water temperature in a canal in an adjacent drained wetland 

at the AGKO AgriMet site (Bureau of Reclamation, 2008a), 

where water temperatures were assumed to be similar to those 

in the Wood River Wetland. The change in heat stored in the 

water body comprising the standing surface water in the North 

and South Units was nearly insignificant relative to the net 

radiation resulting from solar radiation. Ninety-five percent of 

the daily maximum magnitude values for the change in heat 

stored in the water body were equivalent to less than 4 percent 

of the daily net radiation magnitude. A value of 586 cal g-1 was 

used for the latent heat of vaporization L (Allen and others, 

2005, p. 9).

The daily temperature and global solar radiation records 

were complete except for 10 days in March and April 

2005. Missing values were estimated using records at the 

Klamath Falls, Oregon (KFLO) AgriMet station (Bureau 

of Reclamation, 2008b). Because the open-water areas of 

the Wood River Wetland had water freely available for 

evaporation and were not water limited, it was assumed that 

the potential open-water evaporation calculated using the 

Priestley-Taylor equation was equal to the actual open-water 

evaporation. The daily rate of open-water evaporation was 

multiplied by the area representing the daily inundated area 

of the North and South Units to determine the volume of 

open-water evaporation in each unit on a daily basis and then 

summed to obtain monthly estimates.
Study Design and Methods 19

Evapotranspiration from Emergent Vegetation

The evapotranspiration from the emergent vegetation 

component was estimated using a method described in Risley 

and Gannett (2006, p. 5–6). For the months of April–October, 

Risley and Gannett (2006) estimated evapotranspiration using 

results from a USFWS model based on the Priestley-Taylor 

evapotranspiration equation (Ronald R. Thomasson, U.S. Fish 

and Wildlife Service, Portland, Oregon, written commun., 

2005). The model was calibrated using data from energy 

budget studies conducted at several sites in the Klamath Basin 

National Wildlife Refuge Complex (fig. 1) (Bidlake, 1997, 

2000, 2002; Bidlake and Payne, 1998). Using a simulation 

period of 1961–90, the model predicted a median ET loss of 

2.41 ft for April–October. Risley and Gannett (2006) used this 

value and the monthly reference ET rates estimated for the 

KFLO AgriMet station to represent ET losses for November–

March. The annual ET loss for the emergent vegetation 

component was estimated to be 2.63 ft. Although the KFLO 

site is 32 mi south of the Wood River Wetland, comparison 

of the ET data from the AGKO and KFLO sites indicated that 

total ET for October 2003 through September 2005 differed 

by less than 5 percent, justifying their use for emergent 

vegetation ET rates. The monthly rate of evapotranspiration 

from emergent vegetation (table 4) was divided by the 

number of days in each month and then multiplied by the area 

representing the dry areas of the North and South Units to 

determine the volume of evapotranspiration in each unit on a 

daily basis. The daily volumes of evapotranspiration were then 

summed to obtain monthly estimates.

Changes in Storage

Standing Surface-Water Level and Volume

Daily changes in surface-water storage were determined 

using information on standing surface-water volume estimated 

using daily interpolated estimates of surface-water stage and a 

stage-volume relation developed from LiDAR data (Haluska 

and Snyder, 2007) (fig. 4). Measurements of surface-water 

stage consisted of nearly 60 sets of staff gage readings at 

three sites in the wetland (fig. 2) taken by BLM staff from 

May 19, 2003, to September 30, 2005. Each gaging site 

consisted of one to three staff gages to accommodate various 

surface-water levels. These gages were read with varying 

frequency, although many were less than 1 month apart. South 

Unit readings were infrequent during autumn through spring 

(September 2003 to February 2004, and November 2004 to 

May 2005). For the North Unit, readings were infrequent from 

November 2003 to February 2004 and from November 2004 

to May 2005. Gage elevation (NGVD29) was determined by 

surveying instruments and the relation of staff gage readings 

to LiDAR imagery. Linear interpolation was used to estimate 

daily surface-water stage in the North and South Units for 

days with no observations. Although the lack of measurements 

for extended periods introduces uncertainty in the water 

budget, the interpolated results generally followed the waterlevel trend of adjacent Agency Lake.

The relation between the surface-water elevation and 

open-water area and standing water volume in the wetland 

were developed using LiDAR, photographic imagery, and a 

digital elevation model (DEM) (Haluska and Snyder, 2007). 

From these relations, lookup tables were prepared to calculate 

the inundated area and water volume in the wetland at various 

surface-water elevations. The lookup tables were used to 

determine the daily standing surface-water volume and the 

daily change in surface-water storage. Monthly change in 

surface-water storage was determined as the change of storage 

volume between the last day of the month and the last day of 

the previous month.

Month Evaporation from 

open-water

Evapotranspiration from 

emergent vegetation

January 0.062 0.014

February 0.119 0.040

March 0.276 0.122

April 0.397 0.188

May 0.536 0.270

June 0.662 0.394

July 0.811 0.567

August 0.668 0.485

September 0.390 0.324

October 0.207 0.179

November 0.074 0.030

December 0.049 0.014

 Annual 4.25 2.63

Table 4. Estimated monthly evaporation from open water 

and evapotranspiration from emergent vegetation, Wood River 

Wetland, upper Klamath River basin, Oregon, October 2003–

September 2005.

[Values are in feet and do not add exactly due to rounding. Evaporation from 

open water: Monthly average for October 2003 through September 2005. 

Evapotranspiration from emergent vegetation: Source Risley and Gannett, 

2006, table 1, p. 5]
20 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

High water levels at the Wood River Wetland, South Unit (looking south southeast). Photograph taken by Kurt 

Carpenter, U.S. Geological Survey, July 2005.

Low water levels at the Wood River Wetland, North Unit (looking south southeast). Photograph taken by Kurt 

Carpenter, U.S. Geological Survey, July 2005.
Study Design and Methods 21

Ground-Water Storage

The change in shallow ground-water volume in the 

saturated part of the subsurface represents a change in the 

volume of water stored in the wetland. The change in groundwater storage is equal to the change in saturated volume 

multiplied by the change in water or moisture content of the 

soil or subsurface material. The change in saturated volume 

is determined by the area and thickness of the ground-water 

level change. For ground-water level declines, the change in 

water content is equal to the specific yield of the subsurface 

material. Specific yield is a dimensionless number that is the 

ratio of the volume of water that a saturated porous medium 

will yield by gravity to the volume of the porous medium 

(Lohman and others, 1972, p. 12). For rising ground-water 

levels, the water content is dependent on the antecedent soilmoisture content due to the prior addition or subtraction of 

water in the unsaturated zone within the volume encompassed 

by the ground-water level rise. Increases in water content can 

occur through the infiltration of precipitation or applied water 

for irrigation and decreases in water content can occur through 

evapotranspiration from plants or soil. Because no data were 

collected regarding water content of the unsaturated zone, the 

change in water content of the unsaturated zone for groundwater level increases was assumed to be equal to the specific 

yield. 

The monthly change in saturated volume of the 

subsurface materials was determined individually for the 

North and South Units. The change in the ground-water level 

for the shallowest well in each of the piezometer nests in 

each unit was interpolated on a daily basis. The ground-water 

level in each piezometer was assumed to be representative 

of the ground-water level throughout each wetland unit. The 

total volume of saturated soil, surface water, and air above 

the land or water surface between an arbitrary elevation 

(selected as the lowest land-surface elevation in the wetland 

4,129.79 ft. NGVD29) and the daily interpolated ground-water 

level for the piezometers was calculated for each wetland 

unit by multiplying the area of each unit by the height of the 

ground-water above the datum (calculated as the difference 

of the ground-water level elevation and the arbitrary datum 

elevation). Depressions in the land surface of the wetland 

that are below the ground-water level elevation may be filled 

with either surface water or air. The part of the total volume 

containing surface water or air was determined by using the 

stage-volume relation for each unit for the corresponding 

elevation of ground-water and subtracted from the total 

volume. The remaining volume is the saturated wetland soil 

for each unit above the arbitrary datum for that day. The daily 

change in ground-water storage is a function of the daily 

change in saturated wetland soil volume and the specific yield 

of the soil. The monthly change in ground-water storage was 

calculated as the sum of the daily changes in saturated wetland 

soil volume for the month multiplied by the specific yield of 

the soil.

A value of specific yield for peat soils was selected 

for use because peat is the predominant lithology present 

by volume in the upper part of the subsurface at the Wood 

River Wetland (Snyder and Morace, 1997, pl. 1). Boelter 

(1965, p. 229–230) measured specific yield for moderately 

decomposed herbaceous peat and for well-decomposed peat, 

obtaining values of 0.15 and 0.10, respectively. The mean of 

these two values, 0.125, was selected for use in this study. 

Multiplying the monthly change in saturated volume for each 

wetland unit by a specific yield of 0.125 provides an estimate 

of the change in ground-water storage for each unit.

Soil-Moisture Storage

The change in soil-moisture storage in the unsaturated 

part of the subsurface represents a change in volume of 

water stored in the wetland. The change in soil-moisture 

storage often is assumed to be negligible over the course of 

a water year (water year is defined as October 1–September 

30, and is identified by the year in which it ends), because 

depletion of soil-moisture storage is assumed to be equaled by 

replenishment through the infiltration of precipitation or other 

inflows. Although this assumption is generally valid when 

averaged over many years, variations during any single year 

could be significant. Soil-moisture storage can be calculated 

using information on soil-moisture content and volume of 

the unsaturated zone. The volume of the unsaturated zone 

can be estimated by using information on land surface from 

LiDAR data and by using the shallow ground-water levels 

recorded in the piezometers. No information was available on 

soil-moisture content; therefore, the change in soil moisture 

storage in the Wood River Wetland could not be directly 

calculated during this study. 

Calculation of Standing Nutrient Masses

Nutrient dynamics in wetlands are the result of interactive 

relations among physical, chemical, climatic, and biologic 

components. Nutrient sinks include uptake by wetland 

plants, microbial denitrification, ammonia volatilization, and 

precipitation into insoluble compounds. Nutrient sources 

include ground water, wet and dry precipitation, waterfowl 

feces, nitrogen fixation, decomposition, and release of 

nutrients from sediments and decaying plant material. 

Quantifying each of these dynamic processes was beyond 

the scope of this study. However, it was possible to quantify 

the seasonal fluctuation of standing nutrient masses, which 

provided insights into the whole-system responses to dilution, 

evapoconcentration, and biogeochemical processes. Nutrient 

masses (in kilograms) were calculated for the North and South 

Units as the median nutrient concentration multiplied by the 

standing water volume estimated on each sampling date.
22 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Figure 5. Daily water-surface elevations and standing volumes in the (A) North Unit and (B) South 

Unit of the Wood River Wetland, upper Klamath River basin, Oregon, 2003–05. (Dates of stage 

measurements and collection of water-quality samples for each unit are indicated.)

4,134

4,135

4,136

4,137

4,138

4,139

0

500

1,000

1,500

2,000

2,500 A. North Unit 

STANDING WATER VOLUME, IN ACRE-FEET 

4,134

4,135

4,136

4,137

4,138

4,139

0

500

1,000

1,500

2,000

2,500

B. South Unit 

Water-quality samples 

Standing water volume 

Stage measurements 

Water-surface elevation 

WATER-SURFACE ELEVATION, IN FEET 

MAY JULY

2003 2004 2005

SEPT NOV JAN MAR MAY JULY SEPT NOV JAN MAR MAY JULY SEPT

Results

Hydrologic Conditions During 2003–05

Surface Water and Ground Water

Surface-water stage and standing surface-water volume 

in the Wood River Wetland reached a maximum in early 

spring during the 2003–05 data collection period (figs. 3 and 

5). During this time, 80–90 percent of the wetland area was 

inundated. The average depth of the inundated areas was 

about 1.1–1.6 ft and maximum depths outside the canals were 

about 6 ft. Throughout each year, a greater percentage of the 

South Unit became inundated compared to the North Unit. 

The average water depths of the inundated areas in the South 

Unit were greater than the North Unit after discounting the 

canals. Surface-water stage and standing surface-water volume 

reached a minimum from August through November, when 

only about 10 percent of the wetland area was inundated. At 

this time, most of the inundation occurred in the South Unit 

and most of the North Unit was dry with much of the surface 

water confined to canals or ditches (fig. 3). The wetland was 

reportedly frozen over during parts of the winters of 2003–04 

and 2004–05 (Bureau of Land Management, 2006).
Results 23

The highest levels of shallow ground-water during the 

study period were in late winter or early spring and the lowest 

levels were in late summer or early autumn following a trend 

similar to surface-water levels (fig. 6). In the North Unit, 

water levels in all three piezometers (shallow, intermediate, 

and deep) were nearly identical and generally differed by 

only about 0.1 ft. The highest head was typically in the deep 

piezometer and the lowest head was in the shallow piezometer, 

indicating a slight upward gradient for ground-water flow; 

however, water levels in these piezometers did not exceed 

land surface. In the South Unit, water levels in the shallow 

and intermediate piezometers were nearly identical, generally 

differing by only about 0.2 ft. The highest head typically 

was in the shallow piezometer, indicating a slight downward 

gradient for ground-water flow; however, peak ground-water 

levels in these piezometers occasionally exceeded land surface 

indicating the potential for upward flow. The head difference 

in the deep piezometer in the South Unit varied from 5 to 7 ft 

above the head in the shallow and intermediate piezometers. 

The ground-water level in the deep piezometer always 

exceeded land surface by several feet, indicating artesian 

conditions. This is an indication of a strong upward gradient 

for ground-water flow and the likely presence of confining 

conditions resulting from intervening low-permeability layers 

such as clay. 

Water Budget

The water budget was determined monthly for May 

2003 through September 2005. Table 5 presents the summary 

for October 2003 through September 2005 (water years 

2004 and 2005). Excluding May through September 2003 

from the summary of the monthly budgets prevents the 

biasing of the annual averages toward those months that 

have low precipitation and high evapotranspiration due to 

disproportionate representation. This also allowed for a more 

accurate comparison of annual changes in the starting and 

ending magnitudes of the storage components by diminishing 

the effects of seasonal changes in storage.

Inflows

Monthly inflows to the Wood River Wetland (excluding 

contributions from storage components) peaked in September 

and October due to applied irrigation that represented only 

about 12 percent of the total inflow but which was applied 

over just 1.5 months. Inflows peaked again in late autumn 

through late winter or mid-spring due to precipitation. 

Precipitation was the largest component of inflow, accounting 

for about 43 percent of total inflow, most of which occurred 

during this time (fig. 7A, table 5). The remainder of the inflow 

was ground water from several sources. Most ground-water 

inflow resulted from regional ground-water discharge, which 

accounted for 40 percent of the total inflow and remained 

relatively constant throughout the year with a slight peak in 

summer due to increased hydraulic gradient. Ground-water 

discharge from artesian wells and seepage through dikes 

accounted for only 1 percent and 4 percent of the total inflow, 

respectively. Seepage through the dikes peaked in the spring 

when the water levels in the adjacent surface-water bodies 

were highest. The minimum inflows to the wetland resulted 

from decreased precipitation and occurred in summer and 

late autumn, excluding periods of applied irrigation. The 

distribution of inflow between the North and South Units 

generally was proportional to their area. The exceptions were 

applied irrigation, which entered entirely into the North Unit, 

and ground-water seepage inflows through the dikes, which 

were greater in the South Unit due to the long perimeter dikes 

adjacent to surface-water bodies.

Total precipitation during the 2005 water year was about 

normal although the distribution of precipitation throughout 

the year was not. Precipitation was lower than normal during 

January and February 2005 and higher than normal in May 

2005. This resulted in low levels of standing surface-water 

and, to a lesser extent, ground-water during spring and 

summer due to the uptake of precipitation by soil-moisture 

storage.

Outflows

Outflows from the Wood River Wetland (excluding 

contributions to storage components) peaked in June and 

July as a result of evaporation and evapotranspiration 

(fig. 7B). The largest component of outflow was from openwater evaporation, which was equivalent in volume to 

78 percent of the total inflows (table 5) and accounted for 

64 percent of the total outflows. The remaining outflow was 

from evapotranspiration from emergent vegetation, which 

was equivalent in volume to 44 percent of the total inflows 

(table 5) and accounted for 36 percent of the total outflows. 

