Preliminary Hydraulic Analysis and 

Implications for Restoration of

Noyes Slough, Fairbanks, Alaska

Water-Resources Investigations Report 00–4227

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

Photograph by Sharon Richmond, U.S. Geological Survey, 2000
Preliminary Hydraulic Analysis and Implications for 

Restoration of Noyes Slough, Fairbanks, Alaska

By Robert L. Burrows, Dustin E. Langley, and David M. Evetts

U.S. GEOLOGICAL SURVEY

Anchorage, Alaska

2000

Water-Resources Investigations Report 00–4227
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

CHARLES G. GROAT, Director

Any use of trade, product, or firm names in this publication is for descriptive

purposes only and does not imply endorsement by the U.S. Government

For additional information Copies of this report can be

contact: purchased from:

District Chief U.S. Geological Survey 

U.S. Geological Survey Information Services

4230 University Drive, Suite 201 Building 810

Anchorage, AK 99508–4664 Box 25286, Federal Center

Denver, CO 80225–0286

http://ak.water.usgs.gov
CONTENTS III

CONTENTS

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

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

Community Interest.................................................................................................................................................... 2

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

Acknowledgments...................................................................................................................................................... 4

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

Recent River History and Background.................................................................................................................................. 4

Evaluating Present-Day Hydraulics....................................................................................................................................... 14

Data and Assumptions Used in Modeling ............................................................................................................................. 15

Model Adjustment and Calibration ....................................................................................................................................... 19

Using Model With Modified Geometry................................................................................................................................. 22

Related Observations............................................................................................................................................................. 26

Summary and Conclusions .................................................................................................................................................... 31

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

FIGURES

1. Location map and aerial photograph of study area ................................................................................................ 3

2. Map of Fairbanks in 1940, showing Tanana and Chena Rivers; Piledriver, Chena, and Noyes Sloughs; and

location of Moose Creek Dike, built across Chena Slough during 1940–45......................................................... 5

3. Map showing present-day conditions affecting Chena River and Noyes Slough, showing Chena River Lakes

Flood Control Project and other structures in vicinity........................................................................................... 7

4. Aerial photograph of Noyes and Chena Sloughs near entrance to Noyes, also showing Illinois and Cushman

Streets, Fairbanks, 1938 ......................................................................................................................................... 8

5. Aerial photograph of mouth of Chena River on old Chena Slough about 7 miles east of Fairbanks, 1938.......... 9

6. Cross sections for Chena River at Wendell Street bridge, showing mean water-surface and bed elevations in

1959, 1989, and 2000............................................................................................................................................. 10

7. Rating curves for Chena River stream-gaging station, 1957–99 ........................................................................... 11

8. Relations between flows in Noyes Slough and Chena River for three periods during 1947–2000....................... 12

9. Water-table map of Fairbanks, showing ground-water elevations and flow directions ......................................... 13

10. Geohydrologic cross section of Tanana–Chena alluvial plain, showing surface-water–ground-water

interaction in vicinity of Tanana River, Chena River, and Noyes Slough ............................................................. 14

11–13. Photographs of Noyes Slough in 2000:

11. Looking upstream during period of flow in spring, showing beaver dam (station 20209)...................... 17

12. Looking downstream after flow ceased in midsummer, at West Johansen Expressway bridge (station

2917) ........................................................................................................................................................ 18

13. Looking downstream showing channel filled with snow and ice in late winter, at West Johansen 

Expressway bridge (station 2917)............................................................................................................ 19

14. Aerial photograph of study reach, showing locations of cross sections used in model, 10 beaver dams, and

flow directions........................................................................................................................................................ 20

15. Example of cross section used in HECRAS model, showing channel and beaver dam on Noyes Slough

(station 7538.25) .................................................................................................................................................... 22

16. Graph showing regression relation between Noyes Slough and Chena River flows for present-day conditions

as modeled by HECRAS and measured flows in slough (instantaneous) and river (mean daily)......................... 23

17. Example of HECRAS model output, showing water-surface profile (at flow of 2,000 cubic feet per second)

for reach 1, Chena River through Wendell Street bridge, just upstream from entrance to Noyes Slough............. 24

18. Cross-section geometry at entrance to Noyes Slough and modified channel configuration ................................. 24
IV Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

19. Graph showing measured and modeled water-surface and bed profiles at flow of 117 cubic feet per second in

Noyes Slough, for present-day conditions and after channel modification ........................................................... 25

20. Graph showing regression relation between Noyes Slough and Chena River flows for modified channel

conditions in Noyes Slough as modeled by HECRAS .......................................................................................... 26

21. Hydrographs for period April 1–July 31, 2000. A, Chena River, from gaging-station records. B, Noyes

Slough, computed from regression equations for existing and modified channel and also showing discharge

measurements made in May and June.................................................................................................................... 27

22. Estimated hydrographs for Noyes Slough for existing and modified channel conditions at maximum (A),

mean (B), and minimum (C) mean daily flows in Chena River for period April 1–October 31, 1981–99 ........... 29

23. Estimated hydrographs for Noyes Slough for period April 1–September 30, 1999, for existing and modified

channel conditions.................................................................................................................................................. 31

TABLES

1. Discharge and water-surface elevation for Noyes Slough at Illinois Street and Minnie Street bridges and

corresponding discharge for Chena River, 1947–2000.......................................................................................... 15

2. Discharge and water-surface elevation for Noyes Slough and corresponding mean daily discharge and watersurface elevation for Chena River during May, June, and August, 2000............................................................... 16

3. Mean daily discharge for Chena River at Fairbanks (station identification no. 15514000), April 1–September 30, 

1981–99.................................................................................................................................................................. 28

4. Flow duration for Chena River at Fairbanks, April 1–September 30, 1981–99, and for Noyes Slough

(computed for present-day and modified channel geometry) ................................................................................ 30

CONVERSION FACTORS and VERTICAL DATUM

Multiply by To obtain

inch (in.) 25.4 millimeter 

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

cubic foot per second (ft3

/s) 0.02832 cubic meter per second

gallon per minute (gal/min) 0.06308 liter per second

ton per day (ton/d) 0.9072 megagram per day

ton per year (ton/yr) 0.9072 megagram per year

In this report, temperature is reported in degrees Fahrenheit (°F), which can be converted to degrees Celsius (°C) by the equation

°C = (°F – 32) / 1.8

Sea level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929, formerly called “Sea-Level 

Datum of 1929”), which is derived from a general adjustment of the first-order leveling networks of the United States and Canada.
Abstract 1

Abstract

The present-day channels of the Chena River 

and Noyes Slough in downtown Fairbanks, Alaska, 

were formed as sloughs of the Tanana River, and 

part of the flow of the Tanana River occupied these 

waterways. Flow in these channels was reduced 

after the completion of Moose Creek Dike in 1945, 

and flow in the Chena River was affected by regulation from the Chena River Lakes Flood Control 

Project, which was completed in 1980. In 1981, 

flow in the Chena River was regulated for the first 

time by Moose Creek Dam, located about 20 miles 

upstream from Fairbanks. Constructed as part of 

the Chena River Lakes Flood Control Project, the 

dam was designed to reduce maximum flows to 

12,000 cubic feet per second in downtown Fairbanks.

Cross-section measurements made near the 

entrance to Noyes Slough show that the channel 

bed of the Chena River has been downcutting, 

thereby reducing the magnitude and duration of 

flow in the slough. Consequently the slough slowly 

is drying up. The slough provides habitat for wildlife such as ducks, beaver, and muskrat and is a 

fishery for anadromous and other resident species. 

Beavers have built 10 dams in the slough. Declining flow in the slough may endanger the remaining 

habitat.

Residents of the community wish to restore 

flow in Noyes Slough to create a clean, flowing 

waterway during normal summer flows. The desire 

is to enhance the slough as a fishery and habitat for 

other wildlife and for recreational boating.

During this study, existing and new data 

were compiled to determine past and present 

hydraulic interaction between the Chena River and 

Noyes Slough. The U.S. Army Corps of Engineers 

Hydrologic Engineering Center River Analysis 

System (HECRAS) computer program was used to 

construct a model to use in evaluating alternatives 

for increasing flow in the slough. Under present 

conditions, the Chena must flow at about 2,400 

cubic feet per second or more for flow to enter 

Noyes Slough. In an average year, water flows in 

Noyes Slough for 106 days during the open-water 

season, and maximum flow is about 1,050 cubic 

feet per second.

The model was used to test a single method 

of increasing flow in Noyes Slough. A modified 

channel 40 feet wide and about 2 feet deeper 

within the existing slough channel was simulated 

by changing the cross-section geometry in the 

HECRAS model. The resulting model showed that 

flow in such a modified slough channel would 

begin at a flow of about 830 cubic feet per second 

in the Chena River and would increase to a maximum flow of about 1,440 cubic feet per second. In 

an average year, flow would continue for 158 days 

during the open-water season.

Theoretically, enlarging the slough channel 

by lowering its bed could increase flow, but other 

solutions are possible. Possible obstacles to 

Preliminary Hydraulic Analysis and Implications for 

Restoration of Noyes Slough, Fairbanks, Alaska

By Robert L. Burrows, Dustin E. Langley, and David M. Evetts
2 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

excavating the channel, such as bridges and utility 

crossings, and the destruction of desirable features 

such as beaver dams were not considered in the 

study. Further engineering and economic analyses 

would be needed to assess the cost of excavation 

and future maintenance of the modified channel. 

