Preliminary Assessment of Channel Stability and 

Bed-Material Transport in the Coquille River Basin, 

Southwestern Oregon

By Krista L. Jones, Jim E. O’Connor, Mackenzie K. Keith, Joseph F. Mangano, and J. Rose Wallick

Prepared in cooperation with the U.S. Army Corps of Engineers and

the Oregon Department of State Lands

Open-File Report 2012–1064

U.S. Department of the Interior

U.S. Geological Survey
Cover: South Fork Coquille River in the Broadbent Reach (Photograph by Krista L. Jones, U.S. Geological Survey, 

July 2010.) 
Preliminary Assessment of Channel Stability and 

Bed-Material Transport in the Coquille River Basin, 

Southwestern Oregon

By Krista L. Jones, Jim E. O’Connor, Mackenzie K. Keith, Joseph F. Mangano, and J. Rose Wallick

Prepared in cooperation with the U.S. Army Corps of Engineers and the 

Oregon Department of State Lands

Open-File Report 2012–1064

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia 2012

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Suggested citation:

Jones, K.L., O’Connor, J.E., Keith, M.K., Mangano, J.F., and Wallick, J.R., 2012, Preliminary assessment of channel 

stability and bed-material transport in the Coquille River basin, southwestern Oregon: U.S. Geological Survey OpenFile Report 2012–1064, 84 p. 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

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copyright owners to reproduce any copyrighted material contained within this report.
iii

Contents

Figures...........................................................................................................................................................................iv

Tables............................................................................................................................................................................ vi

Conversion Factors.......................................................................................................................................................vii

Datums .........................................................................................................................................................................vii

Significant Findings........................................................................................................................................................ 1

Introduction.................................................................................................................................................................... 3

Locations and Reporting Units....................................................................................................................................... 5

The Coquille River ......................................................................................................................................................... 5

Geographic, Geologic, and Geomorphic Setting ........................................................................................................ 5

Hydrology................................................................................................................................................................... 6

Historical Channel Descriptions ............................................................................................................................... 11

Occupation, Land Use, and Landscape Disturbance ............................................................................................... 13

Settlement and Ownership ................................................................................................................................... 13

Logging and Splash Damming.............................................................................................................................. 13

Dredging and Wood Removal for Navigation........................................................................................................ 15

Instream Gravel Mining ........................................................................................................................................ 17

Mining................................................................................................................................................................... 17

Fire ....................................................................................................................................................................... 17

Mass Movements ................................................................................................................................................. 18

Study Area ............................................................................................................................................................... 18

Powers Reach ...................................................................................................................................................... 21

Broadbent Reach.................................................................................................................................................. 21

Myrtle Point Reach ............................................................................................................................................... 24

Bandon Reach...................................................................................................................................................... 24

Bridge Reach........................................................................................................................................................ 24

Gravelford Reach ................................................................................................................................................. 28

Approach and Key Findings......................................................................................................................................... 28

Review of Existing Datasets..................................................................................................................................... 28

Aerial and Orthophotographs................................................................................................................................ 28

Historical Maps and Survey Data ......................................................................................................................... 30

Previous Hydrologic and Geomorphic Studies ......................................................................................................... 34

Gravel-Operator Information and Surveys................................................................................................................ 35

Bridge-Inspection Reports........................................................................................................................................ 43

Specific Gage Analysis............................................................................................................................................. 52

Delineation of Bars and Channel Features, 1939–2009........................................................................................... 53

Distribution and Area of Bars, 2009...................................................................................................................... 56

Results for Repeat Channel Centerline and Width Delineations, 1939–2009....................................................... 58
iv

Discussion of Changes in Bar and Channel Features, 1939–2009 ...................................................................... 61

Analyses of Bed-Material Particle Sizes................................................................................................................... 71

Discussion and Synthesis ............................................................................................................................................ 73

Spatial Variation in Channel Conditions ................................................................................................................... 73

Temporal Trends in Channel and Bar Conditions .................................................................................................... 75

General Bed-material Transport Conditions............................................................................................................. 75

Outstanding Issues and Possible Approaches............................................................................................................. 76

Streamflow Data....................................................................................................................................................... 77

Bed-Material Transport Rates and Sediment Budget............................................................................................... 77

Detailed Channel Morphology Assessment.............................................................................................................. 78

Legacy and Ongoing Effects of Land Use Activities................................................................................................. 79

Priority Reaches for Future Analysis ........................................................................................................................ 79

Acknowledgments........................................................................................................................................................ 80

References Cited ......................................................................................................................................................... 80

Figures 

Figure 1. Map displaying the stream network, basin and county boundaries, geologic provinces, study reaches, linear 

reference systems, and streamflow gage used in this study of the Coquille River basin, southwestern 

Oregon........................................................................................................................................................................ 4

Figure 2. Graph showing the longitudinal profile of the Coquille River basin, southwestern Oregon, as determined 

from the U.S. Geological Survey 10-m Digital Elevation Model . ................................................................................ 7

Figure 3. Graphs showing longitudinal profiles and floodplain widths for the Powers, Broadbent, Myrtle Point, and 

Bandon Reaches on the mainstem and South Fork Coquille River, Bridge Reach on the Middle Fork Coquille River, 

and Gravelford Reach on the North Fork Coquille River, southwestern Oregon......................................................... 8

Figure 4. Graphs showing mean daily discharge and annual peak discharge for the U.S. Geological Survey 

streamflow-gaging station at Powers (14325000) on the South Fork Coquille River, southwestern Oregon. ...........10

Figure 5. Historical photographs showing: a 200-m-long jam of about 5,400 logs near Prosper, Oregon in 1907, and 

splash damming on Middle Creek, a tributary to the North Fork Coquille River, in 1912.. ........................................14

Figure 6. Graph showing reported annual and cumulative volumes of sediment removed from 1986 to 2010 near the 

mouth of the Coquille River, southwestern Oregon...................................................................................................15

Figure 7. Historical photograph from a Coos Bay Times (1928) article showing the McGeorge Gravel Company’s 

mining site on the South Fork Coquille River near Gaylord, Oregon.........................................................................17

Figure 8. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs 

and field reconnaissance photographs for the Powers Reach on the South Fork Coquille River, southwestern 

Oregon......................................................................................................................................................................22

Figure 9. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs and 

field reconnaissance photographs for the Broadbent Reach on the South Fork Coquille River, southwestern 

Oregon......................................................................................................................................................................23

Figure 10. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs 

and a field reconnaissance photograph for the Myrtle Point Reach on the South Fork Coquille River, southwestern 

Oregon......................................................................................................................................................................25
v 

Figure 11. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs 

and a field reconnaissance photograph for the Bandon Reach on the mainstem Coquille River, southwestern 

Oregon......................................................................................................................................................................26

Figure 12. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs 

and field reconnaissance photographs for the Bridge Reach on the Middle Fork Coquille River, southwestern 

Oregon......................................................................................................................................................................27

Figure 13. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs 

and a field reconnaissance photograph for the Gravelford Reach on the North Fork Coquille River, southwestern 

Oregon......................................................................................................................................................................29

Figure 14. Graphs showing reported estimates of deposited and mined gravel from 1996 to 2009 for instream mining 

sites along the South Fork Coquille River, southwestern Oregon.............................................................................41

Figure 15. Diagrams showing channel cross sections surveyed at RKM 108.3 and 106.1 in the Powers Reach on 

the South Fork Coquille River, southwestern Oregon...............................................................................................46

Figure 16. Diagrams showing channel cross sections surveyed at RKM 89.4 and 74.1 in the Broadbent Reach on the 

South Fork Coquille River, southwestern Oregon.....................................................................................................47

Figure 17. Diagrams showing channel cross sections surveyed at RKM 60.3 in the Myrtle Point Reach of the South 

Fork Coquille River and RKM 38.9 in the Bandon Reach on the Coquille River, southwestern Oregon.. .................48

Figure 18. Diagrams showing channel cross sections surveyed at RKM 13.8, 12.5, 10.0, 5.2, 4.9, 2.4, and 0.5 in the 

Bridge Reach on the Middle Fork Coquille River, southwestern Oregon ..................................................................49

Figure 19. Diagrams showing channel cross sections surveyed at RKM 6.6 and 0.4 in the Gravelford Reach on the 

North Fork Coquille River, southwestern Oregon......................................................................................................51

Figure 20. Graph showing the stage-discharge rating curve for specific discharges for the U.S. Geological Survey 

streamflow-gaging station at Powers (14325000) on the South Fork Coquille River, southwestern Oregon. ...........53

Figure 21. Graphs showing bar area by river kilometer as delineated from orthophotographs taken in 2009 for study 

reaches on the South Fork and mainstem Coquille River, Middle Fork Coquille River, and North Fork Coquille River, 

southwestern Oregon. The upstream extent of the Powers Reach is RKM 115.4. ...................................................59

Figure 22. Graphs showing the results for total bar area, bar number, channel centerline length, and average wetted 

channel width as delineated from photographs taken in 1939, 1967, 2005, and 2009 for the study areas on the 

mainstem and North and Middle Forks of the Coquille River and South Fork Coquille River to RKM 108.1.............60

Figure 23. Images showing repeat bar and channel delineations, lateral channel shifting, and vegetation 

establishment on bars in a section of the Powers Reach on the South Fork Coquille River, southwestern 

Oregon......................................................................................................................................................................62

Figure 24. Images showing repeat bar and channel delineations, lateral channel movement, bank erosion, and other 

channel changes in the Broadbent Reach on the South Fork Coquille River near Warner, Oregon. ........................63

Figure 25. Images showing repeat bar and channel delineations, lateral channel movement, bank erosion, and other 

channel changes in the Broadbent Reach on the South Fork Coquille River near Broadbent, Oregon. ...................64

Figure 26. Images showing repeat bar and channel delineations for Hayes, Elliot/Seals, and Lokan Bars in the 

Broadbent Reach on the South Fork Coquille River, southwestern Oregon. ............................................................65

Figure 27. Images showing repeat bar and channel delineations, vegetation establishment, and lateral channel 

movement in the Bridge Reach on the Middle Fork Coquille River, southwestern Oregon.......................................67

Figure 28. Images showing repeat bar and channel delineations and vegetation establishment in the Gravelford 

Reach on the North Fork Coquille River, southwestern Oregon. ..............................................................................68
vi

Figure 29. Images showing repeat bar and channel delineations and lateral channel movement in the Myrtle Point 

Reach on the South Fork Coquille River, southwestern Oregon...............................................................................69

Figure 30. Images showing repeat bar and channel delineation in Bandon Reach near the mouth of the Coquille 

River, southwestern Oregon. ....................................................................................................................................70

Figure 31. Images showing repeat bar and channel delineations and lateral channel movement in a section of the 

Bandon Reach on the Coquille River, southwestern Oregon....................................................................................72

Figure 32. Graph showing size distributions of surface and subsurface particles and photographs of measurement 

transects for two bed-material sampling sites along the South Fork Coquille River, southwestern Oregon.. ............74

Tables

Table 1. Summary of U.S. Geological Survey (USGS) streamflow-gaging station information for the Coquille River 

basin, southwestern Oregon. ...................................................................................................................................... 9

Table 2. Summary of characteristics for study reaches on the South Fork and mainstem of the Coquille River, 

southwestern Oregon................................................................................................................................................19

Table 3. Summary of characteristics for study reaches on the Middle and North Forks of the Coquille River, 

southwestern Oregon................................................................................................................................................20

Table 4. Available aerial photographs by reach for the Coquille River study area, southwestern Oregon. Aerial 

photographs shown in bold were used to delineate bar and channel features for this study.....................................31

Table 5. Datasets reviewed for this study in the Coquille River basin, southwestern Oregon ..................................33

Table 6. Compilation of reported gravel volumes (in cubic meters) mined from 1974 to 1978 in the Coquille River 

basin, southwestern Oregon. ....................................................................................................................................36

Table 7. Compilation of reported gravel volumes deposited and mined from 1996 to 2009 at instream mining sites in 

the Broadbent Reach of the South Fork Coquille River, southwestern Oregon ........................................................38

Table 7. Compilation of reported gravel volumes deposited and mined from 1996 to 2009 at instream mining sites in 

the Broadbent Reach of the South Fork Coquille River, southwestern Oregon. .......................................................39

Table 8. Reported volumes of deposited and mined gravel from 1996 to 2009 for instream mining sites in the 

Broadbent Reach of the South Fork Coquille River, southwestern Oregon. .............................................................40

Table 9. Summary of net changes measured from channel cross sections surveyed by the Oregon Department of 

Transportation (ODOT) in the Coquille River study area, southwestern Oregon ......................................................44

Table 10. Stream discharge for the aerial and orthophotographs used for repeat bar and channel feature delineation 

in the Coquille River study area, southwestern Oregon............................................................................................55

Table 11. Repeat bar attribute data as delineated from photographs taken in 1939, 1967, 2005, and 2009 for the 

Coquille River study area, southwestern Oregon......................................................................................................57

Table 12. Repeat unit bar area data as delineated from photographs taken in 1939, 1967, 2005, and 2009 for the 

Coquille River study area, southwestern Oregon......................................................................................................58

Table 13. Repeat channel feature data as delineated from photographs taken in 1939, 1967, 2005, and 2009 for the 

Coquille River study area, southwestern Oregon......................................................................................................61

Table 14. Bed-material data collected in the Coquille River study area, southwestern Oregon................................73
vii

Conversion Factors

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Area

square meter (m2) 10.76 square foot (ft2) 

square kilometer (km2) 0.3861 square mile (mi2)

Volume

cubic meter (m3) 0.0008107 acre-foot (acre-ft) 

cubic meter (m3) 35.31 cubic foot (ft3)

cubic meter (m3) 1.308 cubic yard (yd3) 

Flow rate

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

cubic meter per year (m3/yr) 1.308 cubic yard per year (yd3/yr)

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

Mass

kilogram (kg) 2.205 pound avoirdupois (lb)

Datums

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).

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

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

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1 

Preliminary Assessment of Channel Stability and 

Bed-Material Transport in the Coquille River Basin, 

Southwestern Oregon

By Krista L. Jones, Jim E. O’Connor, Mackenzie K. Keith, Joseph F. Mangano, and J. Rose Wallick

Significant Findings

This report summarizes a preliminary study 

of bed-material transport, vertical and lateral 

channel changes, and existing datasets for the 

Coquille River basin, which encompasses 2,745 

km2 (square kilometers) of the southwestern Oregon coast. This study, conducted to inform 

permitting decisions regarding instream gravel 

mining, revealed that:

• The 115.4-km-long study area on the South 

Fork and mainstem Coquille River can be divided into four reaches on the basis of 

topography and hydrology. In the fluvial 

(nontidal, or dominated by riverine processes) 

reaches on the South Fork Coquille River, the 

channel consists of bedrock and alluvium in 

the Powers Reach and mostly alluvium in the 

Broadbent Reach. In both fluvial reaches, the 

channel alternates between confined and unconfined segments and contains gravel bars. 

In the tidally affected Myrtle Point and Bandon Reaches, the channel consists of alluvial 

deposits and contains sparse gravel and sand 

bars as well as expansive mud flats and tidal 

marshes near the Coquille River mouth. 

• The 15.4- and 14.6-km-long study areas on 

the Middle and North Forks of the Coquille 

River, respectively, were treated as distinct 

reaches. The channel beds consist of mixed 

bedrock and alluvium in the Bridge Reach on 

the Middle Fork Coquille River and alluvium 

in the Gravelford Reach on the North Fork 

Coquille River. Both of these reaches contain 

fewer bars than the Powers and Broadbent 

Reaches on the South Fork Coquille River 

and are predominately fluvial.

• Channel condition, bed-material transport, 

and the distribution and area of bars have 

likely been influenced by logging and splash 

damming, dredging and wood removal for 

navigation, historical and ongoing instream 

gravel mining, gold mining, fires, and mass 

movements. These anthropogenic and natural 

disturbances likely have varying effects on 

channel condition and sediment flux throughout the study area and over time. 

• Available data include at least eight sets of 

aerial and orthophotographs that were taken 

of the study area from 1939 to 2011 that are 

available for assessing long-term changes in 

channel condition, bar area, and vegetation 

establishment patterns. Additionally, a highresolution Light Detection And Ranging (LiDAR) survey conducted in 2008 for nearly 

the entire study area would be useful in future 

quantitative analyses of channel morphology 

and bed-material transport.

• Previous studies found (1) substantial bank 

erosion in the Broadbent Reach, resulting in 

banks with near vertical profiles and heights 

exceeding 7.6 m, (2) erosion of over 40,000 

square meters of riparian land from 1939 to 

1992, (3) incision along the South Fork Coquille River, and (4) potential for lateral 

channel migration at several locations along 

the mainstem and South Fork Coquille River. 

• A review of deposited and mined bedmaterial estimates derived largely from repeat 

surveys at instream mining sites on the South 
2 

Fork Coquille River indicates that bed material transported by the river tends to rebuild 

mined bar surfaces in most years. Reported 

annual deposition volumes for 1996–2009 indicate average transport of over 34,700 cubic 

meters per year (m3/yr) of bed material into 

the South Fork Coquille River study area.

• The spatial variation in the number and area 

of gravel bars is controlled by factors such as 

valley confinement, channel slope, basin geology, and tidal extent. The Powers and 

Broadbent Reaches of the South Fork Coquille River have the greatest abundance of 

gravel bars, likely owing to a substantial area 

of the South Fork Coquille River basin draining the gravel-producing Klamath Mountains 

geologic province. 

• From 1939 to 2009, the fluvial reaches all had

a net loss in bar area, ranging from 24 percent 

in the Powers Reach to 56 percent in the 

Bridge Reach. In the Powers and Broadbent 

Reaches, the declines in active bar area were

associated primarily with vegetation establishment on bar surfaces and lateral bar 

erosion. The reductions in active bar area 

were attributed to vegetation establishment in 

the Bridge and Gravelford Reaches as well as 

some lateral bar erosion in the Bridge Reach. 

• In contrast, the tidal Myrtle Point and Bandon 

Reaches had a net increase in bar area (28 and 

29 percent, respectively) from 1939 to 2009. 

In the Myrtle Point Reach, these increases in 

bar area were primarily attributed to lateral 

channel migration that led to the deposition of 

bed material at newly formed bars. In the 

Bandon Reach, bar area increased primarily in 

the lower 5.4 km of the reach owing possibly 

to factors such as tide differences between the 

photographs and sediment deposition. 

• Analyses of multiple channel cross sections 

along the South Fork Coquille River as well 

as historical stage-discharge data collected by 

the U.S. Geological Survey (USGS) at Powers, Oregon, indicate that the bed of the South 

Fork Coquille River has locally lowered, as 

much as 1.9 m from 1994 to 2008 for one site 

in the Broadbent Reach. Stage-discharge data 

indicate persistent incision at the Powers site 

since 1939 (with a net incision of about 0.3 

m) that has been interrupted by episodic aggradation apparently corresponding with large 

floods. 

• For the Bridge and Gravelford Reaches on the 

Middle and North Forks of the Coquille River, channel cross sections indicate a mix of 

aggradation and incision as well as bank erosion and deposition from 1992 to 2010 and 

2000 to 2009, respectively. 

• Cross sections in the tidal reaches indicate 

local incision of 0.4 m in at one site in the 

Myrtle Point Reach from 2004 to 2008 and 

0.5 m at one site in in the Bandon Reach from 

2000 to 2010. 

• On the South Fork Coquille River, the median 

diameter of surface particles varied from 78.0 

mm (millimeters) at China Flat Bar slightly 

upstream of the study area to 48.8 mm at 

Seals Bar in the Broadbent Reach. The armoring ratio (or ratio of the median grain sizes of 

the surface and subsurface layers) for Seals

Bar was 3.5, indicating that the river’s transport capacity likely exceeds sediment supply 

at this site. 

• Most fluvial reaches in the Coquille River 

study area are likely supply-limited, meaning 

that the river’s transport capacity exceeds the 

supply of bed-material, as indicated by the intermittent bedrock outcrops in the Powers and 

Bridge Reaches and the paucity of bars in the 

Bridge and Gravelford Reaches. 

• The Broadbent Reach of the South Fork Coquille River may be presently and probably 

was historically transport-limited, meaning 

that bed-material transport is primarily a function of local transport capacity. However, the 

locally coarse bed texture, high armoring ratio 

measured at Seals Bar, and recent channel 

incision indicate that sediment supply has 
3 

likely diminished relative to transport capacity in recent decades.

• Because of exceedingly low gradients, the 

tidal Myrtle Point and Bandon Reaches are 

transport limited. Bed material in these reaches is primarily sand and finer grain-size 

material, much of which is probably transported as suspended load from upstream 

reaches. The tidal reaches will be most susceptible to watershed conditions affecting the 

supply and transport of fine sediment. 

• Compared to the nearby Chetco and Rogue 

Rivers and Hunter Creek on the southwestern 

Oregon coast, the Coquille River likely has 

lower overall transport of gravel bed material. 

While the conclusion of lower bed-material 

transport in the Coquille River is tentative in 

the absence of actual transport measurements 

or transport capacity calculations, empirical 

evidence including the much lower area and 

frequency of bars for most of the Coquille 

River study area and the head of tide reaching 

to RKM (river kilometer) 63.2 on the South 

Fork Coquille River supports this conclusion. 