Open-water evaporation exceeded emergent vegetation 

evapotranspiration from December through July and peaked 

around June when temperatures increased and large areas 

remained inundated. The reverse was true from August 

through November, when evapotranspiration from emergent 

vegetation exceeded open-water evaporation and peaked 

around August when water levels receded and plant growth 

increased. The minimum outflows from the wetland occurred 

November through January due to decreased evaporation 

and evapotranspiration resulting from lower temperatures, 

decreased solar radiation, and dormant vegetation. Open-water 

evaporation represented a greater proportion of the outflow in 

the South Unit than in the North Unit. This was a consequence 

of the slightly lower land-surface elevation in the South Unit, 

which resulted in large inundated areas that persisted for a 

longer time, allowing for warmer water temperatures (as much 

as 33.4°C, South Unit) that resulted in increased open-water 

evaporation.
24 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Figure 6. Ground-water elevations in wells and surface-water elevations from staff gages in the (A) North Unit 

and (B) South Unit of the Wood River Wetland, upper Klamath River basin, Oregon, 2003-05.

tac08-0249_Figure 06

MAY JULY

2003 2004 2005

SEPT NOV JAN MAR MAY JULY SEPT NOV JAN MAR MAY JULY SEPT

4,132

4,133

4,134

4,135

4,136

4,137

4,138

4,139

4,140

4,141

4,142

4,143

B. South Unit 

Staff plate (South Unit)

PZ-SU1

PZ-SU2

PZ-SU3

PZ-WRDK 

PZ-AGDK 

Staff plate (South Unit)

PZ-SU1 - Shallow

PZ-SU2 - Intermediate

PZ-SU3 - Deep

PZ-WRDK 

PZ-AGDK

Measured Values Interpolated/Extrapolated Values 

South Unit

 piezometer nest 

Dike

 piezometers

4,132

4,133

4,134

4,135

4,136

4,137

4,138

4,139

4,140

4,141

4,142

4,143

A. North Unit 

Staff plate (North Unit pump)

PZ-NU1

PZ-NU2

PZ-NU3 

Staff plate (North Unit pump)

PZ-NU1 - Shallow

PZ-NU2 - Intermediate

PZ-NU3 - Deep 

WATER SURFACE ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

Measured Values Interpolated/Extrapolated Values 

North Unit Piezometer Nest 
Results 25

North Unit South Unit

 

Total wetland

Acre-feet

Feet of 

water 

per year

As 

percentage 

of total 

inflow

Acre-feet

Feet of 

water 

per year

As 

percentage 

of total 

inflow

Acre-feet

Feet of

water per 

year

As 

percentage 

of total 

inflow

Inflows

Precipitation 4,100 1.28 39 3,100 1.31 49 7,200 1.29 43

Ground water:

Discharge from artesian wells 100 0.03 1 0 0.00 0 100 0.02 1

Seepage through dikes 300 0.09 3 400 0.17 6 700 0.13 4

Regional ground-water discharge 3,900 1.22 38 2,800 1.18 45 6,700 1.20 40

Total ground water 4,300 1.34 42 3,200 1.35 51 7,500 1.35 45

Irrigation inflow from Sevenmile Canal 2,000 0.62 19 0 0.00 0 2,000 0.36 12

Total inflow 10,400 3.24 100 6,300 2.66 100 16,700 3.00 100

Outflows

Pumpage 0 0.00 0 0 0.00 0 0 0.00 0

Evapotranspiration:

Open-water evaporation 6,500 2.03 63 6,500 2.74 103 13,000 2.33 78

Emergent vegetation evapotranspiration 4,900 1.53 47 2,500 1.05 40 7,400 1.33 44

Total evapotranspiraton 11,400 3.56 110 9,000 3.79 143 20,400 3.66 122

Total outflow 11,400 3.56 110 9,000 3.79 143 20,400 3.66 122

Change in storage (negative values indicate loss in storage)

Observed change in surface-water storage 0 0.00 0 -200 -0.08 -3 -200 -0.04 -1

Observed change in ground-water storage -300 -0.09 -3 -100 -0.04 -2 -400 -0.07 -2

Total change in storage -300 -0.09 -3 -300 -0.12 -5 -600 -0.11 -3

Water-budget residual1

Residual2 -700 -0.23 -7 -2,400 -1.01 -38 -3,100 -0.55 -19

1

 The residual incorporates errors associated with the measurement or estimation of all budget components as well as values of any unmeasured or 

unestimated budget components such as soil-moisture storage.

2

 Calculated as: Inflows - Outflows - Change in storage. Negative (-) values indicate a deficit of water due to errors in estimation or lack of inclusion of 

additional budget components resulting in one or more of the following conditions: inputs underestimated, outputs overestimated, and (or) change in storage 

overestimated.

Table 5. Water budget summary for the North Unit, South Unit, and total for the Wood River Wetland, upper Klamath River basin, 

Oregon, October 2003–September 2005.

[Volumetric values rounded to the nearest 100 acre-feet. Minor adjustments were made to rates and percentages due to rounding to maintain consistency within 

the table. Feet of water per year: Values represent the annual amount of water gained or lost from the wetland due to a water-budget component as if that 

component were spread across the entire area of each wetland unit.]
Figure 7. Monthly water-budget components (A) inflows, (B) outflows, (C) observed changes in storage, and (D) residuals, Wood River Wet

River basin, May 2003 through September 2005.

tac08-0249_Figure 07a

0

200400600800

1,0001,200

North Unit

Precipitation

0

200400600800

1,0001,200

ACRE-FEETDischarge from artesian wells Seepage through dikes Regional ground-water discharge

0

200400600800

1,0001,200 Irrigation inflow from Sevenmile Canal 

South Unit North and So

MAY JULY

2003 2004 2005

SEPT NOV JAN MAR MAY JULY SEPT NOV JAN MAR MAY JULY SEPT MAY JULY

2003 2004 2005

SEPT NOV JAN MAR MAY JULY SEPT NOV JAN MAR MAY JULY SEPT MAY JULY

2003 2004 

SEPT NOV JAN MAR MAY JULY 

A. Inflows to the Wood River Wetland

Ground water
Figure 7. Continued

tac08-0249_Figure 07b-c

-1,200-1,000

-800-600-400-200

0

Open-water evaporation 

-1,200-1,000

-800-600-400-200

0

ACRE-FEET

ACRE-FEET

Emergent vegetation evapotranspiration 

-2,400-2,000-1,600-1,200

-800-400

0

-2,400-2,000-1,600-1,200

-800-400

0

-1,000

-800-600-400-200

0

200400600800

1,000

Observed change in surface-water storage 

-1,000

-800-600-400-200

0

200400600800

1,000

ACRE-FEET

Observed change in ground-water storage 

-2,000-1,600-1,200

-800-400

0

400800

1,2001,6002,000

ACRE-FEET

-1,000

-800-600-400-200

0

200400600800

1,000

B. Outflows from the Wood River WetlandC. Observed changes in storage for the Wood River Wetland

-1,000

-800-600-400-200

0

200400600800

1,000

ACRE-FEET

North Unit

Water-budget residual:  Calculated as inflows - outflows - change in storage 

South Unit North a

MAY JULY

2003 2004 2005

SEPT NOV JAN MAR MAY JULY SEPT NOV JAN MAR MAY JULY SEPT MAY JULY

2003 2004 2005

SEPT NOV JAN MAR MAY JULY SEPT NOV JAN MAR MAY JULY SEPT MAY JULY

2003 

SEPT NOV JAN MAR MA

D. Water-budget residuals for the Wood River Wetland
28 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Changes in Storage

Changes in surface-water storage began increasing in 

autumn and showed the greatest increases in late winter due 

to increased inflow from precipitation, decreased outflows 

to evaporation and evapotranspiration, and prior satisfaction 

of soil-moisture and ground-water storage requirements 

(fig. 7C). Standing surface-water volumes responded to these 

increases and reached a maximum in early spring (figs. 3 and 

5). Changes in surface-water storage decreased throughout 

the spring and summer and showed their largest declines in 

late spring and early summer due to increased outflows to 

evaporation and evapotranspiration, and decreased inflows 

from precipitation. The inflows from applied irrigation and 

precipitation that occurred in late summer and early autumn 

had to satisfy soil-moisture and ground-water storage before 

surface-water storage could increase. Standing surface-water 

volumes responded to these declines and reached a minimum 

from September through November. The patterns of change 

in surface-water storage were similar for the North and South 

Units, although the North Unit had greater magnitudes for 

the largest rise and decline, which occurred during water 

year 2004. The total decline in surface-water storage was 

equivalent in volume to 1 percent of the total inflows.

Changes in ground-water storage began increasing 

in September and October initially showed the greatest 

increases due to inflow from applied irrigation and increased 

inflow from precipitation (fig. 7C). Decreased outflows to 

evapotranspiration and contemporaneous satisfaction of soilmoisture storage requirements contributed to the increase 

in ground-water storage. Increases in ground-water storage 

superseded increases in surface-water storage until groundwater levels rose to inundate the soils. Throughout the 

autumn and early winter, ground-water storage continued to 

increase; however, the magnitude of the increases declined 

as the available storage for ground water in the unsaturated 

zone became filled. Beginning in spring, changes in groundwater storage declined. The magnitude of the decline 

increased through the summer due to increased outflows to 

evapotranspiration and decreased inflows from precipitation, 

which also must contribute to satisfy soil-moisture 

requirements. However, the declines in ground-water storage 

occurred only after overlying surface-water levels receded 

sufficiently to expose the soils. Patterns of ground-water 

storage changes were similar in the North and South Units, 

although the magnitudes were somewhat greater in the North 

Unit due to the thick unsaturated zone over a larger area.

From October 1, 2003 through September 30, 2005, 

the standing surface-water levels in the North and South 

Units declined about 0.4 ft. However, because the North 

Unit was nearly dry and only a small part of the South Unit 

was inundated, the decline in stage represented only about a 

200 acre-ft loss in surface-water storage, nearly all of which 

occurred in the South Unit (table 5). During this same period, 

shallow ground-water levels declined about 1.7 ft in the North 

Unit and about 0.7 ft in the South Unit. This resulted in a 

decline in ground-water storage of about 300 acre-ft in the 

North Unit and about 100 acre-ft in the South Unit (table 5). 

The total decline in ground-water storage was equivalent in 

volume to 2 percent of the total inflows.

Water-Budget Residual

Monthly water-budget residuals (fig. 7D) were calculated 

using values of the inflows, outflows, and changes in storage. 

Positive residual values are due to errors in estimation or lack 

of inclusion of additional water-budget components. Positive 

residual values indicate an excess of water resulting from one 

or more of the following conditions: inputs overestimated, 

outputs underestimated, or change in storage underestimated. 

Negative residual values indicate a deficit of water resulting 

from one or more of the following: inputs underestimated, 

outputs overestimated, or change in storage overestimated. 

Examination of the monthly residuals reveals that the values 

follow the seasonal pattern expected for soil-moisture storage, 

an unmeasured and unestimated component of the water 

budget. Water goes into soil-moisture storage during the 

autumn and early winter primarily from inflow from applied 

irrigation and precipitation. During winter, soil-moisture 

stored in the unsaturated zone is converted to ground-water 

storage as rising ground-water levels incorporate the water 

into the saturated zone. During mid- to late spring soilmoisture storage may briefly increase as the soil receives 

moisture that remains in the unsaturated zone as ground-water 

levels decline. However, this may be offset by water removed 

from soil-moisture storage through evapotranspiration, which 

increases around mid- to late spring and increases through 

the summer. This cycle is more prominent in the North Unit, 

which had a thicker unsaturated zone over a larger area, and 

which persisted through a longer period of time compared 

with the South Unit. 

Most monthly residual values can be explained by the 

uptake or release of water by soil-moisture storage. However, 

errors in the estimation of the water-budget components are 

also present in the residuals. Sources of error include: 

• unknowns regarding the quantity and timing of surfacewater inflows for applied irrigation, 

• insufficient frequency of measurement of surface-water 

and ground-water levels for the estimation of surfacewater and ground-water storage, 

• uncertainty in the elevations and representativeness of 

staff gages for determination of surface-water levels in 

the estimation of surface-water storage, 

• uncertainty in the estimate of specific yield of the 

saturated soils for the estimation of ground-water 

storage, 

• possible underreporting of precipitation resulting from 

undercatch of solid and liquid precipitation due to wind 

and unshielded rain gage,
Results 29

• uncertainty with regard to the estimates of the 

hydraulic conductivity for the estimation of groundwater inflow,

• estimation of evaporation of open-water using the 

Priestley-Taylor equation, and

• estimates made from similar nearby wetlands for 

estimates of evapotranspiration from emergent 

vegetation. 

These errors may contribute to the water-budget residual 

calculated for October 2003 through September 2005, which 

was -3,100 acre-ft over the 2 year period (table 5). This 

amounted to an unaccounted loss of 0.55 ft/yr of water across 

the wetland and was equivalent in volume to 19 percent of the 

total inflows. 

The magnitudes of the monthly residuals tended to be 

larger for the North Unit than for the South Unit. However, 

the monthly deficits and excesses of water for the North Unit 

tended to balance each other on an annual basis. This is not 

true for the South Unit, which exhibited greater deficits than 

excesses of water. As a result, the cumulative residual for the 

South Unit for the 2-year period of the water-budget accounted 

for 77 percent of the total residual for the units combined. 

Based on the discussion above, possible causes of the 

deficit may be one or more of the following: underestimation 

of inflows from precipitation, ground water, or surface water 

used for irrigation (considered most likely); overestimation 

of evaporation, evapotranspiration, or change in surfaceor ground-water storage. Other unmeasured water-budget 

components such as soil-moisture storage or inflows resulting 

from breaches in the dikes also could contribute to the 

measured deficit.

Surface-Water Quality

Surface-water quality was highly variable depending 

on location (adjacent streams, North Unit, and South Unit) 

and season. Considerably lower concentrations of dissolved 

ions (lower SC) and nutrients and generally higher levels 

of daytime DO were detected in samples collected from 

Sevenmile Canal and Wood River than from wetland surface 

waters (fig. 8, table 6). 

Wetland surface water in the South Unit was warmer 

and had higher median DOC concentrations than the North 

Unit, ground-water, and adjacent stream sites (table 7, fig. 8). 

Maximum concentrations of nitrogen, phosphorus, and 

dissolved organic carbon were exceedingly high in the South 

Unit, reaching 90,000 μg-N/L TKN, 32,200 μg-P/L TP, and 

270 mg-C/L DOC (tables 8 and 9). The median concentrations 

of those parameters also were high. Ammonium concentrations 

reached 2,760 and 5,840 μg-N/L in the North and South 

Units, respectively. Median concentrations of nitrate were 

generally low (3.6 and 115 μg-N/L) in the North and South 

Units, respectively (table 8). In December 2003, however, the 

median nitrate concentration in the North Unit increased to 

2,270 μg-N/L (table 9). Although no pumping occurred during 

2003–05, the total nutrient concentrations in April and May 

(months when pumping typically occurred) ranged from 6,910 

to 10,450 μg-N/L TKN and from 4,400 to 6,350 μg-P/L TP in 

the South Unit, and were about 4,000 μg-N/L TKN and from 

670 to 800 μg-P/L TP in the North Unit (fig. 9, table 9).

Signs of biological activity, such as supersaturated DO 

during the daytime hours of as much as 310 percent, were 

apparent in the wetland surface waters (table 7). Accumulation 

of DO results from photosynthesis by wetland plants and 

algae. The highest recorded surface pH in the North and 

South Units (9.1 and 9.2, respectively) corresponded with DO 

concentrations of 310 percent and 290 percent saturation. DO 

concentrations in surface waters decreased each summer, with 

the lowest daytime values less than 2 mg/L in surface water 

each year. Minimum DO concentrations ranged from 0.3 to 

0.8 in the North Unit and from 0.2 to 1.9 mg/L in the South 

Unit, although concentrations may have been lower at times 

because instantaneous readings did not include early morning 

measurements.

Water-quality conditions varied seasonally, generally 

related to increasing spring and summer temperature and 

simultaneous evapoconcentration of nutrients and salts. SC 

values as much as 2,500 μS/cm were recorded in the South 

Unit (table 7). Most forms of N and P increased during the 

spring and summer months (fig. 9). Particulate N and P 

increased during summer, particularly in the South Unit as 

indicated by the relative concentration patterns of inorganic to 

total nutrients (DIN to TN and SRP to TP, fig. 10). Particulate 

matter and the tea-colored surface water produced significant 

light attenuation, reducing availability for photosynthesis 

and seed germination in areas of appropriate depth. Light 

extinction depths (point where light availability is zero) 

were as low as 30 cm in the South Unit, although values of 

35–70 cm were more common. The combination of low light 

penetration, high water temperature, and high organic content 

contributed to high biological oxygen demand and lowered 

DO concentration to 0.2–2.8 mg/L in surface water each year 

(fig. 9).