A computer-modeling program such as HECRAS 

may provide a means for testing other solutions.

INTRODUCTION

Noyes Slough is a 5.5-mi-long waterway connected to the Chena River in Fairbanks, Alaska (fig. 1). 

The slough is located north of the river and is surrounded by mixed urban and suburban developments. 

Several small tributaries flow southward into the 

slough from the Creamers Field Migratory Waterfowl 

Refuge, which is one of the adjacent wetland areas that 

provide additional wildlife habitat. The State of Alaska 

(1999) classified the slough as an anadromous stream, 

providing rearing areas for juvenile salmon and habitat 

for grayling and other fish species. Local residents 

have been concerned for years that the slough is deteriorating from being a flowing, clean waterway. In spite 

of intermittent cleanup efforts, some reaches of the 

slough have become dumps for solid waste. Also, flow 

in the slough has been declining during the past 50 

years. A hydraulic assessment of present conditions 

and the effect on the hydraulic interaction between the 

Chena River and Noyes Slough was performed to evaluate possible means to increase flow in the slough.

Community Interest

In the past, the Noyes Slough has been a valuable 

resource to the community. The slough is still a fisheries habitat for anadromous and other species; in a 

reconnaissance report concerning the Chena River 

watershed, the U.S. Army Corps of Engineers (1997) 

recommended that further investigations address the 

need to “provide restoration of fisheries habitat on 

Noyes Slough * * *.” Also, the slough and the adjacent 

wetlands such as the Creamers Field Migratory Waterfowl Refuge provide habitat for waterfowl and other 

avian and terrestrial wildlife. Teachers at two elementary schools and one middle school that are near the 

slough consider it to be a natural laboratory where they 

can take students to observe wildlife and learn about 

the value of clean waterways as well as the effects of 

pollution and abuse. At least once a year, each of 20 

separate classes at one of the schools visit the slough. 

A symposium held in 1999 brought together 30 presenters and was attended by 500 students. In addition, 

students collected bottom sediments for analysis at the 

University of Alaska.

 Although presently the Noyes Slough cannot 

be floated the entire length without portages except at 

medium to high flows, the Fairbanks North Star Borough maintains a park that has a small-boat launch 

along the slough. In the 1980’s, the borough hired a 

consulting firm to survey the slough (cross sections 

and bottom profile) and study flow conditions to assess 

the feasibility of establishing a canoe trail in the slough 

(Unwin, Scheben, Korynta, and Huettl, Inc., 1982).

Local residents feel that if Noyes Slough were 

restored, it would provide enhanced educational and 

recreational resources and would protect and improve 

the quality of life for Fairbanks residents. Cleanup 

alone will not restore the slough as a flowing waterway. 

If restoration and maintenance of flow are objectives, 

then present hydraulic conditions and options for channel modification must be evaluated.

Purpose and Scope

Based on current conditions, it seems likely that 

flows in Noyes Slough will continue to decline without 

some intervention to reverse the process. The rate and 

duration of flow in the slough must be increased to 

maintain the channel as an active waterway. Also, sediment regimes in the slough must be understood before 

future flow maintenance can be evaluated.

To allow adequate evaluation of possible restoration schemes, analyses of the hydraulic relation 

between the Chena River and Noyes Slough are 

needed. The purposes of this study were to document 

past and current conditions on the basis of existing 

information, supplemented by new data as time and 

flow conditions allowed, and to construct a hydraulic 

model useful in evaluating different schemes to 

increase flow in Noyes Slough. Because of the short 

duration of the study (spring and summer 2000), only 

limited new data could be collected.
INTRODUCTION 3

Figure 1. Location and aerial photograph (fig. 14) of study area. Arrows indicate flow directions.
4 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

Acknowledgments

The authors wish to thank the Noyes Slough 

Action Committee, particularly the director John Carlson, for help and enthusiastic support; the Binkley 

family for sharing their knowledge of the history of the 

Chena River and Noyes Slough; the Fairbanks North 

Star Borough for providing information and support; 

and many local residents for their interest.

DESCRIPTION OF STUDY AREA

In downtown Fairbanks, Alaska, the study area 

is in the Chena–Tanana alluvial plain (fig. 1). The reach 

length of the Chena River in the study is 27,300 ft, and 

Noyes Slough, 29,100 ft. Noyes Slough branches off to 

the north from the right bank of the Chena River about 

500 ft downstream from the Wendell Street bridge and 

returns to the north bank of the Chena River 450 ft 

upstream from the University Avenue bridge.

Fairbanks has a continental climate typified by 

warm, moist summers and cold, dry winters. Mean 

minimum January temperature is –19°F, and mean 

maximum July temperature is 72°F. On average, Fairbanks receives about 70 in. of snowfall annually. Mean 

annual precipitation at Fairbanks International Airport 

is 11 in. Mean annual flow for the entire period of 

record for the Chena River at Fairbanks is 1,360 ft3/s; 

however, because flow has been regulated by Moose 

Creek Dam since 1981, no water discharge greater than 

12,000 ft3

/s flows through Fairbanks.

RECENT RIVER HISTORY AND

BACKGROUND

For the past several years, concern has been 

expressed by local residents of Fairbanks that Noyes 

Slough is “drying up.” The reduced flows combined 

with the abuse of the waterway as a refuse site have 

depleted the slough's value as aquatic and wildlife habitat. The slough has been a dumping ground for refuse 

and a catchment for storm runoff that introduces nonpoint-source pollution. Appliances, scrap building 

materials, concrete, asphalt, and overburden have been 

discarded in the slough. In many reaches, the slough is

stagnant and unsightly, and water flows through its 

length only intermittently during the open-water season. The local community has a strong desire to restore 

the slough to a clean, flowing waterway.

Fairbanks is built on the alluvial plain of the 

Chena and Tanana Rivers. The Tanana River flows 

from the southeast out of the Alaska Range toward the 

foothills north of Fairbanks and then turns west along 

the south side of the hills. The Tanana has been forced 

into this position along the north edge of its valley by 

the extensive alluvial outwash from the glacier-fed 

streams of the Alaska Range.

Before 1945, a channel of the Tanana River, 

called the Chena Slough, branched off the main river 

upstream from Moose Creek Bluff. The upper part of 

this slough also was known as Piledriver Slough, 

named after a roadhouse on the Old Richardson Trail. 

Water in this channel flowed northward, then westward 

through Fairbanks, and back into the Tanana River near 

Chena Ridge. A smaller subchannel, Noyes Slough, 

branched off of and back into Chena Slough. According to a 1940 map of Fairbanks (fig. 2), the Chena River 

actually entered Chena Slough about 7 miles east of 

Fairbanks.

In the 1930’s, local residents observed and 

expressed concern that the Tanana River was enlarging 

the entrance of Chena Slough and that increasing flow 

from the Tanana was occurring in Chena Slough. These 

conditions indicated that the Tanana River might be 

reestablishing its main channel farther to the north, 

thereby jeopardizing Fairbanks. Also, flow from both 

the Chena and Tanana Rivers were contributing to 

flooding in downtown Fairbanks. At that time, no 

stream-gaging stations had been established on the 

Tanana River, Chena River, or Chena Slough, so exact 

streamflows are not known. On August 15, 1933, flow 

in the Chena Slough at Fairbanks was estimated at 

7,000 ft3/s, of which 5,000 ft3/s was contributed by the 

Tanana River. On the basis of present-day knowledge 

of flow in the Tanana River at Fairbanks, this contribution would be approximately 10 percent of the flow 

of the Tanana River. (Mean August flow in the Tanana 

River at Fairbanks has been 48,490 ft3/s for the period 

of record, 1973–99). In 1937, a summer flood flow was 

estimated at 22,000 ft3

/s, half of which was contributed 

by the Tanana (U.S. Army Corps of Engineers, 1938).
R

ECENTRIVERHISTORYANDBACKGROUND5

Figure 2. Fairbanks in 1940, showing Tanana and Chena Rivers; Piledriver, Chena, and Noyes Sloughs; and location of Moose Creek Dike, built across Chena Slough during 1940–45. Original topographic surveys (U.S. Geological Survey, 1940) were done in 1902 and 1916.
6 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

The proposed solution to reducing the flow contributed to Chena Slough by the Tanana River was to 

construct an earth-and-rock dike across the slough 

extending from Moose Creek Bluff westward to the 

Tanana River (fig. 2). This dike was constructed during 

the period 1940–45, although additional work on it 

may have been done as late as 1947. This construction cut off the flow from the Tanana River into the 

Chena Slough. Considerable seepage through the dike 

occurred during the years after the dike was constructed. Records from a gaging station that operated 

during 1948–52 on the upper part of Chena Slough 

above the old mouth of the Chena River indicate that 

flows ranged from about 50 to 100 ft3

/s throughout the 

year. Some seepage still occurs through the dike, and 

some subsurface flow enters the channel known locally 

as Badger Slough, which is the reach of the old Chena 

Slough from the dike downstream to the confluence of 

the Chena River. (Upstream from the dike, the channel 

still is called the Piledriver Slough.) Various discharge 

measurements made by the U.S. Geological Survey 

(USGS) in the early 1970’s indicate an average flow in 

the slough of about 50 ft3

/s during the open-water 

season, although it is greater at times of high flow on 

the Tanana River. Flow was reduced further in Piledriver Slough from some blockages placed in the upper 

end during the flood-control construction period, 

1977–82, and seepage into Badger Slough possibly is 

even less today. Seepage may have declined as the 

Tanana River deposited sediment against the upstream 

side of the dike and as Piledriver Slough shifted away 

from the dike.