• More detailed investigations of bed-material 

transport rates and channel morphology 

would support assessments of lateral and vertical channel condition and longitudinal trends 

in bed material. Such assessments would be 

most practical for the Powers and Broadbent 

Reaches and relevant to several ongoing management and ecological issues pertaining to 

sand and gravel transport. The tidal Bandon 

and Myrtle Point Reaches may also be logical 

subjects for in-depth analyses of fine sediment deposition and transport (and associated 

channel and riparian conditions and 

processes) rather than coarse bed material.

Introduction

This report summarizes a reconnaissancelevel study of channel condition and bed-material

transport relevant to the permitting of instream 

gravel mining in the Coquille River basin (fig. 1). 

This assessment is based on a review of existing 

datasets (such as channel cross sections and instream gravel mining records), delineation of bar 

and channel features over time from aerial and 

orthophotographs, and field observations and 

bed-material measurements made in July 2010. 

Findings from these datasets and observations in 

the Coquille River basin were used to (1) identify 

key datasets and issues that are relevant to understanding channel condition, bed-material 

transport, and potential effects of instream gravel 

mining, and (2) assess the vertical and lateral stability of river segments and identify locations 

where channels may be incising, aggrading, prone 

to migration, or stable. This reconnaissance-level

study constitutes a “Phase I” assessment similar 

to those completed in the Umpqua River (O'Connor and others, 2009), Hunter Creek (Jones and 

others, 2011), and Rogue River (Jones and others, 

2012) basins, in cooperation with the U.S. Army 

Corps of Engineers (hereafter Corps of Engineers) and the Oregon Department of State Lands 

to inform the permitting of instream gravel mining in Oregon. 
4 

Figure 1. Map displaying the stream network, basin and county boundaries, geologic provinces, study reaches, 

linear reference systems, and streamflow gage used in this study of the Coquille River basin, southwestern Oregon. 
5 

Locations and Reporting Units

Locations along the Coquille River and its 

forks (the North, Middle, and South Forks of the 

Coquille River) within the study area are referenced to river kilometers (RKM). To develop 

this reference system, centerlines were digitized 

for the wetted channels of the Coquille River and 

its forks using orthoimagery taken in 2009 by the 

U.S. Department of Agriculture’s (USDA) National Agriculture Imagery Program (NAIP). 

Points were distributed at 0.2-km intervals along 

these centerlines, starting at the downstream end 

of the jetties at the Coquille River mouth and continuing upstream along the South Fork Coquille 

River and then starting at the mouths of the Middle and North Forks of the Coquille River (fig. 1). 

Even after accounting for the conversion between 

river miles (RM) shown on current (1987, 1988, 

1990, and 1991) USGS quadrangle maps and river kilometers developed by this study, these two 

reference systems differ slightly (fig. 1) owing to

factors such as channel shifting and starting 

points of the linear reference systems.

Prominent landmarks and locations within 

the study area (from up- to downstream) include 

the confluences of the South and Middle Forks of 

the Coquille River (RKM 66.2), South and North 

Forks of the Coquille River (RKM 58.5), and 

North and East Forks of the Coquille River 

(North Fork Coquille River, RKM 14.8). The 

head of tide extends up the South Fork Coquille 

River to approximately RKM 63.2 and up the 

North Fork Coquille River to approximately 

RKM 0.9. Towns within the study area include 

Powers (South Fork Coquille River, RKM 106.3), 

Gaylord (South Fork Coquille River, RKM 89.4), 

Broadbent (South Fork Coquille River, RKM 

75.2), Bridge (Middle Fork Coquille River, RKM 

13.6), Gravelford (North Fork Coquille River, 

RKM 14.8), Myrtle Point (South Fork Coquille 

River, RKM 60.4), Coquille (mainstem, RKM 

39.6), and Bandon (mainstem, RKM 1.4). 

Names for the study reaches were assigned 

based on names of nearby towns or cities. Names 

for bed-material sampling sites were derived from 

USGS topographic maps or gravel-mining permits.

In this publication, we present all data collected and analyzed by this study as well as most 

data reported by other sources in metric, or SI, 

units. The conversions to English units are provided in the report front matter. 

The Coquille River

The Coquille River system is an unregulated 

system that encompasses 2,745 km2

 of southwestern Oregon and flows into the Pacific Ocean near 

the town of Bandon (fig. 1). Over 1,963 kilometers of mapped channels make up the Coquille 

River network (StreamStats, 

http://water.usgs.gov/osw/streamstats). The Coquille River has four major forks, the South, 

Middle, East, and North Forks (fig. 1). Beginning 

in the Rogue River-Siskiyou National Forest, the 

South Fork Coquille River gains the Middle Fork 

Coquille River (drainage area 798 km2

) and shortly thereafter the North Fork Coquille River (749 

km2) (fig. 1). The East Fork Coquille River (347 

km2) joins the North Fork Coquille River near the 

town of Gravelford. Downstream of the confluence of the South and North Forks of the Coquille 

River, the mainstem Coquille River meanders 

westward to the coast. The Coquille River basin 

is located within Coos, Douglas, and Curry Counties in Oregon. The basin is flanked to the north 

by the Coos River basin, to the east by the South 

Umpqua River basin, to the south by the Rogue 

River basin, and to the southwest by the several 

smaller coastal basins, including Floras Creek and 

the Sixes and Elk Rivers. 

Geographic, Geologic, and Geomorphic Setting

The South Fork Coquille River begins near 

Table Rock Mountain and flows southwestward 

for 26 km until reaching Bald Knob, where it 

turns northward for 22 km, gaining Rock (35 

km2), Johnson (42 km2), Elk (13 km2), Coal (40 

km2), and Upper Land Creeks (10 km2; fig. 1). 

The study area on the South Fork Coquille River 
6 

begins at RKM 115.4, slightly downstream of its 

confluence with Upper Land Creek. From here, 

the South Fork Coquille River continues generally northwestward for 49 km, gaining Salmon (58 

km2, RKM 107.4), Rowland (25 km2, RKM 

96.9), and Dement Creeks (38 km2, RKM 82.4) 

before its confluence at RKM 66.2 with the 

westward flowing Middle Fork Coquille River 

(798 km2; fig. 1). Downstream of the Middle 

Fork Coquille River, the South Fork Coquille 

River is joined by Catching Creek (81 km2, RKM 

61.8) and shortly thereafter by the southward 

flowing North Fork Coquille River (749 km2

) at 

RKM 58.5 (fig. 1). The mainstem Coquille River 

then winds westward for its last 58.5 km through 

the Coquille Valley, where the floodplain widens 

as it traverses coastal marine terrace deposits. 

Several small tributaries, including Hall Creek 

(37 km2, RKM 52.5), Cunningham Creek (40 

km2, RKM 38.2), and Beaver Slough (38 km2, 

RKM 31.5), join the Coquille River in this section. The lowermost 63.2 km of the South Fork 

and mainstem Coquille River and 0.9 km of the 

North Fork Coquille River are tidally influenced 

(Oregon Department of State Lands, 2007). 

The Coquille River basin is primarily in the 

Oregon Coast Range, with the river flowing for 

its last 10 km through a sequence of coastal terraces that flank the coastline (fig. 1). The 

Klamath Mountains geologic province underlies 

13 percent of the basin. The Coast Range geologic province covers approximately 76 percent of 

the basin, and includes the sedimentary (primarily 

Tertiary sedimentary rocks; 74 percent) and volcanic (2 percent) subdivisions. Mapped 

Quaternary sedimentary deposits and landslides 

make up 12 percent of the basin. The Klamath 

Mountains province primarily underlies the South 

Fork Coquille River and to a lesser extent the 

Middle Fork Coquille River. The sedimentary 

subdivision of the Coast Range dominates the 

drainages of the Middle and North Forks of the 

Coquille River, whereas Quaternary terraces and 

floodplains flank the channel in the Myrtle Point 

and Bandon Reaches. These diverse geologic environments reflect unique geologic histories and 

conditions, resulting in distinct characteristics 

such as basin relief, drainage density, erosion 

processes, and water permeability that are relevant to sediment yield and transport. 

Within the Coquille River basin, water surface gradient in the headwater sections for each 

of the main forks are variable and locally steep 

(fig. 2). Channel gradient, however, declines as 

the forks converge and then abruptly flattens in 

the tidally affected and lowermost 63.2 km of the 

river (fig. 2; fig. 3A–C). This far-inland gradient 

discontinuity indicates that the rate of gravel 

transported from the Coquille River to the Pacific 

Ocean has likely not kept pace with Holocene 

sea-level rise. In this respect, the Coquille River 

is similar to the many Coast Range drainages that 

have extensive tidal reaches (Komar, 1997), but 

contrasts with rivers of apparently high gravel 

supply such as the Chetco River (Wallick and 

others, 2010), Hunter Creek (Jones and others, 

2011), and the Rogue River (Jones and others, 

2012), which all have graded profiles to the coast 

and tidally affected sections less than 7 km long. 

Hydrology

The USGS has measured streamflow at seven

gages in the Coquille River basin for periods 

ranging from 13 to 91 years (table 1; 

http://waterdata.usgs.gov/or/nwis/). As of 2011, 

however, the only operating USGS streamflowgaging station is on the South Fork Coquille River at Powers, Oregon (Powers gage, 14325000; 

fig. 1). Additionally, a search of the USGS National Water Information System (NWIS; 

http://waterdata.usgs.gov/nwis) database indicates that the USGS has not collected bedload or 

suspended load sediment samples in the Coquille 

River basin as of 2011.
7 

Figure 2. Graph showing the longitudinal profile of the Coquille River basin, southwestern Oregon, as determined 

from the U.S. Geological Survey 10-m Digital Elevation Model (DEM). 

 South Fork Coquille River upstream of Rock Creek
8

Figure 3. Graphs showing longitudinal profiles and floodplain widths for the (A) Powers, Broadbent, Myrtle Point, and Bandon Reaches on the mainstem 

and South Fork Coquille River, (B) Bridge Reach on the Middle Fork Coquille River, and (C) Gravelford Reach on the North Fork Coquille River, southwestern Oregon. Elevations were derived from the 1-m Light Detection And Ranging (LiDAR) topographic survey and floodplain widths were derived from 

LiDAR, soils and geology maps, and aerial photographs.
9

Table 1. Summary of U.S. Geological Survey (USGS) streamflow-gaging station information for the Coquille River 

basin, southwestern Oregon. 

[Station ID, USGS gaging station number; ~, approximately; km; kilometer; RKM, river kilometer; km2, square kilometer; 

WY, water year; m3

/s, cubic meter per second; --, data not available]

Station name Station ID

Study 

reach Location

Drainage 

area 

(km2)

Period of 

record 

(WY)

Mean 

annual 

flow 

(m3/s)

Peak 

flow 

(m3/s)

Date of 

peak flow

South Fork 

Coquille River 

above Panther 

Creek near Illahae

14324600 -- ~28.2 km 

upstream of 

study area

81 1957–70 4.1 250 12/22/1964

South Fork 

Coquille River near 

Illahae

14324700 -- ~22.6 km 

upstream of 

study area

105 1957–74 5.6 340 12/22/1964

South Fork 

Coquille River near 

Powers

14324900 -- ~8.5 km 

upstream of 

study area

241 1957–70 14.6 838 12/22/1964

South Fork 

Coquille River at 

Powers

14325000 Powers RKM 105 438 1917–26, 

1929–

present

22.0 1,385 12/22/1964

Middle Fork 

Coquille River near 

Myrtle Point

14326500 Bridge RKM 3.9 790 1931–46 21.0 668 1/2/1933

North Fork 

Coquille River near 

Fairview

14326800 -- ~20.1 km 

upstream of 

study area

191 1964–81 8.0 220 3/2/1972

North Fork 

Coquille River near 

Myrtle Point

14327000 Gravelford RKM 6.6 730 1929–46, 

1964–68

26.1 1,088 12/24/1964

Streamflow in the Coquille River basin follows seasonal precipitation patterns, peaking in 

winter, when precipitation is the greatest, and receding to baseflow in summer, when precipitation 

is infrequent. Average annual rainfall varies from 

1.14 meters (m) in the Camas Valley (fig. 1) to 

3.05 m in the upper South Fork Coquille River 

basin (Coquille Watershed Association [1997] as 

cited in Coquille Indian Tribes [2007]). Mean annual flow is 22.0 m3

/s on the South Fork Coquille 

River at Powers (1917–1926, 1928–2010; table 

1). High flows (for example, exceeding 200 m3

/s 

on the South Fork Coquille River; fig. 4A) are 

most common from November to March, when

rainfall saturates the thin soils in the steeper, high 

elevation areas of the watershed (fig. 2; Coquille 

Indian Tribe, 2007). In summer, base flows are 

sustained by groundwater contributions, but generally recede to less than 1 m3

/s on the South 

Fork Coquille River (U.S. Geological Survey, 

2010). Although the Coquille River is unregulated by any large-scale hydropower projects, 

hydrologic alterations include withdrawals of surface water for municipal, domestic, and irrigation 

uses as well as diking and channel straightening 

in low elevation areas to speed drainage after 

floods (Coquille Indian Tribe, 2007).
10

Figure 4. Graphs showing (A) mean daily discharge and (B) annual peak discharge for the U.S. Geological Survey 

streamflow-gaging station at Powers (14325000) on the South Fork Coquille River, southwestern Oregon. Flow recurrence intervals from Cooper (2005).

Because the delivery and transport of bed 

material in the Coquille River basin are driven in 

part by high flows, we identified peak flows from 

gaging station streamflow records. Peaks of 

record were 1,088 m3

/s on December 24, 1964, 

for the lower North Fork Coquille River near 

Myrtle Point (14327000) and 668 m3

/s on January 

2, 1933, for the Middle Fork Coquille River near 

Myrtle Point (14326500; table 1). The 1964 flood 

is also the peak of record on the South Fork Coquille River, with streamflow reaching 1,385 m3

/s 

on December 22, 1964, exceeding the current estimate of a 100-year recurrence-interval event 

(table 1; fig. 4B). Prior to 1964, flows on the 

South Fork Coquille River exceeded a 10-year 

event on December 28, 1945, and December 21, 

1955 (fig. 4B). Since 1964, peak flows on the 

South Fork Coquille River have exceeded a 25-
11

year event on December 9, 1981, and a 50-year 

event on November 18, 1996 (fig. 4B). 

Historical large floods in the Coquille River 

basin occurred in 1861, 1881, and 1890 (Benner, 

1991). Although no data are available to compare 

the magnitudes of these and more recent floods, 

the 1861 flood shifted the location of the Coquille 

River mouth, and the 1890 flood triggered a large 

landslide on Salmon Creek, a tributary joining the 

South Fork Coquille River near RKM 107. Dodge 

(1898) provides the following description of the 

1890 event: 

“A journey up the small stream [Salmon 

Creek] in the summer time reveals wonderful 

scenery. For a distance of four miles a tortuous channel has been worn through rocks 

and steep declivities about one hundred rods 

wide, excepting a few narrow gorges, and the 

bottom of this channel is paved with rocks, 

sand and gravel, with occasional clusters of 

boulders that weigh tons, and yet the torrents 

of winter roll them from place to place, 

changing the surface of the bed of the stream 

at each season according to the volume of 

water. Four miles from the mouth of the canyon a wonderful slide took place in 1890, 

when the side of a mountain literally broke 

loose and went down several hundred feet 

with its massive trees and rocks and built a 

dam across Salmon creek seventy-five feet 

high, forming what has since been known as 

Salmon Lake in a narrow valley above, but 

with-in a few days the dam gave way and the 

timber, debris and mass of earth that formed 

the dam was swept down the stream and 

where the junction was made with the main 

river it raised the stream twenty-five feet almost in the twinkling of an eye, and as the 

flood swept onward the farmers could not 

understand why the sudden rise had taken 

place. At Wm. H. Harris' place and the Hermann homestead, the river raised twelve feet 

in a few minutes and trees two or three hundred feet long were so thick for a mile up and 

down the river that one could have crossed 

the stream easily at any point on the driftwood. At Myrtle Point the large bridge came 

near being torn out, and it was said that one 

could have walked on the timber in the river 

from the town to Rackleff's mill. The massive 

pile of timber was stopped at Coquille City 

by J. A. Lyons' boom, and for a mile above 

the town trees piled up and formed a gorge 

that took days to loosen and open the river to 

navigation.” 

This account of the 1890 flood by Dodge 

captures the substantial contributions of wood 

and sediment into the Coquille River network by 

mass movements and the ability of the South 

Fork Coquille River to transport sediment and 

wood nearly 68 km from its confluence with 

Salmon Creek to the town of Coquille. 

Historical Channel Descriptions

As indicated by the above description of the 

effects of the 1890 flood on Salmon Creek and 

the South Fork and mainstem Coquille River, historical observations of river channels are useful 

reference points for comparing present channel 

conditions. Many of the relevant historical observations of channels in the Coquille River basin 

address interactions between the channel, large 

wood, and sediment accumulation and erosion, 

chiefly in relation to navigation and local timber 

industry practices. In particular, Benner (1991) 

documented and summarized the importance of 

large wood in the Coquille River basin prior to 

substantial Euro-American development in the 

late 1800s. Other accounts such as those by the 

Corps of Engineers (1891), also describe wood 

transport in the Coquille River system:

“The various forks of the Coquille drain 

densely timbered territory, and at every freshet many trees, stumps, etc., are brought 

down. Some of these lodge at different 

points, forming isolated snags, or are grouped 

together into jams. These snags and jams, in 

turn, induce the formation of shoals of sand 

and gravel.” 

More detailed accounts by the Corps of Engineers describe conditions along the lower 
12

Coquille River in the section of primary interest 

for navigation. From RKM 39.6 near the town of 

Coquille to the mouth, “the river is described as 

presenting the features of a natural canal, its 

banks steep, its channel free from rocks, shoals, 

or rapids, and obstructed only by a few snags, 

easily to be removed” (U.S. Army Corps of Engineers, 1879). 

Farther downstream, the Coquille River had 

extensive accumulations of driftwood at its mouth 

in the 1800s as indicated on maps produced by 

the Corps of Engineers (Benner, 1991). Reports 

by the Corps of Engineers also highlight the shifting position of the channel and shoaling at the 

river’s mouth (U.S. Army Corps of Engineers, 

1879). Assistant Engineer Channing Bolton 

stated:

“The difficulty here, as at Coos Bay, seems to 

be the shifting sands and crooked channel, 

together with the addition of a much narrower 

entrance, and that obstructed by many dangerous rocks. Captain Parker, owner of the 

tug and pilot at the mouth of the river, informed me that the sands are so shifting that 

he cannot rely on information gained one day 

for the next, but has to make a thorough examination of the channel before each trip.” 

Additionally, these reports by the Corps of 

Engineers (1879) suggest that the position of the 

Coquille River mouth likely shifted seasonally: 

“...sand driven along by the strong northwest 

winds in summer rapidly prolongs this north 

spit, and that the current on the ebb, in the 

dry season, is spread over too great an area to 

give it sufficient scouring force to carry these 

sands out to deep water; the channel is therefore pushed down through the rocks until it 

occupies its present position. As soon as the 

southwest gales commence in the winter the 

formation of the spit ceases, and the current 

of the river, greatly increased by freshets 

from heavy rains, strikes it almost directly a 

short distance below the rocky ledge and 

forces a channel through it, thus entirely 

avoiding the rocks below, near the present 

entrance.”

Other historical accounts highlight the dynamic nature of the channels in upper portions of 

the basin. In Pioneer History of Coos and Curry 

Counties, Orvil Dodge (1898) described changes 

in channel position, streamflow, and tide relevant 

to trade and navigation in the basin. In the following quotation, Dodge indicated changes in the 

location of the South Fork Coquille River channel 

near the town of Norway (RKM 55.6; fig. 1):

“Soon after Reed and Nelson started trade at 

Norway, Asa Myers and Mr. Hoover arrived 

from the east and erected a saw mill in 1876 

and in 1880 a flouring mill on the south side 

of the stream. They made excellent flour and 

good lumber, but the channel of the stream 

changed in a few years leaving the mill so far 

from the river that it was too expensive to get 

logs from the water to the mill.”

Farther upstream near the confluence of the 

South and Middle Forks of the Coquille River 

(RKM 66.2), Dodge described channel aggradation (resulting in a loss of tidal prism) and 

widening: 

“Those pioneers now distinctly remember 

that the tide raised at least two feet at the 

junction of the Middle and South forks, but 

since civilization has set in with its march of 

progress in cultivating the soil, the river has 

widened and filled up so that the tides are only perceptible at Myrtle Point, two miles 

below the confluence of those two arms of 

the river at full moon tide.” 

In another account, Dodge depicted channel 

aggradation and bank erosion also near the confluence of the South and Middle Forks of the 

Coquille River: 

“Hoffman established a ferry across the two 

rivers, and for twenty years it was a lucrative

business, but the stream has filled with debris 

so that fords are now plentiful. Tide water 

raised at this place and swelled the stream 

two or three feet in depth, until the farmer 
13

cleared the timber from the banks and thus 

left them at the mercy of the angry torrents in 

the winter, and the banks soon caved and 

found the bed of the stream, and now the 

mighty ocean fails to send her floods within 

three or four miles of the place they reached 

before civilization planted her feet on the 

shores of the stream.” 

Combined, these historical descriptions indicate that the Coquille River system in the late 

1800s was undergoing vertical and planform 

channel changes, likely in response to large 

floods as well as natural and anthropogenic inputs 

of wood and sediment. Riparian clearing, forestry 

practices, and fires (described below), in particular, likely contributed sediment to the river 

system. Aggradation of channels, buildup of inchannel wood, reduction in tidal extent, shifts in 

the location of the river mouth, and other issues 

culminated in active management of the Coquille 

River system and actions such as dredging, wood 

(snag) removal, and the construction of jetties at 

the mouth (described below). 