Water samples from the Wood River Wetland. Photograph taken by John Duff, 

U.S. Geological Survey, August 2005.
30 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

tac08-0249_Figure 08

0

50

100

150

200

250

300

350

TOTAL PHOSPHORUS (TP), IN

MICROGRAMS PER LITER

DISSOLVED AMMONIUM (NH4),

IN MICROGRAMS PER LITER

TOTAL KJELDAHL +

AMMONIA + NITRATE-N (TN),

IN MICROGRAMS PER LITER

TOTAL KJELDAHL +

AMMONIA-N (TKN),

IN MICROGRAMS PER LITER

DISSOLVED ORGANIC

CARBON (DOC), IN

MICROGRAMS PER LITER

SOLUBLE REACTIVE

PHOSPHORUS, IN

MICROGRAMS PER LITER

DISSOLVED KJELDAHL +

AMMONIA-N (DKN),

IN MICROGRAMS PER LITER NITRITE + NITRATE (NO2+NO3),

IN MICROGRAMS PER LITER

0

10,000

20,000

30,000

40,000

0

10,000

20,000

30,000

40,000

50,000

0

10,000

20,000

30,000

40,000

50,000

0

10,000

20,000

30,000

40,000

50,000

0

3,000

6,000

9,000

12,000

15,000

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

0

20

40

60

80

100

120

140

160

180

0

20

40

60

80

DISSOLVED CHLORIDE, 

IN MILLIGRAMS PER LITER

0

300

600

900

1,200

1,500

Sevenmile Canal

Wood River 

WRW NU-SW 

WRW SU-SW 

WRW ART-1 WRW ART-3 

WRW PZ-NU1 WRW PZ-NU2 WRW PZ-NU3 

WRW PZ-SU1 WRW PZ-SU2 WRW PZ-SU3 

WRW PZ-WRDKWRW PZ-AGDK

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS

PER CENTIMETER

0

5

10

15

20

25

30

WATER TEMPERATURE,

IN DEGREES CELSIUS

0

2

4

6

8

10

12

DISSOLVED OXYGEN, INMILLIGRAMS PER LITER 0

25

50

75

100

125

150

DISSOLVED OXYGEN, IN

PERCENT SATURATION 6.0

6.5

7.0

7.5

8.0

8.5

Sevenmile Canal 

Wood River 

WRW NU-SW 

WRW SU-SW 

WRW ART-1 WRW ART-3 

WRW PZ-NU1 

WRW PZ-NU2 WRW PZ-NU3 

WRW PZ-SU1 WRW PZ-SU2 WRW PZ-SU3 

WRW PZ-WRDK 

WRW PZ-AGDK 

pH, IN STANDARD UNITS

Streams Wetland

surface

 water Wetland ground water Streams Wetland

surface

 water Wetland ground water 

Percentile—Percentage of 

 analyses equal to or less 

 than indicated values. Data 

 points represent median 

 values, and whiskers indicate 

 the 25th and 75th percentiles

EXPLANATION

75 th

25th

Figure 8. Median values for water-quality variables grouped by site type, Wood River 

Wetland, upper Klamath River basin, Oregon, 2003-05. (Surface-water sites are indicated 

by green bars; ground-water sites are indicated by blue bars.)
Results 31

Site type Sampling site

Water temperature

(°C)

Specific conductance

(μS/cm)

Dissolved oxygen

(mg/L)

median min max n median min max n median min max n

Tributary Sevenmile Canal–inflow - SMIN 15.8 7.2 22.7 6 81 71 150 6 9.2 4.6 11.6 6

Sevenmile Canal–mouth - SMDK 18.8 9.8 21.8 8 94 77 580 8 7.7 1.6 11.4 8

Wood River–mouth WRDK 15.9 9.0 21.2 11 94 85 100 11 9.6 8.2 11.3 11

Wetland surface 

water

North Canal–inflow 15.2 5.9 18.6 4 120 110 250 4 5.2 4.3 7.7 4

NU Wetland–surface 19.1 5.8 30.8 68 240 78 790 75 3.5 0.3 20.0 74

NU Wetland–bottom 18.0 10.5 22.5 30 300 79 790 30 0.7 0.1 10.0 30

SU Wetland–surface 21.3 4.5 33.4 83 610 83 2,500 89 5.3 0.2 20.0 89

SU Wetland–bottom 19.0 12.7 25.0 18 430 81 1,260 18 3.1 0.1 11.2 18

Wetland ground 

water

ART-1 7.6 7.4 9.0 4 170 160 180 4 2.0 0.4 3.5 4

ART-3 9.1 8.4 9.8 2 210 210 210 2 2.8 2.5 3.1 2

PZ-NU1 15.4 10.3 16.4 7 480 340 580 7 0.9 0.4 4.6 7

PZ-NU2 11.2 8.8 14.3 8 470 420 600 8 0.8 0.4 1.4 8

PZ-NU3 11.6 9.2 13.7 8 1,340 1,150 1,410 8 0.8 0.6 1.7 8

PZ-SU1 11.5 10.8 14.2 6 430 430 460 5 1.1 0.8 2.0 6

PZ-SU2 10.4 9.1 17.1 8 490 440 560 8 1.4 0.6 5.3 8

PZ-SU3 10.6 9.0 14.6 8 245 230 450 8 0.7 0.3 1.9 8

PZ-WRDK 14.8 13.4 17.0 3 230 190 360 3 1.4 1.4 2.2 3

PZ-AGDK 15.0 12.0 19.9 4 275 260 340 4 1.1 0.4 2.1 4

Site type Sampling site

Dissolved oxygen

(percent saturation)

pH

(standard units)

median min max n median min max n

Tributary Sevenmile Canal–inflow 91 62 140 6 7.2 6.8 7.6 5

Sevenmile Canal–mouth 92 20 100 8 7.4 6.8 7.7 7

Wood River–mouth 110 79 140 11 7.4 6.8 8.2 10

Wetland surface 

water

North Canal–inflow 59 45 85 4 6.8 6.6 7.0 4

NU Wetland–surface 44 3.1 310 68 7.2 6.6 9.1 63

NU Wetland–bottom 5.5 2.3 65 19 7.2 6.7 10.0 19

SU Wetland–surface 60 3.0 290 83 7.7 7.2 9.2 78

SU Wetland–bottom 34 2.2 74 10 7.5 6.8 7.8 10

Wetland ground 

water

ART-1 18 4.0 33 4 7.7 7.6 7.8 3

ART-3 21 17 25 2 7.7 7.7 7.7 2

PZ-NU1 7.6 4.5 50 7 6.2 6.0 6.4 3

PZ-NU2 7.0 4.1 14 8 6.9 6.6 6.9 4

PZ-NU3 8.3 6.3 16 8 7.2 7.1 7.2 4

PZ-SU1 11 8 21 6 6.5 6.4 6.6 2

PZ-SU2 16 7 42 8 7.0 6.9 7.1 4

PZ-SU3 7.1 2.9 17 8 7.6 6.6 7.6 4

PZ-WRDK 17 16 25 3 – – – 0

PZ-AGDK 12 4.5 22 4 6.3 6.3 6.3 1

Table 6. Summary of field parameter surface-water data for Wood River Wetland, adjacent streams, and ground-water sites, upper 

Klamath River basin, Oregon, 2003–05.

[See table 1 for sampling site information. Abbreviations: °C, degrees Celsius; μS/cm, microsiemens per centimeter; mg/L, milligram per liter; min, minimum; 

max, maximum; n, number of observations; NU, North Unit; SU, South Unit; ART, artesian well; PZ, piezometer well; WRDK, Wood River dike; AGDK, 

Agency Lake dike; –, no data]
32 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Wetland 

unit Date

Water temperature

surface

(°C)

Water temperature

bottom

(°C) 

Specific conductance

surface

(μS/cm)

Specific conductance

bottom

(μS/cm)

pH

surface

(standard units)

median min max n median min max n median min max n median min max n median min max n 

North Unit 05-12-03 14.6 14.5 23.2 5 – – – 0

 

240 170 250 5 – – – 0 7.0 6.9 7.3 5

06-19-03 28.3 19.7 30.8 5 17.9 15.5 18.9 5 230 170 350 5 280 240 350 5 7.1 6.7 7.4 5

08-27-03 23.4 19.0 26.9 5 17.9 17.5 18.0 4 690 110 790 5 710 210 760 4 8.2 7.2 8.7 5

12-03-03 6.4 5.8 7.5 4 – – – 0 235 190 350 4 – – – 0 7.1 6.6 7.3 4

03-29-04 9.6 8.6 10.0 6 – – – 0 195 190 210 6 – – – 0 7.5 7.3 7.6 6

04-27-04 14.8 12.5 17.3 5 – – – 0 230 180 250 5 – – – 0 7.1 6.8 7.3 5

06-03-04 17.8 16.4 22.1 5 – – – 0 300 250 310 5 – – – 0 7.3 6.9 7.3 5

07-09-04 20.8 18.0 23.5 6 17.8 17.0 20.0 6 345 280 400 6 375 290 400 6 6.9 6.7 7.1 6

08-17-04 23.1 18.2 26.0 6 18.9 17.0 19.8 6 335 190 680 6 335 190 680 6 7.4 6.8 8.9 6

09-28-04 12.0 11.5 16.5 5 12.0 10.5 14.0 5 81 78 150 5 82 79 270 5 – – – 0

06-08-05 – – – 0 – – – 0 270 120 360 7 – – – 0 – – – 0

07-21-05 21.1 19.1 24.4 6 – – – 0 510 190 650 6 – – – 0 7.2 6.7 7.4 6

08-25-05 27.3 22.3 29.4 5 21.0 19.7 22.5 4 190 130 730 5 245 130 790 4 7.3 6.8 9.1 5

09-27-05 17.6 15.9 20.6 5 – – – 0 94 87 170 5 – – – 0 7.0 6.8 7.7 5

South Unit 05-13-03 19.3 14.4 24.7 11 16.2 12.7 24.8 7 420 380 440 11 420 390 430 7 7.6 7.4 7.6 11

06-19-03 22.6 20.0 28.4 4 – – – 0 580 550 600 4 – – – 0 7.7 7.5 7.8 4

07-16-03 22.5 20.1 26.3 7 – – – 0 790 770 830 7 – – – 0 7.4 7.3 7.5 7

08-27-03 28.5 24.2 30.2 4 18.8 16.6 20.0 3 1,290 1,280 1,290 4 1,220 1,180 1,260 3 8.2 8.0 8.4 4

12-03-03 5.1 4.5 5.9 5 – – – 0 860 770 1,160 5 – – – 0 8.0 7.6 8.2 5

03-30-04 8.6 8.4 9.1 8 – – – 0 445 440 480 8 – – – 0 7.8 7.6 7.8 8

04-28-04 11.5 11.0 12.0 6 – – – 0 515 500 530 6 – – – 0 7.7 7.6 7.7 6

06-02-04 24.4 22.7 27.7 6 – – – 0 640 620 650 6 – – – 0 7.7 7.6 7.8 6

07-09-04 25.0 24.5 26.0 6 24.0 21.5 25.0 5 880 870 890 6 820 770 870 5 7.5 7.2 7.5 6

08-17-04 25.3 24.6 26.1 3 – – – 0 1,720 1,650 1,860 3 – – – 0 8.3 8.1 8.9 3

09-28-04 20.0 18.0 23.5 5 17.0 16.5 22.0 3 86 83 610 5 85 81 100 3 – – – 0

06-09-05 – – – 0 – – – 0 525 510 560 6 – – – 0 – – – 0

07-22-05 27.8 24.0 28.8 6 – – – 0 945 620 1,020 6 – – – 0 7.8 7.2 8.7 6

08-24-05 25.6 20.5 33.4 7 – – – 0 1,660 460 2,100 7 – – – 0 8.3 8.1 9.2 7

09-28-05 11.9 9.9 14.0 5 – – – 0 430 280 2,500 5 – – – 0 7.6 7.3 9.0 5

Table 7. Summary of seasonal field parameter data for the North Unit and South Unit, Wood River Wetland, upper Klamath River basin, 

Oregon, 2003–05.

[Abbreviations: °C, degrees Celsius; μS/cm, microsiemens per centimeter; mg/L, milligram per liter; min, minimum; max, maximum; n, number of 

observations; –, no data]
Results 33

Wetland 

unit Date

pH

bottom

(standard units) 

Dissolved oxygen

surface

(mg/L)

Dissolved oxygen

bottom

(mg/L)

Dissolved oxygen

surface

(percent saturation)

Dissolved oxygen

bottom

(percent saturation)

median min max n median min max n median min max n median min max n median min max n 

North Unit 05-12-03 – – – 0 3.0 2.4 9.0 5 – – – 0 34 27 120 5 – – – 0

06-19-03 7.0 6.7 7.1 5 2.8 0.4 3.5 5 0.4 0.2 0.6 5 44 7.5 51 5 4.2 2.8 5.5 5

08-27-03 7.3 6.9 7.5 4 5.7 2.1 13.8 5 0.9 0.3 2.2 4 86 28 200 5 10 3.4 26 4

12-03-03 – – – 0 9.3 7.3 9.7 4 – – – 0 86 69 90 4 – – – 0

03-29-04 – – – 0 7.1 6.3 8.2 6 – – – 0 72 64 84 6 – – – 0

04-27-04 – – – 0 3.1 1.5 4.7 5 – – – 0 32 13 47 5 – – – 0

06-03-04 – – – 0 1.7 0.8 2.4 5 – – – 0 24 7.8 26 5 – – – 0

07-09-04 – – – 0 1.5 1.0 2.7 6 0.2 0.1 0.7 6 19 13 37 6 – – – 0

08-17-04 7.6 6.7 10.0 6 2.2 0.8 4.1 6 0.5 0.2 1.3 6 30 10 59 6 6.4 2.3 13 6

09-28-04 – – – 0 9.6 7.7 10.4 5 9.6 0.8 10.0 5 100 82 120 5 – – – 0

06-08-05 – – – 0 6.0 1.6 7.8 6 – – – 0 – – – 0 – – – 0

07-21-05 – – – 0 0.5 0.3 2.2 6 – – – 0 5.4 3.1 29 6 – – – 0

08-25-05 7.7 7.1 8.1 4 6.5 2.3 20.0 5 4.9 4.7 7.0 4 82 23 310 5 54 50 65 4

09-27-05 – – – 0 8.5 7.7 9.6 5 – – – 0 100 94 120 5 – – – 0

South Unit 05-13-03 7.5 7.4 7.6 7 5.0 3.8 5.8 11 3.2 2.4 5.2 7 62 48 74 11 37 29 74 7

06-19-03 – – – 0 3.1 2.4 4.1 4 – – – 0 41 32 60 4 – – – 0

07-16-03 – – – 0 2.8 1.9 3.2 7 – – – 0 38 25 44 7 – – – 0

08-27-03 7.5 6.8 7.8 3 8.5 5.9 10.7 4 0.2 0.2 0.4 3 140 81 160 4 2.6 2.2 4.4 3

12-03-03 – – – 0 9.4 7.0 11.1 5 – – – 0 86 65 110 5 – – – 0

03-30-04 – – – 0 7.4 5.8 9.0 8 – – – 0 74 58 89 8 – – – 0

04-28-04 – – – 0 6.1 5.8 6.9 6 – – – 0 55 53 63 6 – – – 0

06-02-04 – – – 0 4.1 2.8 4.4 6 – – – 0 46 34 49 6 – – – 0

07-09-04 – – – 0 4.1 3.5 5.4 6 0.1 0.1 4.1 5 58 50 78 6 – – – 0

08-17-04 – – – 0 1.0 0.8 4.4 3 – – – 0 12 10 65 3 – – – 0

09-28-04 – – – 0 11.0 10.2 14.4 5 11.0 10.4 11.2 3 140 130 200 5 – – – 0

06-09-05 – – – 0 5.7 4.0 7.2 6 – – – 0 – – – 0 – – – 0

07-22-05 – – – 0 2.7 0.2 13.1 6 – – – 0 39 3.0 200 6 – – – 0

08-24-05 – – – 0 9.0 4.1 20.0 7 – – – 0 110 44 290 7 – – – 0

09-28-05 – – – 0 5.8 2.2 9.6 5 – – – 0 65 23 95 5 – – – 0

Table 7. Summary of seasonal field parameter data for the North Unit and South Unit, Wood River Wetland, upper Klamath River basin, 

Oregon, 2003–05.—Continued

[Abbreviations: °C, degrees Celsius; μS/cm, microsiemens per centimeter; mg/L, milligram per liter; min, minimum; max, maximum; n, number of 

observations; –, no data]
34 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Table 8. Summary of nutrients, major ions, and dissolved organic carbon data for adjacent streams, wetland surface water, and 

ground-water sites, Wood River Wetland, upper Klamath River basin, Oregon, 2003–05.

