U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2020-5001

Prepared in cooperation with the Bureau of Reclamation

Modeling a 2- and 4-Foot Drawdown in the Link 

River to Keno Dam Reach of the Upper Klamath River, 

South-Central Oregon
Cover: View looking south along the Link River to Keno Dam reach of the upper Klamath River, 

south-Central Oregon, with Mount Shasta, northern California, in the background. Photograph by 

Chauncey Anderson, U.S. Geological Survey, August 2009.
Modeling a 2- and 4-Foot Drawdown in the 

Link River to Keno Dam Reach of the Upper 

Klamath River, South-Central Oregon

By Annett B. Sullivan and Stewart A. Rounds

Prepared in cooperation with the Bureau of Reclamation

Scientific Investigations Report 2020–5001

U.S. Department of the Interior

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

DAVID BERNHARDT, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2020

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Suggested citation:

Sullivan, A.B., and Rounds, S.A., 2020, Modeling a 2- and 4-foot drawdown in the Link River to Keno Dam reach of the 

upper Klamath River, south-central Oregon: U.S. Geological Survey Scientific Investigations Report 2020–5001, 18 p., 

https://doi.org/10.3133/sir20205001.

ISSN 2328-0328 (online)
iii

Contents

Executive Summary.......................................................................................................................................1

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

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

Methods...........................................................................................................................................................5

CE-QUAL-W2 Model .............................................................................................................................5

Scenario Setup ......................................................................................................................................5

Scenario Output and Analysis ............................................................................................................5

Results and Discussion .................................................................................................................................6

Water Velocity and Travel Time ..........................................................................................................6

Water Quality.........................................................................................................................................6

Model Scenarios Without Macrophytes .................................................................................6

Keno Dam Outflow ..............................................................................................................6

Link-Keno Reach .................................................................................................................6

Algae and Settled Organic Matter ..........................................................................6

Dissolved Oxygen ......................................................................................................8

Water Temperature ...................................................................................................8

Model Scenarios With Macrophytes .......................................................................................9

Acknowledgments.......................................................................................................................................18

References Cited..........................................................................................................................................18

Figures

1. Map showing Link River to Keno Dam reach of the Klamath River, 

south-central Oregon ...................................................................................................................2

2. Graph showing measured water-surface elevation at three locations in 

Klamath River from Link River mouth to Keno Dam (Link-Keno reach), 

south-central Oregon, 1907-08, and modeled water-surface elevation in the 

2007 base case and the 2- and 4-foot drawdown scenarios .................................................4

3. Side view of the two-dimensional hydrodynamic and water quality model 

(CE-QUAL-W2) grid showing the model segments and the model layers, from 

Link River to Keno Dam, south-central Oregon .......................................................................4

4. Graphs showing modeled water velocity in the year 2007 base case, and 

modeled velocity difference between the 4-foot drawdown scenario and the 

base-case model, in the Link River to Keno Dam reach of the Klamath River, 

south-central Oregon ...................................................................................................................7

5. Graphs showing model tracer results from addition of a hypothetical tracer 

at the mouth of Link River and downstream tracer concentrations at the Keno 

Dam outflow indicating the time required for the tracer peak to reach Keno 

Dam, south-central Oregon, during 2007 ..................................................................................8

6. Graphs showing modeled flow, temperature, and water-quality constituents in 

the outflow of Keno Dam for the base case, and the 2- and 4-foot drawdown 

scenarios, in the Link River to Keno Dam reach of the Klamath River, 

south-central Oregon, during 2007 ............................................................................................9
iv

7. Graphs showing modeled chlorophyll a concentration for the year 2007 base 

case and the 4-foot drawdown scenario, in the Link River to Keno Dam reach of 

the Klamath River, south-central Oregon ...............................................................................10

8. Graph showing modeled difference in segment-averaged chlorophyll a

concentration between the 4-foot drawdown and the base-case scenarios, 

and depth profiles showing chlorophyll a at model segment 38 near Miller 

Island for the base case and 4-foot drawdown scenario, in the Link River to 

Keno Dam reach of the Klamath River, south-central Oregon, during 2007 .....................11

9. Graphs showing modeled settled organic matter in the first-order sediment 

compartment for the year 2007 base case, and the difference in modeled 

settled organic matter mass between the 4-foot drawdown scenario and 

the base case, in the Link River to Keno Dam reach of the Klamath River, 

south-central Oregon .................................................................................................................12

10. Graph showing modeled difference between dissolved oxygen concentration in 

the 4-foot drawdown scenario and the year 2007 base case, in the Link River to 

Keno Dam reach of the Klamath River, south-central Oregon ............................................13

11. Dissolved-oxygen profiles showing changes in dissolved oxygen 

concentrations at segments 38 (Miller Island) and 95 (Keno Bridge), with 

depth, during 2007, in the Link River to Keno Dam reach of the Klamath River, 

south-central Oregon .................................................................................................................14

12. Graph showing modeled difference between water temperature in the 4-foot 

drawdown scenario and the year 2007 base case, in the Link River to Keno 

Dam reach of the Klamath River, south-central Oregon ......................................................15

13. Water-temperature profiles showing changes in water temperature at segment 

38 (Miller Island), with depth, during 2007, in the Link River to Keno Dam reach 

of the Klamath River, south-central Oregon ...........................................................................15

14. Graphs showing modeled flow, temperature, and water-quality constituents in 

the outflow of Keno Dam for the base case and 4-foot drawdown scenarios, 

Klamath River, south-central Oregon ......................................................................................16

15. Graphs showing dissolved-oxygen production and respiration fluxes, as 

modeled with the presence of macrophytes, for macrophytes and algae for the 

entire Link-Keno reach, Klamath River, south-central Oregon ...........................................17

16. Dissolved oxygen profiles showing changes in dissolved oxygen 

concentrations at segments 38 (Miller Island) and 95 (Keno Bridge), with depth, 

during 2007 ...................................................................................................................................18
v

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

 Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

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

International System of Units to U.S. customary units

Multiply By To obtain

Length

meter (m) 3.281 foot (ft)

kilometer (km) 0.6214 mile (mi)

Area

square meter (m2) 0.0002471 acre

square meter (m2) 10.76 square foot (ft2)

Volume

liter (L) 0.2642 gallon (gal)

Flow rate

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

cubic meter per second (m3/s) 35.31 cubic foot per second (ft3/s)

Mass

microgram (μg) 0.00000003527 ounce, avoirdupois (oz)

milligram (mg) 0.00003527 ounce, avoirdupois (oz)

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound avoirdupois (lb)

metric ton (t) 1.102 ton, short [2,000 lb]

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

°F = (1.8 × °C) + 32.
vi

Datums

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

A local vertical datum (Upper Klamath Lake Vertical Datum [UKLVD]) is used, established by 

the Bureau of Reclamation. For the purpose of this report, the conversion is UKLVD – 1.78 feet = 

National Geodetic Vertical Datum of 1929 (NGVD 29).