Occupation, Land Use, and Landscape Disturbance

As alluded to in many of the historical observations described above, multiple anthropogenic 

processes and disturbances have had substantial 

effects on sediment yield and transport and channel morphology within the Coquille River basin. 

Logging, dredging, and mining (gravel and mineral) are human activities that directly affected 

channel conditions. Fire and mass movements are 

natural processes affecting sediment yield and 

transport, but both processes have likely been altered by human activities. 

Settlement and Ownership

Several Native American tribes, such as the 

Coos and Upper Coquille Indian Tribes, inhabited 

the Coquille River basin prior to Euro-American 

settlement (Coquille Indian Tribe, 2007). In the 

1850s, however, Euro-American settlement began, initially focusing on beaver fur trading and 

then expanding to fisheries, agriculture, forestry, 

and other uses in subsequent years (Coquille 

Indian Tribe, 2007). Today, approximately 40 

percent of the Coquille River basin is privately 

managed for industrial forestry (Coquille Indian 

Tribe, 2007). Private lands used for nonindustrial 

purposes as well as Federal, State, and county 

lands managed by entities including the Bureau of 

Land Management (BLM), U.S. Forest Service 

(USFS), and Coquille Indian Tribe each make up 

approximately 30 percent of the basin (Coquille 

Indian Tribe, 2007). 

Logging and Splash Damming

Since approximately the 1850s, forests in the 

Coquille River basin have been logged. The first 

mill was constructed in 1853 along the lower Coquille River near the town of Bullards (Coos 

Historical and Maritime Museum, 2011a). Subsequent mills followed, such as the Moore Lumber 

Company, which began work in Bandon in 1900 

and remained a major employer until the 1960s 

(Coos Historical and Maritime Museum, 2011b). 

Despite the long history of logging in the basin, 

we found little data summarizing historical logging volumes and practices. Peck and Park (2006) 

summarized logging-related activities in the upper portions of the South Fork Coquille River 

watershed by decade from 1930 to 2000. They 

reported that logging-related activities have affected approximately 90 km2

 in the upper South 

Fork Coquille River watershed from 1930 to 

2000, with logging activities peaking in the 1960s 

and 1970s (Peck and Park, 2006). 

The tributaries and rivers of the Coquille 

River basin served as transportation routes (fig.

5A) connecting the upland logging areas with the 

lowland mills. Initially, channels were cleared of 

wood and boulders and logs were then floated 

downstream on the South Fork Coquille River 

below Powers, mainstem Coquille River, North 

Fork Coquille River, Middle Fork Coquille River, 

and numerous tributaries (Benner, 1991; Miller, 

2010). The South Fork Coquille River was used 

for these log drives until about 1914 (Farnell, 
14

Figure 5. Historical photographs showing: (A) a 200-m-long jam of about 5,400 logs near Prosper, Oregon (near 

river kilometer 7) in 1907, and (B) splash damming on Middle Creek, a tributary to the North Fork Coquille River, in 

1912. (A) and (B) used by permission of Roxann Gess Smith of Salem, Oregon, and Stephen Beckham of Portland, 

Oregon, respectively.

1979). Starting in about 1911, however, instream 

log transport was enhanced by the use of splash 

dams (temporary wooden dams used to raise the 

water level in streams to float logs downstream to 

sawmills; fig. 5B) to create repeatable and managed floods, which could transport more logs 

faster (Benner, 1991). In conjunction with the 

splash dams, the Port of Coquille Commission 

and other entities cleared riparian vegetation and 

continued removing wood and boulders from 

areas downstream of splash dams on the forks of 

the Coquille River to maximize log transport efficiency (Benner, 1991). About 25 splash dams 

were operated in the Coquille River basin and 

located on the North, East, and Middle Forks of 

the Coquille River and several tributaries, such as 

Dement Creek on the South Fork Coquille River 

as well as Myrtle, Rock, Big, and Sandy Creeks 

on the Middle Fork Coquille River (Benner, 

1991). Splash damming was banned by the Oregon State Legislature in 1957 (Phelps, 2011) after 

a series of court cases citing the deleterious effects of splash damming on riparian properties 

and bank stability (Benner, 1991). 

Splash damming likely has had long-term effects on channels in the Coquille River basin as 

suggested by Miller (2010) for streams with a history of splash damming along the Oregon coast. 

Splash damming in the Coquille River basin likely increased the frequency and magnitude of peak 

floods and associated flux of sediments within the 

river network and scouring of the channel bed 

(possibly to bedrock) As an example, in Camp 

Creek and West Fork Millicoma River to the 

north of the Coquille River basin, Phelps (2011) 

estimated that flows resulting from splash damming likely exceeded 100-year flood events in 

headwater areas and were comparable to 100-year 

flood events in downstream areas. 

Other alterations to maximize splash dam efficiency, such as blasting of boulders and removal 

of in-channel wood and riparian vegetation, also 

contributed to reducing channel complexity while 

increasing sediment flux and bank instability 

(Benner, 1991). Since all of the gages operated by 

the USGS on the South Fork Coquille River were 

upstream of splash damming activities on Dement 

Creek (fig. 1), peak flow data from those gaging 

stations are not useful for identifying flow magnitudes related to splash damming on the South 

Fork Coquille River. Over time, sediment loads 

and channel conditions in the basin have likely 

been influenced by the effects of direct channel 

manipulations associated with log drives and 

splash dams as well as by sediment introduced by 

the subsequent development of logging road net-
15

works (Reid and Dunne, 1984; Furniss and 

others, 1991). 

Dredging and Wood Removal for Navigation

As waterways were historically the primary 

means of transporting goods and materials in the 

Coquille River basin, economic development in 

the basin depended on maintaining navigable 

channels. At the Coquille River mouth, the Corps 

of Engineers has constructed and maintained jetties and dredged since 1880 (Willingham, 1983). 

Historical and ongoing dredging has focused on 

maintaining a stable channel elevation between 

the jetties and along the lower 2 km of the mainstem Coquille River. Between 1986 and 2010, 

more than 533,000 m3 of sediment (primarily 

sand) was removed from the lower 2 km of the 

Coquille River, averaging nearly 22,150 m3

 per 

year (fig. 6). 

Figure 6. Graph showing reported annual and cumulative volumes of sediment removed from 1986 to 2010 near

the mouth of the Coquille River, southwestern Oregon. Data from Judy Linton and Katharine Groth (U.S. Army 

Corps of Engineers, written commun., 2011) and U.S. Army Corps of Engineers (2010). Fiscal year refers to the 

Federal fiscal year of October 1 to September 30. 
16

Upriver from the mouth, however, maintaining a navigable channel proved to be more 

challenging. Early reports described the mainstem 

river from the towns of Coquille to Norway as 

“navigable at all seasons of the year,” with steamers traveling 60 km upriver to Myrtle Point 

without the assistance of any channel dredging 

(quote from the General Land Office Survey of 

the Coquille River, as cited in Benner, 1991). By 

1886, however, steamers had difficulty completing the last mile to Myrtle Point, which prompted 

the Corps of Engineers to begin scraping bars and 

removing snags from Coquille to Myrtle Point in 

1889 (Benner, 1991). Reports by the Corps of 

Engineers indicate that some of these shoals consisted of gravel and sand (U.S. Army Corps of 

Engineers, 1898; Benner, 1991). 

In 1889, the Corps of Engineers removed 

over 22,500 m3

 of material from these shoals. In 

1902, the Corps of Engineers abandoned their 

efforts (except for periodic snagging) between 

Coquille and Myrtle Point owing to the failure of 

dredging and pile dikes to maintain a navigable 

channel (Benner, 1991). From 1889 to 1917, the 

Corps of Engineers removed 6,748 snags along 

the river from Myrtle Point to Bandon (Benner, 

1991). After the U.S. Corps of Engineers ceased 

regular channel maintenance upstream of Coquille at RKM 39.6, the Port of Coquille was 

established in 1911 to maintain the channel in this 

upper section of tidally influenced channel; their 

activities included dredging approximately 

272,000 m3 and removing 1,890 snags in the 7.2 

km of channel near Myrtle Point from 1915 to 

1923 (Benner, 1991). 

Farther downstream, from Coquille to Bandon, channel sedimentation appears to have 

increased during the early 1900s. Shoals were 

absent from the Coquille River from 1889 to 

1902, when the Corps of Engineers dredged the 

channel from Coquille to Myrtle Point (Benner, 

1991). By 1910, six shoals had formed in the 

main channel from Coquille to Bandon, leading 

to repeated dredging of the channel and removal 

of more than 262,300 m3

 of material from 1912 to 

1924 (Benner, 1991). 

In total, from 1889 to 1924, nearly 

557,000 m3 of sediment was removed from the 

South Fork and mainstem Coquille River to maintain a navigable channel (from estimates 

presented in Benner, 1991). From her review of 

navigation maintenance records, Benner (1991) 

concluded, “The depth and dredging history of 

the tidal segment of the Coquille River suggests 

that the channel water depth has decreased since 

the time of Euro-American settlement of the area 

in the 1850s” (pg. 14 of Executive Summary). 

Material filling the channel was likely derived 

from logging activities in the headwaters of the 

basin and splash damming as well as landslides 

(Florsheim and Williams, 1996). Channel aggradation may partially explain the approximately 3-

km reduction in tidal influence on the South Fork 

Coquille River since Euro-American settlement 

(Benner, 1991) with the head of tide moving 

downstream from the confluence of the South and 

Middle Forks of the Coquille River near RKM 

66.2 to approximately RKM 63.2 (Farnell, 1979). 

Florsheim and Williams (1996) suggested that 

repeated dredging to maintain water depths conducive to navigation on the lower Coquille River 

may have initiated channel head cutting and incision farther upstream on the South Fork Coquille 

River.

Although the rate and type of sediment delivered to the South Fork and mainstem Coquille 

River have likely been affected by historical landuse practices, the locus of deposition near Myrtle 

Point reflects the marked reduction in gradient at 

about RKM 60 (fig. 3A). This gradient discontinuity, in turn, reflects the long-term filling of the 

tidally affected portion of the lower Coquille River with sediment as a result of Holocene sea-level 

rise. If sea level stabilizes, then ongoing sedimentation will eventually produce a continuous 

stream gradient profile to the mouth of the Coquille River as the locus of deposition shifts 

downstream. 
17

Instream Gravel Mining

Instream gravel mining can potentially result 

in channel incision and bar armoring (Kondolf, 

1994). As indicated in a July 31, 1928, article by 

the Coos Bay Times, gravel has been mined from 

bars along the South Fork Coquille River to make 

concrete and support construction needs since at 

least the 1920s. In 1928, the McGeorge Gravel 

Company supplied approximately 32,000 m3 of 

material for the Coos Bay-Roseburg and Roosevelt Coast highways (now U.S. Highway 101); 

this material was mined from the South Fork Coquille River near the town of Gaylord (RKM 

98.4; fig. 7) using railroad cars, conveyor belts, 

and other machinery (Coos Bay Times, 1928). A 

compilation of mines by the Oregon Department 

of Geology and Mineral Industries (DOGAMI) 

indicates the approximate locations of 54 mines 

for sand and gravel along the channels and floodplains of the mainstem, forks, and tributaries of 

the Coquille River; a majority of these historical 

sites are concentrated within or adjacent to the 

Coquille River study area (Oregon Department of 

Geology and Mineral Resources, 1999). As of 

2011, six instream mining permits with a cumulative annual removal limit of approximately 

76,400 m3

 from multiple sites on the South Fork 

Coquille River are on file with the Corps of Engineers and Oregon Department of State Lands 

(Judy Linton, U.S. Army Corps of Engineers, 

written commun., 2010; Robert Lobdell, Oregon 

Department of State Lands, written commun., 

2011). See the “Gravel-Operator Information and 

Surveys” section for more details on instream 

gravel mining in the Coquille River study area.

Mineral Mining

Like other rivers along the Oregon coast, the 

Coquille River basin has a history of gold and 

other mineral mining. In 1853, gold was discovered slightly north of the Coquille River mouth at 

Whiskey Run Beach (fig. 1; Coos Historical and 

Maritime Museum, 2011a). Miners also found 

gold in Johnson and Salmon Creeks, two tribFigure 7. Historical photograph from a Coos Bay 

Times (1928) article showing the McGeorge Gravel 

Company’s mining site on the South Fork Coquille River near Gaylord, Oregon. Dolores Knight of the Coos 

Bay Public Library provided this copy of the photograph.

utaries to the South Fork Coquille River (fig. 1), 

in 1854 and 1860, respectively (Dodge, 1898). 

Based on historical mining practices in other 

coastal basins like the Umpqua River basin 

(Beckham, 1986), placer deposits along the South 

Fork Coquille River and its tributaries may have 

been mined hydraulically, potentially liberating 

large volumes of sediment from streamside terraces. Other mineral mining in the basin includes 

historical coal mining in the lower Coquille River 

near Beaver Slough and Riverton (Coos Historical and Maritime Museum, 2011a). Today, 

recreational, small-scale suction dredging occurs 

primarily in the Johnson Creek basin and, to a 

lesser extent, along the South Fork Coquille River 

(Oregon Department of Environmental Quality, 

2000). 

Fire

Since Euro-American settlement, the Coquille River basin has experienced fewer 

widespread forest fires than the neighboring Rogue and Coos River basins. In 1868, a large fire 

burned much of the western portion of the Coos 

River basin, north of the Coquille River, with a 

small portion of the fire affecting the lower Co-
18

quille estuary. In 1889, a fire burned the Salmon 

Creek watershed, which preceded the 1890 flood 

that triggered a large slide and ensuing debris 

flow on Salmon Creek and South Fork and 

mainstem Coquille River (Dodge, 1898; as described in the “Hydrology” section above). Small 

wildfires have been noted along the East Fork 

Coquille River during the latter half of the 19th 

century (Zybach, 2003). Later, in the summer of 

1936, a heat wave accompanied by low humidity 

caused many small fires to break out in Coos 

County, with the most notable being the Bear 

Creek Fire (approximately 590 km2

) that completely destroyed the town of Bandon (Douthit, 

1981). Subsequent fires have affected small (7.5 

km2 or less) areas of the watershed (Peck and 

Park, 2006; U.S. Forest Service, 2008; Oregon 

Partnership for Disaster Resilience, 2010). 

Mass Movements

As described by Dodge (1898), landslides 

and debris flows have probably always been a 

substantial source of sediment to the steep and 

rain-soaked Coquille River basin. In particular, 

formations such as the Tyee, Flournoy, and Lookingglass in the sedimentary subdivision of the 

Coast Range geologic province are susceptible to 

mass movements and debris flows (Lane, 1987; 

Burns, 1998; Roering and others, 2005). The serpentinite rocks within the Klamath Mountains 

geologic province are also susceptible to mass 

movements, but make up less than 1 percent of 

the basin (Oregon Department of Environmental 

Quality, 2000; Ma and others, 2009). Mass wasting is also more prevalent near faults and at the 

contacts between units where the bedding has 

greater dip angles (Lane, 1987). Mass movements 

are also affected by human activities, chiefly road 

construction and clear cutting associated with 

timber harvest (Swanson and Dyrness, 1975; 

Beschta, 1978; Amaranthus and others, 1985; 

Harden and others, 1995). For example, of the 80 

landslides in the Rock and Johnson Creek watersheds (within the South Fork Coquille River 

basin), about 40 were apparently related to logging or road construction (Oregon Department of 

Environmental Quality, 2000; Ma and others, 

2009). In the portions of the watershed underlain 

by the relatively hard rocks of the Klamath 

Mountains geologic province, mass movements 

probably are a substantial contributor of coarse 

bed material to downstream river sections. In the 

areas underlain by other Coast Range sedimentary and volcanic rocks, mass movements likely 

contribute more fine sediment loads as larger 

clasts quickly abrade into smaller particles (Jones 

and others, 2010; Mangano and others, 2011). 

Study Area

For the purposes of this assessment, the 

overall geography, geomorphology, and land-use 

history of the Coquille River basin led to delineation of a focused study area, including (1) the 

South Fork Coquille River from RKM 115.4 near 

its confluence with Upper Land Creek to RKM 

58.5 at its confluence with the North Fork Coquille River, (2) the mainstem Coquille River 

from RKM 58.5 at the confluence of the South 

and North Forks of the Coquille River to its 

mouth, (3) the Middle Fork Coquille River from 

RKM 15.4 to its confluence with the South Fork 

Coquille River, and (4) the North Fork Coquille 

River from RKM 14.6 to its confluence with the 

South Fork Coquille River (fig. 1). These mainstem and tributary corridors contain most of the 

alluvial deposits within the basin and have had 

the most active and historical instream gravel 

mining. This study area, encompassing 145.4 km 

of river channel in total, was further subdivided 

into six reaches based on topography and hydrology (figs. 1 and 3A–C; tables 2 and 3). 

Landslide on the South Fork Coquille 

River upstream of China Flat Bar 
19

Table 2. Summary of characteristics for study reaches on the South Fork and mainstem of the Coquille River, 

southwestern Oregon

[RKM, river kilometer; km2, square kilometers; m, meter]

River reach 

characteristic 

Mainstem Coquille River South Fork Coquille River

Bandon Reach Myrtle Point Reach Broadbent Reach Powers Reach

RKM 58.5-0 66.2–58.5 96.9–66.2 115.4–96.9

Reach and channel 

description

Entire reach tidally affected; unconfined 

channel composed of

alluvium; jetties stabilize location of river 

mouth; intermittent 

bars; larger tidal bars in 

lower 15 km

Tidally affected to 

RKM 63.2; channel 

composed of alluvium 

with localized confinements; bars 

throughout reach

Channel mostly alluvium and alternates 

between unconfined 

and confined segments with some 

bedrock in channel 

and banks; tall, nearly vertical banks in 

several locations; 

bars throughout reach

Channel alternates

between alluvium 

and bedrock and unconfined and

confined segments; 

higher-gradient, confined segments 

dominated by boulders and cascades; 

bars throughout reach

Drainage area at upand downstream 

boundaries1 (km2)

2,284–2,745 1,437–1,536 487–637 339–487

Reach gradient2 (m/m) 0.00002 0.00040 0.00090 0.00270

Major flow factors Water withdrawals for 

municipal, domestic, 

and irrigation uses

Same as Bandon 

Reach

Same as Bandon 

Reach

Same as Bandon 

Reach

Background sedimentation drivers

Low-gradient promotes 

deposition of bed and 

suspended loads from 

upstream sources

Same as Bandon 

Reach

Inputs from tributaries, upstream 

sources, and eroded 

bank material

Inputs from tributaries and other 

upstream sources 

such as eroded bank 

material, debris 

flows, and landslides

Channel disturbance 

factors

Same as Myrtle Point 

Reach plus jetty construction and splash 

damming on tributary; 

ongoing dredging

Historical dredging; 

channel straightening 

and diking; log drives 

and wood removal; 

pile dikes; likely historical gravel 

extraction; upland 

logging

Log drives, wood 

removal on mainstem; splash damming, log drives, 

wood removal on 

Dement Creek; channel straightening, 

diking; pile dikes; 

historical and ongoing instream gravel 

mining; upland logging

Historical placer 

(possible hydraulic) 

mining; ongoing suction dredge mining; 

log drives, wood removal, boulder 

blasting; upland logging; historical 

gravel mining on 

main stem and tributaries

General channel 

trends

Alluvium; potential for 

lateral and vertical 

channel adjustments

Same as Bandon 

Reach

Mostly alluvium with 

some bedrock; substantial lateral 

channel shifting in 

unconfined sections; 

potential for lateral 

and vertical adjustments

Mixed bed of alluvium and bedrock; 

some potential for 

lateral and vertical 

channel adjustments

1 Drainage area determined using StreamStats, http://water.usgs.gov/osw/streamstats/oregon.html

2 Reach water-surface gradient determined from 1-m LiDAR DEM available for the entire study area except RKM 115.4–

113.4 on the South Fork Coquille River
20

Table 3. Summary of characteristics for study reaches on the Middle and North Forks of the Coquille River, 

southwestern Oregon.

[RKM, river kilometer; km2, square kilometers; m, meter]

River reach 

characteristics

Middle Fork Coquille River North Fork Coquille River

Bridge Reach Gravelford Reach

RKM 15.4–0 14.6–0

Reach and channel 

description

Relatively confined channel flowing over 

mixed bed of bedrock, boulders, and alluvium; bars intermittent in reach

Tidally affected to RKM 0.9; relatively confined 

channel flows over sand and clay and between 

muddy banks; bars intermittent in reach

Drainage area at upand downstream 

boundaries1 (km2)

484–798 712–749

Reach gradient2

(m/m)

0.0015 0.0003

Major flow factors Water withdrawals for municipal, domestic, 

and irrigation uses

Same as Bridge Reach

Background sedimentation drivers

Inputs from tributaries and other upstream 

sources such as eroded bank material, debris 

flows, and landslides

Low-gradient promotes deposition of bed and 

suspended loads from upstream sources

Channel disturbance 

factors

Splash dams and log drives on mainstem and 

several tributaries; wood removal; upland 

logging

Same as Bridge Reach

General channel 

trends

Flows on a mixed bed of alluvium and bedrock; potential for lateral and vertical 

channel adjustments

Flows on sand and firm clay; potential for lateral 

and vertical channel adjustments

1 Drainage area determined using StreamStats, http://water.usgs.gov/osw/streamstats/oregon.html

2 Reach water-surface gradient determined from 1-m LiDAR DEM

North Fork Coquille River near Gravelford
21

Powers Reach 

The Powers Reach of the South Fork Coquille River stretches from slightly downstream 

of Upper Land Creek to slightly upstream of 

Rowland Creek (RKM 115.4-96.9; fig. 8, table 

2). The width of the floodplain in the Powers 

Reach ranges from approximately 50 to 180 m 

(fig. 3A). The channel flows over bedrock and 

alluvial deposits and through unconfined (RKM 

115.4–103.6, 100.6–98) and confined (RKM 

103.6–100.6, 98–96.9) segments in this highgradient reach (reach water-surface gradient 

0.0026 m/m; fig. 3A). 