[See table 1 for sampling site information. Abbreviations: N, nitrogen; μg/L, microgram per liter; min, minimum; max, maximum; n, number of observations; 

MDL, method detection limit; NU, North Unit; SU, South Unit; ART, artesian well; PZ, piezometer well; WRDK, Wood River dike; AGDK, Agency Lake dike; 

<, less than; –, no data]

Site 

type

Sampling 

site

Dissolved nitrite+nitrate-N 

(NO2

+NO3)

(μg/L)

Dissolved ammonium-N 

(NH3+NH4)

(μg/L)

Dissolved inorganic 

nitrogen (DIN)

(μg/L)

median min max n median min max n median min max n

Tributary Sevenmile Canal–inflow - SMIN 3.1 0.5 27.6 8 12 5.2 84 8 14 6.9 110 8

Sevenmile Canal–mouth - SMDK 3.2 0.6 9.7 10 20 10 38 11 24 11 42 11

Wood River–mouth WRDK 3.1 0.5 31.9 15 6.6 2.4 19 15 10 4.5 39 15

Wetland 

surface 

water

North Canal–inflow 1.9 <MDL 970 9 180 8.4 4,830 9 220 10 5,800 9

NU wetland–surface 3.6 <MDL 5,120 74 380 2.3 2,760 75 410 7.1 5,710 75

SU wetland–surface 115 <MDL 820 94 510 28 5,840 94 755 32 5,850 94

Wetland 

ground 

water

ART-1 1.2 0.4 8.1 8 5,790 5,620 5,970 8 5,740 0.4 5,970 9

ART-3 2.2 2.2 2.2 1 6,360 6,360 6,360 1 6,360 6,360 6,360 1

PZ-NU1 5.8 0.3 80.1 11 130 78 690 11 130 84 770 11

PZ-NU2 2.6 0.1 8.8 12 4,510 3,320 8,960 12 4,510 3,320 8,960 12

PZ-NU3 8.7 0.6 82.2 12 33,400 22,900 36,500 12 33,450 22,900 36,500 12

PZ-SU1 11.2 3.0 180 10 655 330 2,020 10 670 0.0 2,030 11

PZ-SU2 8.4 0.6 46.8 12 2,810 1,910 3,330 12 2,820 1,920 3,360 12

PZ-SU3 1.2 <MDL 47.7 12 3,290 2,890 3,570 12 3,290 2,890 3,570 12

PZ-WRDK 5.5 3.8 15.5 5 2,430 2,270 3,160 5 2,440 2,290 3,160 5

PZ-AGDK 3.0 1.9 21.6 6 7,380 7,280 7,980 6 7,380 7,290 8,010 6

Site

type

Sampling 

site

Dissolved Kjeldahl 

+ ammonium-N (DKN)

(μg/L)

Total Kjeldahl 

+ ammonium-N (TKN)

(μg/L)

Total Kjeldahl-N 

+ ammonium-N + nitrite

+nitrate-N (TN)

(μg/L)

median min max n median min max n median min max n

Tributary Sevenmile Canal–inflow 265 87 390 4 480 160 1,110 7 480 160 1,110 7

Sevenmile Canal–mouth 430 140 860 7 545 210 790 8 545 210 790 8

Wood River–mouth 120 54 200 7 140 57 430 14 140 57 430 14

Wetland 

surface 

water

North Canal–inflow – – – 0 1,050 920 6,860 5 1,050 960 7,830 5

NU Wetland–surface 3,970 140 13,600 56 4,150 230 17,500 71 4,210 230 17,500 71

SU Wetland–surface 9,240 290 38,600 61 10,600 320 90,000 90 10,600 320 90,000 90

Wetland 

ground 

water

ART-1 6,080 5,720 6,320 4 6,060 5,920 6,670 5 6,060 5,920 6,680 5

ART-3 – – – 0 – – – 0 6,360 6,360 6,360 1

PZ-NU1 1,990 1,270 3,890 7 2,340 1,700 3,910 9 2,340 1,730 3,910 9

PZ-NU2 5,150 4,220 7,170 7 6,050 4,080 9,700 10 6,050 4,080 9,700 10

PZ-NU3 38,250 35,500 42,900 8 40,450 36,800 43,100 10 40,450 36,800 43,100 10

PZ-SU1 1,760 1,260 1,910 6 2,830 1,760 6,710 8 2,830 1,840 6,710 8

PZ-SU2 4,280 3,580 4,400 7 4,130 2,630 5,320 10 4,130 2,630 5,330 10

PZ-SU3 3,700 3,190 6,150 8 3,650 3,450 4,190 10 3,670 3,450 4,190 10

PZ-WRDK 3,490 2,810 3,700 4 5,280 3,370 7,310 3 4,480 3,370 7,310 4

PZ-AGDK 8,090 7,990 9,490 4 13,600 12,800 15,300 4 13,500 7,500 15,300 5
Results 35

Site 

type

Sampling 

site

Soluble reactive 

phosphorus (SRP) 

(μg/L)

Total phosphorus (TP)

(μg/L)

Dissolved silica (Si)

(mg/L)

median min max n median min max n median min max n

Tributary Sevenmile Canal–inflow SMIN 74 59 130 8 130 85 180 7 – – – 0

Sevenmile Canal–mouth SMDK 120 74 320 11 185 91 250 8 48 48 48 1

Wood River–mouth WRDK 100 79 160 15 100 90 210 14 – – – 0

Wetland 

surface 

water

North Canal–inflow 120 50 1,490 9 130 110 1,050 5 – – – 0

NU Wetland–surface 500 41 3,210 75 670 72 6,660 71 58 42 73 2

SU Wetland–surface 7,020 88 19,900 94 7,800 99 32,200 90 49 35 64 4

Wetland 

ground 

water

ART-1 6,240 6,180 6,310 8 6,560 6,340 6,760 5 – – – 0

ART-3 6,790 6,790 6,790 1 – – – 0 – – – 0

PZ-NU1 720 280 1,520 11 780 350 1,680 9 60 60 60 1

PZ-NU2 2,100 290 2,570 12 2,900 2,270 3,670 10 – – – 0

PZ-NU3 3,600 290 4,110 12 4,370 4,060 4,650 10 – – – 0

PZ-SU1 3,010 950 5,030 10 4,920 2,170 5,860 8 – – – 0

PZ-SU2 6,070 3,770 7,000 12 6,940 6,190 7,490 10 – – – 0

PZ-SU3 6,390 6,030 6,630 12 6,710 6,430 7,150 10 – – – 0

PZ-WRDK 1,930 1,620 2,180 5 2,750 2,180 3,270 3 – – – 0

PZ-AGDK 1,090 93 1,270 6 1,920 1,730 2,280 4 – – – 0

Site

type

Sampling 

site

Dissolved organic carbon (DOC)

(mg/L) 

Dissolved chloride (Cl)

(mg/L)

median min max n median min max n

Tributary Sevenmile Canal–inflow 6 3 8 2 3 2 11 8

Sevenmile Canal–mouth 3 3 3 1 4 2 7 10

Wood River–mouth 2 2 2 2 6 5 6 15

Wetland 

surface 

water

North Canal–inflow 15 7 17 3 8 2 33 9

NU Wetland–surface 44 24 66 8 14 2 63 71

SU Wetland–surface 99 95 270 13 43 2 230 94

Wetland 

ground 

water

ART-1 4 4 5 2 1 1 1 8

ART-3 – – – 0 1 1 1 1

PZ-NU1 18 18 18 1 6 4 14 11

PZ-NU2 20 20 20 1 7 5 40 12

PZ-NU3 26 26 26 1 9 8 11 12

PZ-SU1 24 24 24 1 19 8 25 10

PZ-SU2 20 20 20 1 9 2 17 12

PZ-SU3 8 8 8 1 3 2 7 12

PZ-WRDK – – – 0 7 6 18 5

PZ-AGDK – – – 0 5 5 7 6

Table 8. Summary of nutrients, major ions, and dissolved organic carbon data for adjacent streams, wetland surface water, and 

ground-water sites, Wood River Wetland, upper Klamath River basin, Oregon, 2003–05.—Continued

[See table 1 for sampling site information. Abbreviations: N, nitrogen; μg/L, microgram per liter; min, minimum; max, maximum; n, number of observations; 

MDL, method detection limit; NU, North Unit; SU, South Unit; ART, artesian well; PZ, piezometer well; WRDK, Wood River dike; AGDK, Agency Lake dike; 

<, less than; –, no data]
36 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Table 9. Summary of seasonal nutrients, major ions, and dissolved organic carbon data for the North Unit and South Unit, Wood River 

Wetland, upper Klamath River basin, Oregon, 2003–05.

[Abbreviations: N, nitrogen; μg/L, microgram per liter; mg/L, milligram per liter; min, minimum; max, maximum; n, number of observations; <, less than; 

MDL, method detection limit; –, no data]

Wetland 

unit Date

Dissolved nitrite+nitrate-N

(NO2

+NO3)

(μg/L) 

Dissolved ammonium-N 

(NH3+NH4)

(μg/L) 

Dissolved inorganic 

nitrogen (DIN)

(μg/L) 

Dissolved Kjeldahl 

+ ammonium-N (DKN)

(μg/L)

median min max n median min max n median min max n median min max n

North 

Unit

05-12-03 50 26 210 4 270 44 750 4 320 71 960 4 – – – 0

06-19-03 5.4 1.4 23 5 500 89 680 5 510 90 710 5 – – – 0

08-27-03 6.8 1.2 7 5 210 2.3 1,250 5 210 9.1 1,260 5 – – – 0

12-03-03 2,270 350 5,120 4 580 500 840 4 2,940 930 5,710 4 – – – 0

03-29-04 3.5 < MDL 13 6 45 22 48 6 50 22 59 6 2,670 2,530 2,810 6

04-27-04 28 4.1 59 5 500 120 820 6 515 120 880 6 3,680 2,910 4,060 5

06-03-04 100 < MDL 190 5 450 200 710 5 610 200 900 5 4,170 3,870 4,650 5

07-09-04 1.3 0.4 11 6 990 470 2,470 6 995 470 2,470 6 7,550 5,980 9,000 6

08-17-04 0.5 < MDL 3 6 165 42 2,710 6 165 42 2,710 6 5,210 2,160 11,600 6

09-28-04 1.7 1.2 3 5 10 5.8 27 5 12 7.1 29 5 180 140 1,070 5

06-08-05 93 19 380 7 440 260 610 7 560 370 940 7 5,580 4,230 6,700 7

07-21-05 2.8 1.4 7.7 6 895 380 2,760 6 895 390 2,770 6 8,960 2,880 13,600 6

08-25-05 2.5 1.3 5.5 5 200 86 580 5 200 87 580 5 2,750 1,310 12,600 5

09-27-05 1.1 0.2 2.4 5 14 6.9 27 5 14 7.1 29 5 310 240 1,420 5

South 

Unit

05-13-03 340 250 460 11 270 130 420 11 660 430 760 11 – – – 0

06-19-03 335 300 380 4 515 460 660 4 855 840 960 4 – – – 0

07-16-03 190 110 260 7 630 500 740 7 760 690 930 7 – – – 0

08-27-03 18 4.9 94 6 465 260 720 6 525 270 760 6 – – – 0

12-03-03 15 1.7 48 5 250 120 2,060 5 260 150 2,110 5 – – – 0

03-30-04 81 50 130 8 955 630 1,380 8 1,040 760 1,430 8 8,060 7,290 8,900 8

04-28-04 490 270 690 6 1,780 1,190 2,240 6 2,340 1,880 2,540 6 9,150 4,520 9,500 6

06-02-04 340 170 390 6 360 270 970 6 745 560 1,140 6 9,220 8,410 10,800 6

07-09-04 205 92 240 6 505 290 860 6 685 530 950 6 15,100 14,600 15,500 6

08-17-04 2.6 < MDL 25 4 895 280 5,840 4 905 280 5,850 4 28,900 26,600 35,100 4

09-28-04 2.7 < MDL 5.6 6 86 28 350 6 89 32 350 6 455 290 11,900 6

06-09-05 550 240 820 6 490 300 630 6 1,040 870 1,290 6 8,480 7,830 9,070 6

07-22-05 22 5 180 7 1,110 140 1,840 7 1,130 150 1,860 7 14,800 8,000 16,900 7

08-24-05 10 < MDL 61 7 820 110 2,020 7 870 110 2,030 7 29,300 12,600 36,700 7

09-28-05 1.7 < MDL 4.6 5 170 46 630 5 170 47 630 5 4,610 2,390 38,600 5
Results 37

Wetland 

unit Date

Total Kjeldahl-N 

+ ammonium-N (TKN)

(μg/L)

Total Kjeldahl-N 

+ ammonium - N 

+ nitrite+nitrate-N (TN)

(μg/L)

Soluble reactive 

phosphorus (SRP) 

(μg/L)

Total phosphorus (TP)

(μg/L)

median min max n median min max n median min max n median min max n

North 

Unit

05-12-03 4,100 3,600 4,600 3 4,160 3,640 4,810 3 585 260 690 4 800 600 900 3

06-19-03 5,110 2,140 6,090 5 5,120 2,140 6,110 5 610 210 1,500 5 840 280 1,670 5

08-27-03 7,810 750 13,800 4 7,820 750 13,800 4 2,290 44 2,970 5 1,980 88 4,500 4

12-03-03 3,310 3,130 3,590 4 5,520 3,570 8,700 4 79 41 200 4 185 140 350 4

03-29-04 3,000 2,760 3,060 6 3,000 2,760 3,060 6 180 150 340 6 330 260 570 6

04-27-04 4,000 3,130 4,180 5 4,000 3,130 4,180 5 580 320 720 6 670 420 830 5

06-03-04 4,440 3,820 4,800 5 4,440 3,820 4,800 5 1,030 480 1,070 5 1,170 680 1,230 5

07-09-04 7,410 7,160 9,450 6 7,410 7,160 9,450 6 1,570 910 2,330 6 1,810 1,180 2,700 6

08-17-04 6,230 2,420 12,700 6 6,230 2,420 12,700 6 505 73 2,940 6 2,100 260 6,660 6

09-28-04 280 230 2,690 5 280 230 2,690 5 60 55 170 5 110 72 520 5

06-08-05 5,420 4,200 6,330 7 5,460 4,210 6,700 7 750 340 990 7 870 390 1,160 7

07-21-05 9,460 3,280 13,500 6 9,460 3,280 13,500 6 1,720 510 3,210 6 2,080 640 3,640 6

08-25-05 4,560 1,350 17,500 4 4,560 1,350 17,500 4 150 46 1,580 5 655 130 3,470 4

09-27-05 480 300 3,370 5 480 300 3,370 5 71 69 110 5 120 110 560 5

South 

Unit

05-13-03 6,600 6,100 6,800 11 6,910 6,530 7,090 11 4,150 3,620 4,520 11 4,400 3,900 4,900 11

06-19-03 8,380 8,380 8,380 1 8,680 8,680 8,680 1 7,530 7,010 7,740 4 7,720 7,720 7,720 1

07-16-03 11,700 11,200 12,300 6 11,850 11,400 12,500 6 10,700 10,400 11,100 7 11,650 11,400 12,300 6

08-27-03 18,650 10,500 21,700 6 18,650 10,500 21,800 6 13,450 6,810 15,600 6 18,450 11,200 19,900 6

12-03-03 14,400 12,600 19,100 5 14,400 12,700 19,100 5 4,170 3,700 6,890 5 5,070 4,240 7,730 5

03-30-04 8,240 7,270 9,450 8 8,240 7,270 9,450 8 4,040 3,870 4,510 8 4,590 4,500 5,240 8

04-28-04 10,450 9,620 11,200 6 10,450 9,620 11,200 6 5,150 4,100 7,500 6 6,350 5,860 6,460 6

06-02-04 10,450 8,610 11,200 6 10,450 8,610 11,200 6 7,520 7,050 7,810 6 8,170 7,920 8,430 6

07-09-04 14,800 14,000 17,200 6 14,800 14,000 17,200 6 12,950 12,700 13,300 6 14,300 14,000 14,700 6

08-17-04 36,500 29,600 90,000 4 36,500 29,600 90,000 4 15,600 6,830 19,100 4 26,150 23,700 32,200 4

09-28-04 3,470 320 12,300 6 3,470 320 12,300 6 165 88 3,520 6 505 99 5,070 6

06-09-05 8,720 7,750 9,210 6 9,330 8,320 9,780 6 7,190 6,560 7,540 6 7,700 7,220 8,350 6

07-22-05 14,600 9,290 17,000 7 14,600 9,300 17,000 7 14,000 6,340 14,600 7 15,600 7,890 16,000 7

08-24-05 29,800 10,200 42,100 7 29,800 10,200 42,100 7 16,300 3,470 19,900 7 22,800 5,880 28,500 7

09-28-05 6,970 3,470 47,400 5 6,970 3,470 47,400 5 2,810 1,960 3,670 5 3,630 2,350 20,400 5

Table 9. Summary of seasonal nutrients, major ions, and dissolved organic carbon data for the North Unit and South Unit, Wood River 

Wetland, upper Klamath River basin, Oregon, 2003–05.—Continued

[Abbreviations: N, nitrogen; μg/L, microgram per liter; mg/L, milligram per liter; min, minimum; max, maximum; n, number of observations; <, less than; 

MDL, method detection limit; –, no data]
38 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Wetland 

unit Date

Dissolved silica (Si)

(mg/L) 

Dissolved organic carbon (DOC)

(mg/L) 

Dissolved chloride (Cl)

(mg/L)

median min max n median min max n median min max n

North 

Unit

05-12-03 – – – 0 62 53 66 4 8.1 8.1 8.1 1

06-19-03 – – – 0 – – – 0 13 8.6 20 5

08-27-03 – – – 0 – – – 0 46 8.1 51 5

12-03-03 – – – 0 29 24 35 4 13 13 18 4

03-29-04 – – – 0 – – – 0 11 11 12 6

04-27-04 – – – 0 – – – 0 13 9.3 13 5

06-03-04 – – – 0 – – – 0 17 12 17 5

07-09-04 – – – 0 – – – 0 25 16 27 6

08-17-04 58 42 73 2 – – – 0 21 14 45 6

09-28-04 – – – 0 – – – 0 2.4 2.3 5.4 5

06-08-05 – – – 0 – – – 0 17 3.0 24 7

07-21-05 – – – 0 – – – 0 32 5.7 44 6

08-25-05 – – – 0 – – – 0 10 4.2 63 5

09-27-05 – – – 0 – – – 0 3.4 2.8 6.2 5

South 

Unit

05-13-03 – – – 0 98 95 100 8 28 26 29 11

06-19-03 – – – 0 – – – 0 37 35 38 4

07-16-03 – – – 0 – – – 0 52 51 55 7

08-27-03 – – – 0 – – – 0 95 43 100 6

12-03-03 – – – 0 190 150 270 5 76 62 110 5

03-30-04 – – – 0 – – – 0 30 29 31 8

04-28-04 – – – 0 – – – 0 35 34 37 6

06-02-04 – – – 0 – – – 0 43 41 46 6

07-09-04 – – – 0 – – – 0 70 69 71 6

08-17-04 49 35 64 4 – – – 0 155 150 200 4

09-28-04 – – – 0 – – – 0 3.0 2.3 68 6

06-09-05 – – – 0 – – – 0 36 34 39 6

07-22-05 – – – 0 – – – 0 66 38 71 7

08-24-05 – – – 0 – – – 0 150 31 200 7

09-28-05 – – – 0 – – – 0 25 15 230 5

Table 9. Summary of seasonal nutrients, major ions, and dissolved organic carbon data for the North Unit and South Unit, Wood River 

Wetland, upper Klamath River basin, Oregon, 2003–05.—Continued

[Abbreviations: N, nitrogen; μg/L, microgram per liter; mg/L, milligram per liter; min, minimum; max, maximum; n, number of observations; <, less than; 

MDL, method detection limit; –, no data]
Results 39

tac08-0249_Figure 09a

Wood River Wetland North Unit Wood River Wetland South Unit

0

500

1,000

1,500

2,000

2,500

STANDING WATER

VOLUME, IN

ACRE-FEET

0

5

10

15

20

25

30

35

WATER TEMPERATURE,

IN DEGREES CELSIUS 

0

200

400

600

800

1,000

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS

PER CENTIMETER

0

4

8

12

16

DISSOLVED OXYGEN, IN

MILLIGRAMS PER LITER 0

20

40

60

80

100

120

DISSOLVED OXYGEN, IN

PERCENT SATURATION 

0

500

1,000

1,500

2,000

2,500

0

5

10

15

20

25

30

35

0

500

1,000

1,500

2,000

2,500

0

2

4

6

8

10

12

0

40

80

120

160

200

6.5

7.5

8.5

9.5

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S

2003 2004 2005

pH, IN STANDARD UNITS 

7.0

7.5

8.0

8.5

9.0

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S

2003 2004 2005

Percentile—Percentage of analyses equal to or less 

 than indicated values. Data points represent median 

 values, and whiskers indicate the 25th and 75th percentiles.