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

Supplemental Information

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

or micrograms per liter (μg/L).

Abbreviations

CE-QUAL-W2 Two-dimensional hydrodynamic and water-quality model

Link-Keno Klamath River from Link River mouth to Keno Dam

Reclamation Bureau of Reclamation

USGS United States Geological Survey
Modeling a 2- and 4-Foot Drawdown in the Link 

River to Keno Dam Reach of the Upper Klamath River, 

South-Central Oregon

By Annett B. Sullivan and Stewart A. Rounds

Executive Summary

The most upstream, pooled reach of the Klamath 

River in south-central Oregon, from Link River mouth to 

Keno Dam (Link-Keno), has a water-surface elevation that 

remains relatively constant throughout the year. Two model 

scenarios, using an existing two-dimensional hydrodynamic 

and water-quality model (CE-QUAL-W2), were constructed 

to examine the effects of lowering the water-surface elevation 

by 2 and 4 feet (ft) (0.61 and 1.2 meters) throughout an 

entire calendar year to mimic some of the potential effects of 

removal or modification of Keno Dam. Model results for these 

drawdown scenarios were analyzed for changes in velocity, 

travel time, water temperature, total dissolved solids, inorganic 

suspended sediment, nutrients, organic matter, chlorophyll 

a, and dissolved oxygen, compared to the base-case 

model. The model used in this study had been previously 

calibrated with the presence of aquatic plants (macrophytes). 

However, most model analyses were completed for model 

runs where macrophytes were “turned off” because the 

species, abundance, and distribution of macrophytes in 

a lowered-water scenario were all highly uncertain. For 

comparison, a few model scenario runs were completed with 

macrophytes enabled within the model. Findings from this 

study include the following:

• Modeled water velocity increased and travel time 

decreased substantially throughout the reach with 

the 2- and 4-ft drawdown scenarios, with travel time 

roughly halved in the 4-ft scenario under unchanged 

flow conditions.

• For many water-quality constituents in the drawdown 

scenarios, the model showed little to no change in 

outflow concentrations at Keno Dam compared to 

the base case, which represents conditions based on 

year 2007 water-level elevations. However, chlorophyll a and particulate organic carbon concentrations 

increased in the Keno Dam outflow in summer with the 

drawdowns. This seemed to be related to the increased 

water velocity. As suspended algae and other particulate organic matter such as dead algal cells and detritus 

moved farther downstream with the faster velocity, 

there was relatively less deposition of that material in 

the most upstream model segments and relatively more 

deposition in downstream segments of the Link-Keno 

reach, especially in summer and autumn, the period 

with the largest algae bloom.

• Despite minor differences in the Keno Dam outflow, 

modeled dissolved oxygen concentration and water 

temperature showed some changes in the Link-Keno 

reach compared to the base case, with differences as 

large as 2 milligrams per liter and 2 degrees Celsius, 

respectively, computed as segment averages and daily 

averages.

• With macrophytes enabled, the model outflow in the 

drawdown scenarios showed a decrease in dissolved 

oxygen concentration in mid-summer that seemed to 

be related to decreased macrophyte abundance and 

primary production in those scenarios. The withmacrophyte model results have greater uncertainty, 

but the results indicated that macrophytes are likely to 

be an important factor in the dissolved oxygen budget 

under reduced water-surface elevations.

Introduction

The Klamath River flows approximately 255 mi (410 

km) from the mouth of Link River near Upper Klamath Lake 

to the Pacific Ocean. The first 20 mi (32 km) of the Klamath 

River are bounded by the mouth of Link River at the upstream 

end and Keno Dam at the downstream end (Link-Keno) 

(fig. 1). This reach was designated as “water-quality limited” 

for exceeding ammonia toxicity and not attaining minimum 

dissolved oxygen criteria year-round, and failing to meet pH 

and chlorophyll a criteria in summer. This river reach receives 

large algal and nutrient loads in summer from Upper Klamath 

Lake, which is just upstream of Link River, with additional 

inputs from nonpoint and point sources in the Link-Keno 

reach. A Total Maximum Daily Load has been issued for the 

upper Klamath River including this reach (Oregon Department 

of Environmental Quality, 2018).
2 Modeling a 2- and 4-Foot Drawdown in the Link River to Keno Dam Reach, Upper Klamath River, Oregon

Ady Canal

West Canal 

A

Canal

Canal

Canal

North

Klamath

Klamath

Strait

River

Wocus

Drainage

Lake

Ewauna

Spring

Lake

UPPER

KLAMATH

LAKE

Round

Lake

140

140

140

39

39

39

66

66

97

97

420451121510000 Site

EXPLANATION

Upper

Klamath

Basin

OREGON

CALIFORNIA

Wocus

Pelican

City

Midland

Keno

Klamath

Falls

Keno 

Dam

Altamont

Basemap modified from USGS and other digital data sources of various scales. Coordinate 

reference system is UTM, Zone 10N; datum is North American Datum of 1983.

Keno

Reef Keno

11509370

Keno

Outflow

Keno streamgage

11509500

KRS 12a

420615121533600

Link River

11507501

Link River

11507500

Pelican

Marina

Klamath Falls

WWTP

Columbia

Forest

Products

South Suburban

WWTP

Miller Island

420853121505500

Railroad Bridge

421209121463000

Klamath Straits Drain

420451121510000

Lost River 

Diversion Channel

421015121471800

Link River

Dam

121°55' 121°50' 121°45'

42°

15'

42°

10'

42°

05'

0 1 2 3 4 5 MILES

0 1 2 3 4 5 KILOMETERS

Figure 1. Link River to Keno Dam reach of the Klamath River, south-central Oregon. WWTP, wastewater treatment plant.
Introduction 3

A geologic feature made of basalt rock known as the 

Keno reef, located between Keno Dam and the town of 

Keno (fig. 1), served as a historical water-level control in 

this reach. U.S. Geological Survey (USGS) measurements of 

water-surface elevation at three locations in the Link-Keno 

reach in 1907 were similar and all three varied seasonally 

by about 2 ft (0.61 m; fig. 2; Hoyt and others, 1913). Those 

reported measurements did not document the datum used 

by those three streamgages but the datum was assumed to 

be equal to the Reclamation datum that was used for the 

model and for other nearby streamgages in the early 1900s. 