In 1947, the USGS established a gaging station on 

the Chena Slough at the Cushman Street bridge, downstream from the entrance to Noyes Slough. Although 

this site initially was called Chena Slough at Fairbanks, 

after 1952 it was called Chena River at Fairbanks, 

which is the name used in the permanent records for 

the whole period. Flow records at this gaging station 

included Noyes Slough. During 1947–54, separate 

measurements or estimates of flow were made on 

Noyes Slough at Illinois Street when flow in the main 

channel of Chena River was measured at the Cushman 

Street bridge downstream from the entrance to the 

slough. The two measurements were added to get total 

flow for the Chena River. Although discharge measurements begun in 1955 from the newly constructed Wendell Street bridge, upstream from the entrance to the 

Noyes Slough, included the flow into the slough, only 

a few separate measurements of flow in Noyes were 

made since then. In 1957, the gaging station was relocated to the Wendell Street bridge, and in 1967, it was 

moved 800 ft upstream to its present location on the 

right bank (station no.1

 15514000).

On August 14, 1967, a flood of 74,400 ft3

/s 

occurred on the Chena River at Fairbanks. After this 

flood, the Chena River Lakes Flood Control Project 

was designed and built; the project included a diversion 

dam and control structure on the Chena River upstream 

from Fairbanks near Moose Creek Bluff, a floodway 

and spillway leading to the Tanana River, and a raised 

levee along the north side of the Tanana River (fig. 3). 

In the event of a major flood on the Chena River, water 

is impounded behind the Moose Creek Dam and 

diverted into the Tanana River. During lesser floods, 

water is impounded behind the dam without spilling 

into the Tanana River and is regulated down the Chena 

at levels below flood stage until the impounded floodwater drains. Such regulation of the Chena River was 

applied for the first time in July 1981; more recent 

impoundments have been imposed since that time, and 

in 1992, water was diverted into the Tanana River for 

the first and only time to date. During impoundment to 

date, regulated flow down the Chena River to Fairbanks has not exceeded 11,400 ft3/s at the gaging station; under the present plan, impounded flow will not 

exceed 12,000 ft3

/s.

What does this mean in relation to Noyes Slough?

(1) The Tanana River formed Chena Slough and Noyes 

Slough (figs. 2 through 4). The mouth of the Chena 

River was on the Chena Slough at a point east of Fairbanks (figs. 3 and 5). The channel of the Chena River 

as defined today and the Noyes Slough can convey a 

higher flow than the flows now occurring through Fairbanks. The greater channel capacity is readily evident 

when the Chena River upstream from the confluence of 

Badger Slough is compared to the reach through town. 

Upstream from Badger Slough, the channel is about 

175 ft wide, whereas in town it is about 250 ft wide.

1

This and similar numbers (eight or more digits beginning with 15) 

were assigned by the U.S. Geological Survey and are retained indefinitely 

to identify surface-water stations on the basis of downstream order. Other 

station numbers used in this report apply only to this study and were based 

on stationing (in feet) determined for use in the HECRAS model.
RECENT RIVER HISTORY AND BACKGROUND 7 Figure 3. Present-day conditions affecting Chena River and Noyes Slough, showing Chena River Lakes Flood Control Project and other structures in vicinity. Chena Slough is also known locally as Badger Slough. Arrows indicate flow directions. Modified from Burrows and Harrold (1983).

Area offigure 5

Area offigure 4

10 MILES

10 KILOMETERS

5

5

0

0

Fairbanks

International Airport

Floodway

sill groin

Eielson

Air Force

Base

Wainwright

Army Air Field

Moose Creek Bluff

North

Pole

FAIRBANKS

MOOSE CREEK DAM

LEVEE

Floodway

CHENA RIDGE

Piledriver

Slough

Salchaket

Slough

Chena

Slough

CHENA

RIVER

NOYES

SLOUGH

T A N A N A

R I V E R
8 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

(2) Except for minor seepage through Moose Creek 

Dike, the absence of flow from the Tanana River means 

an absence of sediment load from the river. The Tanana 

River at Fairbanks transports an average of 25,000,000 

tons/yr of suspended sediment (Burrows and others, 

1981). The reduction in flow and loss of a substantial 

sediment load in Chena Slough are similar to observed 

effects of dams on other alluvial rivers. One of the possible downstream effects is channel scour or degradation (Williams and Wolman, 1984). Channel cross 

sections measured at the Wendell Street bridge on 

the Chena River (immediately upstream from Noyes 

Slough) in 1959, 1989, and 2000 are shown in figure 6. 

Although the flows are about the same for the three 

years (3,450 ft3/s, 3,180 ft3

/s, and 3,270 ft3/s, respectively), the main deep part of the channel broadened 

Figure 4. Noyes and Chena Sloughs near entrance to Noyes, also showing Illinois and Cushman Streets, Fairbanks, 

1938. Light color of water indicates high suspended-sediment load from Tanana River’s contribution to flow. Arrows 

indicate flow direction in sloughs. See figure 3 for location. Photograph courtesy of U.S. Army Corps of Engineers.
RECENT RIVER HISTORY AND BACKGROUND 9

and shifted to the left from 1959 to 1989. Further 

enlargement of the main channel and scouring of the 

thalweg occurred by 2000. These changes caused a 

lowering of the mean bed elevation and consequently 

a decline in water-surface elevation of about 1.8 ft 

(fig. 6).

(3) The ratings reflect the scouring or lowering of the 

mean bed elevation of the main channel of the Chena 

River downstream from the gaging station. A range 

of discharge measurements at their respective gage 

heights at different times from 1957 to 2000 (rating 

numbers 5, 14, 18, and 22) are shown in figure 7. No 

measured flow data are available for the Chena Slough 

prior to the construction of Moose Creek Dike. By 

1957, the dike had been in place for about 10 years. 

Rating 5 was in effect during 1957–59. In 1967, the 

river flooded, and then rating 14 was in effect during 

1968–73. Rating 18, in use 1987–89, reflected conditions after the Moose Creek Dam had been in effective 

operation. Rating 22 is the present-day stage–discharge 

relation.

Figure 5. Mouth of Chena River on old Chena Slough about 7 miles east of Fairbanks, 1938. Silt-laden water of 

slough (light) contrasts notably with clear water of river (dark). Arrows indicate flow direction in slough and river. See 

figure 3 for location. Photograph courtesy of U.S. Army Corps of Engineers.
10 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

(4) Noyes Slough acts as an overflow channel for high 

flows on the Chena River. Because flows greater than 

12,000 ft3

/s no longer occur and the main channel of 

the Chena River has been lowered, flow into Noyes 

Slough might be expected to be reduced. Discharge 

measurements that were made on Noyes Slough during 

the periods 1947–53, 1967–93, and 1994–2000, plotted 

against total flow of the Chena River, and the corre0 50 100 150 200 250 300

DISTANCE OF STATION FROM LEFT END OF WENDELL STREET BRIDGE, IN FEET

414

416

418

420

422

424

426

428

430

Bed elevation (dashed line is computed mean)

1959

1989

2000

WATER-SURFACE ELEVATION, IN FEET

Mean water-surface elevation 

1959

1989

2000 

EXPLANATION

Figure 6. Cross sections for Chena River at Wendell Street bridge, showing mean water-surface and bed 

elevations on May 13, 1959, at discharge of 3,450 cubic feet per second; April 28, 1989, at discharge of

3,180 cubic feet per second; and May 3, 2000, at discharge of 3,270 cubic feet per second.
RECENT RIVER HISTORY AND BACKGROUND 11

sponding regression relations are shown in figure 8. 

During 1947–53, when flow was about 2,400 ft3

/s in 

the Chena River, flow in Noyes Slough was about 

100 ft3/s, and when the flow in the river was about 

1,600 ft3/s, the slough had almost no flow. During 

1967–93, the same flow of about 2,400 ft3/s in the 

Chena River corresponded to a flow in Noyes Slough 

of only about 40 ft3

/s, and when the flow in the river 

was about 2,000 ft3

/s, the slough had almost no flow. 

To reach 100 ft3

/s in Noyes Slough under present conditions, the Chena River must be flowing at about 

3,800 ft3/s; when flow in the river drops below about 

3,000 ft3/s, the slough has no flow. Because of regulation, flow cannot exceed 12,000 ft3

/s in the Chena 

River; at that level, maximum flow into Noyes Slough 

would be about 1,100 ft3

/s. In winter, no water flows in 

the slough, and the channel is filled with ice and snow.