In the upstream-most unconfined segment 

(RKM 115.4–103.6), the South Fork Coquille 

River has a local gradient of 0.0021 m/m (fig.

3A), varies in active channel width from 28 to 95 

m (from 2009 ortho-imagery for this and all 

widths reported in this section), and contains 

elongated point, lateral, and medial bars, particularly at high-amplitude channel bends. At RKM 

103.6, the South Fork Coquille River enters the 

first confined segment (RKM 103.6–100.6) between Hood and Bingham Mountains, where the 

gradient of the channel increases (0.0054 m/m; 

fig. 3A) and the active channel narrows to 19 to 

39 m. This confined segment is dominated by 

cascades and boulders, and contains lateral and 

point bars predominately in eddies, adjacent to 

rapids, or as a veneer over bedrock outcrops. Entering the downstream-most unconfined segment 

(RKM 100.6–98), the channel returns to a gradient of 0.0021 m/m (fig. 3A). Here, the channel 

alternates between valley walls, but remains relatively narrow (29–32 m in active channel width) 

and contains lateral and point bars comparatively 

smaller than those in the upstream unconfined 

segment. In the downstream-most confined segment (RKM 98–96.9), the channel again 

increases in gradient (0.0041 m/m; fig. 3A), narrows slightly to an active channel width of 15 to 

32 m, with rapids, boulders, and bedrock outcrops 

in and along the channel. The drainage area of the 

South Fork Coquille in this reach ranges from 

339 to 487 km2

 (table 2). 

Broadbent Reach 

The Broadbent Reach on the South Fork Coquille starts slightly upstream of Rowland Creek 

and ends at the confluence of the South and Middle Forks of the Coquille River, where the 

drainage area of the South Fork Coquille River is 

637 km2 (RKM 96.9–66.2; fig. 9; table 2). Like 

the Powers Reach, the channel in the Broadbent 

Reach alternates between unconfined (RKM 

96.9–90.2, 89.9–86.8, and 83.2–66.2) and confined (RKM 90.2–89.9, 86.8–83.2) segments with 

the width of the floodplain approaching 1,200 m 

in its widest section near the town of Broadbent 

(fig. 3A; fig. 9). Although bedrock outcrops occur 

in and along the channel throughout this reach, 

the channel flows predominantly over alluvial 

deposits and has a lower gradient (0.0009 m/m; 

fig. 3A; table 2) compared to the Powers Reach. 

The active channel varies from 25 to 71 m in 

width. Generally, the channel in the Broadbent 

Reach contains more numerous, elongated point 

and lateral bars in the unconfined segments and 

less numerous, smaller bars in the confined segments. Exposed, nearly vertical banks are visible 

in several locations (such as near RKM 79, 77.6, 

73.4, and 73) in the 2008 LiDAR survey and 

2009 orthophotographs. 

In the Broadbent Reach, channel modifications include those related to splash damming on 

Dement Creek and log drives on the South Fork 

Coquille River (Benner, 1991; Miller, 2010) as 

well as rock bank-protection structures, construction of access roads (and likely dikes), and 

instream gravel mining (Clearwater Biostudies, 

Inc., 2003). In particular, the channel from RKM 

78.4–76.9 and 73.8–72.1 has shifted in position 

owing to rock bank-protection structures and the 

November 18, 1996 flood (Clearwater Biostudies, 

Inc., 2003). As of 2011, at least 14 gravel bars in 

the Broadbent Reach are sites of permitted instream gravel mining (Judy Linton, U.S. Army 

Corps of Engineers, written commun., 2010; Robert Lobdell, Oregon Department of State Lands, 

written commun., 2011).
22

Figure 8. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs and 

field reconnaissance photographs for the Powers Reach on the South Fork Coquille River, southwestern Oregon.
23

Figure 9. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs and 

field reconnaissance photographs for the Broadbent Reach on the South Fork Coquille River, southwestern Oregon.
24

Additional sites, such as those operated by the 

McGeorge Gravel Company near Gaylord, were 

mined historically. Ongoing mitigation efforts 

aim to increase bank stability and riparian vegetation (Clearwater Biostudies, Inc., 2003; 

Florsheim and Williams, 1996). 

Myrtle Point Reach 

The Myrtle Point Reach on the South Fork 

Coquille River runs from the confluence of the 

South and Middle Forks of the Coquille River to 

the confluence of the South and North Forks of 

the Coquille River (RKM 66.2-58.5; fig. 10). This 

7.7-km-long reach spans the transition from 

fluvial (or river influenced) to tidally influenced, 

with the lower 4.7 km currently affected by tides. 

Floodplain width ranges from 450 to 1,330 m 

(fig. 3A). This low-gradient (0.0004 m/m; fig.

3A, table 2) section of the South Fork Coquille 

River flowing over alluvium was treated as one 

distinct reach for the purposes of this study based 

on tributary inputs and the occurrence of bars 

throughout the reach even though it contains a 

mixture of fluvial and tidal environments. Comparison of the aerial photographs used in this 

study suggests that the active channel is moderately confined in places such as near RKM 

66.2–64.8 and 61.4–59.4, owing possibly to dikes 

and other anthropogenic modifications of the 

floodplain. The width of the active channel varies 

from 28 to 62 m. The drainage area of the South 

Fork Coquille River ranges from 1,437 km2 at the 

reach’s upstream boundary to 1,536 km2 at the 

reach’s downstream boundary (table 2). Historically, the Corps of Engineers, Port of Coquille, 

and other entities removed sediment and wood 

from the channel, cleared riparian vegetation, and 

stabilized banks in this reach (Benner, 1991; Farnell, 1979). Like the Broadbent Reach, channel 

conditions have changed owing to the addition of 

rock bank protection and road construction 

(Clearwater Biostudies, Inc., 2003).

Bandon Reach 

The tidally influenced Bandon Reach encompasses the entire mainstem Coquille River 

from the confluence of the South and North Forks 

to the river’s mouth (RKM 58.5–0; fig. 11). The 

low-gradient channel (0.00002 m/m; fig. 3A, table 2) flows over alluvium with an active channel 

ranging from 34 to 87 m wide in the reach’s upper 32.5 km and from 63 to approximately 1,160 

m wide in the reach’s lower 26 km. The width of 

floodplain varies greatly from 380 m near RKM 

17 to 2,830 m near RKM 33 (fig. 3A). The floodplain is generally the narrowest from Riverton to 

where the river enters the coastal Quaternary terraces (fig. 11). Bars are present in the upper 1.2 

km of the reach and then are rare until the lowermost 15 km, where bars and tidal flats increase in 

size as the Coquille River enters the coastal plain. 

The drainage area of the Coquille River at its 

mouth is 2,745 km2

. River management actions 

include the construction and maintenance of jetties at the river’s mouth, historical and ongoing 

dredging to maintain the navigation channel in 

the lowermost 2 km of the river, and historical 

dredging and wood removal throughout the reach 

(Benner, 1991; Willingham, 1983). 

Bridge Reach 

The Bridge Reach is the only study reach on 

the Middle Fork Coquille River; it extends from 

near the town of Bridge to the confluence of the 

Middle and South Forks of the Coquille River 

(RKM 15.4–0; fig. 12). Draining a rugged, mountainous area, this section of the Middle Fork 

Coquille River has a gradient of 0.0015 m/m and 

step-pool morphology (fig. 3B; table 3). The 

floodplain is narrow in this reach, ranging from 

50 m where the floodplain traverses the Roseburg 

Formation basalts (part of the volcanic subdivision of the Coast Range geologic province) to 

400 m near the confluence with the South Fork 

Coquille River (fig. 3B). Comprising a mixed bed 

of bedrock, boulders, and alluvium, the 20–44-mwide channel is narrow and active. This reach 

contains intermittent bars (primarily within eddies 

of high-amplitude bends) that increase in abundance downstream of RKM 3.2. The drainage 

area of the Middle Fork Coquille River ranges 

from 484 to 798 km2

 in this reach (table 3). 
25

Figure 10. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs and 

a field reconnaissance photograph for the Myrtle Point Reach on the South Fork Coquille River, southwestern 

Oregon.
26

Figure 11. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs and a field reconnaissance photograph for 

the Bandon Reach on the mainstem Coquille River, southwestern Oregon.
27

Figure 12. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs and field reconnaissance photographs for 

the Bridge Reach on the Middle Fork Coquille River, southwestern Oregon.
28

The Middle Fork Coquille River accounts for 

29.2 percent of the drainage area in the Coquille 

River basin. Historically, log drives and splash 

damming occurred on the Middle Fork Coquille 

River (Farnell, 1979), likely resulting in the removal of in-channel wood and boulders as well as

riparian vegetation. 

Gravelford Reach 

The Gravelford Reach on the North Fork 

Coquille River encompasses the 14.6-km-long 

section from near the confluence of the North and 

East Forks of the Coquille River to the confluence of the North and South Forks of the Coquille 

River (RKM 14.6–0; fig. 13). This low gradient 

reach (0.0003 m/m; fig. 3C; table 3) is tidally affected to RKM 0.9. The floodplain varies from 

150 to 347 m in width for most of the reach, but 

then widens to 800 m near the confluence with 

the South Fork Coquille River (fig. 3C). Flowing 

over alluvium such as sand and clay in locations 

(Oregon Department of Transportation, written 

commun., 2010) and between muddy banks, the 

active channel is relatively narrow, ranging from 

12 to 19 m wide upstream of RKM 6.6, 12 to 23 

m wide downstream of RKM 6.6, and up to 48 m 

wide near the river’s mouth. Pile dikes and bank 

protection structures flank the channel in several 

locations. The drainage area of the North Fork 

Coquille River in this reach ranges from 712 to 

749 km2

 (table 3). The combined contributing 

area of the North Fork Coquille River is 27.3 percent of the area in the Coquille River basin. Like 

the Middle Fork Coquille River, the North Fork 

Coquille River was subject to log drives and 

splash damming (Farnell, 1979). 

Approach and Key Findings

For this study, we reviewed existing datasets 

and studies regarding channel condition and bedmaterial transport in the Coquille River basin, 

applied reconnaissance-level GIS analyses, and 

made field observations and particle size measurements in July 2010. The objectives of these 

efforts were to (1) identify existing datasets that 

would support more detailed analyses of bedmaterial transport and channel condition, (2) 

summarize reported volumes of mined and deposited material at instream gravel mining sites, (3) 

identify locations where the channel may be aggrading, incising, prone to lateral channel 

migration, or stable, (4) characterize broad-scale 

patterns in bar and channel features using photographs spanning 1939–2009, and (5) assess the 

relations between transport capacity and sediment 

supply for each study reach. This study provides a 

preliminary review of channel condition and bedmaterial transport in the Coquille River basin and 

identifies outstanding issues relevant to the permitting of instream gravel mining that may be 

addressed by future studies. The following sections summarize each of the major activities and 

key findings.

Review of Existing Datasets

We assessed the availability of spatial datasets in the Coquille River basin that could be used 

to evaluate channel condition and bed-material 

transport. This search focused primarily on aerial 

and orthophotographs, but included geospatial 

datasets, such as LiDAR topographic data, geologic maps, General Land Office surveys, and 

navigation surveys. 

Aerial and Orthophotographs 

This study reviewed aerial and orthophotograph coverages of the Coquille River basin 

available from the Corps of Engineers’ Aerial 

Photograph Library (Portland, Oregon) and the 

University of Oregon Map and Aerial Photography Library (Eugene, Oregon) as well as digital 

orthophotographs available from online sources. 

Other potential sources of photographs not investigated for this review include the Bureau of Land 

Management, National Archives, county government collections, and private timber companies.
29

29

Figure 13. Map showing key locations and bars and channel centerline delineated from 2009 orthophotographs and a field reconnaissance photograph for 

the Gravelford Reach on the North Fork Coquille River, southwestern Oregon. 
30

At least 11 sets of photographs taken from

1942 to 2011 provide complete coverage of the 

entire Coquille River study area (table 4). Additional sets of aerial photographs provide coverage 

of multiple reaches, with the most comprehensive 

coverages taken in 1939, 1957, 1986, and 1989. 

The Bandon Reach, particularly in the lowermost 

section near the coast, was photographed more 

frequently (table 4). In addition to the aerial photographs listed in table 4, at least 29 sets of aerial 

photographs of the Coquille River mouth were 

taken for navigation and jetty maintenance purposes from 1959 to 2002. 

Eight photograph sets taken in 1939, 1967, 

1989, 1995, 2000–01, 2005, 2009, and 2011 (table 4) provide comprehensive coverage of all or 

most of the study area and were taken during low 

flow months at scales of 1:24,000 or greater. 

These photograph sets would be suitable for use 

in future studies assessing long-term changes in

channel attributes, bar frequency and area, and 

vegetative cover. 

For this study, we used photographs taken in 

1939, 1967, 2005, and 2009 for repeat bar and 

channel delineations (table 4). At the time of this 

study, the 2009 photographs provided the most 

recent coverage of the study area. Additionally, 

we selected the 1939, 1967, and 2005 photographs to enable data comparisons between this 

study and completed studies on the Chetco (Wallick and others, 2010), Umpqua (Wallick and 

others, 2011), and Rogue (Jones and others, 

2012) Rivers and Hunter Creek (Jones and others, 

2011). Additionally, the 1939 photographs are the 

earliest photographic coverage of the study area 

(table 4) and the 1967 photographs provide complete coverage of the study area following the 

December 22, 1964, flood, which exceeded a 

100-year flood event on the South Fork Coquille 

River (table 1; fig. 4B). 

Historical Maps and Survey Data

We reviewed historical maps and survey data 

available for the Coquille River study area from 

several sources (table 5). The purpose of this review was to identify datasets with information on 

channel condition, the extent and distribution of 

gravel bars, and channel morphology and bed 

elevations that could support assessments of 

channel change in future studies.

The earliest available surveys of the study 

reaches on the mainstem Coquille River were 

conducted by the General Land Office (GLO) 

from 1857 to 1876 (table 5). As summarized by 

Atwood (2008), the main purpose of GLO surveys was to establish the Township, Range, and 

Section lines of the Public Land Survey System 

(PLSS). In some instances, as in the case for the 

Coquille River, the channel banks were surveyed 

during the mapping (typically described as 

“meandering”), thereby providing an accurate 

plan-view depiction of channel geometry at the 

time of survey. Further review of the GLO maps 

and accompanying surveyor notes would help 

determine if surveyors also recorded any descriptions of channel and vegetation features. Existing 

reconstructions of the GLO data for the Coquille 

River basin such as those by Benner (1991) have 

primarily focused on the Bandon Reach. 

In addition to the GLO mapping, the USGS 

surveyed channel planforms and profiles for the 

South Fork Coquille River in 1926 (table 5). LiDAR topographic data collected in 2008 provide 

a 1-m resolution topographic survey of the entire 

study area except for the upper 2 km of the study 

area on the South Fork Coquille River (table 5). 

Major geologic units and geomorphic divisions of 

the river basin are depicted in the digital compilation of Oregon geologic maps (Ma and others, 

2009). English and Coe (2011) mapped channel 

migration and potential hazard areas along the 

South Fork Coquille River and mainstem from 

approximately RKM 113.4–103.2 near Powers 

and approximately RKM 76.8–2.4 from the towns 

of Broadbent to Bandon. 
31

Table 4. Available aerial photographs by reach for the Coquille River study area, southwestern Oregon. 

Aerial photographs shown in bold were used to delineate bar and channel features for this study—continued

[RKM, river kilometer; ~, approximately; USACE, U.S. Army Corps of Engineers; UO, University of Oregon Map 

and Aerial Photography Library; --, not applicable; NA, not available; USGS, U.S. Geological Survey; USDA, U.S. 

Department of Agriculture; WAC, Western Aerial Contractor; OSDR, Oregon State Department of Revenue; AM; 

Aerial Mapping; BLM, Bureau of Land Management; m, meter]

Full coverage of 

reach(es) Partial coverage of reach(es) Year Collection month/day Scale Collection entity Repository

All reaches except 

Powers

Powers (RKM 108–96.9) 1939 Multiple 

dates1

~1:10,200 USACE USACE, 

UO

All reaches -- 1942 NA 1:27,200 USGS UO

All reaches -- 1954 NA 1:20,000 USDA UO

Myrtle Point, Bandon, GravelfordBroadbent (RKM 70–66.2) 1956 11/24 1:10,000 WAC USACE

Bandon Myrtle Point (RKM 60.4–

58.5)

1956 11/23 1:24,000 WAC USACE

Powers, Broadbent, Myrtle Point, 

Gravelford

Bandon (RKM 58.5–52, 40–

7.2)

1957 2/12; 2/17 1:9,600 USACE USACE

Bridge Bandon (RKM 40–16.2) 1957 4/26 1:10,000 USACE USACE

-- Bandon (RKM 7.2–0) 1964 4/13 1:24,000 USACE USACE

All reaches -- 1967 5/8; 5/25 1:20,000 USDA UO

-- Bandon (RKM 58–11.4), Gravelford (~RKM 3–0)1972 6/4 1:12,000 WAC USACE

-- Bandon (RKM 11.4–0) 1972 5/18 1:12,000 WAC USACE

All reaches -- 1976 NA 1:12,000 OSDR UO

-- Bandon (RKM 56.2–0) 1978 5/19 1:12,000 AM USACE

Bandon -- 1978 9/23 1:24,000 AM USACE

Bandon Myrtle Point (RKM 60.4–

58.5)

1978 10/18 1:24,000 AM USACE

-- Bandon (RKM 56.2–0) 1980 6/29–30 1:12,000 AM USACE

-- Bandon (intermittent coverage 

RKM 56.3–40, all RKM 10–0)

1982 3/23 1:48,000 WAC USACE

All reaches -- 1982 NA 1:80,000 USGS UO

-- Bandon (RKM 10–0) 1983 9/16 1:48,000 WAC USACE

Powers, Broadbent, Myrtle Point, 

Bandon

Gravelford (RKM 10–0), 

Bridge (RKM 7.1–0)

1986 6/12 1:48,000 WAC USACE

All reaches -- 1986 NA 1:12,000 BLM UO

Broadbent, Myrtle 

Point, Bandon

Powers (RKM 114.8–96.9) 1989 11/2 1:24,000 Bergman USACE

-- Gravelford (intermittent coverage)1990 7/20 1:24,000 Bergman USACE

All reaches -- 1995 Multiple 

dates2

1 pixel = 

1 m

USGS USGS; 

UO
32

Table 4. Available aerial photographs by reach for the Coquille River study area, southwestern Oregon. 

Aerial photographs shown in bold were used to delineate bar and channel features for this study—continued

[RKM, river kilometer; ~, approximately; USACE, U.S. Army Corps of Engineers; UO, University of Oregon Map 

and Aerial Photography Library; --, not applicable; NA, not available; USGS, U.S. Geological Survey; USDA, U.S. 