These historical elevations were within 2.5 ft (0.76 m) of the 

water-surface elevation of Link-Keno in recent years (fig. 2).

Keno reef was notched and excavated twice to increase 

flow through this part of the Klamath River and to allow the 

drainage of upstream lands. The first notching occurred in 

1908 (Dicken and Dicken, 1985). The second notching of 

Keno reef occurred in the mid-1960s around the time that 

Keno Dam was constructed.

Keno Dam was built in 1966 and serves as the 

present-day control for the water-surface elevation in the 

Link-Keno reach. In most years, water-surface elevation 

is maintained near 4,085.5 ft (1,245.3 m). In this modeling 

study, the water-surface elevation was simulated with 

measured conditions from 2007, called the base case, and 

with drawdown scenarios that lowered the water surface by 

2 and 4 ft (0.61 and 1.2 m; figs. 2, 3). Year 2007 was selected 

because it had annual average and annual mean flows that 

were moderate for the years modeled and the water-quality 

calibration was based on a rich dataset.

The U.S. Geological Survey (USGS), Bureau of 

Reclamation (Reclamation), and Watercourse Engineering, 

Inc., are collaborating to better understand water quality in 

the Link-Keno reach of the Klamath River. One outcome 

of this collaboration was a calibrated water-quality model 

(Sullivan and others, 2011; Sullivan, Rounds, and others, 

2013). The model has already been used to provide insights 

into the potential effects of management strategies on water 

quality (Sullivan, Sogutlugil, and others, 2013; Sullivan and 

others, 2014).

Purpose and Scope

The purpose of this study was to use an existing 

calibrated two-dimensional hydrodynamic and water-quality 

model (CE-QUAL-W2) of the Link-Keno reach of the 

Klamath River to simulate the flow, velocity, water 

temperature, and water-quality effects of a 2- and 4-ft 

drawdown of the water-surface elevation for the period of a 

calendar year.

The calibrated model (calendar year 2007) was used 

in this study as the base case, in which water quality in the 

Link-Keno reach and the outflow from Keno Dam were 

simulated. Changes in the water level were superimposed on 

top of those base-case conditions for the drawdown scenarios. 

Model results were output at an hourly time step for all model 

layers for each model segment as well as Keno Dam outflow. 

Model output included water-surface elevation, flow, velocity, 

travel time, water temperature, total dissolved solids, inorganic 

suspended sediment, nutrients, organic matter, chlorophyll 

a, and dissolved oxygen. This report documents the results 

of this study, and compares and discusses the simulated 

differences in model results between the drawdown scenarios 

and the base case.
4 Modeling a 2- and 4-Foot Drawdown in the Link River to Keno Dam Reach, Upper Klamath River, Oregon

EXPLANATION

1907–08, 4 miles below Klamath Falls, measured

1907–08, Lees ranch, 12 miles below Klamath Falls, measured

1907–08, Teeters, 17 miles below Klamath Falls, measured

2007 model, base case

2007 model, 2-foot drawdown

2007 model, 4-foot drawdown

4,080

4,082

4,084

4,086

4,088

4,090

4,081

4,083

4,085

4,087

4,089

J F M A M J

2007 2008

J A S O N D J F M A M J J A S

Water surface elevation, in feet in feet above Upper Klamath 

Lake Vertical Datum

Figure 2. Measured water-surface elevation at three locations in Klamath River from Link River mouth to Keno Dam (Link-Keno 

reach), south-central Oregon, 1907-08, and modeled water-surface elevation in the 2007 base case and the 2- and 4-foot drawdown 

scenarios.

Water surface elevation, 

location approximate

Base case

2-foot drawdown

4-foot drawdown

EXPLANATION

Not to scale

Keno Dam

Link River

Figure 3. Two-dimensional hydrodynamic and water quality model (CE-QUAL-W2) grid showing the model segments (columns 

of cells, right to left) and the model layers (rows, top to bottom), from Link River (right) to Keno Dam (left), south-central Oregon. 

Approximate locations of the water-surface elevation for the base case, 2-foot drawdown, and 4-foot drawdown are shown.
Methods 5

Methods

This study used a previously calibrated CE-QUAL-W2 

model for calendar year 2007 (Sullivan and others, 2011). Two 

scenarios were constructed with the water-surface elevation 

lowered by 2 and 4 ft, and the model output was analyzed 

for changes in flow, water temperature, and water quality, 

compared to the base-case model conditions with no changes.

CE-QUAL-W2 Model

CE-QUAL-W2 is a two-dimensional mechanistic 

flow, temperature, and water-quality model used to 

simulate variability both longitudinally (from upstream to 

downstream) and vertically. The third dimension, from bank 

to bank, is considered to be well mixed, which is a good 

approximation for many long and narrow waterbodies such 

as the upper Klamath River that tend to thermally stratify. 

This is because variations in the vertical dimension in these 

waterbodies typically are often far greater than those in the 

lateral dimension. The CE-QUAL-W2 model is capable of 

simulating velocity, flow, temperature, and water quality 

in lakes, reservoirs, rivers, and estuarine systems. The 

CE-QUAL-W2 model has been applied successfully to 

hundreds of river and reservoir systems around the world and 

is under active and ongoing development and enhancement 

(Cole and Wells, 2008). It has proved to be a useful model 

for planning and management, and for enhancing our 

understanding of water-quality status and processes in river 

and reservoir systems.

The USGS upper Klamath River model CE-QUAL-W2 

grid consists of 102 segments in the main model branch that 

connect in the direction of flow; segments average 1,009 ft 

(308 m) in length. Each segment represents a cross-sectional 

shape of the river channel, with stacked layers of varying 

width from the river surface to the channel bottom. Vertical 

layers in the grid are 2 ft (0.61 m) in height. The original 

model grid was developed to provide averaged bathymetric 

information for each segment. For this scenario, with the 

decreased water levels, the maximum elevation of basaltic 

features on the river bottom could become more important. 

Thus, some minor modifications were made to the segment 

lengths and layer widths for segments 16, 17, 18, 90, 91, 

92, 97 and 98 for the scenarios described in this report. The 

grid volume was unchanged. Base-case model runs with the 

original and modified grid indicated no substantial change in 

model results. A side-view of the model grid from the mouth 

of Link River to Keno Dam depicting the model segments and 

layers is shown in figure 3.