Studies done by the USGS (Nelson, 1978; Glass 

and others, 1996) show that, in general, the flow of subsurface water (or ground water) is from the Tanana 

River toward the northwest in the alluvial plain (fig. 9). 

A section of the alluvial plain from Noyes Slough to the 

Tanana River is shown in figure 10. During high flows 

on the Tanana River and low flows on the Chena River, 

ground-water flow is contributed to the Chena. Conversely, when the Chena River is at higher flows, 

0

1

2

3

4

5

6

7

8

9

10

100 1,000 10,000

GAGE HEIGHT, IN FEET

DISCHARGE, IN CUBIC FEET PER SECOND

Rating 22, years 1999 2000

Rating 5, years 1957 59

Rating 14, years 1968 73

Rating 18, years 1987 89

EXPLANATION

Figure 7. Rating curves for Chena River stream-gaging station, 1957–2000. (Gage datum, 422.92 feet above sea 

level.)
12 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

it contributes water to the aquifer, thereby raising the 

ground-water levels near the river. Farther from the 

river, ground-water levels rise as long as high flow continues. At times of no surface-water flow from the 

Chena River into the entrance of Noyes Slough, pools 

of water in the deeper parts of the slough correspond to 

local ground-water levels. Depending on whether flow 

in the Chena River is rising or falling, Noyes Slough 

may lose flow along its reach or gain flow from sustained high ground-water levels.

Figure 8. Relations between flows in Noyes Slough and Chena River for three periods during 1947–2000.

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

0 2,000 4,000 6,000 8,000 10,000 12,000

DISCHARGE AT CHENA RIVER AT FAIRBANKS, IN CUBIC FEET PER SECOND

DISCHARGE AT NOYES SLOUGH AT MINNIE STREET BRIDGE, 

IN CUBIC FEET PER SECOND

EXPLANATION

1947 53

1967 93

1994 2000

Instantaneous discharge

1994 2000 curve

1947 53 curve

1967 93 curve

Regression relations
RECENT RIVER HISTORY AND BACKGROUND 13 Figure 9. Water-table map of Fairbanks, showing ground-water elevations, in feet above sea level (contour interval, 2 feet), and flow directions (red arrows). Dashed contours indicate uncertainty. Modified after Glass and others (1996). Tanana River Tanana River

Chena River

Chena River

Levee

Levee 64°

48'

147°40'

64°

52'

64°

50'

147°50' 147°45'

440

438

442

436

432 430 428 434 426

424 422 420

FAIRBANKS

AIRPORT

0 3 KILOMETERS0 2 3 MILES 1

2 1

Noyes Slough
14 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

EVALUATING PRESENT-DAY

HYDRAULICS

The approach to establishing present-day hydraulic interaction between the Chena River and Noyes 

Slough was to build a hydraulic model using the 

Hydrologic Engineering Center River Analysis System 

(HECRAS) computer program, a one-dimensional 

water-surface-profile model developed by the U.S. 

Army Corps of Engineers (Brunner, 1997). Although 

model details are not presented herein, basic assumptions used, the source of input data, and graphic presentation of results are given along with some hydraulic 

information such as roughness coefficients and starting 

friction slope. The reader should refer to the HECRAS 

program user manuals (Brunner, 1997) for more explanation.

Most water-discharge measurements made on 

Noyes Slough near the entrance at Illinois and Minnie 

Streets were compiled (table 1). Because Chena River 

spring runoff was sufficiently high in 2000 to cause 

flow in Noyes Slough, discharge and water-surface 

elevations were determined at eight sites along Noyes 

Slough at various flows (table 2). After spring runoff, 

a construction project discharging water into the slough 

near the entrance provided an opportunity to measure a 

very low flow in the slough when no flow was entering 

Noyes Slough from the Chena River. Additional cross 

sections of the Noyes Slough were surveyed at seven 

sites. Cross-section geometry for the Noyes Slough 

was derived from a combination of discharge data, 

bridge-scour data (Heinrichs and others, in press), and 

surveyed bank geometry. Water-surface profiles of 

Noyes Slough were derived from measurements at the 

bridge crossings on the slough.

Although water discharge in the Chena River was 

measured several times in conjunction with the operation of the Chena River at Fairbanks gaging station, 

reported river flows are generally the mean daily discharge from the gaging station. Discharge measurements are assumed to be the instantaneous flow at the 

time of measurement, whereas mean flows, derived 

from gaging-station records, are computed from the 

recorded stage record for the day and the discharge 

rating at the gaging station (tables 1 and 2). Watersurface elevations on the Chena River were measured 

at bridge crossings. An additional cross section was 

surveyed at the gaging station, upstream from Wendell 

Street.

Cross-section geometry for the study reach of the 

Chena River was derived from a combination of the 

discharge measurements made at several of the bridges; 

the bridge-scour study (Heinrichs and others, in press); 

and other cross sections obtained from the U.S. Army 

Corps of Engineers, the Natural Resources Conservation Service, and the Alaska Department of Transportation and Public Facilities. Water-surface profiles of the 

Chena River were derived from measurements at the 

bridge crossings on the river.

Figure 10. Geohydrologic cross section of Tanana–Chena alluvial plain, showing surface-water–ground-water 

interaction in vicinity of Tanana River, Chena River, and Noyes Slough. Modified after Nelson (1978).

0 5,000 10,000 FEET

APPROX. VERTICAL EXAGGERATION, 10.5X

S

450

440

430

420

410

ELEVATION,

 IN FEET ABOVE SEA LEVEL

N

TANANA RIVER

WELL

WELL

WELL

WELL

CHENA RIVER

NOYES SLOUGH

WATER TABLE
DATA AND ASSUMPTIONS USED IN MODELING 15

One set of suspended-sediment samples and one 

set of bed-load samples were collected on the Chena 

River, and a single set of suspended-sediment samples 

was collected on Noyes Slough. A single-point bedload sample was collected at the entrance to Noyes 

Slough.

Photographs of the slough under different flow 

conditions are shown in figures 11 through 13. Also, 

the locations and dimensions of the 10 beaver dams 

along the length of the slough were determined and 

included in the model because they significantly affect 

water-surface elevations along the slough.

A HECRAS model of the Chena–Noyes hydraulic system was constructed. Initial simulations agreed 

reasonably well with flows and water-surface profiles 

in the Chena River and Noyes Slough. The model then 

was used to present one theoretical means of increasing 

the magnitude and frequency of flow in Noyes Slough. 

(HECRAS models used in this report were constructed 

to mimic flow in the Noyes Sough and Chena River to 

compare different conditions. One-dimensional, preliminary models, they should not be used for any other 

purpose without considerable additional data and 

refinement. Input files for final runs of HECRAS models used in this report are available through Alaska 

District offices of the U.S. Geological Survey.)

DATA AND ASSUMPTIONS USED IN 

MODELING

Aerial photography flown in 1996 was provided 

to the USGS by the Natural Resources Conservation 

Service. The individual photographs were scanned, 

composited and cropped to correspond to the study 

area, and saved as digital files in bitmap format. The 

composite image (fig. 14) was used as a background 

in the creation of the model schematic. By comparing 

measured distances between known features on the 

composite and USGS 1:25,000-scale topographic 

maps, the scale of the composite image was determined. Thereafter, all locations were given x-y coordinates relative to a superimposed grid. A digitaldisplay measuring wheel was used to measure reach 

lengths (in feet) between sections on both channels to 

establish stationing used in the HECRAS simulations.

Table 1. Discharge and water-surface elevation for Noyes 

Slough at Illinois Street and Minnie Street bridges and 

corresponding discharge for Chena River, 1947–2000

[—, no data]

Date

Noyes Slough Chena River

Discharge

(cubic feet

per second)

Watersurface 

elevation

(feet)

Discharge

(cubic feet

 per second)

Noyes Slough at Illinois Street bridge (station no. 1551400435):

1947 July 31 25 — 1,430

1948 June 6 1,120 — 7,520

July 24 592 — 4,890

September 16 167 — 2,690

1949 July 8 814 — 6,180

August 12 438 — 4,090

1950 May 15 1,600 — 9,430

1952 June 27 243 — 3,560

July 25 115 — 2,520

August 19 101 — 2,670

September 25 88 — 2,500

Noyes Slough at Minnie Street bridge (station no. 1551400425):