Department of Agriculture; WAC, Western Aerial Contractor; OSDR, Oregon State Department of Revenue; AM; 

Aerial Mapping; BLM, Bureau of Land Management; m, meter]

Full coverage of 

reach(es) Partial coverage of reach(es) Year Collection month/day Scale Collection entity Repository

All reaches -- 2000–

01

Multiple 

dates3

1 pixel = 

1 m

USGS USGS

-- Bandon (intermittent coverage 

RKM 52–19, all RKM 19–0)

2001 5/10 1:24,000 WAC USACE

Myrtle Point Broadbent (RKM 75.2–66.2), 

Bandon (RKM 58.5–52)

2001 5/18 1:24,000 WAC USACE

All reaches -- 2005 07/15; 08/5 1 pixel = 

0.5 m

USDA USGS

All reaches -- 2009 Multiple 

dates4

1 pixel = 

1 m

USDA USGS

All reaches -- 2011 Multiple 

dates5

1 pixel = 

1 m

USDA USGS

1 5/3, 5/5, 7/17

2 5/1–3, 5/6/, 5/27, 5/30, 8/5

3 7/27/2000, 8/08/2000, 8/12/2000, 8/17/2000, 8/21/2000, 7/14/2001, 7/23/2001

4 6/17-18, 6/22, 7/15

5 6/17, 6/20, 7/5
33

Table 5. Datasets reviewed for this study in the Coquille River basin, southwestern Oregon

[BLM, Bureau of Land Management; RKM, river kilometer; NA, not available; USCS, U.S. Coast Survey; NOAA, National Oceanic and Atmospheric Administration; USGS, U.S. Geological Survey; OSU, Oregon State University; ODFW, 

Oregon Department of Fish and Wildlife; DOGAMI, Oregon Department of Geology and Mineral Industries; LiDAR, Light 

Detection and Ranging; m, meter]

Dataset Scale Date(s) Source Depository Description

General Land 

Office Surveys 

(GLO)

~1:31,680 1857–76 GLO maps BLM1 Earliest surveys conducted in 1857–59; meander surveys conducted in 1857, 1867, 1871, and 

1874; study areas on the mainstem and North 

Fork Coquille River are meandered; South Fork 

Coquille River is meandered to RKM 108.7; 

maps show planview of river and surrounding 

lands; limited details on channel features; See 

Brenner (1991) for additional GLO information

Reconnaissance 

of Entrance & 

Part of Coquille 

River

NA 1861 USCS NOAA2 Bathymetric map of ~RKM 4.8–0 of Coquille 

River

Bathymetric 

survey

NA 1905 USACE; 

Farnell 

(1979)

USACE Bathymetric map of ~RKM 0.8–0 of the Coquille River following jetty improvements

Plan and profile 

of Coquille River (South Fork), 

Oregon

1:31,680 1926 USGS OSU; 

USGS

Contour map of Coquille River in study area 

from RKM 105 to 115.4 on the South Fork Coquille River; includes profiles

Nautical chart of 

the Coquille 

River entrance

1:10,000 Multiple 

dates3

USCS NOAA2 Bathymetric map of ~RKM 6.2–0 of Coquille 

River

Habitat map of 

the Coquille 

estuary

NA 1978 ODFW OSU4 Map of estuary categorized by tidal inundation, 

habitat type, vegetation, and sediment for RKM 

8–0 

LiDAR ~1 m 2008 DOGAMI DOGAMI High resolution topographic survey of basin, 

complete coverage of study area except for 

RKM 113.4–115.4 on South Fork Coquille 

River

Geologic map 1:12,000–

1:500,000

2009 DOGAMI DOGAMI Digital compilation of geologic maps in Oregon 

(Ma and others, 2009); full coverage

Channel migration hazard maps1:6,000–

1:12,000

2011 DOGAMI; DOGAMI Maps identifying potential channel migration 

zones derived from LiDAR and repeat aerial 

photography from ~RKM 113.4–103.2, 76.8–

2.4 (English and Coe, 2011)

Bathymetric 

survey

1:1,000 2011 USACE USACE5 Bathymetric map of ~RKM 2–0 of Coquille 

River

1 BLM website: http://www.blm.gov/or/landrecords/survey/ySrvy1.php 

2 NOAA website: http://historicalcharts.noaa.gov/

3 1945, 1967, 1971, 1973, 1977, 1978, 1981, 1987, 1992, 2000, 2003, 2004

4 OSU library: http://oregondigital.org/digcol/index.php

5 USACE website: http://www.nwp.usace.army.mil/navigation/
34

The Bandon Reach has several additional topographic and bathymetric datasets that could 

support assessments of channel condition and 

change for the lower Coquille River. For example, the U.S. Coast Survey surveyed the lower 

Coquille River in 1861 (table 5). Several recent 

bathymetric surveys of approximately the lower 6 

km of the Coquille River were performed by the 

U.S. Coast Survey, whereas a 2011 survey by the 

Corps of Engineers collected bathymetry for approximately the lower 2 km of the Coquille River 

(table 5). 

Previous Hydrologic and Geomorphic Studies

A search for previous hydrologic and geomorphic studies in the Coquille River basin 

yielded few studies that directly addressed hydrology, channel geomorphology, and sediment 

dynamics. Here, we summarize two geomorphic 

studies on the South Fork Coquille River by Florsheim and Williams (1996) and Clearwater 

Biostudies, Inc. (2003) and a channel migration 

hazards study on the South Fork and mainstem 

Coquille River by English and Coe (2011). A 

summary of more general watershed analyses describing bed-material and channel condition for 

several tributaries joining the South Fork Coquille River above the study area is provided by 

Peck and Park (2006). 

Florsheim and Williams (1996) summarized 

watershed geomorphic and hydrologic processes 

contributing to bank erosion in a short section 

(RKM 75.1–66.2) of the Broadbent Reach on the 

South Fork Coquille River. Within this section, 

banks were composed of unconsolidated silty 

clay loam and silt loam, and were described as 

eroded to vertical profiles and with heights exceeding 7.6 m in several locations (Florsheim and 

Williams, 1996). Using aerial photographs, they 

estimated that approximately 40,469 m2 of riparian land had been lost from 1939 to 1992 owing 

to bank erosion at channel bends or erosion of 

areas lacking riparian vegetation (Florsheim and 

Williams, 1996). On the basis of their observations, including the presence of tall (7.6 m) and 

steep banks and the elevation differences between 

the channel bed and floodplain, Florsheim and 

Williams (1996) concluded that the channel in 

this section is likely incising and adjusting to a 

reduction in sediment supply (after a substantial 

loading of sediment during the late 1800s) as a 

result of instream gravel mining and recently implemented forestry practices that reduce hill-slope 

erosion. 

Clearwater Biostudies, Inc. (2003) conducted 

a riparian and geomorphic assessment of the 

South Fork Coquille River from the Siskiyou National Forest Boundary (approximately 350 m 

upstream of the Powers Reach) to its confluence 

with the North Fork Coquille River (RKM 58.5), 

encompassing the Powers, Broadbent, and Myrtle 

Point Reaches. They determined that eroding 

banks generally lacked woody riparian vegetation, increased in number and/or severity from 

RKM 64.2 to 59.8, and reached heights of 7.6–9.1 

m in several locations (Clearwater Biostudies, 

Inc., 2003). They attributed bank instability to the 

lack of riparian vegetation and changes in channel 

planform following the installation of rock structures for bank protection (Clearwater Biostudies, 

Inc., 2003). The authors reported that the South 

Fork Coquille River had a moderate sediment 

supply and a channel with either stable or unknown condition above Dement Creek (RKM 

82.4), but moderate to high sediment inputs and 

indicators of channel aggradation and incision 

below Dement Creek (Clearwater Biostudies, 

2003). In particular, they noted that channel instability was greatest from RKM 78.4 to 76.9 

owing to bank erosion and increases in channel 

width and sinuosity after the November 1996 

flood (Clearwater Biostudies, 2003). Although 

they did not detect any differences in gravel surface area up- and downstream of Dement Creek, 

they noted that exposed bar area was lowest from 

RKM 64.2 to 63 near sites of instream gravel 

mining and that gravel deposits were more extensive along the lower South Fork Coquille River in 

1939 than in 1997 (Clearwater Biostudies, Inc., 

2003). Particle measurements indicated that median particle sizes (D50) ranged from 1 to 243 

millimeters (mm) in riffles within the river, and 
35

fine sediments (derived possibly from natural deposition, tributary sources, and bank erosion) 

increased in riffles as the river approached its 

confluence the North Fork Coquille River, particularly from approximately RKM 61.8 to 59.8 

(Clearwater Biostudies, Inc., 2003). 

Clearwater Biostudies, Inc. (2003) also assessed patterns in channel planform using field 

data collected in 2001 and historical spatial data. 

On the basis of their field measurements of channel width at 206 locations, they determined that 

channel widths varied by a factor of 7 within their 

study area, indicating frequent adjustments in 

channel width and the potential for the channel to 

locally widen or narrow. Comparison of river position from maps dating from approximately 1870 

and 1980 suggests that channel alignment and 

sinuosity changed little between Powers and Dement Creek (RKM 68.9–63.0) and the 

confluences of the South Fork with the Middle 

and North Forks of the Coquille River (approximately RKM 60.8–59.8). This analysis, however, 

did indicate a 14-percent reduction in channel sinuosity, a 12-percent reduction in channel length, 

and loss in river bend frequency between Broadbent and the Middle Fork Coquille River 

(approximately RKM 61.8–61.4) as well as a 5-

percent reduction in both sinuosity and channel 

length between Dement Creek and Broadbent 

(RKM 62.2–61.8) (Clearwater Biostudies, Inc., 

2003). The authors also concluded that (1) decreases in channel length reflect channel incision 

and increasing channel slope and bank heights, 

(2) further comparison of their results and those 

of Florsheim and Williams (1996) suggest that 

historical changes in channel meander patterns 

generally occurred prior to 1939, and (3) channel 

width did not increase systematically in a downstream direction, but varied throughout the study 

section (Clearwater Biostudies, Inc., 2003). They 

also state that the river channel was clearly incised in the 1939 photographs, but do not 

document the basis of this statement (Clearwater 

Biostudies, Inc., 2003). 

In a channel-migration hazard study, English 

and Coe (2011) reviewed aerial and orthophotographs taken from 1939 to 2005 and the LiDAR

topographic data collected in 2008 (table 5) to 

identify locations along the South Fork and 

mainstem Coquille River where lateral channel 

migration may be expected in the future. English 

and Coe (2011) reported that most channel migration along the South Fork Coquille River 

occurred between Broadbent and Myrtle Point 

(approximately RKM 75.2–60.4) and between 

two time periods (1942–1967, 1968–1996), coinciding with the large floods of 1964 and 1996 

(fig. 4B). They also identified several avulsionprone areas (such as RKM 75.1–71.2, 70.4–68.8, 

and 67–66; fig. 9) in the Broadbent Reach, a large 

historically active avulsion area south of the town 

of Coquille (near RKM 51.2; fig. 11), and two 

paleo-channels southwest of Coquille (starting 

near RKM 45; fig. 11; English and Coe, 2011). 

Near Powers, they noted bank erosion (in some 

locations up to 13 m in a 50-year period) and 

mass wasting that can lead to channel widening 

and increased sediment fluxes to downstream sections (English and Coe, 2011). 

Gravel-Operator Information and Surveys

In June 2011, we reviewed permit files at the 

Oregon Department of State Lands (DSL) to obtain estimates of deposited and mined volumes of 

bed material reported for instream gravel mining 

sites in the Coquille River basin. Although some 

permit files included notes describing mining activities in the 1930s, mined volume estimates 

were mainly available from 1974 to 78 for 12 operators in the Coquille River basin and from 1996 

to 2009 for 9 sites on the South Fork Coquille 

River. Estimates from the 1970s appeared to be 

based primarily on operator estimates, whereas 

more recent estimates were based predominantly 

on repeat topographic surveys at the mining sites.

From 1974 to 1978, a total gravel volume of 

at least 306,600 m3 was mined from multiple sites 

on Salmon Creek, the South and Middle Forks of 

the Coquille River, and mainstem (table 6). For 

this period, total reported annual mined volumes 

ranged from at least 58,700 to 68,300 m3

. Reported annual mined volumes were greatest for 
36

the multiple sites operated by Benham Concrete 

Co. on the South Fork Coquille River (22,900 m3

reported per year) and by the Oregon State Highway Division on the Middle Fork Coquille River 

(15,300 m3 reported per year). Although changes 

in channel position and site ownership made it 

challenging to assess and track mining

operations at each location over time, gravel mining likely has occurred more recently at sites such 

as the Lokan, Herman, Broadbent, Coos Highway, Thompson, and Hayes Bars in the 

Broadbent Reach of the South Fork Coquille River (fig. 9).

Table 6. Compilation of reported gravel volumes mined from 1974 to 1978 in the Coquille River basin, southwestern Oregon. 

[m3, cubic meter; RKM, river kilometer; --, data gaps; data compiled from permit files housed at Oregon Department of 

State Lands (accessed 6/2011)]

River/Creek Operator

Reported mined volumes (m3) Ongoing mining 

1974 1975 1976 1977 1978 site (if available)

Salmon 

Creek

Merchen and Reed Gravel Company 5,000 5,000 2,700 2,400 600 --

South Fork 

Coquille 

River

Benham Concrete Company 22,900 22,900 22,900 22,900 22,900 Lokan, Herman, 

and Broadbent 

Bars

Oregon State Highway Division 3,800 -- 3,100 -- 3,800 --

Coos County Highway Department 7,900 7,900 7,900 7,900 7,900 Coos Highway 

Bar

Oregon State Highway Division -- 5,700 -- -- 5,700 --

Train Farms 1,900 1,900 1,900 1,900 -- --

Merchen and Reed Gravel Company 6,100 13,700 4,600 9,900 2,500 Thompson Bar

Clyde D. Lundy 800 800 -- -- -- Hayes Bar

Gordon Hayes -- -- 1,500 1,500 2,300 Hayes Bar

Merchen and Reed Gravel Company -- -- 2,100 -- 200 --

Middle Fork 

Coquille 

River

Oregon State Highway Division 15,300 15,300 15,300 15,300 15,300 --

Coquille 

River

Coos County Highway Department, 

Parks

-- 100 100 100 100 --

Cumulative annual mined volume 58,700 68,300 59,400 59,500 60,700
37

From 1996 to 2009, estimates of deposited 

and mined gravel volumes were reported for eight 

and nine sites, respectively, in the Broadbent 

Reach of the South Fork Coquille River (tables 7 

and 8; fig. 14A–I). During this period, the cumulative deposition volumes per site ranged from at 

least 10,500 to 176,100 m3, with the mean annual 

deposition per site exceeding 3,000 m3 at the 

Hayes, Elliot, Seals, Broadbent, and Herman Bars 

(table 7). For all sites, the cumulative surveyed 

deposition totaled at least 485,600 m3

 during this 

period, and the annual average deposited volume 

was 34,700 m3

/yr (table 8). 

The reported cumulative mining volumes at 

each site ranged from 2,000 to 81,600 m3

, and the 

mean annual mining volumes exceeded 3,000 m3

at the Hayes and Broadbent Bars (table 7 ). From 

1996 to 2009, the reported cumulative volume of 

gravel mined from the Broadbent Reach of the 

South Fork Coquille River was at least 207,100 

m3, or approximately 43 percent of the reported 

volume of deposited sediment (table 8). On average, nearly 15,000 m3 per year was reported as 

mined from the Broadbent Reach from 1996 to

2009 (table 8). Actual mined and deposited volumes may have been greater than indicated by 

this compilation of available data because volumes were not reported for several sites and 

years (table 7). 

The available estimates of deposited and 

mined gravel volumes for sites on the South Fork 

Coquille River indicate that bed material transported by the river mostly rebuilds mined bar 

surfaces (table 7; fig. 14A–I). Cumulative deposition volumes were greatest following the 2-year 

recurrence-interval flood on December 2, 1998 

(WY 1999; table 8; fig. 4B) and 50-year recurrence-interval flood on November 18, 1996 (WY 

1997; table 8; fig. 4B). For individual sites with 

multiple deposition estimates, however, annual 

deposition volumes varied between sites and 

years. Deposition at the Hayes and Elliot Bars 

was slightly greater in 1997 than in 1999, whereas deposition was greatest at Seals Bar (located 

at RKM 88.8 opposite of Elliot Bar) in 2004 (table 7; fig. 14C). Differences in deposition 

patterns between the adjacent Seals and Elliot

Bars are likely related to local channel hydraulics 

and changes in deposition patterns evident in the 

repeat bar mapping described below. Meanwhile, 

deposition was greatest in 1999 at the Broadbent 

and Herman Bars (table 7; fig. 14E, G) and in 

2000 at Isenhart Bar (table 7; fig. 14F). Compared with other sites, estimated deposition 

volumes have been markedly lower since 2005 at 

Broadbent Bar and since 2001 at Lokan Bar (table 7). 

Because gravel mining likely creates preferential depositional areas on mined bar surfaces, 

these deposition estimates at individual bars cannot be reliably extrapolated to assess overall 

deposition rates for all bars along the South Fork 

Coquille River. However, these estimates do indicate that annual deposition volumes at mined 

bars averaged over 34,700 m3

 from 1996 to 2009 

(table 8), suggesting that the annual bed-material 

transport in the South Fork Coquille River at least 

exceeded this value. 

Our repeat delineation of bar and channel 

features shows that several of these mined bars 

changed in size, shape, or position relative to the 

main channel from 1939 to 2009 (see “Delineation of Bar and Channel Features, 1939–2009” 

section). Detailed analyses of bed-material flux 

and morphological changes along the South Fork 

Coquille River would enable more quantitative 

assessments of changes in bar replenishment and 

morphology in relation to peak flows as well as 

support the evaluation of possible effects of gravel mining on overall bed-material flux and 

downstream channel conditions. Historical aerial 

photographs such as those taken in 1995 and 

2000 (table 4) would likely support such a detailed geomorphic assessment.
38

Table 7. Compilation of reported gravel volumes deposited and mined from 1996 to 2009 at instream 

mining sites in the Broadbent Reach of the South Fork Coquille River, southwestern Oregon 

[Hwy, highway; m3, cubic meter; RKM, river kilometer; --, data gaps; data compiled from permit files housed at 

Oregon Department of State Lands (accessed 6/2011)]

Bar name and location (RKM)

Hayes Elliot Seals Thompson

93.8, 93.3, 92.3 88.8 88.8 87.9, 87.4, 87.1

Volume deposited (+) or mined (–)(m3)

Year + – + – + – + –

1996 11,200 -- 2,300 -- 4,000 -- 0 0

1997 26,100 -- 10,400 -- 3,600 -- 6,500 7,000

1998 15,600 6,100 6,000 3,400 4,300 0 6,500 5,000

1999 25,500 19,300 10,200 5,600 4,900 5,300 -- 0

2000 13,200 8,800 2,100 3,200 2,900 2,800 -- 0

2001 6,100 -- 3,100 -- 3,400 -- -- 0

2002 7,500 11,900 -- 1,100 -- 3,600 -- 0

2003 9,800 5,000 3,400 1,800 4,700 2,100 -- 0

2004 7,700 0 1,700 0 9,200 0 -- 0

2005 12,600 9,800 -- -- 4,800 5,800 -- 0

2006 15,500 13,300 4,600 2,200 5,200 4,600 -- 0

2007 -- -- -- -- -- -- -- 0

2008 9,200 -- 1,800 -- 5,200 -- -- 0

2009 16,100 7,400 5,000 2,000 8,100 1,800 -- 0

Mean annual 

volume by 

site

13,500 9,100 4,600 2,400 5,000 2,900 1,100 900

Cumulative 

volume by 

site

176,100 81,600 50,600 19,300 60,300 26,000 13,000 12,000
39

Table 7. Compilation of reported gravel volumes deposited and mined from 1996 to 2009 at instream mining sites 

in the Broadbent Reach of the South Fork Coquille River, southwestern Oregon—continued.

[Hwy, highway; m3, cubic meter; RKM, river kilometer; --, data gaps; data compiled from permit files housed at Oregon 

Department of State Lands (accessed 6/2011)]

Bar name and location (RKM)

Broadbent Isenhart Herman Lokan Coos County Hwy

83 81.8 79 76.4 80.2, 75.9

Volume deposited (+) or mined (–)(m3)

Year + – + – + – + – + –

1996 11,200 -- -- -- -- -- -- -- -- --

1997 15,200 -- 3,100 -- 2,900 -- -- -- -- --

1998 11,800 -- 3,200 0 3,600 0 5,200 3,100 -- --

1999 20,500 19,800 2,900 1,900 5,000 3,200 -- -- -- --

2000 12,300 0 4,100 1,800 3,500 3,000 1,200 1,000 -- --

2001 -- -- 500 -- -- 700 600 -- -- 0

2002 19,600 8,700 900 0 1,500 1,500 300 0 -- 2,000

2003 7,100 11,200 2,800 600 4,100 1,400 500 0 -- 0

2004 12,000 0 2,300 0 3,400 0 800 0 -- --

2005 1,400 1,900 -- 0 2,200 2,000 500 0 -- 0

2006 2,000 2,200 -- -- -- -- 800 -- -- 0

2007 -- -- -- -- -- -- -- -- -- --

2008 1,200 -- 3,600 -- 4,700 -- 600 -- -- --

2009 2,200 500 -- -- 4,300 1,700 -- -- -- --

Mean annual 

volume by 

site

9,700 5,538 2,600 600 3,500 1,500 1,200 300 -- 200

Cumulative 

volume by 

site

116,500 44,300 23,400 4,300 35,200 13,500 10,500 4,100 -- 2,000

South Fork Coquille River, upstream of RKM 79
40

Table 8. Annual summary of reported volumes of deposited and mined gravel from 1996 to 2009 for 

instream mining sites in the Broadbent Reach of the South Fork Coquille River, southwestern Oregon.

[m3, cubic meter; --, data gaps; Hwy, highway; data compiled from permit files housed at Oregon Department 

of State Lands (accessed 6/2011)]

Reported cumulative volumes (m3)

Year Deposited Mined Notes

1996 28,700 -- Only mining inactivity at Thompson Bar reported

1997 67,800 7,000

1998 56,200 17,600

1999 69,000 55,100

2000 39,300 20,600

2001 13,700 700

2002 29,800 28,800

2003 32,400 22,100

2004 37,100 0 Mining inactivity reported for all sites except for Coos County Hwy Bar

2005 21,500 19,500

2006 28,100 22,300

2007 -- -- Only mining inactivity at Thompson Bar reported

2008 26,300 -- Only mining inactivity at Thompson Bar reported

2009 35,700 13,400

Mean 

volume

34,700 14,800

Cumulative 

volume

485,600 207,100

South Fork Coquille River, downstream of RKM 79
41

Figure 14. Graphs showing reported estimates of deposited and mined gravel (in cubic meters) from 1996 to 2009 

for instream mining sites along the South Fork Coquille River, southwestern Oregon. Data compiled from permit 

files housed at Oregon Department of State Lands (accessed June 2011). 
42

Figure 14 (continued). Graphs showing reported estimates of deposited and mined gravel (in cubic meters) from 

1996 to 2009 for instream mining sites along the South Fork Coquille River, southwestern Oregon. Data compiled from permit files housed at Oregon Department of State Lands (accessed June 2011). 
43

Bridge-Inspection Reports

The Oregon Department of Transportation 

(ODOT) conducts routine bridge inspections to 

assess overall bridge condition, footing stability, 

and scour. ODOT’s bridge inspection database 

contains reports for 17 of the 18 bridges within 

the study area (Oregon Department of Transportation, written commun., 2010; table 9). ODOT 

has resurveyed channel cross sections near 15 of 

these bridges, including at least one bridge in 

each study reach. Sites were surveyed in different 

years (table 9) with the first surveys conducted 

between 1992 and 2006 and most recent surveys 

between 2008 and 2010. Some bridges have had 

as many as four channel surveys. In addition to 

examining the resurveyed (or repeat) channel 

cross sections, we examined supplemental data 

such as underwater reports, photographs, and 

scour assessments that are helpful for assessing 

channel condition and bed material adjacent to 

the bridges. 