The model uses a variable time step that can be as short 

as 1 second, but can produce output for all constituents in 

all layers and segments at a user-selected time interval. The 

model was constructed and calibrated for calendar years 

2006–09 and 2011 (Sullivan and others, 2011; Sullivan, 

Rounds, and others, 2013); year 2007 was selected for this 

study as a representative year.

Scenario Setup

Water-surface elevations for the drawdown scenarios 

were adjusted by lowering the initial water-surface elevations 

on January 1 in the representative year by exactly 2 or 4 ft. 

The model uses flow boundary conditions at the upstream 

(Link River) and downstream (Keno Dam) ends of the reach; 

therefore, the change in the initial water-surface elevation 

was sufficient to maintain the drawdown through the rest 

of the year, with some differences due to varying levels 

of evaporation over the altered surface widths. The actual 

elevation difference relative to the base case during the year 

varied from 1.6 to 2.2 ft, with an average difference of 1.9 ft, 

for the “2-ft” scenario, and from 3.3 to 4.3 ft, with an average 

difference of 3.8 ft, for the “4-ft” scenario. The average river 

width was about 750 ft (229 m) in the base case, about 690 ft 

(210 m) in the 2-ft drawdown scenario, and about 600 ft (183 

m) in the 4-ft drawdown scenario.

A hypothetical tracer test was run with the model using 

the “generic” water-quality constituent capability of the 

CE-QUAL-W2 model. This type of tracer test can be used 

to analyze travel time differences between the regular and 

altered scenarios. The numerical tracer was added at the 

model upstream boundary at the mouth of Link River, and the 

model results for the outflow at Keno Dam were analyzed to 

determine when the tracer peak arrived.

The original calibrated model had been constructed and 

calibrated with macrophytes (aquatic plants) active through 

the model reach, based on data from a field survey (Sullivan, 

Rounds, and others, 2013). Because macrophyte species, 

abundance, and distribution have greater uncertainty in a 

lowered water-surface elevation scenario, they were “turned 

off” in the first set of model scenarios. A second set of model 

runs included macrophytes as part of a sensitivity analysis.

Scenario Output and Analysis

The model provided hourly results for all cells in the 

model grid, and at Keno Dam. Three separate outflows at 

Keno Dam are specified in the model: the spill gates, a sluice 

conduit, and a fish ladder. The model provided results for these 

outlets separately and as a whole; the latter total outflow was 

used in this study. Postprocessing of model output included 

the calculation of segment-average results, combining results 

from all layers weighted by cell volume. Color index maps 

over space and time were produced to visualize model results 

over the entire year and for every model segment. These plots 

included depth-averaged concentration and daily average 

concentration results.
6 Modeling a 2- and 4-Foot Drawdown in the Link River to Keno Dam Reach, Upper Klamath River, Oregon

Results and Discussion

Results for the model scenarios are presented in this 

section, starting with water velocity and travel time, and 

followed by various water-quality constituents. Because the 

4-ft drawdown was the larger departure from the base-case 

scenario, those results were included in this report more often 

than results from the 2-ft drawdown.

Water Velocity and Travel Time

Modeled segment-average velocities ranged from about 

0 to 1.0 ft/s (0 to 0.3 m/s) in 2007 (fig. 4A). August and 

September velocities were lowest overall, which was expected 

because streamflow in this reach tends to be lowest at that 

time of year, due to the dry summer climate and increased 

diversions for agriculture and other uses. With a modeled 4-ft 

decrease in water-surface elevation, segment-average velocity 

increased by as much as double in all segments on almost 

all dates throughout the year (fig. 4B). The largest velocity 

increase was at the shallower segments just upstream of Keno 

Dam and near the inflow of the Lost River Diversion Channel. 

Velocities also increased during high-flow periods; flows in 

March 2007 were as high as 2,800 ft3/s (79.3 m3/s).

Model tracer test results showed that a lowered 

water-surface elevation resulted in faster travel times and 

higher velocities through the Link-Keno reach for the same 

flow conditions (fig. 5). For a tracer test starting on April 1, 

2007 with flow at 2,154 ft3/s (61.0 m3/s), a hypothetical model 

tracer added at the mouth of Link River took 5.2 days (peak 

concentration) to traverse the reach and exit at Keno Dam 

under base-case conditions. With the water surface lowered 

by 4 ft, the tracer took only 2.7 days (52 percent of the base 

case) to travel the same distance. For a tracer test starting 

on September 7, 2007 under a lower flow of 565 ft3/s (16.0 

m3/s), the peak tracer concentration took 11.1 days to traverse 

the Link-Keno reach for the base case. In the 4-ft drawdown 

scenario, the tracer required only 6.7 days (60 percent of the 

base case) to traverse the same distance. The decreased travel 

time could affect processes such as water-quality reactions that 

take place over time and also the settling of particulate organic 

matter, sediment, or algae.

Water Quality

Results of the base-case and drawdown scenarios were 

compared at the Keno Dam outflow and throughout the 

Link-Keno reach. The comparison at Keno Dam provides 

a cumulative overview of modeled water-quality changes 

throughout the reach. Simulations were first run without the 

presence of macrophytes (aquatic plants) because a substantial 

decrease in water level could have a large effect on the 

presence and amount of macrophytes, and few data exist 

to determine how the macrophytes might change in such a 

scenario. A second set of scenarios were run with macrophytes 

as a sensitivity test to determine their potential effect on river 

water quality.

Model Scenarios Without Macrophytes

Keno Dam Outflow

With macrophytes “turned off,” simulated changes in 

water quality at Keno Dam seemed to be relatively minor 

between the base-case and drawdown scenarios for water 

temperature, total dissolved solids, dissolved oxygen, total 

nitrogen, dissolved organic carbon, inorganic suspended 

sediment, total phosphorus, orthophosphate, nitrate, and 

ammonia (fig. 6). Chlorophyll a and particulate organic 

carbon, however, showed notable differences between the 

base-case and the drawdown scenarios in mid-summer 

and early autumn. For those two constituents, the lower 

water-surface elevation produced higher concentrations at 

Keno Dam, compared to the base case at that time of year. In 

the model, the particulate organic carbon is composed of both 

dead algal material and matter that entered the reach from the 

upstream inflow or tributaries. The difference likely is partly 

attributable to the decreased time available for particulate 

material to settle under the drawdown scenarios—a factor 

that was examined in more detail in an analysis of model 

differences throughout the Link-Keno reach.