1967 May 5 205 — 4,180

May 29 1,020 — 9,130

1971 May 18 1,050 — 9,240

1989 May 14 30.3 — 2,160

1990 September 4 229 — 6,300

1992 May 31 808 — 10,200

1993 April 26 — 425.83 3,720

April 30 159 427.37 4,130

May 7 202 426.9 4,570

May 28 — — 2,730

June 1 49.2 424.8 2,420

June 7 23.1 424.16 1,950

June 30 11.9 424.17 1,690

September 9 16.2 425.15 2,450

September 22 296 427.92 5,610

September 30 38.7 425.66 2,940

1994 May 20 .2 424.62 1,610

May 25 — 424.62 1,380

June 24 651 430.8 9,340

July 7 129 426.09 3,660

2000 May 3 13.5 425.56 3,300

May 10 67.2 426.20 3,580

May 11 34.1 425.72 3,190

May 19 — 425.40 2,520

May 20 37.3 426.14 3,330

May 21 88.0 426.63 4,200

May 24 311 428.28 5,790

May 27 431 429.40 7,760

May 30 89.9 425.99 3,620

June 6 117 426.24 3,950

June 15 31.9 425.76 2,870

June 19 .54 424.84 2,150

August 12 2.0 425.49 1,350
16 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska Table 2. Discharge and water-surface elevation for Noyes Slough (all sites) and corresponding mean daily discharge and water-surface elevation for Chena River during May, June, and August, 2000 [Number in parentheses after Noyes Slough station name is U.S. Geological Survey station-identification number. —, no data] Date Noyes Slough Chena River Minnie Street (no. 1551400425) Illinois Street (no. 1551400435) O’Connor Street (no. 1551400455) Danby Street (no. 1551400550) Aurora Drive (no. 1551400650) West Johansen Expressway (no. 1551401550) Indiana Street Goldizen Street Mean discharge (cubic feet per second) Mean water- surface elevation based on rating 22 (feet) Discharge (cubic feet per second) Water- surface elevation (feet) Discharge (cubic feet per second) Water- surface elevation (feet) Discharge (cubic feet per second) Water- surface elevation (feet) Discharge (cubic feet per second) Water- surface elevation (feet) Discharge (cubic feet per second) Water- surface elevation (feet) Discharge (cubic feet per second) Water- surface elevation (feet) Discharge (cubic feet per second) Water- surface elevation (feet) Discharge (cubic feet per second) Water- surface elevation (feet) May 2000 3 13.5 425.56 — — — — — — — — — — — — — — 3,300 426.65 10 67.2 426.20 — 424.88 79.8 424.10 73.8 422.73 — 422.41 — — — — — — 3,580 426.95 11 34.1 425.72 — — — 423.89 — 422.47 — — 97.6 420.11 — — 112 420.54 3,190 426.53 19 — 425.40 — 423.31 — 423.35 — 421.98 — 421.92 — 419.35 — 419.37 — 419.18 2,520 425.78 20 37.3 426.14 — — — — — — — — 14.2 420.19 — — — — 3,330 426.68 21 88.0 426.63 95.0 424.97 125 424.43 113 423.13 — — 98.8 420.87 — — — — 4,200 427.57 24 311 428.28 — — — 425.78 — 424.35 — 423.81 — 422.36 — 422.33 — 421.88 5,790 429.02 27 431 429.40 — — — — — — — — — — — — — — 7,760 430.61 30 89.9 425.99 87.9 424.55 — — — — — — 145 420.51 — — 97.2 420.03 3,620 426.99 June 2000 6 117 426.24 116 424.90 117 424.06 126 422.79 — — 115 420.87 — — 131 420.42 3,950 427.32 15 31.9 425.76 — — — — — — — — — — — — — — 2,870 426.18 18 — — — — 0 423.52 0 421.56 — — — — — — 6.0 419.44 2,380 425.61 19 .54 424.84 — — — — — — — — 15.8 420.54 — — — — 2,150 425.33 21 — — — — — — — — 2.2 — — — — — — — 2,010 425.15 22 — — — — — — .93 421.65 1.2 — 3.7 420.43 3.0 — 2.9 — 1,900 425.00 August 2000 12 2.0 425.49 .0 423.93 — — — — — — — — — — — — 1,350 424.18
DATA AND ASSUMPTIONS USED IN MODELING 17

Cross-section geometry for Noyes Slough was 

determined from discharge measurements made in 

2000 at Minnie, Illinois, O’Connor, Danby, and Goldizen Streets and at West Johansen Expressway. The 

cross section for the slough at Aurora Drive was from 

the bridge-scour study (Heinrichs and others, in press). 

At all measured sections, bank geometry was determined by using a reel and sounding weight referenced 

to the water-surface elevation at the time of the survey 

and extending up the dry banks on both sides.

Assuming that no contraction occurs at the highest flows to be modeled, none of the bridges on Noyes 

Slough were treated as hydraulic structures in the 

HECRAS model. However, for effective channel modeling, additional cross sections were needed, particularly for the 2.5-mi-long reach between Aurora Drive 

and West Johansen Expressway. Also, the effects of 

the 10 beaver dams on channel geometry had to be 

considered.

At seven locations requiring a survey of channel 

geometry, including cross sections at the entrance 

and at the mouth, a survey-grade Global Positioning 

System (GPS) was used to establish reference marks. 

Calibrating against known control points yielded a 

measurement accuracy of about +0.2 ft vertically, 

which was sufficient for channel geometry. The vertical control for water-surface elevations had been established already by using levels from benchmarks at 

other cross-section locations. The reference marks 

were established at the unknown sections by using 

GPS, and later the channel was surveyed by using levels. Then these sections were located in the local x-y 

grid and added to the model.

The slough was floated by canoe and the location 

of the beaver dams marked on a field copy of the photo 

image. The relative geometry of each beaver dam was 

measured by using a tagline and measuring depths and 

dam height relative to the channel bottom. The locations were established in the local-grid coordinate 

Figure 11. Noyes Slough looking upstream during period of flow in spring 2000, showing beaver dam 

(station 20209, fig. 14)
18 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

system used to construct the HECRAS model. The 

average height of the beaver dams then was used to 

modify the cross-sectional area at these sections and 

hence the channel geometry (fig. 15).

In HECRAS, cross sections between established 

sections can be synthesized by interpolation (Brunner, 

1997). This feature of the computer program was used 

to generate 25 additional intermediate cross sections 

for a total of 47 (one cross section about every 600 ft or 

one every 10 channel widths). Cross sections were not 

subdivided for the first model runs; Manning’s roughness coefficient n was assumed to be 0.040 for all sections.

Cross sections for the Chena River were from the 

bridge-scour study (Heinrichs and others, in press) or 

were derived from discharge measurements. The 

bridge-scour study was based on a different one-dimensional hydraulic model that required an approach and 

exit section and sections at the upstream and downstream sides of each bridge. These sections were used 

in the HECRAS model for the reaches through the 

bridges at Wendell Street, Cushman Street, Peger 

Road, and University Avenue.

For the Chena River HECRAS simulations, 

additional cross sections were required immediately 

upstream and downstream from the Noyes Slough 

entrance and mouth to establish junctions. These 

sections were interpolated or extrapolated from the 

nearest cross-section geometry and channel slope in 

HECRAS. This divided the Chena River channel into 

three reaches: Reach 1 is upstream from the slough, 

reach 2 is between the slough entrance and mouth, 

and reach 3 is downstream from the mouth. 

The cross section at the Wendell Street bridge 

shows considerable scour, particularly around the left 

pier. Because the channel upstream does not reflect this 

geometry, a section was surveyed at the gaging station 

and used to template the next section downstream in 

the reach approaching the bridge. Additional sections 

were interpolated on the Chena River in the reaches 

Figure 12. Noyes Slough looking downstream after flow ceased in midsummer 2000, at 

West Johansen Expressway bridge (station 2917, fig. 14).
MODEL ADJUSTMENT AND CALIBRATION 19

between bridges. For the first model runs, the cross 

sections were not subdivided; Manning’s n was set at 

0.035 for all sections.

Both a flow at the most upstream section and a 

starting friction slope at the most downstream section 

of the river reach were required for the initial model 

run. A slope of 0.0002 ft/ft was computed from the 

reach distance between the bridges and water-surface 

elevations measured at the Chena River bridges during 

spring 2000. The assumed water discharges (Q) were 

based on measurements made in Noyes Slough and the 

corresponding flow in the Chena River. For model 

input, flow had to be split between the two channels. 

For each model run, a Q value was assigned for each 

of the three Chena River reaches and a Q value was 

assigned to Noyes Slough. For example, given a measured flow in Noyes Slough of 117 ft3

/s and corresponding flow in the Chena River of 3,950 ft3

/s, the input to 

the model would be 3,950 ft3/s for each of the reaches 

1 and 3 of the Chena River; 117 ft3

/s for the Noyes 

Slough; and the difference between these flow values, 

or 3,833 ft3/s, for reach 2 of the river.

MODEL ADJUSTMENT AND

CALIBRATION

For this study, the model was calibrated primarily 

to match observed conditions on Noyes Slough at 

Minnie Street and at the stream-gaging station on the 

Chena River upstream from Wendell Street. All the 

flows that were measured in 2000 were run. For Noyes 

Slough, Manning’s n values were adjusted to 0.037 

except at Aurora Drive, where a roughness of 0.15 was 

assigned to part of that section to account for a log jam. 

With the exception of flows less than about 50 ft3/s in 

the slough, the model matched measured water-surface 

elevations at Minnie Street on the slough reasonably 

well.

For the Chena River, the model output nearly 

matched the stage–discharge relation derived from 

gaging-station records at lower flows but not at higher 

flows, for which the modeled stage was lower than the 

rating. The cross sections were subdivided such that the 

banks at flows greater than about 2,000 ft3

/s were 

assigned a higher Manning’s n value. Thus, to adjust 

Figure 13. Noyes Slough looking downstream showing channel filled with snow and ice in 

late winter, at West Johansen Expressway bridge (station 2917, fig. 14).
20 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

Figure 14. Study reach (fig. 1), showing locations of cross sections used in model, 10 beaver dams, and flow

Aerial photograph courtesy of Natural Resources
MODEL ADJUSTMENT AND CALIBRATION 21

directions (arrows). Scale is approximate. Numbers labeling some cross sections refer to stationing, in feet.