EXPLANATION

75 th

25th

Figure 9. Trends in water-quality variables in the North Unit and South Unit, Wood River Wetland, upper 

Klamath River basin, Oregon, 2003–05. 
40 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

tac08-0249_Figure 09b

0

500

1,000

1,500

2,000

2,500

0

1,000

2,000

3,000

4,000

5,000

TOTAL KJELDAHL +

AMMONIA - NITROGEN,

IN MICROGRAMS PER LITER 

DISSOLVED AMMONIUM,

IN MICROGRAMS

PER LITER 

DISSOLVED INORGANIC

NITROGEN (NITRITE +

NITRATE + AMMONIUM),

IN MICROGRAMS 

PER LITER 

DISSOLVED KJELDAHL +

AMMONIA - NITROGEN,

IN MICROGRAMS

PER LITER 

TOTAL NITROGEN,

IN MICROGRAMS 

PER LITER 

SOLUBLE REACTIVE

PHOSPHORUS, IN 

MICROGRAMS PER LITER 

TOTAL PHOSPHORUS,

IN MICROGRAMS PER LITER 

DISSOLVED NITRITE +

NITRATE, IN MICROGRAMS 

PER LITER 

0

500

1,000

1,500

2,000

2,500

0

1,000

2,000

3,000

4,000

5,000

6,000

0

5,000

10,000

15,000

0

3,000

6,000

9,000

12,000

15,000

0

3,000

6,000

9,000

12,000

15,000

0

500

1,000

1,500

2,000

2,500

3,000

0

1,000

2,000

3,000

4,000

0

200

400

600

800

1,000

0

500

1,000

1,500

2,000

2,500

3,000

0

500

1,000

1,500

2,000

2,500

3,000

0

10,000

20,000

30,000

40,000

0

20,000

40,000

60,000

0

20,000

40,000

60,000

0

5,000

10,000

15,000

20,000

0

10,000

20,000

30,000

North Unit South Unit

STANDING WATER

VOLUME, IN

ACRE-FEET

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S

2003 2004 2005

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S

2003 2004 2005

0

500

1,000

1,500

2,000

2,500

Figure 9. Continued
Results 41

The increases in dissolved inorganic N and P (NO3, NH4, 

and SRP) outpaced the rate of evapoconcentration in the South 

Unit from spring and early summer to July, indicating the 

importance of other mechanisms. Ratios for individual nutrient 

to SC were calculated to examine temporal shifts in nutrients 

relative to a conservative tracer; SC was highly correlated 

with Cl (fig. 11), a conservative tracer unaffected by biological 

activity. Increases in the NO3 to SC, NH4 to SC, and SRP to SC 

ratios indicated that inorganic nutrients were produced faster 

than by evapoconcentration alone.

The seasonal pattern in nutrient to SC ratios were more 

pronounced in the South Unit than in the North Unit, but the 

general patterns were the same. Nutrient concentrations and 

ratios were more variable in the North Unit, where a notable 

increase in the NO3 to SC ratio was measured in December 

2003 (fig. 12), when the median NO3 concentration was 

2,270 μg/L. The phosphorus to SC ratio exhibited similar 

seasonal increases in nutrient mass and concentration (fig. 12).

Seasonal Patterns in Standing Nutrient Masses

Standing mass of TN and TP changed markedly, showing 

seasonal increases during spring and decreases in winter that 

were inconsistent with simple evapoconcentration and dilution 

mechanisms (fig. 13). Nitrogen mass was lowest during the 

autumn and winter, peaked in April, and decreased through 

the growing season, whereas SRP and TP peaked one to two 

months later in June and July and then decreased (fig. 13). 

Trace Metals

Dissolved trace metal concentrations, determined on a 

small number of samples, were dominated by iron, especially 

in the South Unit, where concentrations were 522–748 

μg-Fe/L (table 10). Samples containing high dissolved iron 

also contained high manganese concentrations, ranging from 

65 to 103 μg-Mn/L. The South Unit sites also had lower DO 

concentrations and higher dissolved iron, manganese, and 

phosphorus than the adjacent surface-water bodies (fig. 14). 

tac08-0249_fig10

0 

2,000 

4,000 

6,000 

8,000 

10,000 

0 

1,000 

2,000 

3,000 

0 

5,000 

10,000 

15,000 

20,000 

25,000 

30,000 

0 

10,000 

20,000 

30,000 

40,000 

Dissolved inorganic nitrogen

Total nitrogen

Soluble reactive phosphorus 

Total phosphorus 

North Unit South Unit

NUTRIENT CONCENTRATION, IN MICROGRAMS PER LITER 

2003 2004 2005 2003 2004 2005

M J J A S O N D J F M A M S J J A O N D J F M A M S J J A M J J A S O N D J F M A M S J J A O N D J F M A M S J J A

Figure 10. Median concentrations of bioavailable and total forms of nitrogen and phosphorus in the North and 

South Units, Wood River Wetland, upper Klamath River basin, Oregon, 2003–05.
42 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

tac08-0249_Figure 11

r

2

 = 0.95 

0

200

400

600

800

1,000

0 10 20 30 40 50 60 70

r

2

 = 0.98 

0

500

1,000

1,500

2,000

2,500

3,000

0 50 100 150 200 250

DISSOLVED CHLORIDE, IN MILLIGRAMS PER LITER

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

A. North Unit 

B. South Unit 

Figure 11. Relation between dissolved chloride and specific conductance in the (A) North Unit and

(B) South Unit of the Wood River Wetland, upper Klamath River basin, Oregon, 2003–05.
Results 43

tac08-0249_Figure 12

`

0

2

4

6

8

10

12

14

16

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0.0

1.0

2.0

3.0

4.0

5.0

0

5

10

15

20

0.0

1.0

2.0

3.0

4.0

5.0

6.0

5

10

15

20

0.0

1.0

2.0

3.0

4.0

5.0

6.0 Dissolved Kjeldahl + Ammonia Nitrogen Dissolved Kjeldahl + Ammonia Nitrogen

Dissolved Inorganic Nitrogen Dissolved Inorganic Nitrogen

Dissolved Ammonium Dissolved Ammonium

Dissolved Nitrate + Nitrite ratio Dissolved Nitrate + Nitrite ratio 

0

5

10

15

20

25

0

10

20

30

40 Total Kjeldahl + Ammonia Nitrogen Total Kjeldahl + Ammonia Nitrogen

0

5

10

15

20

25

30

0

5

10

15

20

25

30

35

40 Total Nitrogen

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

0

5

10

15

20 Soluble Reactive Phosphorus

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0

5

10

15

20 Total Phosphorus

Total Nitrogen

Soluble Reactive Phosphorus

Total Phosphorus

SPECIFIC CONDUCTANCE : NUTRIENT RATIO

North Unit South Unit

Percentile—Percentage of 

 analyses equal to or less 

 than indicated values. Data 

 points represent median 

 values, and whiskers indicate 

 the 25th and 75th percentiles.

EXPLANATION

75 th

25th

M J J A S O N D J F M A M S J J A O N D J F M A M S J J A

2003 2004 2005

M J J A S O N D J F M A M S J J A O N D J F M A M S J J A

2003 2004 2005

Figure 12. Ratios of nutrients to specific conductance for the North and South Units, Wood River 

Wetland, upper Klamath River basin, Oregon, 2003–05.
44 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

tac08-0249_Figure 13

North Unit South Unit

0

500

1,000

1,500

2,000

2,500

3,000

ACRE FEET 

Standing water volume 

0

500

1,000

1,500

2,000 Dissolved Ammonium-N 

0

500

1,000

1,500

2,000 Dissolved Inorganic Nitrogen (Nitrite+Nitrate+Ammonium-N) 

0

3,000

6,000

9,000

12,000

15,000 Total Nitrogen 

0

500

1,000

1,500

2,000

2,500

3,000 Soluble Reactive Phosphorus 

0

1,000

2,000

3,000

4,000 Total Phosphorus 

0

5,000

10,000

15,000

20,000 Total Phosphorus 

0

5,000

10,000

15,000

20,000 Soluble Reactive Phosphorus 

0

5,000

10,000

15,000

20,000

25,000 Total Nitrogen 

0

2,000

4,000

6,000 Dissolved Inorganic Nitrogen Nitrite+Nitrate+Ammonium-N 

0

1,000

2,000

3,000

4,000

5,000 Dissolved Ammonium-N 

0

500

1,000

1,500

2,000

2,500

3,000 Standing water volume 

0

300

600

900

1,200

1,500 Dissolved Nitrite + Nitrate-N Dissolved Nitrite + Nitrate-N 

0

200

400

600

800

KILOGRAMS

ACRE FEET KILOGRAMS

0

3,000

6,000

9,000

12,000 Dissolved Kjeldahl + Ammonium-N 

0

5,000

10,000

15,000

20,000

25,000 Dissolved Kjeldahl + Ammonium-N 

0

5,000

10,000

15,000

20,000

25,000 Total Kjeldahl + Ammonium-N 

0

5,000

10,000

15,000 Total Kjeldahl + Ammonium-N 

0

40,000

80,000

120,000

160,000

200,000 Dissolved Organic Carbon 

0

100,000

200,000

300,000

400,000 Dissolved Organic Carbon 

Percentile—Percentage of 

 analyses equal to or less 

 than indicated values. 

 Data points represent 

 median values, and 

 whiskers indicate the 25th 

 and 75th percentiles.

EXPLANATION

75 th

25th

M J J A S O N D J F M A M S J J A O N D J F M A M S J J A

2003 2004 2005

M J J A S O N D J F M A M S J J A O N D J F M A M S J J A

2003 2004 2005

 Values represent the median 

 nutrient concentrations plus 

 or minus the absolute 

 uncertainty in the water 

 volumes. All concentrations 

 reported in units of nitrogen [N], 

 phosphorus [P], or carbon [C].

Figure 13. Trends in standing nutrient masses (nitrogen, phosphorus, and carbon) in the North and 

South Units, Wood River Wetland, upper Klamath River basin, Oregon, 2003–05.
Results 45

Site name

Dissolved metal concentrations, in μg/L Select water-quality variables

Cadmium

(Cd)

Cobalt

(Co)

Copper

(Cu)

Iron

(Fe)

Manganese

(Mn)

Nickel

(Ni)

Lead

(Pb)

Vanadium

(V)

Zinc

(Zn)

DOC 

(mg/L) 

Cl 

(mg/L) 

Temp 

(°C)

SC 

(μS/cm)

DO 

(mg/L) 

DO (percent 

saturation)

pH 

(units)

Sevenmile Canal near 

mouth

<0.001 0.03 0.36 184 24 0.17 0.002 4.6 0.14 3.2 – 9.8 80 10.1 103 7.7

Wood River near mouth 0.008 0.01 0.29 83 5.8 0.17 0.108 7.1 0.63 2.0 5.5 11.8 97 9.6 102 7.2

Wood River Wetland South 

Unit–S-C south central

0.005 0.48 3.2 522 65 2.3 0.104 26.3 1.08 98 27.6 16.2 420 5.3 62 7.6

Wood River Wetland South 

Unit–NW northwest

0.007 0.49 2.8 657 103 2.3 0.115 24.8 1.16 26.0 19.3 380 4.5 56 7.4

Wood River Wetland South 

Unit–NE north east

0.007 0.54 3.3 748 81 2.5 0.226 27.1 1.15 97 27.8 20.3 428 4.8 62 7.6

Agency Lake along shore 

near WRW

<0.001 0.02 0.50 42 1.1 0.15 0.007 7.2 0.11 3.8 4.7 15.6 102 9.0 105 8.0

Agency Straits adjacent to 

TNC property

0.025 0.02 0.53 42 1.2 0.15 0.014 7.2 0.46 3.7 4.4 – – – – –

Table 10. Trace metals and other selected water-quality variables from the Wood River Wetland and Agency Lake, upper Klamath 

River basin, Oregon, May 2003.

[Abbreviations: μg/L, microgram per liter; DOC, dissolved organic carbon; Cl, chloride; Temp, water temperature; SC, specific conductance; DO, dissolved 

oxygen; mg/L, milligram per liter; °C, degrees Celsius; μS/cm, microsiemens per centimeter; <, less than laboratory method detection limit; WRW, Wood River 

Wetland; TNC, The Nature Conservancy]

2

4

6

8

10

12

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500

DISSOLVED OXYGEN, IN MILLIGRAMS PER LITER

SOLUBLE REACTIVE PHOSPHORUS, IN MICROGRAMS PER LITER

Sevenmile Canal 

South Unit sites 

Agency Lake 

Wood River 

A.

2

4

6

8

10

12

0 100 200 300 400 500 600 700 800 900

DISSOLVED IRON PLUS MANGANESE, IN MICROGRAMS PER LITER

Sevenmile Canal 

South Unit sites 

Agency Lake 

Wood River 

B.

Figure 14. Relations between dissolved oxygen and (A) soluble reactive phosphorus and (B) dissolved iron 

and manganese, at surface water sites in and around the Wood River Wetland, upper Klamath River basin, 

Oregon, May 2003.
46 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Ground-Water Quality

Ground-water quality from the artesian wells and 

piezometers at the wetland is presented in figure 8 and tables 6

and 8. Ground-water quality generally varied less over time 

than surface water, with the artesian wells showing the least 

variation. Variations in water quality between wells generally 

was greater than within an individual well, as shown for SC 

and SRP in figure 15. SC and SRP were similar in the two 

intermediate-depth wells along the dike road (PZ-WRDK and 

PZ-AGDK, fig. 2).

On four occasions, the water temperature of artesian well 

water at the northeast corral (ART-1) ranged from 7.4 to 9oC, 

with DO concentrations between 0.4 and 3.5 mg/L (table 6). 

Nutrient concentrations from ART-1 were intermediate 

between the adjacent streams and wetland surface water, with 

median TKN concentrations of 6,060 μg-N/L (5,790 μg-N/L 

was dissolved ammonium) and median TP concentrations of 

6,240 μg-P/L (mostly bioavailable SRP). Samples collected 

from ART-1 contained 4 mg-C/L DOC and 1 mg/L chloride, 

relatively low concentrations compared with the other wells 

(table 8).

DO in piezometer wells ranged from 0.3 to 5.3 mg/L 

(2.9–50 percent saturation, table 6) with median DO 

concentrations ranging from 0.7 to 5.3 mg/L. Minimum DO 

decreased slightly with increasing depth in the South Unit 

wells, from 0.8 mg/L DO in the shallow well to 0.3 mg/L 

in the deep well. Overall, the median pH in shallow wells 

(6.2 and 6.5 units in PZ-NU1 and PZ-SU1, respectively) 

was less than the median in the deep wells in both units (pH 

ranged from 7.2 to 7.6 units). The highest pH in ground water 

(7.8 units) was measured in the artesian well ART-1 (table 6

and fig. 8).