Link-Keno Reach

Algae and Settled Organic Matter

Elevated chlorophyll a concentration in the Link-Keno 

reach in summer and early autumn largely was due to algae 

flowing into Link and Klamath Rivers from Upper Klamath 

Lake, which has large blooms of the cyanobacterium 

Aphanizomenon flos-aquae at that time of year. During 

much of the summer, that species of algae did not thrive 

in the Link-Keno reach, so an important process was its 

settling, death, and decomposition. Thus, the highest algae 

and chlorophyll a concentrations occurred in the upstream 

end of the reach, near the mouth of Link River (base 

case, fig. 7A). Photosynthesis and oxygen production by 

algae still occurred, but at times could be overwhelmed 

by decomposition processes leading to anoxia or hypoxic 

conditions at certain locations and periods of time. With a 4-ft 

water-surface elevation drawdown, the model showed higher 

concentrations of algae and chlorophyll a moving farther 

downstream towards Keno Dam before settling from the water 

column (fig 7B), owing to the higher water velocities in that 

scenario than in the base-case scenario. The differences in 

the modeled chlorophyll a concentrations are shown in figure 

8A, and an increase in the peak chlorophyll a concentration 

was discernable at the Miller Island monitoring site (model 

segment 38, fig. 8B).
Results and Discussion 7

0.5

0.4

0.3

0.2

0.1

0

Velocity, in meters

per second

EXPLANATION

0.33

-0.33

0.2

-0.2

0.3

-0.3

0.1

-0.1

0

Velocity difference, 

in meters

per second

EXPLANATION

2007 2007

A. Base case

B. 4-foot drawdown minus base case

Apr.

Jan.

Feb.

Mar.

May

June

July

Aug.

Sept.

Oct.

Dec.

Nov.

Apr.

Jan.

Feb.

Mar.

May

June

July

Aug.

Sept.

Oct.

Dec.

Nov.

KSD

COL

LRDC

SSSD

KF

Keno Dam

Link River

Figure 4. Modeled water velocity in the year 2007 base case (A), and modeled velocity difference between the 4-foot drawdown 

scenario and the base-case model (B), in the Link River to Keno Dam reach of the Klamath River, south-central Oregon. Colors 

correspond to model-segment averages across the modeled reach and for the whole year. X-axis represents the Klamath River 

reach from Link River mouth (right) to Keno Dam (left). X-axis labels are the locations of inflows and point sources: KF, Klamath Falls 

wastewater treatment plant (WWTP); SSSD, South Suburban WWTP; LRDC, Lost River Diversion Channel; COL, Columbia Forest 

Products; KSD, Klamath Straits Drain. Positive velocity differences in (B) indicate that the 4-foot drawdown scenario had higher 

velocities than the base case.
8 Modeling a 2- and 4-Foot Drawdown in the Link River to Keno Dam Reach, Upper Klamath River, Oregon

EXPLANATION

Tracer injection

Tracer at Keno Dam

1 2 3 4 5 6 7 8 9

April 2007

September 2007

0

2,000

4,000

6,000

8,000

10,000

Tracer concentration, in milligrams per liter

0

2,000

4,000

6,000

8,000

10,000

Tracer concentration, in milligrams per liter

Inject tracer

Flow = 2,154 cubic feet per second

Flow = 565 cubic feet per second

4-foot drawdown 

= 2.7 days

4-foot drawdown 

= 6.7 days

Base

= 5.2 days

Base

= 11.1 days

6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Figure 5. Model tracer results from addition of a hypothetical 

tracer at the mouth of Link River (black peak, dashed lines) and 

downstream tracer concentrations at the Keno Dam outflow 

indicating the time required for the tracer peak to reach Keno Dam 

(solid-line peaks), south-central Oregon, during 2007. Model tracer 

runs were started on April 1, 2007, with flow at 2,154 cubic feet per 

second (ft3/s) (61 cubic meters per second [m3/s]) (top graph), and 

September 7, 2007, with flow at 565 ft3/s (16.0 m3/s) (bottom graph).

If the decreased travel time under a drawdown scenario 

affected the mass flux and deposition location of settling 

particulate material, then that hypothesis can be tested by 

examining the model first-order sediment compartment 

(fig. 9). Decomposition of organic material is another process 

that controls how much material is in the model first-order 

sediment compartment. In the CE-QUAL-W2 model, the 

first-order sediment compartment tracks the mass of settled 

algae and organic matter that settles to the river bottom and 

the oxygen demand from their decay. The dissolved oxygen 

status of the overlying water matters, such that decomposition 

does not occur when oxygen concentrations are less than a 

threshold of 0.1 mg/L. In the base-case model, the distribution 

of first-order sediment (fig. 9 A) showed that a large quantity 

of organic matter, much of it derived from algae, settled in 

the upper part of the Link-Keno. With a 4-ft drawdown, the 

model showed relatively less accumulation of settled organic 

matter in those upper reaches (fig. 9B). Instead, the algae and 

particulate organic matter had a higher chance of being swept 

farther downstream by the higher velocities, which resulted 

in relatively more settling in downstream reaches and higher 

concentrations in the Keno Dam outflow in summer and 

autumn when the blooms occurred (fig. 6).

Dissolved Oxygen

The CE-QUAL-W2 model considers various sinks and 

sources of dissolved oxygen, including inflow concentrations, 

atmospheric exchange across the river surface, algal 

photosynthesis and respiration, ammonia and nitrate oxidation, 

and organic matter decay in the water column and sediments. 

Although modeled dissolved oxygen concentrations in the 

Keno Dam outflow indicated that overall changes were minor 

in the drawdown scenarios (fig. 6), some spatial variability 

in dissolved oxygen results in the Link-Keno reach (fig. 10) 

merited a more-detailed examination because oxygen levels 

influence many processes in the model and are important to 

aquatic life.

The segment-average, daily-average results showed that 

simulated dissolved oxygen concentrations changed by as 

much as 2.0 mg/L in the 4-ft drawdown scenario (fig. 10). 

Concentrations increased and decreased in that scenario, 

depending on day and location. An examination of results 

over the depth of the water column at two locations indicated 

that areas of hypoxia and anoxia (<0.1 mg/L) in spring 

through autumn were more limited in the drawdown scenario 

(fig. 11). Where anoxic water is in contact with the sediment, 

aerobic decomposition of organic matter in the surficial, 

first-order sediments would not occur. The increase in 

dissolved oxygen at Keno (segment 95) in late June in the 4 ft 

drawdown scenario likely was due to the increased quantity of 

photosynthesizing algae at that downstream location compared 

to the base case.