Conservation Service; flown in 1996.
22 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

the model output to more closely match the rating, 

Manning’s n values were changed to 0.029 for the main 

channel and 0.055 for the banks of the Chena River.

Measured flows in Noyes Slough and measured 

or gaged flows in the Chena River were used for the 

initial simulations. If the model accurately calculated 

water-surface elevations at all measured flows, the 

water-surface elevations at the entrance to Noyes 

Slough and at Chena River upstream and downstream 

from the entrance should be very similar but did not 

always match, particularly at flows less than about 

50 ft3

/s. Discrepancies likely were due to variation in 

ground-water inflow and outflow on rising or falling 

stage of the Chena River, which in turn may have 

caused Noyes Slough to lose flow to the ground-water 

aquifer during rising stages and to gain flow during 

falling stages. These variations may amount to as much 

as 50 ft3

/s (table 2). A one-dimensional, steadystate model such as HECRAS does not adjust 

automatically for varied flow within a reach.

For the final model, the flow was split between 

Noyes Slough and the Chena River to make the values 

for water-surface elevations at the junction of Noyes 

Slough and Chena River approximately equal. The 

resulting modeled flows for the slough and river match 

the measured values reasonably well except at lower 

flows, for which the model overestimates discharge 

(fig. 16). Flow in the slough begins at a flow of 2,400 

ft3/s in the Chena River (stage 2.72 ft, elevation 

425.64 ft above sea level, rating 22; fig. 7). An example of output from the HECRAS model is shown in 

figure 17, a perspective view depicting cross sections, 

the Wendell Street bridge, and the water-surface profile 

at a flow of 2,000 ft3/s for Chena River reach 1.

USING MODEL WITH MODIFIED

GEOMETRY

Complete restoration of Noyes Slough would 

require returning flow from the Tanana River to the old 

Chena Slough. Although this would increase flow in 

Noyes Slough, it also would increase silt load and 

hence possibly endanger habitat for wildlife dependent 

on clearer water and cause potentially serious flooding 

of much of Fairbanks. Increasing the magnitude and 

frequency of flow from the present-day Chena River 

into Noyes Slough by enlarging the slough channel 

and lowering its bed has been the most commonly 

suggested means of restoration.

HECRAS may be used to examine the effects of a 

modified slough-channel geometry. In the model, cross 

sections may be altered, structures or obstructions may 

be added, or the channel may be enlarged. The following analysis shows how flow might be increased in 

Noyes Slough by changing the slough-channel geometry. Basic assumptions in the model were that the entire 

length of the channel could be excavated and that the 

10 beaver dams would be removed. Utility crossings 

and the possible effects of excavation on bridge foundations were ignored.

The first step of this analysis was to select a 

desired flow in the Noyes Slough for a given flow in 

the Chena River. Conditions approximating those a few 

years after the construction of Moose Creek Dike, were 

chosen: a flow of 100 ft3/s in the slough and a flow of 

2,000 ft3

/s in the river. Recent discharge measurements 

show velocities of 1 to 1.5 ft/s at a flow of 100 ft3

/s in 

the slough; the desired discharge could be achieved by 

enlarging the slough channel about 80 ft2 in crosssectional area.

A channel 40 ft wide at the bottom, 2 ft deeper 

than at present, and having sides that rise 2 ft for every 

1 ft of width would yield the additional area needed. 

Although such steep sides likely would be unstable, the 

actual width of Noyes Slough at the channel bottom is 

constrained to about 40 ft in some parts and thus would 

require steeper banks to gain the necessary increase in 

cross-sectional area. Assuming this geometry and a 

Figure 15. Example of cross section used in HECRAS model, 

showing channel and beaver dam on Noyes Slough (station 

7538.25, fig. 14).

418

420

422

424

426

428

430

0 20 40 60 80 100 110

DISTANCE OF STATION FROM LEFT BANK, IN FEET

ELEVATION, IN FEET

Water surface

Top of 

beaver dam

10 30 50 70 90
USING MODEL WITH MODIFIED GEOMETRY 23

channel-bottom elevation of 422.35 ft above sea level, 

the channel-modification option in HECRAS (Brunner, 

1997) first was used to model conditions for the most 

upstream cross section, at the entrance to Noyes Slough 

(fig. 18). Then this channel geometry was replicated 

by specifying a slope of 0.0003 ft/ft, about that of the

natural channel, at each down-channel cross section.

Rerunning the model using the same modifiedchannel geometry, flows, and boundary conditions 

and optimizing the flow split produced a lower watersurface profile throughout the reach. Actual Noyes 

Slough channel-bed and water-surface profiles compared to modified-channel profiles, assuming a flow 

of 117 ft3/s, are shown in figure 19.

Figure 16. Regression relation between Noyes Slough and Chena River flows for present-day 

conditions as modeled by HECRAS and measured flows in slough (instantaneous) and river 

(mean daily).

0

200

400

600

800

1,000

1,200

0

DISCHARGE IN NOYES SLOUGH, IN CUBIC FEET PER SECOND (

QN)

Noyes Chena measurements

Noyes Chena modeled flow

Modeled-flow regression

DISCHARGE IN CHENA RIVER, IN CUBIC FEET PER SECOND (QC)

2,000 4,000 6,000 8,000 10,000 12,000 14,000

EXPLANATION

Regression equation: QN = 0.000006 QC + 0.0173 QC 28.348 2
24 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

The regression relation between modeled flows in 

Noyes Slough and Chena River for the modified conditions in the slough are shown in figure 20. Flow in

the slough begins at a flow of 1,200 ft3

/s in the Chena 

River (stage 1.08 ft, elevation 423.30 ft above sea 

level, rating 22; fig. 7). Hydrographs for the river 

(based on discharge data) and the slough (based on 

regression equations; see figs. 16 and 20) for water year 

2000 are shown in figure 21. Hydrographs for Noyes

Slough under existing and modified conditions show 

flow of increased magnitude and duration in the modified channel.

For the period April 1–October 31 of water 

years 1981–99, the maximum, mean, and minimum 

of the mean daily flows for the Chena River (table 3) 

were used to construct three theoretical periods of flow. 

In turn, these Chena River conditions were used to 

compute theoretical maximum, mean, and minimum 

hydrographs for modified Noyes Slough (fig. 22) from 

regression equations.

If the theoretical mean or maximum hydrographs 

for Noyes Slough pertained, given present conditions 

and channel geometry, flow apparently would occur in 

the slough throughout most of the open-water season; 

if instead the theoretical minimum hydrograph pertained under present conditions and geometry, the 

slough would flow for only about 5 days. Noyes Slough 

flow would be greater for all Chena River flows after 

modifying the slough channel. Because these hydrographs are theoretical and are unlikely to represent 

actual flows for any particular water year, the effect of 

modifying the channel was assessed also in relation to 

a recent year’s hydrograph. Mean flow for the Chena 

Water-surface

profile

27323

26753

26322

25923

Wendell Street bridge

Figure 18. Cross-section geometry at entrance to Noyes 

Slough and modified channel configuration.

422

424

426

428

430

432

434

436

Water surface

Existing channel

Modified channel

0 20 40 60 80 100

DISTANCE OF STATION FROM LEFT BANK, IN FEET

ELEVATION, IN FEET

10 30 50 70 90

Figure 17. Example of HECRAS model output, showing water-surface profile (at flow of 2,000 cubic feet per 

second) for reach 1, Chena River through Wendell Street bridge, just upstream from entrance to Noyes Slough. 

Note differences in cross-section geometry of channel through reach. At points where red lines intersect channel, it was subdivided for different roughness (Manning’s n) values. Number labels refer to stationing, in feet.
USING MODEL WITH MODIFIED GEOMETRY 25

River at Fairbanks during water year 1999, a relatively 

low runoff year, was 809 ft3/s, or only about 60 percent 

of the mean for the period of record. The computed 

hydrographs for Noyes Slough for water year 1999 are 

shown in figure 23. Increasing the channel capacity and 

lowering of the bed would have increased flow duration from 72 to 131 days.

To compile flow-duration data, mean daily flows 

for the Chena River during April 1–October 31 of 

water years 1981–99 were divided into ascending 

ranges of flow, commonly referred to as flow classes. 

The number of days flow occurs in each class defines 

flow duration for the period. The compiled flow durations help in estimating how many days to expect flow 

in Noyes Slough. The regression relation between 

Noyes Slough and Chena River flows was applied to 

derive flow-duration data for Noyes Slough under both 

present and modified channel geometry for an average 

year (table 4). The model predicts that flow begins in 

Noyes Slough at a lower discharge in the Chena River 

than indicated by flow measurements. Therefore, and 

because of the varied effects of ground-water–surfacewater interaction, flows less than 11 ft3

/s for existing 

conditions and less than 15 ft3/s for a modified channel 

were assumed to be days of no flow.

Figure 19. Measured and modeled water-surface and bed profiles at flow of 117 cubic feet per second in 

Noyes Slough, for present-day conditions and after channel modification.