Most total nitrogen (TN) was dissolved organic 

nitrogen + NH4 (dissolved Kjeldahl nitrogen—DKN). In 

many instances, dissolved NH4 comprised most DKN in 

the piezometers. Nitrate concentrations in wells were low, 

ranging from less than detection to 180 μg-N/L (table 8). 

Concentrations of NH4 and SRP in ground water generally 

increased with depth (fig. 8, table 8), especially in the North 

Unit, where the deep well (PZ-NU3) had exceedingly high 

concentrations: NH4 (as much as 36,500 μg-N/L), SRP (as 

much as 4,110 μg-P/L) and SC (as high as 1,410 μS/cm) 

(tables 6 and 8). Nitrate levels, although low, were highest in 

the shallow South Unit wells, which contained slightly higher 

DO levels. The highest SRP concentrations in the South Unit 

ground water (about 6,600–7,000 μg-P/L) were detected in 

the intermediate and deep wells (PZ-SU2, and PZ-SU3). The 

median SRP concentration in the South Unit shallow well 

(PZ-SU1) was about four times higher than in the North Unit 

shallow well (PZ-NU1) (table 8). 

Concentrations of NO3, NH4, and SRP in the shallow 

and intermediate depth wells in the North Unit showed 

seasonal patterns somewhat related to DO concentrations 

(fig. 16). In 2003, the SRP concentration in PZ-NU1 was 

highest in December (1,265 μg-P/L) and decreased by 

spring when the DO concentration was 4.6 mg/L. SRP 

concentrations in PZ-NU1 increased from about 300 to 1,500 

μg/L during summer (fig. 16). DO concentrations in the 

North Unit decreased during summer to about 0.4 mg/L in 

the shallow and intermediate depth wells by July and August. 

The DO concentration in the intermediate depth well (PZNU2) was lower compared with the shallow or deep wells. 

Seasonal decreases in DO concentrations did not appear to 

increase SRP, but NH4 concentrations decreased from about 

9,000 μg-N/L to about 3,500 μg-N/L. Modest increases in DO 

concentrations occurred in September, especially in the North 

Unit wells, possibly in response to flood irrigation (fig. 16).

Biogeochemistry Experiments

Chamber studies were conducted in June and August 

2005 at various locations in the South Unit to examine 

potential for biogeochemical controls on nutrient dynamics 

at the sediment-water interface. Overall, nutrient flux was 

about twice as high for SRP (2.9 milligrams of phosphorous 

per liter per square meter per hour [mg-P/L/m2/h]) than for 

NH4 (1.3 mg-N/L/m2/h). The SRP increased in all chambers, 

averaging about 500 μg-P/L (6.5 percent) after an incubation 

period of 18–20 hrs. The NH4 concentrations increased 

about 200 μg-N/L (25 percent) in all but two chambers, 

where the NH4 concentration decreased (fig. 17). The DO 

concentrations decreased in most chambers to nearly anoxic 

levels (0.1-0.2 mg/L) by the end of the incubations, producing 

DO consumption rates between 0.15 and 1.0 mg/L/h. Slight 

increases in DO, potentially indicative of plant photosynthesis, 

occurred in two of the South Unit west chambers (fig. 17). 

A decrease in NO3 concentration was measured in all 

five control chambers, with simultaneous production of 

N2

O, indicating active denitrification by microbes (fig. 18). 

Denitrification rates were low in the controls due to low 

background NO3 (about 10–20 μg-N/L). Nitrate depletion and 

denitrification were enhanced with NO3 addition, indicating 

availability of DOC for microbes. The NO3 + glucose addition 

further enhanced NO3 depletion, producing N2O during 

denitrification and NH4, possibly by dissimilatory nitrate 

reduction to ammonia (DNRA) (fig. 18).
Results 47

tac08-0249_Figure 15

0

2,000

4,000

6,000

8,000

0 100 200 300 400 500 600

B. South Unit 

ART-1 

PZ-SU1

PZ-SU2

PZ-SU3

PZ-WRDK

PZ-AGDK

0

2,000

4,000

6,000

8,000

0 200 400 600 800 1,000 1,200 1,400 1,600

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

A. North Unit 

ART-1 

PZ-NU1

PZ-NU2

PZ-NU3

SOLUBLE REACTIVE PHOSPHORUS, IN MICROGRAMS OF PHOSPHOROUS PER LITER 

Well or 

—piezometer

Well or 

—piezometer

Figure 15. Soluble reactive phosphorus and specific conductance in wells and piezometers in the (A) 

North Unit and (B) South Unit of the Wood River Wetland, upper Klamath River basin, Oregon, 2003–05.
tac08-0249_fig 16

0.0 1.0 2.0 3.0 

0 

2,000 4,000 6,000 PZSU-1 (5-6 ft) 

0.0 1.0 2.0 3.0 4.0 5.0 6.0 

0 

2,000 4,000 6,000 8,000 

PZSU-2 (15-17 ft) 

0.0 1.0 2.0 3.0 4.0 5.0 

0 

500 

1,000 1,500 2,000 

PZNU-1 (3-5 ft) NH4 NO3 

SRP 

DO 

0.0 0.3 0.6 0.9 1.2 1.5 

0 

2,000 4,000 6,000 8,000 

10,000 

PZNU-2 (10-12 ft) 

0 

1,000 2,000 3,000 4,000 

PZ-WRDK (8-10 ft) 

0.0 0.5 1.0 1.5 2.0 

0 

2,000 4,000 6,000 8,000 

PZSU-3 (30-32 ft) 

0.0 0.5 1.0 1.5 2.0 

0 

10,000 20,000 30,000 40,000 PZNU-3 (26-28 ft) 

0 

2,000 4,000 6,000 8,000 

10,000 

PZ-AGDK (14-16 ft) 

0 

2,000 4,000 6,000 8,000 ART-1 (208 ft) 

DISSOLVED OXYGEN, IN MILLIGRAMS PER LITER

DISSOLVED OXYGEN, IN MILLIGRAMS PER LITER

NUTRIENT CONCENTRATION, IN MICROGRAMS PER LITER

NUTRIENT CONCENTRATION, IN MICROGRAMS PER LITER

NUTRIENT CONCENTRATION, IN MICROGRAMS PER LITER

M J S N J M M 

J 

2003 200

M J S N J M M S J N J M M S J

2003 2004 2005

M J S N J M M S J N J M M S J

2003 2004 2005

Figure 16. Seasonal patterns in nutrients and dissolved oxygen concentrations in wells at the Wood River Wetland, upper Klamath River ba

2003–05.
Results 49

tac08-0249_Figure 17

0

1,000

2,000

3,000

A. Dissolved Ammonium 

Starting concentration 

Ending concentration 

6,000

7,000

8,000

9,000

10,000

B. Soluble Reactive Phosphorus 

NUTRIENT CONCENTRATION, IN MICROGRAMS PER LITER

0

1

2

3

4

5

6

DISSOLVED OXYGEN,

IN MILLIGRAMS PER LITER

C. Dissolved Oxygen 

2 Chambers

(South Unit dock) 

2 Chambers

(South Unit west) 

2 Chambers

(South Unit east) 

2 Chambers

(South Unit west) 

4 Chambers

(South Unit dock) 

4 Chambers

(South Unit west) 

2 Chambers

(South Unit east) 

2 Chambers

(South Unit west) 

4 Chambers

(South Unit dock) 

4 Chambers

(South Unit west) 

2 Chambers

(South Unit east) 

2 Chambers

(South Unit west) 

Figure 17. Results of nutrient flux chamber experiments showing concentrations of (A) dissolved 

ammonium, (B) soluble reactive phosphorus, and (C) dissolved oxygen in the South Unit of the Wood 

River Wetland, upper Klamath River basin, Oregon, June 2005.
50 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

tac08-0249_Figure 18

-1,000

-750

-500

-250

0

250

500

750

1,000

C. Controls - No Additions 5 Endogenous control chambers 

-500

0

500

1,000

1,500

2,000

2,500

3,000

A. NO3-Addition

2 Endogenous control

chambers (no additions) 

-2,000

-1,000

0

1,000

2,000

3,000

4,000

5,000

B. Glucose + NO3- Addition 

2 Endogenous control

chambers (no additions) 

4 Treatment chambers 

ABSOLUTE CHANGE IN CONCENTRATION DURING INCUBATION, IN MICROGRAMS PER LITER

4 Treatment chambers 

Ammonium (NH4-N)

Nitrous oxide (N2O-N)

Nitrate (NO3-N)

Figure 18. Effect of (A) nitrate addition, (B) glucose plus nitrate addition, and (C) no addition on 

nitrogen concentrations during in-situ chamber experiments conducted in the South Unit of the 

Wood River Wetland, upper Klamath River basin, Oregon, August 2005.
Discussion 51

Discussion

Water Quality 

Water-quality in the Wood River Wetland was dynamic 

and related to seasonal water availability and temperature, 

major controls of biological activity, and continued release 

of nutrients and DOC. Potential sources of N and P include 

leaching from previously oxidized peat soils, the decay of 

recently grown vegetation, waterfowl feces (Manny and 

others, 1994), and remnant cattle waste. Evaporation and 

evapotranspiration water losses further increased nutrient and 

mineral concentrations in surface waters.

during the field sampling—possibly because the inlet structure 

includes a fish screen—water with elevated NH3 discharged 

to Wood River or Sevenmile Canal might affect fish in the 

immediate vicinity of the pump outlet station, depending on 

the total ammonia concentration, water temperature, pH, and 

streamflow in the receiving stream.

One logical source of NO3, NH4, and SRP during spring 

and early summer is sediment flux. Increasing nutrient to SC 

ratios coincided with increased water temperature, which 

stimulated bacterial activity and decomposition of peat soils. 

Although this hypothesis was supported by the chamber 

experiments, other potential sources of inorganic nutrients, 

including waterfowl feces or N-fixation, may be important 

at times. The decrease in DIN (NO3 + NH4) and phosphorus 

(SRP) concentrations during mid-August through September 

and the decrease in the DIN to SC and SRP to SC ratios 

indicate the presence of sinks such as plant uptake, rapid 

nitrification-denitrification for N, and sorption for P.

Legacy Effect of Wetland Drainage and Land 

Management

Intact wetland soils typically are inundated or water 

saturated, limiting air penetration into deep layers where 

anaerobic conditions limit decomposition and allow peat to 

accumulate (Cameron and others, 1989). Draining lowers the 

water table, increases aeration, and enhances soil microbial 

activity, which accelerates decomposition of organic matter 

(Maciak, 1972; Lee and Manoch, 1974; Lévesque and Mathur, 

1979; Mathur and Farnham, 1985; Efimov and Lunina, 1988; 

Laine and others, 1992). Because decomposition is most 

efficient in aerobic environments, decay rates are typically 

highest in aerated, unsaturated soils, and lowest in deep, 

water-saturated anoxic zones. Decomposition rates generally 

decrease exponentially as oxygen becomes depleted through 

progressively deeper layers.

Historical land management at the former Wood River 

Ranch included 50 years of wetland draining for beef 

production, which caused peat decomposition resulting in 

decreased peat thickness and mass, and promoted C, N, and 

P loss. Cattle waste also accumulated. Snyder and Morace 

(1997) determined that the extent of peat decomposition 

in drained wetlands surrounding Upper Klamath and 

Agency Lakes is related to the time since drainage, among 

other factors. In many places, soils have oxidized and lost 

substantial bulk, resulting in compaction and land subsidence 

as much as 13 ft (Snyder and Morace, 1997, p. 26). Loss of 

peat thickness at the Wood River Wetland may be as high 

as 4–4.4 ft (table 11). Wetland soils in the Twitchell Island 

restoration wetland in the Sacramento-San Joaquin River 

Delta, California, show land subsidence as much as 6 m 

(Rojstaczer and others, 1991; Fleck and others, 2004). In the 

Wood River Wetland, similar mineralization has released large 

quantities of carbon, nitrogen, and phosphorus, with respective 

losses averaging 36, 31, and 18 percent (table 11).

Pelican at the Wood River Wetland. Photograph 

taken by John Duff, U.S. Geological Survey, 

April 2005.

Concentrations of nutrients, DOC, and SC were 

substantially higher than in other area wetlands, including 

the Lower Klamath National Wildlife Refuge (Mayer, 2005) 

and restored wetlands surrounding Upper Klamath Lake (for 

example, Caledonia Marsh [MacLaren and Geiger, 2001] and 

Agency Lake Ranch [Damion Ciotti, Bureau of Reclamation, 

oral commun., 2007]). SRP and NH4 concentrations were 

particularly high in the South Unit. Benthic nutrient-flux 

experiments indicated that N and P were released from the 

soils (figs. 17 and 18). 

Despite the high NH4 concentrations, concerns about 

toxicity to aquatic life are lessened because at most times, a 

relatively insignificant amount of the more toxic, un-ionized 

free ammonia (NH3) was present. The median ammonium

concentrations in the North and South Units were 380 

and 510 μg-N/L, respectively, which would produce NH3

concentrations less than 30 μg-N/L. The maximum surfacewater concentration of total ammoniawas 5,840 μg-N/L (in 

the South Unit during August 2004), which would produce 

about 390 μg-N/L un-ionized ammonia (with concurrent 

temperature of 25°C and pH of 8.1 pH units). This maximum 

ammonia level might stress fish, including endangered Lost 

River and shortnose sucker fish, which have respective 

96-hour LC50 (median lethal concentration for one-half the 

test population) values of 780 and 530 μg/L NH3

 (Saiki and 

others, 1999). Although no fish were observed in the wetland 
52 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Wetland 

unit

 Core

name

 Area of 

wetland 

represented 

by core 

(acres)

 Peat thickness Peat mass Total organic carbon mass 

 Initial 

(ft)

1995 

 (ft)

 Loss 

(ft)

 Initial 

(kg)

1995 

(kg)

 Loss 

(kg)

 Loss 

 (percent)

 Initial 

(kg)

1995 

(kg)

 Loss 

(kg)

 Loss 

(percent)

 North 

Unit 

 WRR-05 343 4.3 3.5 0.8 220,000,000 210,000,000 12,000,000 5 84,000,000 70,000,000 14,000,000 17

 WRR-07 223 0.7 0.3 0.4 25,000,000 23,000,000 2,000,000 8 8,300,000 4,000,000 4,200,000 51

 WRR-08 491 11.3 7.3 4.0 900,000,000 730,000,000 170,000,000 19 290,000,000 100,000,000 190,000,000 65

 WRR-03 421 10.1 10.1 0 840,000,000 840,000,000 0 0 230,000,000 230,000,000 0 0

 WRR-04 165 10.7 10.0 0.7 290,000,000 290,000,000 74,000,000 3 100,000,000 92,000,000 7,700,000 8

 South 

Unit

 WRR-01 225 2.5 1.2 1.3 90,000,000 71,000,000 19,000,000 21 30,000,000 13,000,000 16,000,000 56

 WRR-02 187 7.0 3.7 3.3 210,000,000 180,000,000 34,000,000 16 69,000,000 32,000,000 37,000,000 53

 WRR-10 390 8.5 5.5 3.0 500,000,000 430,000,000 74,000,000 15 160,000,000 90,000,000 70,000,000 44

 WRR-09 225 14.5 10.1 4.4 520,000,000 480,000,000 36,000,000 7 160,000,000 110,000,000 53,000,000 33

 Sum 2,670 3,600,000,000 3,200,000,000 360,000,000 1,100,000,000 750,000,000 390,000,000

 Average 297 7.7 5.7 2.0 400,000,000 360,000,000 40,000,000 10 130,000,000 83,000,000 44,000,000 36

 NU average 329 7.4 6.2 1.2 460,000,000 420,000,000 39,000,000 7 140,000,000 100,000,000 43,000,000 28

 SU average 257 8.1 5.1 3.0 330,000,000 290,000,000 41,000,000 15 100,000,000 61,000,000 44,000,000 46

Table 11. Changes in peat thickness and nutrient content in soil cores collected from Wood River Wetland, upper Klamath River basin, 

Oregon. 

[Data from Snyder and Morace (1997, p. 39) and D.T. Snyder (U.S. Geological Survey, unpub. data, 1997). Shading indicates cores closest to the ground-water 

piezometer nests. Initial: prior to the beginning of drainage of a wetland for agricultural use. 1995: quantity present in the year 1995, the year of core sample 

acquisition. Loss: the difference between initial and 1995. See Snyder and Morace (1997, p. 21–24) for method of calculation. Abbreviations: NU, North Unit; 

SU, South Unit; WRR, Wood River Ranch; ft, foot; kg, kilogram]

Wetland 

unit 

 Core

name 

 Area of 

wetland 

represented 

by core 

(acres)

 Total nitrogen mass Total phosphorus mass 

 Initial 

(kg)

1995 

(kg)

 Loss 

(kg)

 Loss 

(percent)

 Initial 

(kg)

1995 

(kg)

 Loss 

(kg)

 Loss 

(percent)

 North 

Unit

 WRR-05 343 4,900,000 4,000,000 870,000 18 130,000 120,000 800 1

 WRR-07 223 590,000 390,000 200,000 34 17,000 17,000 0 0

 WRR-08 491 21,000,000 10,000,000 10,000,000 50 550,000 280,000 270,000 49

 WRR-03 421 19,000,000 19,000,000 0 0 350,000 350,000 0 0

 WRR-04 165 4,900,000 4,400,000 500,000 10 140,000 120,000 13,000 10

 South 

Unit 

 WRR-01 225 2,100,000 1,000,000 1,100,000 51 56,000 54,000 1,500 3

 WRR-02 187 4,900,000 2,700,000 2,200,000 45 130,000 81,000 53,000 39

 WRR-10 390 12,000,000 6,800,000 4,800,000 42 250,000 180,000 76,000 30

 WRR-09 225 11,000,000 7,900,000 3,400,000 30 270,000 190,000 73,000 28

 Sum 2,670 79,000,000 56,000,000 23,000,000 1,900,000 1,400,000 480,000

 Average 297 8,800,000 6,200,000 2,600,000 31 210,000 160,000 54,000 18

 NU average 329 9,900,000 7,500,000 2,400,000 23 230,000 180,000 56,000 12

 SU average 257 7,500,000 4,600,000 2,900,000 42 180,000 130,000 51,000 25
Discussion 53

Other studies at the newly restored Twitchell Island have 

demonstrated that permanently flooded conditions (25–55 cm 

depth) resulted in an average plant-material accumulation 

rate of 4 cm/yr in planted test plots (Miller and others, 2008). 