Water Temperature

Water temperature in the Keno Dam outflow was similar 

in the base case and drawdown scenarios (fig. 6), but some 

important spatial differences in water temperature occurred 

within the Link-Keno reach, with differences as large as 2.0 

°C on a segment-average, daily average basis (fig. 12). The 

shallower water depths of the 4-ft drawdown scenario might 

not allow for some of the vertical stratification that occurred 

in the deeper water of the base-case scenario, particularly in 

springtime when the flows were higher. The 4-ft drawdown 

scenario showed slightly smaller temperature differences with 

depth throughout the water column compared to the base case 

at Miller Island, a site in the middle of the Link-Keno reach 

(fig. 13). The strong seasonal pattern in water temperature was 
Results and Discussion 9

10

20

30

40

50

60

70

80

90

0

10

20

30

0

10

20

30

0

50

100

150

200

250

Total dissolved solids,

in milligrams per liter

0

5

10

15

20

0

5

10

15

20

0

1

2

3

4

5

0

5

10

15

20

0

20

40

60

0

0.1

0.2

0.3

0.4

0.5

0

1

2

3

4

5

6

0

40

80

120

160

0

0.1

0.2

0.3

0.4

0.5

J F M A 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 O N D

0

0.2

0.4

0.6

0.8

1

0

0.5

1

1.5

2

Flow, daily average, in 

cubic meters per second

Total nitrogen, in 

milligrams per liter

Total phosphorus, in 

milligrams per liter

Orthophosphate, in 

milligrams per liter

Temperature, in 

degrees Celsius

Dissolved oxygen, in 

milligrams per liter

Dissolved organic 

carbon, in milligrams 

per liter

Particulate organic 

carbonin milligrams 

per liter

Nitrate, in milligrams 

per liter as N

Ammonia, in milligrams 

per liter as N

Chlorophyll a, in 

micrograms per liter

Inorganic suspended 

sediment, in 

milligrams per liter

Dissolved oxygen daily 

average, in milligrams 

per liter

Temperature daily 

average, in degrees 

Celsius

EXPLANATION

Base case

2-foot drawdown

4-foot drawdown

Figure 6. Modeled flow, temperature, and water-quality constituents in the outflow of Keno Dam for the base case, and the 2- and 

4-foot drawdown scenarios, in the Link River to Keno Dam reach of the Klamath River, south-central Oregon, during 2007. Macrophyte 

effects are not included in these runs.

relatively unaltered, with slightly different levels of thermal 

stratification due to shallower depths constituting most of the 

differences.

Model Scenarios With Macrophytes

Several species of aquatic plants (macrophytes) were 

present in field surveys from 2011, and those field data 

were used to calibrate the model rates and parameters for 

macrophytes in the Link-Keno model (Sullivan, Rounds, 

and others, 2013), but extrapolating model predictions of 

macrophyte growth to the lower water-surface elevations in 

these scenarios involves greater uncertainty. The algorithms 

used by the CE-QUAL-W2 model to simulate macrophyte 

growth depend on water depth, cross-sectional shape, initial 

conditions, and light extinction rates, among other factors. A 

lower water level possibly could influence the colonization 

of channel margins or parts of the Link-Keno reach by the 

same or different species of macrophytes in ways that do not 

mirror the conditions measured in 2011. To the extent that 

macrophytes in a drawdown scenario might colonize and 

grow in areas that were similar to the base case, simulating the 

presence of macrophytes was determined to be useful at least 

as a sensitivity test, and as a means of gaining insight into the 

potential importance of the influence of macrophytes on water 

quality in a drawdown scenario.
10 Modeling a 2- and 4-Foot Drawdown in the Link River to Keno Dam Reach, Upper Klamath River, Oregon

195

160

180

120

80

40

140

100

60

20

0

Chlorophyll a, in

micrograms per liter

195

160

180

120

80

40

140

100

60

20

0

Chlorophyll a, in

micrograms per liter

EXPLANATION

EXPLANATION

2007 2007

A. Base case

B. 4-foot drawdown

Apr.

Jan.

Feb.

Mar.

May

June

July

Aug.

Sept.

Oct.

Dec.

Nov.

Apr.

Jan.

Feb.

Mar.

May

June

July

Aug.

Sept.

Oct.

Dec.

Nov.

KSD

COL

LRDC

SSSD

KF

Keno Dam

Link River

Figure 7. Modeled chlorophyll a concentration for the year 2007 base case (A), and the 4-foot drawdown scenario (B), in the 

Link River to Keno Dam reach of the Klamath River, south-central Oregon. Colors correspond to model-segment averages across 

the modeled reach and for the whole year. X-axis represents the Klamath River reach from Link River mouth (right) to Keno Dam 

(left). X-axis labels are the locations of inflows and point sources: KF, Klamath Falls wastewater treatment plant (WWTP); SSSD, 

South Suburban WWTP; LRDC, Lost River Diversion Channel; COL, Columbia Forest Products; KSD, Klamath Straits Drain. Note: To 

emphasize the spatial pattern, values are capped in these two plots. Values greater than 195 micrograms per liter (μg/L) are plotted as 

195 μg/L. Actual modeled chlorophyll a concentrations could be as much as 600 μg/L or more.
Results and Discussion 11

EXPLANATION

Chlorophyll a difference, in

micrograms per liter

EXPLANATION

Chlorophyll a, in micrograms per liter

0

120

100

80

60

40

20

-120

-100

-80

-60

-40

-20

0

50 100 150 200 250 300 350 400 450 500 550 600

2007

B. Segment 38: Base case

Apr.

Jan.

Feb.

Mar.

May

June

July

Aug.

Sept.

Oct.

Dec.

Nov.

A. 4-foot drawdown minus base case

Water depth, in feet

Segment 38: 4-foot drawdown

0

20

0

16

2007

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. KSD COL LRDC SSSDKF

Keno Dam

Link River

Segment 38

Figure 8. Modeled difference in segment-averaged chlorophyll a concentration between the 4-foot drawdown and the base-case 

scenarios (A), and depth profiles showing chlorophyll a at model segment 38 near Miller Island for the base case (top) and 4-foot 

drawdown scenario (bottom) (B), in the Link River to Keno Dam reach of the Klamath River, south-central Oregon, during 2007. X-axis 

labels are the locations of inflows and point sources: KF, Klamath Falls wastewater treatment plant (WWTP); SSSD, South Suburban 

WWTP; LRDC, Lost River Diversion Channel; COL, Columbia Forest Products; KSD, Klamath Straits Drain. Profiles are plotted every 0.2 

day, with colors representing chlorophyll a concentrations.