A review of the most recent bridge inspection 

reports indicates that the channels of the South 

Fork Coquille (RKM 106.1, 103.2, 75.1), mainstem Coquille (RKM 38.9, 5.4), Middle Fork 

Coquille (RKM 13.8, 12.5, 5.2, 4.9, 2.4, 0.5), and 

North Fork Coquille Rivers (RKM 0.4) show evidence of bank erosion, such as bank slumping or 

“minor channel damage” (as stated in ODOT reports). Inspections note signs of bank erosion at 

nine of these locations as well as scour of the 

channel and bridge infrastructure at two additional locations (Powers Reach, RKM 108.3; Bridge 

Reach, RKM 10). The report for the bridge at 

RKM 89.4 in the Broadbent Reach indicates that 

the west (or left) abutment was built on an earthflow deposit that moves during winter; this 

deposit may explain the 1.5–5.1 m erosion along 

the base of the left bank from 1994 to 2008 (see 

figure 16A below). Although few bridge inspection reports included notes describing bed 

material, the bed of the Coquille River was described as sand and silt (Bandon Reach, RKM 

38.9) and sand (Bandon Reach, RKM 5.4), whereas the bed of the North Fork Coquille River was 

described as firm clay (Gravelford Reach, RKM 

0.4). Multiple observations document variation in 

the bed material of the Middle Fork Coquille 

River as it is sand and cobbles (Bridge Reach, 

RKM 13.8), sand and gravel (Bridge Reach, 

RKM 12.5), sand (Bridge Reach, RKM 5.2), and 

boulder and sand (Bridge Reach, RKM 4.9). No 

bed observations were available for the South 

Fork Coquille River. 

The repeat cross sections indicate that the 

channels near bridge crossings in the study area 

are dynamic and many are subject to channel 

shifting as well as aggradation or incision (table 

9). The patterns of channel change, however, differed between the river segments. On the South 

Fork and mainstem Coquille River (fig. 15A–B to 

fig. 17A–B), the thalweg of the channel near 

three bridges incised more than 0.5 m in elevation 

over the survey periods; exceptions were near 

bridges at RKM 108.3 in the Powers Reach (fig.

15A), where the channel flows over bedrock, and 

RKM 60.3 in the Myrtle Point Reach, where the 

river is affected by tide (fig. 17A). Incision of the 

thalweg occurred in the Broadbent Reach of the 

South Fork Coquille River from 1994 to 2008 as 

the channel shifted toward the left bank near 

RKM 89.4 and 75.1 (fig. 16A–B; table 9). In conjunction with the lateral shifting in the Broadbent 

Reach, the channel banks experienced several 

meters of deposition and erosion. 

The repeat surveys on the Middle and North 

Forks of the Coquille River showed that changes 

in channel geometry varied between sites. In the 

Bridge Reach of the Middle Fork Coquille River, 

the thalweg incised a net 0.8 m at RKM 13.8, 

primarily from 1992 to 2000, but then aggraded 

1.1 m at RKM 12.5 from 1992 to 2004 and 1.2 m 

at RKM 2.4 from 2000 to 2004 (fig. 18A–B, F; 

table 9). Near the other bridges in the Bridge 

Reach, the elevation of the thalweg was relatively 

stable while the banks experienced some erosion 

and deposition (fig. 18C–E, G). In the Gravelford 

Reach of North Fork Coquille River, the thalweg

incised 1.6 m from 2006 to 2008 at RKM 6.6, but 

aggraded a net 0.8 m from 2000 to 2009 at tidally 

affected RKM 0.4 (fig. 19A–B; table 9).
44

Table 9. Summary of net changes measured from channel cross sections surveyed by the Oregon Department of Transportation (ODOT) in the 

Coquille River study area, southwestern Oregon—continued

[RKM, river kilometer; m, meter; Rd, road, Hwy, highway; --, no data available; St, street; CBR, Coos Bay-Roseburg]

River Reach Bridge RKM

ODOT 

bridge 

ID

Survey 

year(s)

Net 

thalweg 

elevation 

change 

(m)

Maximum net 

erosion (m)

Maximum net 

deposition 

(m)

Notes

Left 

bank

Right 

bank

Left 

bank

Right 

bank

South Fork Coquille River

Powers Johnson 

Mountain Rd

108.3 11C761 1994, 

2008

-0.2 -0.5 -0.5 +3.3 +0.4 Relatively stable except for deposition on upper 

left bank; channel flows over bedrock

County Hwy 

219

106.1 01942A 2001, 

2005, 

2009

-0.6 -1.5 -1.7 +1.0 +0.6 Thalweg shifted from right to left channel from 

2001 to 2005; mid-channel feature aggraded 

from 2001 to 2005 but then eroded from 2005 

to 2009

Powers Hwy 103.2 01745A 2005 -- -- -- -- -- --

Baker Creek 

Lane

100.0 -- -- -- -- -- -- -- Bridge and channel conditions not monitored by 

ODOT

Broadbent Gaylord Rd 89.4 16349 1994, 

2008

-1.9 -5.1 0 0 +2.7 Mainly erosion on left bank and deposition on 

right bank; channel shifted toward left bank

West Side Rd 75.1 05066A 1994, 

2008

-0.6 -0.2 0 +0.5 +1.2 Same as channel near RKM 89.4

Myrtle 

Point

Spruce St 60.3* 18136 2004, 

2008

-0.4 -0.3 -0.1 +1.0 +0.2 Decrease in thalweg elevation; variable bank 

erosion and deposition

Mainstem

Bandon CoquilleBandon Hwy38.9* 00589D 2000, 

2003, 

2010

-0.5 -0.9 -1.8 +2.0 +0.5 Same as channel at RKM 60.3

Hwy 101 5.4* 07020 2000 -- -- -- -- -- --
45

Table 9. Summary of net changes measured from channel cross sections surveyed by the Oregon Department of Transportation (ODOT) in the 

Coquille River study area, southwestern Oregon—continued

[RKM, river kilometer; m, meter; Rd, road, Hwy, highway; --, no data available; St, street; CBR, Coos Bay-Roseburg]

River Reach Bridge RKM

ODOT 

bridge 

ID

Survey 

year(s)

Net 

thalweg 

elevation 

change 

(m)

Maximum net 

erosion (m)

Maximum net 

deposition 

(m)

Notes

Left 

bank

Right 

bank

Left 

bank

Right 

bank

Middle Fork Coquille River

Bridge CBR Hwy 13.8 08935 1992, 

2000, 

2004, 

2009

-0.8 -0.8 -0.4 +0.5 +0.3 Channel erosion and deposition over time

CBR Hwy 12.5 08936 1992, 

2000, 

2004, 

2009

+1.1 0 -0.8 +1.6 +0.9 --

McMullen Rd 10.0 11C65I 1994, 

2004, 

2008

-0.1 -0.4 -0.3 +0.3 +1.4 Deposition on right bank and in channel from 

1994 to 2004; main channel eroded from 2004

to 2008

CBR Hwy 5.2 08876 2000, 

2004, 

2010

+0.3 0 0 +0.6 +2.9 Channel deposition from 2000 to 2004 and less 

from 2004 to 2010; erosion between surveys

CBR Hwy 4.9 08875 2000, 

2004, 

2010

-0.1 0 -0.2 +0.4 +0.4 --

CBR Hwy 2.4 08830 1993, 

2000, 

2004, 

2009

+1.2 -8.3 -2.3 +1.0 +1.3 --

CBR Hwy 0.5 08842 1993, 

2000, 

2004, 

2009

+0.5 -1 -1.9 +0.9 +0.9 --

North Fork 

Coquille River

Gravelford Sitkum Lane 6.6 20127 2006, 

2008

-1.6 -2 -1.7 0 0 Deposition in channel but stable geometry

8th St 0.4* 01056A 2000, 

2004, 

2009

+0.8 -0.2 -1.3 +1.1 +0.2 Deposition on right bank from 2000 to 2004 

that erodes by 2009; thalweg relatively stable 

from 2000 to 2004, but aggraded and shifted 

right by 2009; tidally affected

*Bridge within tidally influenced river section
46

Figure 15. Diagrams showing channel cross sections surveyed at RKM 108.3 and 106.1 in the Powers Reach on 

the South Fork Coquille River, southwestern Oregon. Data provided by the Oregon Department of Transportation 

(written commun., 2010). Mean daily discharge record is from the U.S. Geological Survey streamflow-gaging station 

at Powers, Oregon (14325000) on the South Fork Coquille River for each survey date. 
47

Figure 16. Diagrams showing channel cross sections surveyed at RKM 89.4 and 74.1 in the Broadbent Reach on 

the South Fork Coquille River, southwestern Oregon. Data provided by the Oregon Department of Transportation 

(written commun., 2010). Mean daily discharge record is from the U.S. Geological Survey streamflow-gaging station 

at Powers, Oregon (14325000) on the South Fork Coquille River for each survey date. 
48

Figure 17. Diagrams showing channel cross sections surveyed at RKM 60.3 in the Myrtle Point Reach of the South 

Fork Coquille River and RKM 38.9 in the Bandon Reach on the Coquille River, southwestern Oregon. Data provided by the Oregon Department of Transportation (written commun., 2010). Mean daily discharge record is from 

the U.S. Geological Survey streamflow-gaging station at Powers, Oregon (14325000) on the South Fork Coquille 

River for each survey date.
49

Figure 18. Diagrams showing channel cross sections surveyed at RKM 13.8, 12.5, 10.0, 5.2, 4.9, 2.4, and 0.5 in 

the Bridge Reach on the Middle Fork Coquille River, southwestern Oregon. Data provided by the Oregon Department of Transportation (written commun., 2010). Mean daily discharge record for each survey date is from the U.S. 

Geological Survey streamflow-gaging station at Powers, Oregon (14325000) on the South Fork Coquille River because the Middle Fork Coquille River gage near Myrtle Point (14326500) was no longer operational. 
50

Figure 18 (continued). Diagrams showing channel cross sections surveyed at RKM 13.8, 12.5, 10.0, 5.2, 4.9, 2.4, 

and 0.5 in the Bridge Reach on the Middle Fork Coquille River, southwestern Oregon. Data provided by the Oregon 

Department of Transportation (written commun., 2010). Mean daily discharge record for each survey date is from 

the U.S. Geological Survey streamflow-gaging station at Powers, Oregon (14325000) on the South Fork Coquille 

River because the Middle Fork Coquille River gage near Myrtle Point (14326500) was no longer operational. 
51

Figure 19. Diagrams showing channel cross sections surveyed at RKM 6.6 and 0.4 in the Gravelford Reach on the 

North Fork Coquille River, southwestern Oregon. Data provided by the Oregon Department of Transportation (written commun., 2010). Mean daily discharge record for each survey date is from the U.S. Geological Survey 

streamflow-gaging station at Powers, Oregon (14325000) on the South Fork Coquille River because the North Fork 

Coquille River gage near Myrtle Point (14327000) was no longer operational.
52

Near the bridges where the net thalweg elevation changes were less than +/- 0.5 m, 

substantial cross-section changes include (1) bank 

aggradation (up to 3.3 m) and erosion (up to 0.5 

m) at RKM 108.3 in the Powers Reach from 1994 

to 2008 (fig. 15A), (2) aggradation of 1 m near 

the channel at RKM 60.3 in the Myrtle Point 

Reach from 2004 to 2008 (fig. 17A), and (3) bank 

aggradation of 1.4 m from 1994 to 2008 at RKM 

10 and 2.9 m from 2000 to 2010 at RKM 5.2 in

the Bridge Reach (fig. 18C–D).

Specific Gage Analysis

Following the approach of Klingeman 

(1973), a specific gage analysis was conducted 

for the USGS streamflow-gaging station on the 

South Fork Coquille River at Powers, Oregon

(14325000; RKM 105; fig. 1; table 1). Of the 

available gaging stations (table 1), the gaging station at Powers was selected for this analysis 

because it has a long-term period of record and is

operational as of 2011. The specific gage analysis 

enables the detection of changes in streambed 

elevation by assessing changes in water elevation 

(stage) over time for specific discharge values. At 

USGS streamflow-gaging stations, discharge is 

related to stage by a stage-discharge rating curve, 

which is based on multiple, paired stage and discharge measurements that are taken at a range of 

streamflows. New rating curves are developed if 

the channel conditions change substantially (as 

shown by consistent offsets of newer measurements from the established rating curves) or if a 

station is relocated. The specific gage analysis 

evaluates trends in downstream hydraulic control 

as indicated by the sequence of rating curves; hydraulic control, is in turn a function of bed 

elevation. 

The USGS has collected streamflow records 

at the Powers gaging station on the South Fork 

Coquille River (RKM 105) since 1917 (table 1). 

Because the datum for stage measurements made 

prior to November 1939 cannot be reliably verified, the analysis period for the specific discharge 

analysis was November 1939–January 2010. 

Changes in stage were assessed for low to moderate flows (0.57–87.8 m3

/s) because these flows 

are more sensitive to minor adjustments in bed 

elevation and are less likely to be influenced by 

temporal changes in bank vegetation or bank 

shape. 

From November 1938 to January 2010, the 

stage-discharge relations for the five analyzed 

discharges show variations spanning as much as 

0.5 m, but all lowered by a net 0.27–0.31 m over 

the analysis period (fig. 20). Although in-channel 

bedrock immediately downstream of the gage 

(such as near RKM 103.6; fig. 8) would serve as 

a local barrier preventing substantial channel incision from propagating up- or downstream, this 

general trend of a reduction in stage for specific 

discharges, indicating either channel incision or 

widening, is consistent with the channel incision 

evident in repeat channel cross sections up- and 

downstream of the gage at RKM 106.1 and 89.4 

on the South Fork Coquille River (table 9; figs. 

15B and 16A). 

Over the period of record, the overall declining stage trend has been interrupted by short 

periods of rising stage during three periods 

(1955–1956, 1963–1965, and 1995–1997; fig.

20). These episodes coincide with the floods exceeding a 10-year return period on December 21, 

1955, December 22, 1964, and November 18, 

1996 (fig. 4B), and perhaps indicate bed-material 

transport and channel aggradation associated with 

these relatively large floods. Future review and 

analysis of station notes, historical cableway surveys, and individual discharge measurements 

could provide additional information on trends in 

channel geometry and bed-material at this station. 
53

Figure 20. Graph showing the stage-discharge rating curve for specific discharges for the U.S. Geological Survey 

streamflow-gaging station at Powers (14325000) on the South Fork Coquille River, southwestern Oregon. The 

source data are station records housed at the Oregon Water Science Center, U.S. Geological Survey, Portland, 

Oregon. 

Delineation of Bars and Channel Features, 

1939–2009

For this reconnaissance-level study, we 

mapped: 

1. Channel centerlines for the full study area extent using orthophotographs taken in 2009 

(table 4) to develop the linear reference system for this study, and 

2. Bars, channel centerlines, and wetted channel 

edges for the Powers Reach from RKM 108.1 

to 96.9 and the full extent of all other reaches 

using aerial and orthophotographs taken in 

1939, 1967, 2005, and 2009 (table 4) to assess 

temporal changes in the location and areal 

coverage of bars and the length and wetted 

width of the channel. 

For both efforts, we delineated lateral and medial 

bars greater than 300 m2 from aerial and orthophotographs at a scale of 1:10,000 for the 

lowermost 24.8 km of the Bandon Reach and 

1:3,000 for the rest of the study area using the 

Geographic Information System (GIS) programs 

ESRI ArcGISTM 9.3.1 and 10.0.3. Although bars 

were not classified according to grain size (or vegetation or habitat types), field observations made 

during July 2010 indicated that most bars in the 

Powers, Broadbent, and Myrtle Point Reaches 

were composed of rounded gravel and finer particles with bar texture generally fining toward the 

head of tide at RKM 63.2. Bars were primarily 

composed of coarse, subangular basalt clasts in 

the Bridge Reach and sand and fine grain particles in the Gravelford and Bandon Reaches. The 

Bandon Reach also contains mud flats and tidal 

marshes near the Coquille River mouth. While 

most of the mapped bars had little to no vegetation, some bars included small areas that were 

partly or wholly covered by grasses, shrubs, and 

(to a lesser extent) mature trees. The delineation 

of bars, channel centerlines, and wetted channel 

edges was repeatedly verified to ensure consistent 

delineation of features among years and throughout the study area following the protocol of 

Wallick and others (2011). 
54

Our mapping and change analysis relied on 

vertical aerial photographs obtained from various 

sources (table 4). Photographs from 2005 and 

2009 were taken by the USDA’s NAIP program. 

Scanned copies of black and white photographs 

taken in 1939 and 1967 were acquired from the 

University of Oregon Map and Aerial Photography Library and georeferenced for this study 

using techniques similar to Wallick and others 

(2011). Because the 1939 aerial photographs covered only the Powers Reach between RKM 108.1 

and 96.9, repeat feature delineation was done for 

only this segment of the Powers Reach (fig. 8). 

Streamflows were generally lowest during the 

2005 photography (1.6 m3/s) and slightly greater 

during the collection of the 2009 (approximately 

1.6–2.5 m3/s) and 1939 (2.7–4.1 m3/s) photography (table 10). Streamflow during the 1967 

photography was substantially greater than during 

the other photographic activities and ranged from 

7.3 to 26.1 m3/s. These streamflow differences 

between the photographs likely affect the year to 

year comparisons of mapped features.

The quality of underlying photographs and 

errors introduced by georectified and digitizing 

processes are three of many potential sources of 

uncertainty in digital channel maps (Gurnell, 

1997; Mount and Louis, 2005; Hughes and others, 2006; Walter and Tullos, 2009). Aerial 

photographs of the Coquille River study area 

were of sufficient resolution and generally free of 

glare and shadow to enable precise mapping. The 

1939 and 1967 photographs were georectified 

with a minimum of eight ground-control points 

concentrated near the main channel and rectified 

with a second-order polynomial transformation. 

The total root mean square error (RMSE) values 

of the rectified photographs from 1939 and 1967 

indicated that horizontal-position uncertainties 

associated with the georectification process 

ranged from 1.4 to 6.4 m for individual photographs, but averaged 3.2 m for the 1939 

photographs and 3.4 m for the 1967 photographs. 

Because control points were concentrated near 

the channel, error associated with mapped features along channel corridor should be lower than 

the total RMSE values for the entire photograph. 
55

Table 10. Stream discharge for the aerial and orthophotographs used for repeat bar and channel feature delineation in the Coquille River study area, southwestern Oregon. 

[m3/s, cubic meter per second; --, same as main discharge; UO, University of Oregon; USACE, U.S. Army Corps of 

Engineers; USGS, U.S. Geological Survey]

Year Reach Flight dates

USGS gaging station used to determine discharge on day of 

photograph collection

Mean daily discharge (m3/s)

Minimum Maximum Main1

19392 Powers 5/5 South Fork at Powers (14325000) -- -- 2.7

Broadbent 5/5 South Fork at Powers (14325000) -- -- 2.7

Myrtle 

Point

5/5 South Fork at Powers (14325000) -- -- 2.7

Bandon 5/5 South Fork at Powers (14325000) -- -- 2.7

Bridge 5/5 Middle Fork near Myrtle Point 

(14326500)

-- -- 2.5

Gravelford 5/5 North Fork near Myrtle Point 

(14327000)

-- -- 4.1

1967 Powers 5/8; 5/25 South Fork at Powers (14325000) 7.3 26.1 7.3, 26.1

Broadbent 5/8; 5/25 South Fork at Powers (14325000) 7.3 26.1 26.1

Myrtle 

Point

5/8; 5/25 South Fork at Powers (14325000) 7.3 26.1 26.1

Bandon 5/25; 8/5 South Fork at Powers (14325000) 0.9 7.3 7.3

Bridge 5/8; 5/19; 5/25 South Fork at Powers (14325000)3 7.3 26.1 26.1

Gravelford 5/8 North Fork near Myrtle Point 

(14327000)

-- -- 18.8

2005 Powers 7/17; 7/19; 8/5 South Fork at Powers (14325000) 0.9 1.6 1.6

All other 

reaches

7/17 South Fork at Powers 

(14325000)3,4

-- -- 1.6

2009 Powers 6/22; 7/15 South Fork at Powers (14325000) 1.6 2.5 1.6, 2.5

Broadbent 6/18; 7/15 South Fork at Powers (14325000) 1.6 2.3 1.6, 2.3

Myrtle 

Point

6/18; 7/15 South Fork at Powers (14325000) 1.6 2.3 1.6, 2.3

Bandon 6/17/; 6/18; 7/15 South Fork at Powers (14325000) 1.6 2.4 2.3

Bridge 6/22; 7/15 South Fork at Powers (14325000)3 1.6 2.5 1.6

Gravelford 6/22; 7/15 South Fork at Powers (14325000)4 1.6 2.5 1.6, 2.5

1 Main discharge is the streamflow when most of the reach was photographed. Two discharge values are provided 

when areal coverages were approximately equal for photograph collection dates.