Such high rates of accumulation in the Sacramento-San 

Joaquin River Delta are producing land subsidence reversal, 

storing carbon and other nutrients and minerals in partly 

decomposed young peat that resemble the older peat in terms 

of composition and bulk weight. The highest rates of 7–9 cm/

yr were in plots with water depth of 55 cm in an area receiving 

a relatively low degree of flushing (Miller and others, 2008), 

which contributed to low decomposition rates and high overall 

accumulation of vegetation. Vegetative growth at the Wood 

River Wetland is occurring in many habitats less than 55 cm 

deep, whereas the open-water areas (canals and deep water 

habitats) are largely unvegetated. Because of the similarities 

in plant community composition between the Twitchell Island 

and Klamath Basin wetlands, hydrologic restoration of Wood 

River Wetland may produce results similar to those at the 

restoration of Twitchell Island. Although potential growth 

rates of wetland vegetation may be lower for upper Klamath 

River basin wetlands because of lower temperatures, light 

availability may be greater during summer months due to the 

higher elevation (about 4,000 ft) of the basin. As Miller and 

others (2008) point out, reversal of land subsidence through 

hydrologic restoration is an important strategy for reducing 

carbon emissions that contribute to global warming for two 

reasons: (1) a large amount of carbon can be stored (1 kg 

of carbon per square meter per year in the Twitchell Island 

wetlands) and (2) losses are minimized due to development of 

anaerobic conditions that limit further loss of carbon dioxide 

to the atmosphere from oxidation of peat soil.

Wood River Wetland peat beds were often buried 

beneath layers of silt, ash, pumice, or clay (Snyder and 

Morace, 1997) that further restricted oxygen penetration. In 

some areas, seasonally fluctuating water tables may infuse 

oxygenated surface water to peat layers, promoting aerobic 

decomposition. Permeable pumice layers also may facilitate 

the horizontal transport of oxygenated water, also enhancing 

peat decomposition. Oxygen availability in the deep peat 

horizons probably is limited, however, because of the high 

concentrations of ammonium and low nitrate in the deep wells, 

particularly in the North Unit (fig. 8). 

Biogeochemical cycling and (or) diffusive processes 

have enhanced P content in sediments relative to C or N. 

The Redfield ratio (C:N:P of 106:16:1 [by atom]) describes 

their relative proportions in healthy plant tissue. When 

compared with the Redfield ratios, C losses from the Wood 

River Wetland were 2–7 times greater than expected relative 

to losses for N and 2–451 times greater than expected for 

P (table 12). This disproportionate C loss resulted from 

decomposition and aerobic respiration of the organic-rich peat 

soils, producing carbon dioxide (CO2). Losses of N also were 

disproportionate compared with P because N is lost in gaseous 

form (NO, N2O, and N2) during denitrification, whereas P, 

which has no gaseous phase, is continuously recycled by 

biotic uptake/release or physiochemical sorption-desorption. 

Two cores (WRR-08, in the North Unit, and WRR-02, in the 

South Unit) showed significantly greater P-loss (relative to N), 

indicated by the low N:P Redfield ratio factors for these two 

cores (0.2–0.3) (table 12). These cores were collected from the 

deeper inundated areas of the wetlands (see plate 1, Snyder 

and Morace [1997]), on the north side of each dike. The large 

P loss might have been due to greater anaerobic release in 

these deeper areas.

 Wetland 

unit 

 Core 

name 

 Loss ratios Redfield ratio factor 

 C:N C:P N:P 5.7

 C:N 

41

 C:P 

7.23

 N:P 

 North 

Unit 

 WRR-05 16 18,479 1,123 3 451 156 

 WRR-08 18 712 39 6 2 0.2 

 WRR-04 15 583 38 2 369 155 

 South 

Unit 

 WRR-01 15 10,715 706 1,880 17 260 

 WRR-02 17 700 42 7 2 0.3 

 WRR-10 15 927 64 3 23 9 

 WRR-09 15 718 46 2 379 173 

 Average 17 4,690 294 4 240 97 

 NU average 18 6,591 400 4 274 104 

 SU average 16 3,265 214 5 190 87 

Table 12. Losses of carbon, nitrogen, and phosphorus from 

soil cores, and comparison to Redfield ratio factors, Wood River 

Wetland, upper Klamath River basin, Oregon. 

[Data from Snyder and Morace (1997) and D.T. Snyder (U.S. Geological 

Survey, unpub. data, 1997). Shading indicates cores closest to the groundwater piezometer nests. Redfield ratio factor: The loss ratio divided by the 

Redfield ratio (by weight); that is, a ratio of 1 would indicate balanced loss, 

whereas ratios greater than 1 indicate greater relative loss. Abbreviations: C, 

carbon; N, nitrogen; P, phosphorus]
54 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Biogeochemical Processes and Nutrient 

Transformation

Wetlands host diverse microbial communities 

whose metabolism drives carbon and nutrient cycles. The 

biogeochemical reactions are complex, and are driven by 

the presence or absence of DO. Reduction-oxidation (redox) 

conditions dictate the position, composition, and activity 

of microbes (Cameron, 1970; Cameron and others, 1989). 

Alternating bands of dark-colored decomposed soil and 

unmineralized light soil in Wood River Wetland cores may 

be due to redox gradients. Abiotic processes, including 

sorption and sequestering of inorganic phosphorus to iron 

and manganese compounds, also may be occurring in the 

sediment. In the presence of DO, phosphorus can be bound to 

iron and manganese, whereas anaerobic conditions may cause 

phosphorus to be released (fig. 14). 

The dried and oxygenated surface soils at the Wood River 

Wetland have been decomposed by bacteria that metabolize 

organic matter into CO2

, producing carbonic, humic, and 

fulvic acids that lower pH. Median pH values in the shallow 

wells in the North and South Units (6.2 to 6.5 units) were 

less than in the deep wells (7.2 to 7.6 units) (table 6), 

which is consistent with this theory. Lower NH4 and SRP 

concentrations in the shallow wells may indicate preferential 

decomposition and loss of nutrients from surficial soil layers 

by flushing. The high SC and ammonium concentrations in the 

North Unit deep well (PZ-NU3) (fig. 8) might have been due 

to a lack of flushing of the deeper soil layers by precipitation 

or surface-water irrigation. In contrast, the deep water from 

the South Unit (PZ-SU3) had lower SC than the intermediate 

or shallow depth wells. Greater flushing of the deeper layer 

compared with the shallow wells (PZ-SU1 and PZ-SU2) might 

explain this pattern, especially given the artesian nature of the 

deeper piezometer well (tables 1 and 2). The influence of deep 

artesian water on PZ-SU3 appeared for several water quality 

parameters, including SC, pH, and SRP (fig. 8). Less flushing 

in PZ-SU3 is consistent with the lower concentrations of DO 

and higher water temperatures compared with the deeper 

artesian wells (fig. 8). The differences in DO between the 

wells, and closer proximity to surficial peat soils for PZ-SU3, 

may allow ammonia to accumulate (from the breakdown of 

peat) if DO concentrations limit the conversion of ammonium 

to nitrate by nitrifying bacteria.

Decomposition of peat releases large quantities of DOC, 

amino acids, and other forms of dissolved organic nitrogen 

(DKN), which is mineralized to NH4

 (ammonification) by 

bacteria. This is one potential source of NH4 in the wetland. In 

the presence of oxygen, NH4 can be oxidized to NO2 and NO3

by nitrifying bacteria Nitrosomonas and Nitrobacter, although 

the relatively low DO levels in ground water (0.8–1.9 mg/L) 

may suppress this process below surficial sediments, resulting 

in relatively low NO3 in ground-water discharge. Low 

NO3 concentrations also may result from denitrification. 

Although denitrification rates at ambient NO3

 levels were not 

especially high in the chamber experiments (fig. 18), they 

were stimulated by adding NO3. This indicates that coupled 

nitrification-denitrification could maintain the low NO3 in the 

wetland throughout the year. Denitrification is the primary 

removal mechanism for nitrogen in many wetlands (Kadlec 

and Knight, 1996), with rates determined by factors such as 

temperature, organic carbon availability, nitrate loading, and 

anoxic conditions (Bachard and Horne, 2000).

Wetlands often contain water with little or no oxygen, 

particularly during summer, when biological oxygen demand 

from bacteria is high. DO gradients form in the water column, 

producing redox boundaries near or in the sediments where 

anaerobic microbes generate energy by oxidizing C, N, S, 

and other elements. During anaerobic metabolism, bacteria 

produce NO, N2O, N2, hydrogen sulfide (H2S), and methane 

(CH4), among other gases. Hydrogen sulfide gas odors were 

occasionally detected in the mucky soils in the wetland 

and in water samples collected from the deep North Unit 

well (PZ-NU3). Anaerobic conditions can also stimulate 

microbial reduction of nitrate to ammonium in a process called 

dissimilatory nitrate reduction (DNRA), which is carried out 

by Clostridia and certain sulfate reducing bacteria (Atlas 

and Bartha, 1993). The increase in NH4 during the chamber 

experiments with the simultaneous addition of nitrate and 

glucose (fig. 18) indicates that DNRA could be occurring in 

the wetland sediments.

Potential Management Strategies

The Wood River Wetland, and other drained wetlands 

adjacent to Agency and Upper Klamath Lakes, present 

difficult challenges to restoring wetland function, such as 

enhancing plant growth and retention of nutrients. The 

draining of wetlands has caused large losses of NH4 and SRP 

to surface waters that produce exceedingly high concentrations 

of dissolved nutrients and salts. Such legacy effects require a 

water-level and water-quality management strategy that slows 

the oxidation of peat soils and reduces nutrient concentrations 

while promoting growth of wetland vegetation.

Water-Quality Management

Although the wetland generates large amounts of N 

and P, nutrient loading from the wetland to adjacent water 

bodies was eliminated during 2003–05 by not pumping water 

from the wetland (fig. 19). High water in 2006 increased the 

water-surface elevation to about 4,138 ft (NGVD29) in the 

North Unit (fig. 2), and water was pumped from the wetland 

to relieve stress on dikes and encourage seed germination 

of wetland plants (Andrew Hamilton, Bureau of Land 

Management, written commun., 2006). About 4,500 acre-ft 

of water was pumped into Wood River and Sevenmile Canal 

between April and early June 2006, lowering the water level 
Potential Management Strategies 55

by about 3.2 ft. Although the nutrient load may have been 

high, the biological effects to the receiving waters depend 

on many factors, including the rate of loading, dilution by 

receiving waters, and residence time. Management strategies 

that could reduce the negative effects of pumping nutrient 

rich water on receiving waters include varying the timing 

so potential nutrient loading would occur during the nongrowing season (late autumn and winter), or pumping smaller 

amounts more frequently. Additional flushing of the wetland 

by flood irrigation and pumping may be required to dilute 

the sometimes exceptionally high levels of dissolved salts 

in the wetland surface waters that may interfere with seed 

germination, particularly in the South Unit.

Water-Level Management

Water levels influence biogeochemical reactions, seed 

germination, and other aspects of wetland ecology through 

their influence on habitat, DO concentrations, pH, temperature, 

and a number of other factors. The high DOC concentrations 

impart a brown color to the water that decreases light available 

for photosynthesis, and the high salt concentrations may 

interfere with osmotic water uptake in germinating seeds and 

young plants. Although adding water to the wetland during 

the summer could reduce the buildup of salts or DOC to 

levels more favorable for growth of wetland vegetation, lower 

water levels are required for seeds of many emergent plant 

species to germinate (Shipley and Parent, 1991). Bathymetric 

maps generated for the Wood River Wetland (fig. 3) can be 

used to optimize water levels in the North and South Units to 

help achieve management goals related to water quality and 

restoration of the wetland plant community.

To prevent further oxidation of peat soils, water could be 

added to the North Unit during summer to raise the water table 

and induce anaerobic conditions. Drying alters the structural 

integrity of soils, increases the surface area for decomposition, 

and allows air (with oxygen) to penetrate, further accelerating 

degradation. An intermediate water level may provide 

sufficient water to prevent oxidation of peat soils and would 

have the added benefit of increasing germination potential for 

wetland plants that cannot reproduce in a continuously flooded 

condition. Studies conducted on soil cores in the nearby 

Williamson River Delta Preserve detected higher nutrient 

losses from both flooded and dried cores compared with 

continuously moist cores (Aldous and others, 2005). Keeping 

soils moist and marginally flooded may be one management 

strategy to minimize nutrient loss in restored wetlands. 

Pumping of standing water from the wetland during spring to 

achieve water depths of between 25 and 55 cm (as determined 

during the Twitchell Island studies) might enhance plant 

growth, although creation of drier habitat may be necessary 

for initial seed germination. Plant growth can begin to rebuild 

peat soils, store carbon and nutrients, and reverse their losses.

One challenge for hydrologic restoration at the Wood 

River Wetland is that the land surface is sloped and irregular, 

with natural stream channels and deep canals that provide 

topographic relief. A particular water level will, therefore, 

produce a range in water depths throughout the wetland. 

The inundation analysis of the Wood River Wetland (fig. 20) 

portrays the number and size of ponded areas produced at a 

given water level that can be used to optimize water levels in 

the North and South Units. 

Due to wetter than average precipitation during winter 

2005, water was pumped from the wetland in April 2006 to 

ease pressure on the dikes. Future management could include 

permanent flooding to maintain saturated soil conditions and 

limit aerobic peat mineralization, with pumping to maintain 

target levels. Water level targets of 4,140.5 ft (NGVD29) in 

the North Unit and 4,135 ft in the South Unit were proposed 

by the BLM for enhancing seed germination (Bureau of Land 

Management, 2006). In the South Unit, this corresponds to tac08-0249_Figure 19

1

10

100

1,000

10,000

1975-1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

ANNUAL NUTRIENT LOAD, IN KILOGRAMS OF

NITROGEN AND PHOSPHORUS PER YEAR 

YEAR 

Total Kjeldahl nitrogen load (kilograms) 

Total phosphorus load (kilograms) 

* No pumping 

* ** *

This

study

Figure 19. Annual loads of total Kjeldahl nitrogen and total phosphorus discharged from the Wood 

River Wetland, upper Klamath River basin, Oregon, 1975–2005.
56 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

tac08-0249_fig 20 new

0 

1 

10 

100 

1,000 

10,000 

100,000 

0 

1 

10 

100 

1,000 

10,000 

100,000 

0 

1 

10 

100 

1,000 

10,000 

100,000 

NUMBER OF PONDED AREAS 

0 

1 

10 

100 

1,000 

10,000 

100,000 

0 

1 

10 

100 

1,000 

10,000 

100,000 

4,130 4,132 4,134 4,136 4,138 4,140 4,142 4,144 4,146 4,148 

WATER-SURFACE ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929 

POND SIZE 

LESS THAN 1 ACRE

POND SIZE 

LESS THAN 1 ACRE

POND SIZE 

1 TO 10 ACRES

POND SIZE 

1 TO 10 ACRES

POND SIZE 

10 TO 100 ACRES

POND SIZE 

10 TO 100 ACRES

POND SIZE 

100 TO 1,000 ACRES

POND SIZE 

100 TO 1,000 ACRES

POND SIZE 

GREATER THAN 

1,000 ACRES

POND SIZE 

GREATER THAN 

1,000 ACRES

A. North Unit B. South Unit

4,130 4,132 4,134 4,136 4,138 4,140 4,142 4,144 4,146 4,148 

Figure 20. Effect of water depth (stage) on formation and size of ponded areas (polygons) in the (A) North 

Unit and (B) South Unit of the Wood River Wetland, upper Klamath River basin, Oregon.

the level where many small ponds begin to coalesce into 

larger water parcels (fig. 20) reaching a maximum number 

of ponds at about 4,134.8 ft (NGVD29). In the North Unit, 

the maximum number of ponds occurs at a water elevation 

of about 4,135.8 ft (NGVD29), which is 4.7 ft lower than 

the proposed target of 4,140.5 ft. This higher water level 

will result in fewer wetted parcels in the North Unit, but will 

produce a greater area of inundation, which will help prevent 

further oxidation of peat soils.