Base-case and 4-ft drawdown scenario results at the 

Keno Dam outflow location were largely similar after 

adding macrophytes back into the model (fig. 14), with a 

few exceptions. Particulate organic carbon and chlorophyll 

a showed increases in the drawdown scenario in the same 

manner as results from the without-macrophytes model 

runs (fig. 6). Similarly, those effects were attributable to 

the higher velocities and less time for settling. Unlike the 

without-macrophytes simulations, however, dissolved oxygen 

showed a notable decrease in the outflow between the base 

case and a 4-ft drawdown when macrophytes were included in 

the simulation. The daily fluctuation in dissolved oxygen also 

was greater with macrophytes enabled, owing to the greater 

combined primary production and respiration of macrophytes 

and algae together. Modeled dissolved oxygen fluxes showed 

decreased oxygen production and respiration in the drawdown 

scenarios compared to the base case, particularly for the 

macrophytes (fig. 15A), that led to the lower dissolved oxygen 

concentrations in the outflow. Whole-reach dissolved oxygen 

fluxes for algae (fig. 15B) were more similar for the various 

water-level scenarios.
12 Modeling a 2- and 4-Foot Drawdown in the Link River to Keno Dam Reach, Upper Klamath River, Oregon

First-order sediment,

in grams per square

meter

EXPLANATION

First-order sediment

difference, in

metric tons

EXPLANATION

1,040

1,000

900

800

700

600

500

400

300

200

100

0

20

15

10

5

0

-20

-15

-10

-5

2007 2007

A. 4-foot drawdown

B. 4-foot drawdown minus base case

Apr.

Jan.

Feb.

Mar.

May

June

July

Aug.

Sept.

Oct.

Dec.

Nov.

Apr.

Jan.

Feb.

Mar.

May

June

July

Aug.

Sept.

Oct.

Dec.

Nov.

KSD

COL

LRDC

SSSD

KF

Keno Dam

Link River

Figure 9. Modeled settled organic matter in the first-order sediment compartment for the year 2007 base case (A), and the 

difference in modeled settled organic matter mass between the 4-foot drawdown scenario and the base case (B), in the Link River to 

Keno Dam reach of the Klamath River, south-central Oregon. Macrophyte effects are not included in these model runs. All values are 

model-segment averages (A), or totals (B) for the whole year. X-axis represents the reach from Link River mouth (right) to Keno Dam 

(left). X-axis labels are the locations of inflows and point sources: KF, Klamath Falls wastewater treatment plant (WWTP); SSSD, South 

Suburban WWTP; LRDC, Lost River Diversion Channel; COL, Columbia Forest Products; KSD, Klamath Straits Drain.
Results and Discussion 13

2007

Apr.

Jan.

Feb.

Mar.

May

June

July

Aug.

Sept.

Oct.

Dec.

Nov.

KSD

Keno Dam

Segment 95Segment 38

COL

KF Link River

SSSD

4-foot drawdown minus base case

LRDC

EXPLANATION

Dissolved oxygen 

difference, in 

milligrams per liter

-2.0

-1.5

-1.0

-0.5

0

0.5

1.0

1.5

2.0

Figure 10. Modeled difference between dissolved oxygen concentration in the 4-foot drawdown scenario 

and the year 2007 base case, in the Link River to Keno Dam reach of the Klamath River, south-central Oregon. 

Positive values represent times and locations of dissolved oxygen increases in the drawdown scenario and 

negative values represent times and locations of dissolved oxygen decreases. Macrophyte effects are not 

included in these model runs. All values are model-segment averages across the modeled reach and for the 

whole year. X-axis represents the reach from Link River mouth (right) to Keno Dam (left). X-axis labels are the 

locations of inflows and point sources: KF, Klamath Falls wastewater treatment plant (WWTP); SSSD, South 

Suburban WWTP; LRDC, Lost River Diversion Channel; COL, Columbia Forest Products; KSD, Klamath Straits 

Drain.

Several possible reasons might explain the decreased 

oxygen production from macrophytes in the drawdown 

scenario. In the 2011 Link-Keno macrophyte survey, 

macrophytes were limited to shallow areas throughout 

the reach, including shallow waters along the edges of the 

Klamath River. Macrophytes were not found in deep water 

because the relatively high light extinction from dissolved 

organic matter restricted the available light needed by those 

plants in deep-water habitats. The bathymetry for the model 

grid, based on a field survey, resulted in slightly shallower 

slopes near the river edges in the base case, as compared to the 

slopes occurring at the river edges in the drawdown scenarios. 

As a result, macrophytes in the drawdown scenario had a 

smaller area of nearshore habitat with ideal light conditions 

compared to the base case.

Vertical profiles of dissolved oxygen at two locations 

from model runs with macrophytes enabled (fig. 16) showed 

patterns that were similar to those run without macrophytes 

(fig. 11). The 4-ft drawdown scenario had less frequent anoxia 

at the river bottom, but the overall patterns were similar, with 

large oxygen demands co-occurring with the presence of large 

algal abundances moving through the river in July and August. 

The deposited organic matter from that algae continued 

to exert an oxygen demand at upstream locations through 

September.

The model results with macrophytes enabled should be 

treated with higher uncertainty for multiple reasons. First, a 

lower water level possibly could lead to different macrophyte 

species colonizing the reach; this possibility was not captured 

with the existing model. A water-level drawdown also possibly 

could alter the nearshore bathymetry over time owing to 

erosion or deposition, thereby affecting the amount of shallow 

nearshore habitat for macrophytes. Regardless of this, the 

model shows that macrophyte dynamics could be a substantial 

factor affecting dissolved oxygen concentrations and patterns 

with a drawdown of the Link-Keno reach.
14 Modeling a 2- and 4-Foot Drawdown in the Link River to Keno Dam Reach, Upper Klamath River, Oregon

EXPLANATION

Dissolved oxygen, in milligrams per liter

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Water depth, in feet

2007

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Segment 38: Base case

Segment 38: 4-foot drawdown

Segment 95: Base case

Segment 95: 4-foot drawdown

0

20

0

16

0

22

0

18

Figure 11. Dissolved-oxygen profiles showing changes in dissolved oxygen concentrations at segments 38 (Miller Island) and 95 

(Keno Bridge), with depth, during 2007, in the Link River to Keno Dam reach of the Klamath River, south-central Oregon. Output is every 

0.2 day. Macrophyte effects are not included in these model runs.
Results and Discussion 15

EXPLANATION

Temperature difference, 

in degrees Celsius

-2.0

-1.5

-1.0

-0.5

0

0.5

1.0

1.5

2.0

2007

Apr.