2 Dates derived from 1939 photographs at USACE library in Portland, Oregon

3 USGS streamflow-gaging station on Middle Fork Coquille River near Myrtle Point, Oregon (14326500) not operational 

4 USGS streamflow-gaging station on North Fork Coquille River near Myrtle Point, Oregon (14327000) not operational 
56

Distribution and Area of Bars, 2009

In 2009, the total area of bars delineated 

along the Coquille River and its forks within the 

study area was 2,896,020 m2 (table 11). Unit bar 

area, or the total area of bars per meter of channel 

length (m2

/m), was 21.0 m2/m for all reaches (table 12). The tidal Bandon Reach had the greatest 

unit bar area for an individual reach (39.2 m2/m), 

with extensive bars mapped in the lower 10 km 

(table 12). In the fluvial reaches, unit bar area 

ranged from 0.4 m2/m in the Gravelford Reach to 

12.6 m2/m in the Powers Reach (table 12). Unit 

bar area values for fluvial reaches in the Coquille 

River basin are generally less than those reported 

for fluvial reaches in the bedrock-dominated 

Umpqua River basin (5.0–17.6 m2/m from 2005 

orthophotographs; Wallick and others, 2011) and 

substantially less than some values reported for 

fluvial or predominately fluvial reaches in the 

Hunter Creek basin (19.1 and 19.7 m2/m from 

2009 orthophotographs; Jones and others, 2011) 

and in the Rogue (10.6–63.1 m2/m from 2009 orthophotographs; Jones and others, 2012), 

Applegate (4.3 and 71.5 m2

/m from 2009 orthophotographs; Jones and others, 2012), Illinois 

(91.8 m2/m from 2009 photographs; Jones and 

others, 2012), and Chetco (9.3–77.5 m2

/m from

2005 orthophotographs; Wallick and others, 

2010) River basins. 

Examination of the bars delineated from the 

2009 photographs (fig. 21A–C) shows that the 

location, abundance, and size of bars in fluvial 

reaches are mainly dictated by interrelated factors 

such as channel slope (fig. 3A–C) and confinement, which owe to factors such as valley 

physiography, the associated increase in floodplain width (fig. 3A–C) as the river approaches its 

mouth, and anthropogenic modifications including dikes and levees. As shown in figure 21A–C 

and table 11, bar area is substantially less in the 

Bridge and Gravelford Reaches on the Middle 

and North Forks of the Coquille River, respectively (figs. 12 and 13) and in the confined 

segments in the Powers (such as RKM 103.6–

100.6; fig. 8), Broadbent (such as RKM 86.8–

83.2; fig. 9), and Myrtle Point (such as RKM 

66.2–64.8; fig. 10) Reaches on the South Fork 

Coquille River. Conversely, the greatest areal 

coverage of bars are in the unconfined segments 

of the Powers (such as RKM 115.4–103.6; fig. 8) 

and Broadbent (such as RKM 93, 88–87, and 73; 

fig. 9) Reaches.

The distribution of bars in the fluvial reaches 

also indicates key sources of gravel to the Coquille River. The greater area of bars in the 

reaches along the South Fork Coquille River relative to the reaches on the Middle and North Forks 

of the Coquille River indicates that the South 

Fork Coquille River basin is a primary source of 

gravel to the river network. Gravel production 

from the South Fork Coquille River is consistent 

with its situation as a high-relief basin draining 

the Klamath Mountains geologic province (fig.

1). The increase in bar area along the lower 3 km 

of the Bridge Reach (fig. 21B) likely reflects the 

river’s cutting through an outcrop of Coast Range 

volcanic rocks, which produce much more competent material than the Coast Range sedimentary 

rocks that dominate much of the Middle Fork 

Coquille River basin (fig. 1).

The tidally influenced Bandon Reach has by 

far the greatest bar area, ranging from bars consisting of sand and finer particle sizes near the 

reach’s upstream boundary to extensive mud flats 

and tidal wetlands in the reach’s lowermost 15 

km. Bar area is greatest near the Coquille River 

mouth (fig. 21A), corresponding with the increase 

in floodplain width (fig. 3A). The marked decline 

in channel gradient near the confluence of the 

South and North Forks of the Coquille River 

(RKM 58.5) likely promotes the deposition of 

coarse sediment load as well as suspended sediment loads transported from steeper and more 

confined upstream sections (figs. 2; and 3A–C), 

leading to bars in the uppermost Bandon Reach 

being composed of much finer material than bars 

in upstream reaches. 
57

Table 11. Repeat bar attribute data as delineated from photographs taken in 1939, 1967, 2005, and 2009 for the Coquille River study area, southwestern Oregon.

[ m2, square meter; %, percent]

Reach

Bar area (m2) Number of bars Average bar area (m2)

1939 1967 2005 2009

Net % 

change 1939 1967 2005 2009

Net % 

change 1939 1967 2005 2009

Net % 

change

Powers1 184,640 72,040 130,010 140,530 -23.9 64 49 55 49 -23.4 2,890 1,470 2,360 2,870 -0.6

Broadbent 631,880 327,940 329,790 349,970 -44.6 122 77 128 134 9.8 5,180 4,260 2,580 2,610 -49.6

Myrtle Point 49,710 26,090 55,200 63,460 27.6 22 15 20 29 31.8 2,260 1,740 2,760 2,190 -3.2

Bandon 1,773,770 1,792,440 2,227,730 2,295,930 29.4 23 40 21 47 104.3 77,120 44,810 106,080 48,850 -36.7

Bridge 89,090 85,630 51,780 39,770 -55.4 62 42 36 26 -58.1 1,440 2,040 1,440 1,530 6.4

Gravelford 13,620 11,220 7,550 6,370 -53.2 18 7 10 8 -55.6 760 1,600 750 800 5.3

All reaches 2,742,710 2,315,350 2,802,050 2,896,020 5.6 311 230 270 293 -5.8 8,820 10,070 10,380 9,880 12.1

Tidal reaches2 1,823,480 1,818,530 2,282,920 2,359,390 29.4 45 55 41 76 68.9 40,520 33,060 55,680 31,040 -23.4

Fluvial reaches3 919,230 496,820 519,120 536,630 -41.6 266 175 229 217 -18.4 3,460 2,840 2,270 2,470 -28.4

1 Repeat attribute data compiled for RKM 108.1–96.9

2 Myrtle Point and Bandon Reaches

3 Powers, Broadbent, Bridge, and Gravelford Reaches
58

Table 12. Repeat unit bar area data as delineated 

from photographs taken in 1939, 1967, 2005, and 

2009 for the Coquille River study area, southwestern 

Oregon. 

[m2, square meter; %, percent]

Reach

Unit bar area (bar area per meter of 

channel; m2/m)

1939 1967 2005 2009

Net % 

change

Powers1 16.5 6.5 11.6 12.6 -23.9

Broadbent 20.6 10.9 10.8 11.4 -44.6

Myrtle Point 6.6 3.5 7.2 8.3 26.0

Bandon 30.4 30.8 38.1 39.2 28.9

Bridge 5.8 5.6 3.4 2.6 -55.6

Gravelford 0.9 0.8 0.5 0.4 -53.3

All reaches2 19.9 16.9 20.3 21.0 5.3

Tidal reaches2,3 27.7 27.7 34.6 35.6 28.7

Fluvial reaches2,412.8 7.0 7.2 7.5 -41.7

1 Repeat attribute data compiled for RKM 108.1–96.9

2 Unit bar area calculated using cumulative bar area and 

length for specified reaches

3 Myrtle Point and Bandon Reaches

4 Powers, Broadbent, Bridge, and Gravelford Reaches

The mapping of bars from photographs dating 1939 to 2009 shows that total bar area 

decreased in the fluvial reaches, but increased in

the tidal reaches (table 11; fig. 22A). Along the 

South Fork Coquille River, total bar area declined 

by 24 and 45 percent in the fluvial Powers and 

Broadbent Reaches, respectively. Total bar area 

in the fluvial Bridge and Gravelford Reaches of 

the Middle and North Forks of the Coquille River 

decreased by 55 and 53 percent, respectively. In 

contrast, total bar area increased by 26 and 29 

percent in the tidal Myrtle Point and Bandon 

Reaches, respectively. Net changes in the repeat 

measurements of unit bar area were similar to the 

net changes in total bar area (table 12).

Net changes in the number (fig. 22B; table 

11) and average area of bars (table 11) varied by 

reach from 1939 to 2009. Generally, the number 

of mapped bars declined for the Powers, Bridge, 

and Gravelford Reaches with bars remaining approximately the same average area or increasing 

slightly in area. In the Broadbent Reach, bars became more numerous, but diminished by nearly 

50 percent in average area from 1939 and 2009 

(table 11). Likewise, in the tidal Myrtle Point and 

Bandon Reaches, bars increased in number while 

decreasing in average area (table 11). 

Results for Repeat Channel Centerline and Width 

Delineations, 1939–2009

Comparison of channel centerline length over 

time reveals that the length of the channel 

changed little for all reaches from 1939 to 2009 

and that the greatest change was channel length 

increasing 1.3 percent, or 100 m, in the Myrtle 

Point Reach (fig. 22C; table 13). Despite the 

overall stability in channel length (as delineated 

for this study), specific areas with lateral channel 

shifting include RKM 107.6–105.4 in the Power 

Reach (fig. 23), RKM 94–93.4, 83.2–78.8, and 

75–69.6 in the Broadbent Reach (figs. 24, 25, and

26), RKM 4.2 and 2–0 in the Bridge Reach (fig.

27), and RKM 4.2–4 in the Gravelford Reach 

(fig. 28). In all of these reaches, however, lateral 

movement of the channel centerline was less than 

120 m. 

Mapped wetted channel width is sensitive to 

the streamflow and tide levels at the time the photographs were taken. Nevertheless, from 1939 to 

2009, the average wetted width of the channel 

increased in all reaches except the Bandon Reach 

(fig. 22D; table 13). In fluvial reaches, the net 

increases in average wetted width ranged from 1 

m in the Powers and Bridge Reaches to 5 m in the 

Broadbent Reach. Because discharge was similar 

during the collection of the 1939 and 2009 photographs (table 10), these changes in average 

wetted width in the fluvial reaches may indicate 

actual channel widening, possibly in association 

with the loss of bar area. A more detailed delineation of the active channel width (instead of wetted 

channel width, which can be influenced by small 

streamflow or tide differences) may help better 

quantify possible changes in channel width for 

the fluvial study reaches and its relation to the 

extent and number of bars.
59

Figure 21. Graphs showing bar area by river kilometer as delineated from orthophotographs taken in 2009 for study reaches on the (A) South Fork and 

mainstem Coquille River, (B) Middle Fork Coquille River, and (C) North Fork Coquille River, southwestern Oregon. The upstream extent of the Powers 

Reach is RKM 115.4. 
60

Figure 22. Graphs showing the results for (A) total bar area, (B) bar number, (C) channel centerline length, and (D) 

average wetted channel width as delineated from photographs taken in 1939, 1967, 2005, and 2009 for the study 

areas on the mainstem and North and Middle Forks of the Coquille River and South Fork Coquille River to RKM 

108.1.
61

Table 13. Repeat channel feature data as delineated from photographs taken in 1939, 1967, 2005, and 

2009 for the Coquille River study area, southwestern Oregon. 

[m, meter; %, percent; RKM, river kilometer]

Centerline length (m) Average wetted channel width (m)

Reach 1939 1967 2005 2009

Net % 

change 1939 1967 2005 2009

Net % 

change

Powers1 11,180 11,040 11,180 11,170 0.0 21 36 24 22 7.6

Broadbent 30,740 30,050 30,570 30,710 -0.1 19 29 26 24 24.6

Myrtle Point 7,580 7,530 7,640 7,680 1.3 25 31 29 28 14.0

Bandon 58,260 58,170 58,410 58,520 0.4 119 116 108 107 -9.9

Bridge 15,330 15,330 15,420 15,410 0.5 23 25 24 24 3.7

Gravelford 14,560 14,520 14,560 14,600 0.2 14 17 16 16 11.6

All reaches 137,650 136,640 137,770 138,090 0.3 60 60 60 60 -5.3

Tidal reaches2 65,840 65,710 66,050 66,200 0.5 108 106 99 98 -9.3

Fluvial reaches3 71,810 70,940 71,730 71,890 0.1 19 26 23 22 14.5

1 Repeat attribute data compiled for RKM 108.1–96.9

2 Myrtle Point and Bandon Reaches

3 Powers, Broadbent, Bridge, and Gravelford Reaches

Discussion of Changes in Bar and Channel Features, 1939–2009

For the Powers and Broadbent Reaches on 

the South Fork Coquille River, the reductions in 

bar area were greatest from 1939 and 1967 (table 

11, fig. 22A). Inspection of the photographs reveals that most of this apparent reduction owes to 

the higher streamflows of the 1967 photographs 

(table 10). Additional examination of the photographs, however, suggests that the net reduction 

in bar area between 1939 and 2009 is associated 

with changes in channel position and deposition 

patterns (such as RKM 107.4–105.8, fig. 23; 

RKM 83.2–78, fig. 24; RKM 74.8–71.6, fig. 25; 

RKM 95–93, fig. 26) and vegetation establishment on previously active bar surfaces (such as 

RKM 76.8; fig. 26). Also, some bar surfaces delineated from the 1939 photographs have been 

eroded laterally, becoming part of the wetted 

channel in 2009 (such as near RKM 108–107.8 

and 106.8, fig. 23; RKM 82.8–82.2, 81.6–81.2, 

and 78.6–78.4, fig. 24). This lateral bar erosion is 

probably one cause of local increases in average 

wetted channel width (table 13).

As documented in the hazard maps by English and Coe (2011), segments of the South Fork 

Coquille River have shifted laterally in the past 

and are expected to shift in the future. From 1939 

to 2009, the wetted channel has shifted laterally 

in the Powers Reach (such as near RKM 106.2 

and 107.2, fig. 23). In the Broadbent Reach, lateral channel movement has lengthened some 

channel meanders, altering the extent and configuration of bars (figs. 24 and 25). At some 

dynamic channel bends, bar growth has likely 

resulted in the scour and erosion of banks on the 

opposite side of the river (such as near RKM 79, 

fig. 24; RKM 73.4, fig. 25). More nuanced conclusions regarding bank erosion processes in the 

Broadbent Reach will likely require detailed field 

measurements, hydraulic modeling, and a sediment budget to document trends in flow and 

sediment in relation to bank erosion in this dynamic section of the South Fork Coquille River. 

Lateral channel movement, bar geometry 

changes, and vegetation establishment on bar surfaces were evident in the repeat delineation of bar 

and channel features near instream gravel mining 

sites on the South Fork Coquille River. For 
62

Figure 23. Images showing repeat bar and channel delineations, lateral channel shifting, and vegetation establishment on bars in a section of the Powers Reach on the South Fork Coquille River, southwestern Oregon.
63

Figure 24. Images showing repeat bar and channel delineations, lateral channel movement, bank erosion, and other channel changes in the Broadbent Reach on the South Fork Coquille River near Warner, Oregon.
64

Figure 25. Images showing repeat bar and channel delineations, lateral channel movement, bank erosion, and other channel changes in the Broadbent Reach on the South Fork Coquille River near Broadbent, Oregon.
65

Figure 26. Images showing repeat bar and channel delineations for Hayes, Elliot/Seals, and Lokan Bars in the 

Broadbent Reach on the South Fork Coquille River, southwestern Oregon.
66

instance, at Hayes Bar (referred to as three sites at 

RKM 93.8, 93.3, and 92.3), the large bar on the 

west bank was stabilized by vegetation from 1939 

to 1967, but then was partially eroded from 1967 

to 2005 when the channel shifted westward following bar building on the east bank near RKM 

93.8 (fig. 26). Downstream at the Elliot and Seals 

Bars (RKM 88.8), the channel has shifted toward 

the south bank at the bend, resulting in the conversion of the multiple bars into primarily one 

point bar with the Seals and Elliot Bars connected 

at low streamflow (fig. 26). Near Lokan Bar 

(RKM 76.4), the extent of bars has declined following the lateral migration of the channel at 

RKM 76.6-76.4 from 1939-1967 as well as vegetation establishment on multiple bars and an 

increase in wetted channel width near RKM 76.6 

from 1967 to 2005 (fig. 26). Near Warner, Oregon (fig. 24), changes in the position of the 

channel have split Broadbent Bar (RKM 83) into 

two bars, reduced the area of Coos County Highway Bar (RKM 80.2), and eroded Isenhart Bar 

(RKM 81.8) with deposition occurring primarily 

on the east bank in 2009. Upstream and downstream of Herman Bar at RKM 79.0, four 

alternating channel bars are present along the 

channel in 1939 (fig. 24). Following changes owing to factors such as lateral channel movement 

and vegetation establishment, the channel flanking bars in this section have changed in 

distribution and extent and reduced in number 

from four to two bars. In particular, the erosion of 

the east bank opposite of the bar at RKM 79.0 has 

become more pronounced. 

On the basis of this preliminary analysis, it is 

unclear how these changes in bar area and configuration may specifically relate to gravel mining 

activities. In the absence of gravel mining, the 

Broadbent Reach is likely dynamic, with active 

bar building and channel migration. Changes in 

gravel volumes and associated mining activities 

probably have some effects on local channel behavior and bar geometry; documenting such 

effects would require in-depth, comprehensive 

studies including hydrologic and sediment modeling of the South Fork Coquille River. 

On the Middle and North Forks of the Coquille River, the greater than 50-percent net 

reductions in bar area from 1939 to 2009 were 

associated primarily with vegetation growth and 

subsequent stabilization of formerly unvegetated

bar surfaces (fig. 27; fig. 28). In the Bridge Reach 

on the Middle Fork Coquille River, bars changed 

shape and increased slightly in area (such as 

RKM 1.8; fig. 27; table 11), possibly owing to 

lateral channel migration and changes in deposition patterns. The 1967 photographs of the Bridge 

Reach show evidence of scour and bank erosion, 

likely from the December 1964 flood (fig. 27). 

On the North Fork Coquille River, the net reduction in bar area is mainly from vegetation 

stabilizing banks, particularly in areas that were 

eroding and sloughing sediment into the channel 

in 1939 (fig. 28).

Unlike the fluvial reaches, the tidally affected 

Myrtle Point and Bandon Reaches exhibited net

increases in total bar area between 1939 and 2009 

(table 11; fig. 22A). Inspection of the aerial photographs indicates that the apparent initial 

decrease in bar area from 1939 to 1967 in the 

Myrtle Point Reach is mainly due to discharge 

differences between the photographs (table 10). A 

review of the 1967 photographs also reveals areas 

with scour (such as near RKM 62; fig. 29), possibly from the December 22, 1964, flood. From

1967 to 2005, the South Fork Coquille River 

shifted its position and eroded into some banks 

within the Myrtle Point Reach; some of this migration resulted in new bars such as those near 

RKM 62 and 64.6 (fig. 29). 

In the Bandon Reach, bar area increased by 1 

percent from 1939 to 1967 and then increased by 

24 percent from 1967 to 2005. Substantial portions of the increase in bar area and some of the 

decrease in average wetted channel width (table 13) are likely associated with an increase in 

bar area near the mouth of the Coquille River 

(fig. 30). Based on a qualitative review of the 

USGS quadrangle and National Oceanic and Atmospheric Administration (NOAA) nautical 
67

Figure 27. Images showing repeat bar and channel delineations, vegetation establishment, and lateral channel 

movement in the Bridge Reach on the Middle Fork Coquille River, southwestern Oregon.
68

Figure 28. Images showing repeat bar and channel delineations and vegetation establishment in the Gravelford 

Reach on the North Fork Coquille River, southwestern Oregon.
69

Figure 29. Images showing repeat bar and channel delineations and lateral channel movement in the Myrtle Point Reach on the South Fork Coquille River, 

southwestern Oregon.
70

Figure 30. Images showing repeat bar and channel delineation in Bandon Reach near the mouth of the Coquille 

River, southwestern Oregon.
71

charts to the Coquille River entrance (table 5), 

differences in the mapping of the large tidal mudflat on the east side of the bay are likely 

associated with tide differences between the photographs. Other factors contributing to the 

increased bar area include possible sediment deposition from 1967 to 2005 and reductions in 

dredging volumes near the Coquille River mouth 

(fig. 6). Quantitative comparison of bathymetric 

surveys may be useful for assessing the potential 

changes in sediment deposition within the bay. 

Farther upstream, in the upper 1.3 RKM of 

the Bandon Reach, the channel has contained 

larger bars since 1967 (fig. 31). Scour of vegetated surfaces, sediment deposition, and lateral 

channel movement (likely following the December 22, 1964, flood) are evident in the 1967 

photographs. Since 1967, vegetation has become 

established, stabilizing some of the previously 

scoured bars. 

Analyses of Bed-Material Particle Sizes

In July 2010, we measured surface particle 

size distributions at two bars and collected a subsurface bulk sample at one bar along the South 

Fork Coquille River. Surface and subsurface particle data were collected at Seals Bar (an active 

instream mining site at RKM 88.8, Broadbent 

Reach), whereas only surface particle data were 

collected at China Flat Bar (approximately 2.4 

km upstream of the Powers Reach; fig. 1). These 

bars were selected on the basis of bar size, accessibility, and condition (such as little to no recent 

vehicle disturbance). To maintain consistency 

with other completed and ongoing bed-material 

studies (Wallick and others, 2010, Wallick and 

others, 2011, Jones and others, 2011, and Jones 

and others, 2012), we collected bed material data 

at a point bar (Seals Bar) and a lateral bar (China 

Flat Bar) likely formed by recent deposition 

events as indicated by the absence or minimal 

coverage of vegetation. 