412

414

416

418

420

422

424

426

428

0 5,000 10,000 15,000 20,000 25,000 30,000

DISTANCE OF STATION FROM MOUTH, IN FEET

ELEVATION, IN FEET

Actual water-surface Modeled present-day water-surface profile

measurements

Q = 117 cubic feet per second

Existing 

bed profile

Modeled water-surface profile based on modified channel

Modified bed profile
26 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

RELATED OBSERVATIONS

In general, as the Chena River rises and Noyes 

Slough begins to flow, most of the flow is lost from 

the slough channel to the aquifer; for example, this 

occurred in August 2000 during the installation of a 

sewer lift station about 500 ft from the Minnie Street 

bridge. Because the bottom of the excavation was well 

below the water table, dewatering was required. Water 

was pumped from the project into the storm drain, 

which has an outfall immediately upstream from the 

Minnie Street bridge on the right bank. Because no 

water had flowed from the river into the slough for 

several weeks, the pumped water was the only surface 

inflow to the slough. According to J.L. Hulsey (Great 

Northwest, Inc., oral commun., 2000), the pump rate 

was 1,300 gal/min (or 2.7 ft3

/s). A discharge measurement of 2.0 ft3/s was made in the slough just downstream from the outfall, and a second one was made at 

the Illinois Street bridge showing zero flow. The entire 

discharge presumably recharged the aquifer within 

2,900 ft along the length of the Noyes Slough channel.

Regression equation

QN = 0.000004 QC + 0.0774 QC 66.634 2

0

200

400

600

800

1,000

1,200

1,400

1,600

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000

DISCHARGE IN CHENA RIVER (QC), IN CUBIC FEET PER SECOND

DISCHARGE IN NOYES SLOUGH (

QN), IN CUBIC FEET PER SECOND

Modeled Noyes Slough and Chena River flow

Regression

EXPLANATION

Figure 20. Regression relation between Noyes Slough and Chena River flows for modified channel 

conditions in Noyes Slough as modeled by HECRAS.
RELATED OBSERVATIONS 27

Figure 21. Hydrographs for period April 1–July 31, 2000. A, Chena River, from gagingstation records. B, Noyes Slough, computed from regression equations for existing and 

modified channel and also showing discharge measurements made in May and June.

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

A

Present condition

Modified condition

Actual measurements

B

DATE

0

100

200

300

400

500

600

700

800

900

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

April 1 April 21 May 11 May 31 June 20 July 10 July 30

NOYES SLOUGH

CHENA RIVER
28 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska Table 3. Mean daily discharge for Chena River at Fairbanks (station no. 15514000), April 1–September 30, 1981–99 Day of month Mean daily discharge (cubic feet per second) April May June July August September Maximum Mean Minimum Maximum Mean Minimum Maximum Mean Minimum Maximum Mean Minimum Maximum Mean Minimum Maximum Mean Minimum 1 390 277 180 6,000 2,262 400 9,770 2,774 1,030 7,180 2,484 633 3,920 1,782 780 6,630 2,450 1,030 2 395 278 180 7,300 2,380 460 9,680 2,720 996 5,610 2,286 623 3,540 1,762 756 7,760 2,572 1,020 3 410 281 185 8,400 2,528 500 9,860 2,760 943 4,580 2,143 604 3,240 1,729 748 7,460 2,598 1,010 4 410 284 185 8,340 2,667 540 10,300 2,686 893 4,140 1,969 591 3,050 1,687 722 7,170 2,506 989 5 410 286 190 9,470 2,698 580 9,800 2,536 836 3,990 1,846 578 2,950 1,645 718 8,020 2,429 981 6 410 288 190 10,600 2,745 640 9530 2,355 796 3,930 1,827 574 2,950 1,627 730 7,490 2,347 961 7 430 292 195 11,200 2,749 680 9,500 2,240 809 4,000 1,852 576 2,870 1633 768 6,500 2,320 942 8 430 295 190 11,400 2,794 720 9,240 2,232 803 4,440 1,767 574 2,710 1,660 798 7,980 2,353 930 9 440 298 195 11,300 2,854 730 9,010 2,159 766 4,450 1,746 577 2,710 1,705 911 8,440 2,392 913 10 450 304 200 10,500 2,929 750 8,850 2,045 726 4,690 1,735 609 2,700 1,774 1,030 7,190 2,349 899 11 490 311 200 10,100 2,946 790 8720 2,016 692 3,930 1690 625 2,900 1,860 1,050 5,990 2,247 897 12 495 316 200 9,570 2,944 890 6,370 1,904 668 3,350 1,681 613 3,640 1,895 1,040 5,460 2,159 890 13 500 323 200 9,260 2,954 1,050 4,900 1,839 653 4,900 1,794 612 3,220 1,809 1,020 5,090 2,105 930 14 540 332 200 9,100 2,962 987 3770 1,704 632 6,060 1,878 609 2,780 1,747 1,000 4,610 2,068 952 15 615 343 200 8,300 2,996 938 3,430 1,688 620 6130 1,916 613 2,570 1,754 1,040 4,230 2,031 1,000 16 579 350 200 660 3,044 917 3,190 1,680 600 5,240 1,953 625 3,620 1,854 1,080 4,040 2,022 1,130 17 633 366 210 6,350 3,094 940 3,600 1,795 594 4,150 1,940 628 3,560 1,878 1,120 5,080 2,040 1,130 18 700 384 210 6,750 3,036 1,000 7,470 2,091 635 3,840 1,863 626 4,330 1,949 1,150 5,400 2,040 1,120 19 890 416 220 8,030 2,971 1,030 5,670 2,034 709 4,260 1,880 670 4,830 2,083 1,130 4,810 1,986 1,090 20 1,100 461 220 7,740 2,819 1,050 3,990 1,970 767 4,500 1,846 757 6,700 2,249 1,130 4,300 1,925 1,060 21 1,300 520 230 6,000 2,693 1,020 6,010 2,239 746 4,910 1,922 758 7,420 2,288 1,150 5,150 1,954 1,030 22 2,120 611 240 6,750 2,661 978 8,300 2,658 725 6,970 2,028 742 5,870 2,350 1,200 5,610 1,943 1,020 23 2,800 730 250 7,020 2,787 976 9,040 2,496 718 6,790 2,155 726 5,920 2,402 1,230 5,300 1,902 1,010 24 3,350 850 260 7,650 2,862 1,020 9,340 2,306 704 8,270 2,247 755 8,140 2,513 1,210 4,800 1,857 935 25 3,690 993 270 7,900 2,782 972 7,720 2,305 711 6,820 2,167 901 8,320 2,555 1,180 4,180 1,819 920 26 3,760 1,153 280 9,590 2,923 965 6,980 2522 707 5,110 2,123 980 8280 2,569 1,150 4,350 1,809 920

27 3,500 1,328 300 10,600 3,140 1,120 8,960 2,848 710 6,180 2,135 1,020 6,980 2,476 1,130 4,690 1,793 88028 4,000 1,626 310 10,400 3,204 1,080 9,570 2,990 691 7,580 2,226 955 5,230 2,407 1,110 4,290 1,762 86029 5,220 1,869 330 10,500 3,020 1,060 9,340 3,060 666 6,910 2,174 899 4,450 2,293 1,090 3,990 1,733 84030 4,870 2,022 370 10,400 2,898 1,040 8,610 2,842 651 5,310 1,974 852 4,030 2,207 1,070 3,880 1,702 86531 10,200 2,832 1,020 4,440 1,842 814 5,170 2,280 1,050
RELATED OBSERVATIONS 29

0

5

10

15

20

25

30

35

40

0

50

100

150

200

250

0

200

400

600

800

1,000

1,200

1,400

1,600

MEAN DAILY DISCHARGE IN NOYES SLOUGH AT MINNIE STREET, IN CUBIC FEET PER SECOND

A

B

C

Existing conditions

Modified conditions

Maximum for 1981 99

Mean for 1981 99

Minimum for 1981 99

DATE

EXPLANATION

April 1 May 1 June 1 July 1 August 1 September 1 October 1

Figure 22. Estimated hydrographs for Noyes Slough for existing and modified channel 

conditions at maximum (A), mean (B), and minimum (C) mean daily flows in Chena 

River for period April 1–October 31, 1981–99.
30 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

In years when the slough receives little flow, trash 

and brush may accumulate and entrance conditions 

change. Conversely, as in the spring of 2000, when 

the slough receives significant flow, the obstructions 

are washed out and flow conditions in the channel 

improve. As flow in the Chena River recedes, the 

slough entrance again becomes an area of deposition, 

affecting the threshold at which flow begins to enter the 

slough; subsequently the entrance is scoured out again 

during another rise. This alternating pattern and the 

ground-water inflow and outflow likely account for the 

variation in the discharge measurements at lower flows 

(fig. 8).

The trend of the lowering of the bed of the Chena 

River at the entrance of Noyes Slough may or may not 

continue but seems likely. During 1999–2000, the 

lower Chena River was dredged near its mouth on the 

Tanana River; as a result, the upstream channel may 

adjust its bed to the change in slope along the reach. 

Also unknown are the present-day sediment load of the 

Chena River and the sedimentation rate in the Noyes 

Slough.