Many drained wetlands around Upper Klamath and 

Agency Lakes have subsided several feet, and reconnection 

with the lake can produce large areas of relatively deeper 

water habitat. In the Twitchell Island wetland, depths 

ranging from 25 to 55 cm produced conditions favorable for 

wetland plant vegetation propagation and growth, leading 

to accumulation of plant material (Miller and others, 2008). 

Future studies at the Wood River and other area wetlands 

might include similar experiments to determine which water 

levels are most favorable to optimize plant growth while 

minimizing decomposition rates and water losses from ET at 

greater depths.

In 2007, The Nature Conservancy wetland restoration 

project at the nearby Williamson River Delta Preserve 

removed parts of the dike and reconnected the former wetland 

to Agency Lake. Although this change may initially release 

DOC and nutrients (Aldous and others, 2005), over the 

long term, nutrient losses would be expected to decrease as 

vegetation becomes established and peat soils rebuild (Fleck 
Potential Future Studies 57

and others, 2007). Regaining hydrologic connection to the 

lake will also produce a more natural flooding regime as 

wetland water levels decline in step with Upper Klamath and 

Agency Lakes, which drop an average of about 3 ft between 

June and October. Water may be applied to prevent soil drying 

during the late summer and early autumn, when water levels 

are lowest.

Capping Artesian Wells

Although the five artesian wells discharge 1 percent of 

the total water inflow, the water has relatively high nutrient 

concentrations (about 6,000 μg/L of NH4-N and SRP), much 

higher than those measured in Agency and Upper Klamath 

Lakes. Stopping the flow by decommissioning or capping 

these wells would reduce this input of nutrients to the wetland.

Potential Future Studies

In addition to the Wood River Wetland, other drained 

wetlands in the upper Klamath River basin are being restored 

through changes in water-level management (Agency Lake 

Ranch) or reconnecting the wetlands by removing dikes 

(for example, at TNC Williamson River Delta Preserve). 

Restoration of these wetlands presents unique opportunities 

to gain knowledge about how drained wetlands respond to 

various management strategies. The wetland character and 

history that govern the content and relative decomposition 

of the organic content of the soils, along with variables that 

control biogeochemical processes, determines to a large extent 

how a wetland responds to flooding or other changes in waterlevel management.

Comparing Managed Wetlands

Functioning wetlands support healthy vegetation that 

take up and store nutrients and carbon, trap sediment, and 

generally improve downstream water quality. Active wetlands 

process nutrients through removal of nitrogen by plant uptake 

and denitrification and removal of phosphorus from uptake 

and precipitation into insoluble forms along with iron and 

other minerals. Each process requires a specific suite of 

conditions dictated by the local hydrology, soil type, and plant 

or bacterial assemblage. Future studies of managed wetlands 

around Agency and Upper Klamath Lakes could examine 

how current and future water-level management affects 

soil conditions, plant assemblage structure, biogeochemical 

processing, and nutrient losses/storage over time. Additional 

monitoring of DO, pH, SC, and nutrients and additional flux 

studies in different types of wetlands could provide additional 

feedback to refine adaptive management strategies.

Plant Physiology Studies

Vegetation surveys indicate a continuing trend toward 

more obligate wetland plant species and a decrease or 

stabilization in the proportion of weedy, upland, or edge 

species (Bureau of Land Management, 2006). Enhanced 

production of emergent wetland species might be achieved by 

targeting water levels to specific concentrations of nutrients 

or dissolved salts. The high SC (as much as 2,500 μS/cm) 

and temperature (33.4°C) in the South Unit during summer 

could exceed the tolerance for seed germination of target plant 

species. The high DOC color in water effectively absorbs 

light wavelengths utilized during photosynthesis. As a result, 

light extinction depths were generally shallow (35–70 cm), 

which indicates that light probably limits photosynthesis in 

much of the open-water areas. Such light limitation might also 

decrease successful germination of dormant wetland plant 

seeds. Future studies could determine the light requirements 

for seed germination to promote recruitment and stimulate 

plant biomass, thereby increasing nutrient uptake and build 

plant biomass. Understanding individual plant preferences and 

tolerances for dissolved salts, nutrients, and light, for example, 

could accelerate wetland restoration by optimizing growth or 

mitigating unfavorable conditions.

Potential Effects of Dissolved Organic Carbon 

Export from Restored Wetlands

Potential inhibitory effects of DOC on Aphanizomenon 

flos-aquae—Decomposition of peat soils in the Wood 

River Wetland resulted in as much as 270 mg/L DOC in 

surface water (table 8). Certain types of DOC may inhibit 

or interfere with the growth of blue-green algae such as 

Aphanizomenon flos-aquae (AFA) (Geiger, 2001). If future 

management includes pumping high-DOC water into Agency 

Lake, monitoring the abundance and health of the AFA 

could verify potential interactive effects. Alternatively, as a 

result of wetland draining, export of DOC and bioavailable 

N and P may have enriched the lake with excess carbon and 

nutrients that stimulated heterotrophic activity and enriched 

the lake sediments with organic matter. This scenario may 

have contributed to the current condition of near complete 

dominance by AFA in Upper Klamath and Agency Lakes.
58 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Summary

Hydrologic and water-quality conditions were 

monitored in the newly restored Wood River Wetland in 

the upper Klamath River basin, Oregon, from May 2003 to 

September 2005 to establish baseline conditions as a prelude 

to development of future adaptive management options. 

Nitrogen, phosphorus, and instantaneous measures of field 

parameters (water temperature, dissolved oxygen, pH, and 

specific conductance) were monitored approximately monthly 

during the growing season at surface- and ground-water sites 

in the North and South Units of the Wood River Wetland. 

Limited dissolved organic carbon and selected dissolved 

metals data also were collected.

Solute concentrations in the wetland were higher than 

in adjacent streams or Agency Lake. Potential sources 

of nutrients in the wetland include releases from peat 

soils and decomposition of organic matter, including 

emergent, submergent, and floating macrophytes, algae, and 

waterfowl feces. Another factor contributing to high solute 

concentrations is summer evaporation and evapotranspiration, 

which averaged about 3.7 feet of water per year. The 

highest surface-water concentrations for most nutrients 

occurred in late summer, when water volumes were lowest. 

Evapoconcentration helped raise nutrient, carbon, and 

dissolved ion concentrations to exceedingly high values. 

This effect was most pronounced in the deeper South Unit, 

where specific conductance (SC) values reached 2,500 

microsiemens per centimeter (μS/cm) in September 2005. 

During the three year study, the median concentrations of total 

nitrogen (TN) and total phosphorus (TP) in the South Unit 

reached about 18,000–36,000 and 18,000–26,000 micrograms 

per liter (μg/L), respectively. Most of the TN and TP was in 

dissolved form, primarily as dissolved organic nitrogen or 

ammonium, and soluble reactive phosphorus (SRP). Nutrient 

concentrations in surface water generally were much lower 

in the North Unit than in the South Unit, which has deeper 

peat soils, although one set of samples collected in December 

2003 from the North Unit contained elevated concentrations of 

nitrate. 

Spring and early summer increases in dissolved 

ammonium and SRP outpaced chloride, a conservative 

tracer indicative of evapoconcentration. This indicates that 

biogeochemical processes other than evapoconcentration 

are responsible for the elevated nutrient concentrations in 

the wetland. Lower SRP and TP levels occurred in autumn 

following the annual flood irrigation of the North Unit and a 

return to cooler and wetter winter conditions. The SRP and TP 

concentrations decreased at a rate that was faster than dilution, 

indicating that inorganic sorption may have occurred in the 

wetland, possibly involving iron, manganese, or calcium.

Because of the elevated ammonium concentrations 

(and relatively high water temperature and moderate pH), 

some highly toxic un-ionized ammonia (NH3

) developed 

in the wetland surface waters. The median ammonium 

concentrations in the North and South Units were 380 and 

510 μg-N/L, respectively, which equates to NH3 concentrations 

of less than about 30 μg-N/L at the ambient temperature and 

pH. The maximum total ammonia concentration of 2,020 μg/L 

in the South Unit during August 2004 equates to 390 μg-N/L 

un-ionized ammonia (NH3) at the ambient water temperature 

and pH (25°C and 8.1 units, respectively). This NH3 level 

might stress fish, including endangered Lost River and 

shortnose sucker fish, which have respective 96-hour LC50

(median lethal concentration for one-half the test population) 

values of 780 and 530 μg/L NH3 (Saiki and others, 1999). 

Although a fish screen is used at the wetland inlet structure, 

water with elevated NH3 discharged to Wood River or 

Sevenmile Canal during pumping might affect fish in the 

immediate vicinity of the pump outlet station, depending on a 

number of factors, including the total ammonia concentration, 

pH, water temperature, and streamflow (amount of dilution) in 

the receiving stream (Wood River or Sevenmile Canal).

Seasonal increases in dissolved nutrients and minerals 

result from mineralization of peat soils. Previous studies 

of soil cores indicated land subsidence of about 4–5 feet, 

resulting in carbon, nitrogen, and phosphorus losses of about 

36, 31, and 18 percent of their initial (predrainage) mass, 

respectively. Peat-associated nitrogen likely contributed 

to the high ammonium concentrations (22,900–36,500 

μg-N/L) in the 26–28 ft well in the North Unit. Elevated 

nitrogen and phosphorus concentrations (about 6,000–

7,000 μg/L of ammonium and SRP) were measured in water 

samples from the five continuously flowing artesian wells. 

Biological activity was apparent in the wetland, including 

development of algae and floating and submerged aquatic 

plants, which boosted median total Kjeldahl nitrogen levels 

to 10,600 μg-N/L and TP to about 7,800 μg-P/L in the 

South Unit. The rapid decrease in ammonium, nitrate, and 

SRP during the latter part of the growing season (August 

and September) indicated biological uptake from algae, 

macrophytes, and other wetland vegetation. Photosynthesis 

by aquatic plants sometimes produced supersaturated midday 

dissolved oxygen concentrations in surface waters (as much as 

310 percent saturation) and pH up to 9.2 units during summer. 

Dissolved oxygen concentrations at wetland surfacewater sites decreased each summer, and minimum values 

were less than 0.5 mg/L each year. Decomposition of peat 

soils and vegetation likely contributed to the decreased 

dissolved oxygen levels measured in the wetland surface and 

ground waters. Some areas of the wetland supported sulfate 

reduction indicative of anaerobic conditions. Anaerobic soil 

conditions in wetland sediments act to halt the oxidation and 

decomposition of peat soils, and are a natural condition in 

functioning and healthy wetlands.
Summary 59

In-situ mesocosm dome chamber experiments conducted 

in the South Unit during June and August 2005 indicated 

active demand for dissolved oxygen (0.15–1.0 milligrams 

of oxygen per liter per hour [mg-O2/L/h]). Positive flux 

of ammonium and SRP from the bed sediment also was 

measured during the chamber experiments. This release 

may be attributed to the upward movement of ground water 

through nutrient-rich decomposing peat soils (for nitrogen 

and phosphorus), and desorption from iron or manganese in 

the soil under anaerobic conditions (for phosphorus). The 

chamber experiments also confirmed active denitrification, 

but rates were low due to low nitrate levels in the incubation 

water (wetland surface water). The low nitrate probably results 

from a combination of denitrification in the wetland, uptake 

by wetland vegetation, and perhaps from a microbial process 

termed dissimilatory nitrate reduction to ammonium (DNRA). 

The concentration of dissolved ammonium increased in the 

chambers with additions of nitrate and carbon, which indicates 

the possible occurrence of DNRA. Overall, these experiments 

showed active nutrient cycling by microbial populations in the 

wetland sediments.

Surface-water levels and standing surface-water volumes 

in the Wood River Wetland reached a maximum in early 

spring, inundating 80–90 percent of the wetland. Minimum 

water levels occurred in August through November, when 

the South Unit was 10 percent inundated and the North Unit 

was nearly dry. Shallow ground-water levels followed a 

trend similar to surface-water levels and indicated a strong 

upward gradient. The hydrologic conditions and water levels 

measured during this study were influenced by the relatively 

dry conditions in 2003–05, and may not be representative of 

conditions during wet years. Additionally, water levels may 

not get as low considering that current management includes 

irrigation in late July to maintain a greater area of saturated 

soils.

Monthly water budgets were developed individually 

for the North and South Units of the Wood River Wetland 

and then summed to produce a water budget over a 2 year 

period (2004 and 2005 water years). The budget was based 

on estimates of inflows from precipitation, ground water, 

and surface water applied for irrigation; outflows to openwater evaporation and evapotranspiration due to emergent 

vegetation; and changes in surface-water and ground-water 

storage. Precipitation was the largest component of inflow 

for the entire wetland, representing 43 percent of the total 

inflow. Precipitation values were obtained from a nearby 

automated agricultural weather station. Inflow from regional 

ground-water discharge accounted for 40 percent of the total 

and was estimated using Darcy’s Law. Reported inflow from 

applied water for irrigation from adjacent surface-water bodies 

contributed 12 percent of the total inflow. Combined inflows 

from ground-water seepage through dikes and discharge 

from five artesian wells represented 5 percent of the total 

inflow. Outflows from the wetland consisted of open-water 

evaporation (estimated using an empirical evaporation 

equation) and evapotranspiration from emergent vegetation 

(estimated from energy balance studies of nearby wetlands) 

which accounted for 64 and 36 percent of the total outflow, 

respectively. Outflows exceeded inflows by about 22 percent 

over the 2-year period. Changes in surface-water and groundwater storage during this period were determined by the 

change in surface- and ground-water levels and amounted 

to losses of only 1 and 2 percent relative to the total inflow, 

respectively. A water-budget residual consisting of the errors 

in measurement or estimation of all water-budget components 

and the sum of any unestimated components indicated a water 

deficit of 19 percent relative to the total inflow. The monthly 

patterns in water-budget residuals for the wetland resembled a 

soil-moisture signal, which, although not measured, could be a 

significant part of the water budget.

The distribution of inflow between the North and 

South Units generally was proportional to their area. The 

primary exception was applied irrigation, which entered 

entirely into the North Unit. Open-water evaporation was a 

greater proportion of the outflow in the South Unit relative 

to the North Unit as a consequence of the South Unit’s large 

persistent areas of open water.

Inundation models developed for this study can be used 

to guide future water management of the wetland to reduce 

further oxidation of peat soils while providing shallow 

habitats for wetland plant seed germination. Given the current 

conditions, higher water levels in the North Unit and lower 

water levels in the South Unit (achieved through pumping) 

may be needed to achieve both of these management goals. 

Additional flushing of the wetland by flood-irrigation 

and pumping may be required to dilute the sometimes 

exceptionally high levels of dissolved salts and dissolved 

organic carbon in the wetland surface waters that may impede 

seed germination in the South Unit. Focused studies could 

determine the particular salt tolerances and light requirements 

for successful germination and growth of wetland plant 

species.

Determining the appropriate water level to minimize 

oxidation of soils while promoting seed germination is 

challenging due to the presence of relatively deep canals, 

patchy distribution of swales and ponds, and areas of subsided 

soils. Future studies of the various managed wetlands around 

Agency and Upper Klamath Lakes could examine how 

current and future water levels affects soil conditions, plant 

assemblage structure, and nutrient losses/storage over time. 

Such studies would provide useful feedback to help guide 

restoration of wetlands for water quality improvements and 

carbon storage.
60 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

Acknowledgments

The authors wish to thank the former and present Bureau 

of Land Management Wood River Wetland coordinators 

Wedge Watkins, Michael Turaski, Andrew Hamilton, and 

Robert Roninger for their support and assistance with logistics, 

staff gage readings, and land survey data. David Ross from 

the U.S. Fish and Wildlife Service Klamath Basin Ecosystem 

Restoration Office was helpful during the early planning of the 

study and we thank him for sponsoring this research. Several 

USGS employees contributed to this work—Andrew Arnsberg 

and Curt Hughes helped with field sampling, Kevin Knutson 

and Charley Palmer installed the network of ground-water 

piezometers, and Tana Haluska provided valuable assistance 

processing the LiDAR data. April McKeller, Scott Vanderkooi 

and Rip Shively (USGS) provided field and logistical support. 

George Aiken, James Kuwabara, and Ronald Avanzino (USGS 

National Research Program) provided dissolved organic 

carbon, nitrate, ammonium, chloride, and various trace metal 

analyses. Special thanks to Allison Aldous (The Nature 

Conservancy), Larry Dunsmoor (Klamath Tribes), Stan Geiger 

(Aquatic Scientific Resources), and Tim Mayer (U.S. Fish and 

Wildlife Service), who contributed through discussions about 

the history and condition of the upper Klamath River basin 

and the ecology of its wetlands—their insights and expertise 

were most helpful. 

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Appendix A. Water-Quality Data, Wood River Wetland, Oregon, 2003–05 65

Appendix A. Water-Quality Data, Wood River Wetland, Oregon, 2003–05

Appendix data can be accessed by downloading files at http://pubs.usgs.gov/sir/2009/5004.
66 Hydrologic and Water-Quality Conditions, Wood River Wetland, Upper Klamath River Basin, Oregon, 2003–05

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