Jan.

Feb.

Mar.

May

June

July

Aug.

Sept.

Oct.

Dec.

Nov.

KSD

Keno Dam

Segment 38

COL

KF Link River

SSSD

4-foot drawdown minus base case

LRDC

Figure 12. Modeled difference between water temperature in the 4-foot drawdown scenario and the year 

2007 base case, in the Link River to Keno Dam reach of the Klamath River, south-central Oregon. Positive values 

represent times and locations of temperature increase in the drawdown scenario and negative values represent 

times and locations of temperature decreases. Macrophyte effects are not included in these model runs. Colors 

correspond to model-segment averages across the modeled reach and for the whole year. X-axis represents the 

Klamath River reach from Link River mouth (right) to Keno Dam (left). X-axis labels are the locations of inflows and 

point sources: KF, Klamath Falls wastewater treatment plant (WWTP); SSSD, South Suburban WWTP; LRDC, Lost 

River Diversion Channel; COL, Columbia Forest Products; KSD, Klamath Straits Drain. Segment 38 is the location of 

the Miller Island sampling location.

EXPLANATION

Temperature, in degrees Celsius

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Water depth, in feet

2007

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Segment 38: Base case

Segment 38: 4-foot drawdown

0

20

0

16

Figure 13. Water-temperature profiles showing changes in water temperature at segment 38 (Miller Island), with depth, during 2007, 

in the Link River to Keno Dam reach of the Klamath River, south-central Oregon. Output is every 0.2 day. Macrophyte effects are not 

included in these model runs.
16 Modeling a 2- and 4-Foot Drawdown in the Link River to Keno Dam Reach, Upper Klamath River, Oregon

J F M A 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 O N D

0

50

100

150

200

250

0

5

10

15

20

0

5

10

15

20

0

1

2

3

4

5

0

5

10

15

20

0

20

40

60

0

0.1

0.2

0.3

0.4

0.5

0

2

4

6

0

40

80

120

160

0

0.1

0.2

0.3

0.4

0.5

0

0.2

0.4

0.6

0.8

1

0

0.5

1

1.5

2

Ammonia, in 

milligrams per liter 

as N

Chlorophyll a, in 

micrograms per liter

Inorganic suspended 

sediment, in 

milligrams per liter

Dissolved oxygen 

daily average, in 

milligrams per liter

Dissolved oxygen, in 

milligrams per liter

Dissolved organic 

carbon, in milligrams 

per liter

Particulate organic 

carbon, in milligrams 

per liter

Nitrate, in milligrams 

per liter as N

Total dissolved solids, 

in milligrams per liter

Total nitrogen, in 

milligrams per liter

Total phosphorus, in 

milligrams per liter

Orthophosphate, in 

milligrams per liter

EXPLANATION

Base case

4-foot drawdown

Figure 14. Modeled flow, temperature, and water-quality constituents in the outflow of Keno Dam for the base case and 4-foot 

drawdown scenarios, Klamath River, south-central Oregon. Macrophyte effects are included in these runs.
Results and Discussion 17

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

-30,000

-10,000

10,000

0

30,000

50,000

70,000

20,000

-20,000

40,000

60,000

80,000

90,000

-30,000

-10,000

10,000

0

30,000

50,000

70,000

20,000

-20,000

40,000

60,000

80,000

90,000

Dissolved oxygen flux, in kilograms per day

A. Macrophytes

Dissolved oxygen flux, in kilgrams per day

B. Algae

EXPLANATION

Base case

4-foot drawdown

Base case

4-foot drawdown

Dissolved oxygen production

Dissolved oxygen respiration

Figure 15. Dissolved-oxygen production and respiration fluxes, as modeled with the presence of macrophytes, for 

macrophytes (A), and algae (B) for the entire Link-Keno reach, Klamath River, south-central Oregon.
18 Modeling a 2- and 4-Foot Drawdown in the Link River to Keno Dam Reach, Upper Klamath River, Oregon

EXPLANATION

Dissolved oxygen, in milligrams per liter

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Water depth, in feet

2007

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Segment 38: Base case

Segment 38: 4-foot drawdown

Segment 95: Base case

Segment 95: 4-foot drawdown

0

20

0

16

0

22

0

18

Figure 16. Dissolved oxygen profiles showing changes in dissolved oxygen concentrations at segments 38 (Miller Island) and 95 

(Keno Bridge), with depth, during 2007. Output is every 0.2 day. Macrophyte effects are included in these model runs.

Acknowledgments

The authors gratefully acknowledge Rick Carlson 

(Bureau of Reclamation), Mike Deas (Watercourse 

Engineering), and Brian Cluer and Shari Whitmore (National 

Oceanic and Atmospheric Administration) for providing 

insights and helpful discussions during this study. Comments 

from two peer reviewers also improved this report.

References Cited

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Instruction Report EL-08-1 [variously paged].

Dicken, S.N., and Dicken, E.F., 1985, The legacy of ancient 

Lake Modoc—A historical geography of the Klamath Lakes 

Basin: Distributed by University of Oregon Bookstore, 

Eugene, Oregon [variously paged].

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sir20135016.

Sullivan, A.B., Rounds, S.A., Deas, M.L., Asbill, J.R., 

Wellman, R.E., Stewart, M.A., Johnston, M.W., and 

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upstream of Keno Dam, Oregon, 2006–09: U.S. Geological 

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Sullivan, A.B., Sogutlugil, I.E., Deas, M.L., and Rounds, S.A., 

2014, Water-quality modeling of Klamath Straits Drain 

recirculation, a Klamath River wetland, and 2011 conditions for the Link River to Keno Dam reach of the Klamath 

River, Oregon: U.S. Geological Survey Open-File Report 

2014–1185, 75 p., https://doi.org/10.3133/ofr20141185.

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M.L., 2013, Modeling the water-quality effects of changes 

to the Klamath River upstream of Keno Dam, Oregon: 

U.S. Geological Survey Scientific Investigations Report 

2013–5135, 60 p., https://doi.org/10.3133/sir20135135.
Publishing support provided by the U.S. Geological Survey

Science Publishing Network, Tacoma Publishing Service Center

For more information concerning the research in this report, contact the

Director, Oregon Water Science Center

U.S. Geological Survey

2130 SW 5th Avenue

Portland, Oregon 97201

https://www.usgs.gov/centers/or-water
Sullivan and Rounds—Modeling a 2- and 4-Foot Drawdown in the Link River to Keno Dam Reach, Upper Klamath River, Oregon—Scientific Investigations Report 2020-5001

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20205001