 The sediment-transport rate computed from the 

one bed-load sample collected on the Chena River, at 

a flow of 6,380 ft3

/s, was 50 tons/d, and a point sample 

collected midchannel in Noyes Slough yielded a rate of 

less than 1 ton/d. Although no other bed-load data are 

available for the Chena River at Fairbanks, Burrows 

and others (1981) reported that bed-load-transport rates 

on the Tanana River ranged from 300 to 9,000 tons/d. 

Suspended-sediment-transport rates for the Chena 

River, computed from samples collected during 

1953–75, range from less than 100 to 29,500 tons/d.

Table 4. Flow duration for Chena River at Fairbanks, April 1–September 30, 1981–99, and for Noyes 

Slough (computed for present-day and modified channel geometry)

[<, less than or equal to; —, none]

Chena River flow Noyes Slough flow

Discharge

(cubic feet

per second)

Average 

number of 

days for period

Present-day channel geometry Modified channel geometry

Equivalent 

discharge

(cubic feet

per second)

Average 

number of

days for period

Equivalent 

discharge

(cubic feet

per second)

Average 

number of

 days for period

<499 24 — — — —

500–999 32 — — 0 56

1,000–1,499 52 0 108 15–57 52

1,500–1,999 40 11–29 40 58–103 40

2,000–2,499 22 30–51 22 104–150 22

2,500–2,999 13 52–77 13 151–201 13

3,000–3,499 8 78–105 8 202–252 8

3,500–3,999 6 106–136 6 253–306 6

4,000–4,499 4 137–170 4 307–362 4

4500–4,999 3 171–207 3 363–419 3

5,000–5,499 2 208–247 2 420–479 2

5500–5,999 2 248–290 2 480–541 2

6,000–6,999 2 291–386 2 542–670 2

7,000–7,999 1 387–493 1 671–808 1

8,000–8,999 1 494–612 1 809–953 1

9,000–9,999 1 613–744 1 954–1,106 1

10,000–10,999 1 745–887 1 1,107–1,268 1

Days of greater than zero discharge

Total, all periods.......................... 214 106 158

As percentage of total.................. 100 49.5 73.8
SUMMARY AND CONCLUSIONS 31

SUMMARY AND CONCLUSIONS

Prior to 1945, both the Chena River and the 

Tanana River contributed water to Chena Slough, 

which is now the lower Chena River through Fairbanks. Chena Slough, in turn, contributed to Noyes 

Slough at times of high flow. In 1947, two years after 

the completion of the Moose Creek Dike, Tanana River 

water no longer flowed through Fairbanks, and flow in 

Noyes Slough was from high flow only of the Chena 

River. Peak flows in the Chena River were reduced 

further in 1980 after the completion of the Chena River 

Lakes Flood Control Project, which was designed to 

limit Chena River flow through Fairbanks to 12,000 

ft3

/s. The impact on Noyes Slough from these flow 

reductions has been increased by downcutting (or lowering) of the channel of the Chena River at the entrance 

to Noyes Slough. This downcutting means that the 

Chena River must be at a higher stage and greater flow 

for water to enter Noyes Slough today than in the past. 

Levels in the Tanana and Chena Rivers affect groundwater levels in the Fairbanks alluvial plain. Without 

any apparent surface flow in Noyes Slough, water in 

isolated ponds along the slough is assumed to represent 

local ground-water levels. During rising flow of the 

Chena River, Noyes Slough loses flow along the channel by recharge to the ground-water system.

The regression of flow in Noyes Slough based 

on recent discharge measurements indicates that the 

slough presently receives flow from the Chena River 

when the Chena reaches about 2,400 ft3/s at a stage of 

about 2.72 ft (elevation 425.64 ft above sea level). The 

regression based on the HECRAS model predicts that 

flow in the slough begins at about 1,200 ft3

/s at a stage 

of 1.08 ft (elevation 423.30 ft above sea level). This 

discrepancy resulted because the HECRAS model was 

calibrated to fit the wide range of flows measured in 

Noyes Slough for a given flow in the Chena River. 

Based on flow-duration analysis, the slough would be 

flowing about 106 days during the open-water season. 

Figure 23. Estimated hydrographs for Noyes Slough for period April 1–September 30, 1999, for existing 

and modified channel conditions.

0

50

100

150

200

250

300

Existing channel (72 days of flow greater than 0)

Modified channel (131 days of flow greater than 0)

DATE

DISCHARGE IN NOYES SLOUGH, IN CUBIC FEET PER SECOND

April 1 May 1 June 1 July 1 August 1 September 1

EXPLANATION
32 Preliminary Hydraulic Analysis and Implications for Restoration of Noyes Slough, Fairbanks, Alaska

The modeled flows indicated that at the maximum regulated flow of 12,000 ft3

/s in the Chena River, flow in 

Noyes Slough would be 1,050 ft3/s.

One possible way to increase flow in Noyes 

Slough is to increase the capacity of the slough channel. The HECRAS model was used to analyze this 

option by altering the existing cross-section geometry 

in the model to reflect a modified, trapezoidal channel 

40 ft wide at the bottom and about 2 ft deeper than 

present mean bed elevation at the entrance to the 

slough. This altered geometry was propagated downstream through all sections at a channel slope of 0.0003 

ft/ft.

The model results indicate that after modifying 

the channel, Noyes Slough would begin to receive 

water from the Chena River at a flow of 830 ft3

/s and 

at a stage of 0.48 ft (elevation 423.4 ft above sea level) 

and could receive water at a maximum rate of 1,440 

ft3/s, based on the regulated maximum flow for the 

Chena River, 12,000 ft3

/s. On average, under these 

modified-channel conditions, Noyes Slough would 

flow 158 days during the open-water season.

Increasing channel capacity is only one possible 

engineering option for increasing flow in Noyes 

Slough. The resulting model runs did not account for 

real-world problems or issues associated with sloughchannel excavation such as required allowances for 

utility crossings, probable destruction of beaver dams, 

and potential damage to bridge foundations. Increasing 

flow may yield indirect benefits such as increasing 

recreational opportunities and helping to maintain the 

channel by moving sediment through the reach. Significantly modifying the channel could diversify wildlife habitat in the slough but also is likely to destroy 

or damage some existing habitats. Such vulnerable 

features, which are difficult to reproduce, include 

the beaver dams, pools, and overhanging vegetation. 

Insufficient data are available to estimate rates of sediment deposition in Noyes Slough, which would affect 

further channel evolution.

Because flow has been declining in Noyes Slough 

for at least five decades, present-day conditions likely 

will not change significantly without some intervention. If the trend continues, the slough could have some 

years of almost no flow.

REFERENCES CITED 

Brunner, G.W., 1997, HEC-RAS, River analysis system 

user’s manual—Version 2.0: U.S. Army Corps of Engineers Hydrologic Engineering Center, 243 p.

Burrows, R.L., Emmett, W.W., and Parks, Bruce, 1981, 

Sediment transport in the Tanana River in the vicinity 

of Fairbanks, Alaska, 1977–79: U.S. Geological Survey 

Water-Resources Investigations Report 81–20, 56 p.

Burrows, R.L., and Harrold, P.E., 1983, Sediment transport 

in the Tanana River near Fairbanks, Alaska, 1980–81: 

U.S. Geological Survey Water-Resources Investigations Report 83–4064, 116 p.

Glass, R.L., Lilly, M.R., and Meyer, D.F., 1996, Groundwater levels in an alluvial plain between the Tanana and 

Chena Rivers near Fairbanks, Alaska, 1986–93: U.S. 

Geological Survey Water-Resources Investigations 

Report 96–4060, 39 p., 1 app.

Heinrichs, T.A., Kennedy, B.W., Langley, D.E., and Burrows, R.L., in press, Methodology and estimates of 

scour at selected bridge sites in Alaska, U.S. Geological 

Survey Water-Resources Investigations Report.

Nelson, G.L., 1978, Hydrologic information for land-use 

planning, Fairbanks, Alaska: U.S. Geological Survey 

Open-File Report 78–959, 47 p.

State of Alaska, 1999, Catalog of waters important for the 

spawning, rearing, or migration of anadromous fishes: 

Department of Fish and Game Habitat Division, Alaska 

Administrative Code, Regulation 5AAC95.010, [variously paged].

Unwin, Scheben, Korynta, and Huettl, Inc., 1982, Feasibility 

study—Noyes Slough canoe trail, 1982: Fairbanks 

North Star Borough, 49 p.

U.S. Army Corps of Engineers, 1938, Preliminary examination of the Tanana River and Chena Slough: Letter 

Report, U.S. Army Corps of Engineers, Office of the 

Chief Engineer, 20 p., 6 pls.

———1997, Chena River watershed study: Reconnaissance 

Report, U.S. Army Corps of Engineers, 247 p., 4 apps.

U.S. Geological Survey, 1940, The Alaska Railroad—Yanert 

Fork to Fairbanks: U.S. Geological Survey, Alaska Map 

27, scale 1:250,000.

Williams, G.P., and Wolman, M.G., 1984, Downstream 

effects of dams on alluvial rivers: U.S. Geological Survey Professional Paper 1286, 83 p.