At the China Flat and Seals Bars, 200 surface 

particles were measured using a modified grid 

technique (Kondolf and others, 2003) and gravelometer measurement template (Federal Interagency Sediment Project US SAH-97 

Gravelometer), which allows for the standardized 

measurement of sediment clasts greater than 2 

mm in diameter. Diameter measurements of surface particles were taken at 0.3-m increments 

along two parallel 30-m tapes that were placed 1–

2 m apart and parallel to the long axis of the bar. 

To support consistent intersite comparisons, the 

measurement transects were located at the bar 

apex (defined as the topographic high point along 

the upstream end of the bar) when possible. At 

China Flat Bar, measurement transects were located in a section of the bar that appeared active 

and representative of bar texture since the apex 

was obstructed by some vegetation. Measurements at Seals Bar were taken prior to that 

summer’s gravel mining by the Knife River Corporation. 

At the surface bed-material measurement 

transect at Seals Bar, we also sampled the subsurface bed material to evaluate particle size 

differences between surface and subsurface bed 

material (a measure of bar “armoring”). We removed approximately 1 m2

 of the bar-surface 

material, and then collected 72 kg of the barsubstrate material. This bulk sample then was 

dried and analyzed for 1⁄2-phi particle sizes by the 

USGS Sediment Laboratory in Vancouver, Washington. 

At the two sites on the South Fork Coquille 

River, the median diameter (D50) of surface particles varied from 78.0 mm at China Flat Bar 

slightly upstream of the study area to 48.8 mm at 

Seals Bar in the Broadbent Reach (table 14, fig.

32A–C). Bar-surface material was larger than 

bar-subsurface material at Seals Bar (table 14, fig.

32A). Differences in the sizes of surface and subsurface particles can be related to the balance 

between sediment supply and transport capacity, 

with the surface layer coarsening when the transport capacity of a river exceeds its supply of fine 

sediments (Dietrich and others, 1989; Buffington 

and Montgomery, 1999) as well as with the selective transport of bed material (Lisle, 1995). The 

armoring ratio, or ratio of the 
72

Figure 31. Images showing repeat bar and channel delineations and lateral channel movement in a section of the 

Bandon Reach on the Coquille River, southwestern Oregon.
73

median grain sizes (D50) of the surface to subsurface layers, provides an indication of the degree 

of armoring. Armoring ratios are typically close 

to 1 (meaning surface and subsurface particles are 

of similar sizes) for rivers with a high sediment 

supply, and approach or exceed 2 for supplylimited rivers (Bunte and Abt, 2001). The armoring ratio for Seals Bar was 3.5, indicating 

sediment supply limitation at this site (table 14). 

For comparison, armoring ratios ranged from 

0.99-4.73 in the Umpqua River basin (30 sites; 

Wallick and others, 2011), 1.2–3.4 in the Rogue 

River basin (7 sites, Jones and others, 2012), 1.38 

to 2.09 in the Chetco River basin (3 sites; Wallick 

and others, 2010), and 0.97–1.5 in the Hunter 

Creek basin (2 sites; Jones and others, 2011). Because bar texture can vary tremendously between 

sites on gravel-bed rivers (as evident for Oregon 

coastal rivers), additional bed-material measurements within the study area would help refine 

assessments of transport and sediment-supply 

conditions and longitudinal bed-material trends 

for the Coquille River basin. 

Discussion and Synthesis

On the basis of literature review, field observations, topographic analysis and delineation of 

bars and channels from multiple photographs, we 

defined a study area encompassing 145.4 km of 

the mainstem Coquille River and the lower parts 

of three main forks—the South, Middle, and 

North Forks of the Coquille River. Within the 

study area, the channels locally flow on or adjacent to bedrock as well as alluvial deposits. The 

active channels alternate between being confined 

and unconfined by flanking valley margins. Tide 

affects the entire mainstem Coquille River, South 

Fork Coquille River to RKM 63.2, and North 

Fork Coquille River to RKM 0.9. Within this 

study area, our analysis in conjunction with previous studies allows for a broad synthesis of 

channel and floodplain characteristics as well as 

overall bed-material transport conditions. 

Table 14. Bed-material data collected in the Coquille River study area, southwestern Oregon.

[--, no data; km, kilometer; RKM, river kilometer; m, 

meter; mm, millimeter; D16, 16th percentile diameter 

in mm; D50, median diameter in mm; D84, 84th percentile diameter in mm]

Bar China Flat Seals

Reach -- Broadbent

Location 2.4 km upstream of 

Powers Reach RKM 88.8

Northing (m) 4,736,738 4,756,715

Easting (m) 412,633 409,352

Surface particles

D16 (mm) 23.0 16.4

D50 (mm) 78.0 48.8

D84 (mm) 267.1 90.0

Subsurface particles

D16 (mm) -- 0.8

D50 (mm) -- 13.8

D84 (mm) -- 58.7

Armoring ratio -- 3.5

Spatial Variation in Channel Conditions

The full length of river within the study area 

can be divided into six study reaches based on 

topography and hydrology. The channels flow 

over alternating alluvial deposits and bedrock in 

the Powers (South Fork Coquille River) and 

Bridge (Middle Fork Coquille River) Reaches. 

Meanwhile, the channels flow over predominantly alluvial deposits in the Broadbent (South Fork 

Coquille River), Gravelford (North Fork Coquille 

River), Myrtle Point (mainstem Coquille River), 

and Bandon (mainstem Coquille River) Reaches. 

As for many coastal rivers in Oregon, (for 

example, Wallick and others, 2011; Jones and 

others, 2011, 2012), valley confinement exerts a 

considerable control on the character of the tributaries and mainstem in the Coquille River basin. 

Generally, the confined segments contain fewer 

bars and have relatively stable planforms, whereas the unconfined segments have a greater 

number and area of bars and greater rates and 

magnitudes of lateral channel migration. Likewise, the geologic environment is a primary 
74

Figure 32. Graph showing (A) size distributions of surface and subsurface particles and (B-C) photographs of measurement transects for two bed-material sampling sites along the South Fork Coquille River, southwestern Oregon. 

Surface size distributions were determined by measuring 200 clasts; subsurface size distribution was determined 

from a bulk sample taken below the armor layer.

factor controlling bed-material transport and 

channel morphology in the Coquille River and 

other Oregon coastal rivers. The South Fork Coquille River is the only tributary draining a 

substantial area of the Klamath Mountains geologic province. The metamorphic Mesozoic rocks 

of this geologic province combined with steep 

slopes and dense stream networks enhance the 

production and delivery of bed-material sediment, 

resulting in large bed-material fluxes as reported 

for the Chetco (Wallick and others, 2010) and 

Smith (MFG and others, 2006) Rivers and contributes to expansive bars and alluvial reaches on 

the Rogue and Illinois Rivers (Jones and others, 

2012) and Hunter Creek (Jones and others, 2011). 

The reaches along the South Fork Coquille 

River have the greatest unit bar area of the fluvial 

reaches, and have been historically subject to the 

most instream gravel mining. Of the two South 

Fork Coquille River reaches, however, the 

Broadbent Reach is likely the only fully alluvial 

reach as indicated by the much lower frequency 

of bedrock outcrops and greater measurements of 

total bar area in this reach compared to the Powers Reach (table 11; fig. 21A). 

Unit bar area measurements were lowest for 

the Bridge and Gravelford Reaches on the Middle 

and North Forks of the Coquille River, which 

drain predominantly the sedimentary subdivision 

of the Coast Range geologic province. The local 

outcrop of the Coast Range volcanic rocks at the 

lower end of the Bridge Reach, however, apparently results in increased bed material as 

indicated by the greater frequency of bars in the 

lowermost 3 km of the Middle Fork Coquille 

River (figs. 12 and 21B).

The Bandon Reach (mainstem Coquille River), Myrtle Point Reach (South Fork Coquille 

River), and lower part of the Gravelford Reach 

(North Fork Coquille River) are tidally influenced 

river segments. In these reaches, gradients are 

much lower (fig. 3A,C) and substantial transport 

of gravel-sized bed material is unlikely. Bedload, 

and consequently most bed material in these 

reaches, is probably mostly sand and finer particles, much of which was probably transported as 

suspended load from the steeper upstream sections. The large bars in the lower 15 km of the 

Bandon reach are largely composed of this finer 

material. Additionally, the substantial length of 

river (about 64 km of channel, including all of the 

mainstem Coquille River and the lower parts of 

the South and North Forks of Coquille River) affected by tide reflects the Holocene sea-level rise 
75

and the consequent drowning of the lower Coquille River valley at a rate faster than it is being 

filled by coarse bed material (sand and gravel). 

This difference between sea-level rise and coarse 

sediment flux suggests that the Coquille River has 

relatively lower sand and gravel transport rates 

than other coastal rivers, such as the Rogue River 

(Jones and others 2012), Chetco River (Wallick 

and others, 2010), and Hunter Creek (Jones and 

others, 2011), where the tide affects less than 7 

km of channel. 

Temporal Trends in Channel and Bar Conditions

Patterns in the accumulation and texture of 

bed material logically relate to channel and valley 

physiography, hydrology, and geology. However, 

temporal trends in channel and bar conditions and 

their interpretation are more ambiguous and vary 

by reach. The interpretation of temporal trends is 

also hindered by the complex and locally intense 

land-use practices historically affecting the channels in the basin, including splash damming, 

dredging, and sand and gravel mining. 

Multiple lines of evidence indicate that all 

reaches within the Coquille River study area have 

the potential for local vertical and lateral channel 

adjustments in response to changes in flow, sediment, and possibly riparian vegetation. In some 

sections, in-channel bedrock may locally constrain channel incision. The four fluvial reaches 

experienced a net reduction in bar area from 1939 

to 2009, ranging from 24 percent in the Powers 

Reach to 55 percent in the Bridge Reach (figs. 

23–fig. 31; table 11). In the Powers and Broadbent Reaches, the net loss in bar area is associated 

with multiple factors, including (1) channel planform changes and corresponding reconfigurations 

of deposition patterns, (2) vegetation establishment on bar surfaces thereby converting them to 

floodplain surfaces, and (3) lateral erosion of individual bars. In the Bridge and Gravelford 

Reaches, the reduction in bar area resulted from 

vegetation establishment on bar surfaces that 

were apparently unvegetated and eroding banks 

in 1939, as well as channel migration. These results are consistent with our findings of channel 

widening and local incision for each of the fluvial 

reaches based on channel width measurements 

(table 13), channel cross sections (table 9), and 

specific gage analysis for the Powers streamflowgaging station (fig. 20). Particularly for the South 

Fork Coquille River, the channel appears to have 

both widened and deepened in many places since 

1939. These findings are consistent with prior 

studies that noted incision and planform changes 

along the South Fork Coquille River (Florsheim 

and Williams, 1996; Clearwater Biostudies, Inc., 

2003; English and Coe, 2011).

In contrast, bar area expanded in both tidal 

reaches and the channel narrowed in the Bandon 

Reach (tables 11 and 13). The net 28–29 percent 

increases in bar area owe to channel migration 

and deposition of newly formed bars in the Myrtle Point Reach and upper 1.2 RKM in the 

Bandon Reach as well as increases in mapped 

tidal flats near the Coquille River mouth. In the 

Bandon Reach, the channel has apparently narrowed by nearly 10 percent between 1939 and 

2009. It is unclear if these trends in the tidal 

reaches are the consequence of some combination 

of (1) different streamflow and tide levels during 

the collection of aerial photographs, (2) increased 

loads of sand and silt from upstream sources, and 

(3) the long-term trajectory of sedimentary filling 

the extensive tidally affected section. 

General Bed-Material Transport Conditions

Our observations of the spatial and temporal 

characteristics of the reaches support preliminary 

interpretations of bed-material transport conditions. Although the fluvial Powers, Bridge, and 

Gravelford Reaches are diverse in terms of bar 

area (fig. 21A–C; fig. 22A) and slope (fig. 3A–

C), all three reaches have areas of in-channel bedrock or long segments with few bars (fig. 21A–

C). These attributes indicate that the reaches are 

likely sediment supply limited in terms of bed 

material; that is, the transport capacity of the river

generally exceeds its supply of bed material. In 

the Powers Reach on the South Fork Coquille 

River, high transport capacity is likely a result of
76

the steeper gradient (0.0027 m/m; table 2) and 

locally confined valley that enables the South 

Fork Coquille River to transport bed material received from the upstream Klamath Mountain 

geologic province to the downstream and lower 

gradient Broadbent Reach. The Bridge Reach on 

the Middle Fork Coquille River also has a relatively high gradient (0.0015 m/m; table 3), 

contributing to its high transport capacity. Unlike 

the Powers Reach on the South Fork Coquille 

River, however, the Bridge Reach and upstream 

Middle Fork Coquille River are predominantly 

underlain by the highly erodible sedimentary 

subdivision of the Coast Range geologic province. This sedimentary subdivision produces large 

suspended sediment loads (Beschta, 1978) and 

bed-material clasts that disintegrate rapidly relative to those from other geologic provinces, such 

as the Klamath Mountains (Jones and others, 

2010; Mangano and others, 2011), likely resulting 

in the limited supply of coarse sediment in this 

reach. The sediment-supply limitation of the Gravelford Reach on the North Fork Coquille River 

is likely attributable to its low transport capacity 

(gradient of 0.0003 m/m; table 3) in conjunction 

with presumably limited bed-material supply 

from the sedimentary Coast Range rocks that underlie most of this basin. 

Contrasting with the Powers, Bridge, and 

Gravelford Reaches, the Broadbent Reach on the 

South Fork Coquille River is the only gravel-bed 

reach in the Coquille River basin where bedmaterial conditions may be transport-limited; 

meaning the bed-material flux through this reach 

is controlled by transport conditions rather than 

sediment supply. The nearly continuous alluvial 

channel of this reach and comparatively high unit 

bar area (table 12) are the primary reach characteristics supporting this inference. 

Although the Broadbent Reach may be transport-limited, changes in recent decades may be 

shifting the reach toward supply limitation. In 

particular, the coarse surface texture and armoring ratio of 3.5 at Seals Bar (table 14), historically 

diminishing bar areas (fig. 22A; table 11), and 

local channel incision (table 9) are evidence of 

such a trend. The isolated exposures of in-channel 

bedrock are also consistent with a shift toward 

supply limitation. As suggested by Florsheim and 

Williams (1996), historical sediment fluxes to this 

reach were possibly greater as a result of log 

drives, splash damming, and timber harvesting in 

the mid-19th to mid-20th centuries. Additionally, 

instream gravel mining over the last several decades has reduced the volume of bed-material 

moving through the reach (tables 6–8). Regardless of the current state of the balance between 

transport capacity and sediment supply in the 

Broadbent Reach, this reach is likely to be the 

most responsive of the four fluvial reaches to watershed conditions affecting sand and gravel 

supply and transport because of its low gradient, 

relatively unconfined floodplain, and location 

downstream of the gravel-producing Klamath 

Mountains geologic province. 

Both tidal reaches are transport limited because of their low gradients. Bed material 

supplied to the Myrtle Point and Bandon Reaches, however, is primarily sand and finer materials. 

As illustrated by the historical descriptions of 

channel conditions and management actions intended to maintain a navigable channel, these 

reaches will be most susceptible to watershed 

conditions affecting the supply and transport of 

fine sediment.

Outstanding Issues and Possible Approaches

This reconnaissance-level study provides a 

framework and baseline information for understanding bed-material transport in the Coquille 

River basin. Future efforts addressing data gaps 

could greatly refine the understanding of historical and ongoing bed-material transport processes 

and their effects on channel morphology. Many 

of these approaches (as outlined below) could focus on individual reaches. Additionally, such 

information would provide a solid basis for evaluating future hydrologic and geomorphic 

changes in the basin. 
77

Streamflow Data

Understanding and predicting bed-material 

transport require high-quality streamflow information, particularly for peak flows. As of 2011, 

no streamflow-gaging station is operated that 

measures the streamflow of the Middle or North 

Fork of the Coquille River. Such hydrologic data 

would be required by most approaches used to 

quantify sediment supplied to the Bridge or Gravelford Reaches or for the mainstem Bandon 

Reach in the continued absence of mainstem 

streamflow-gaging stations downstream of the 

North Fork Coquille River. The most accurate 

approach for obtaining such information would 

be to expand the gaging station network to include additional stations. Mean daily streamflow 

measured at the new stations could then be used 

to estimate annual sediment fluxes for the period 

of record and shorter time periods (such as water 

years) using methods outlined in Wallick and 

others (2010) and employed in Wallick and 

O’Connor (2011). An alternative approach (that is 

less costly but with greater uncertainties) would 

be to apply regional regression equations to estimate discharge for a range of flow events for 

specific locations. However, an operational gage 

would be the optimal location for sampling bedload and later estimating sediment flux. 

Bed-Material Transport Rates and Sediment 

Budget

Understanding the possible effects of instream gravel mining on channel condition and 

longitudinal and temporal changes in bed material 

requires an accounting of sediment inputs from 

upstream and lateral sources as well as sediment 

losses due to particle attrition, transport, and storage. Such information would support an 

assessment of the volumes of gravel mined from 

the system by ongoing and past mining activities 

relative to gravel delivered to the study area. Developing a sediment budget may include the 

following components: 

1. Estimate sediment flux using published bedload transport equations following the 

approach used by Wallick and others (2010, 

2011) for the Chetco and Umpqua Rivers. 

This approach could be used with most confidence in the reaches where bed-material 

transport is likely transport-limited, such as 

the Broadbent Reach. Similar to the analysis 

by Wallick and others (2010) for the Chetco 

River, such analyses would be best performed 

by developing a hydraulic model for the reach 

of interest in conjunction with systematic 

measurements of bed-material size. Existing 

data, including the LiDAR survey for most of 

the Powers Reach and entire Broadbent 

Reach, and discharge data from the Powers 

streamflow-gaging station in conjunction with 

a future bathymetric study of streambed topography, would support this approach. 

2. Perform empirical GIS-based sediment yield 

analyses, factoring in sediment production, 

delivery to channels, and in-channel attrition. 

This approach would be similar to that applied for the Umpqua River basin (Wallick 

and others, 2011). While such an analysis 

could focus on specific reaches regardless of 

their alluvial or bedrock character, it would 

require analysis of their entire contributing 

area. Such analyses would be bolstered by assessments of bed-material composition, 

thereby confirming the source areas for bedmaterial delivered to the Coquille River.

3. Make direct measurements of bedload transport to verify equations for bedload transport 

and estimate actual bedload fluxes. Possible 

locations for bedload measurements on the 

South Fork Coquille River are the China Flat 

bridge (approximately 2.4 km upstream of 

study area) and the Gaylord Road bridge 

(Broadbent Reach, RKM 89.4). Ideally, such 

measurements would be made at a site of continuous discharge measurement; however, the 

Powers USGS streamflow-gaging station is 

not an ideal location for making bedload measurements because measurements would have 

to be made from either the station’s cableway 

or the downstream two-lane bridge with a relatively high traffic load. 
78

4. Estimate sediment flux based on mapped 

changes in bar area over specific temporal intervals in a manner similar to the 

morphological approach used on the Chetco 

River by Wallick and others (2010). Ideally, 

this approach would use LiDAR or other 

high-resolution topographic data from two 

time periods to directly calculate volumetric 

change in sediment storage. This method, 

however, can also be implemented using sequential aerial photographs along with the 

single available LiDAR survey. Like the 

analysis of bed-material transport using established transport capacity relationships

(described above), this approach is best applied in alluvial reaches. Despite the inherent 

uncertainties associated with this type of 

analysis (Wallick and others, 2010), such data 

and analyses can also serve as a basis for efficient monitoring of the long-term changes in 

channel and floodplain conditions. This approach would be most feasible for the 

Broadbent Reach on the South Fork Coquille 

River as well as for the tidal reaches.

5. Review pre- and post-gravel-mining surveys. 

The review conducted for this study indicates 

that these surveys can provide quantitative information on bed-material deposition. Indepth and comprehensive review of all mining surveys on the Coquille River may 

provide better estimates of coarse gravel recruitment that can assist in constraining 

sediment budgets (see, for example, Wallick 

and others, 2011). 

6. Assess bed-material composition throughout 

the study area. Additional measurements of 

particle size would be required for calculating 

bed-material transport and also may support 

assessments of temporal changes in bedmaterial composition in conjunction with other study components. 

Detailed Channel Morphology Assessment

In this study, we delineated bar surfaces from 

aerial and orthophotographs spanning 1939– 2009 

and found that bar area declined within all fluvial 

reaches (tables 11 and 12). These datasets and 

measurements could serve as the starting point for 

more detailed and comprehensive temporal analyses of morphological trends in the Coquille 

River study area. On the basis of the findings reported here, more detailed analyses could 

document changes in bar area due to erosion, deposition, and vegetation establishment along 

previously unvegetated bar surfaces. These analyses will require accounting for uncertainties 

associated with the mapping protocols and differences in discharge between the aerial 

photographs. An approach that would meet these 

objectives would include the following elements: 

1. Detailed mapping of land cover for multiple 

time periods. This effort would involve delineating the active floodplain and geomorphic 

features on the basis of vegetation density. 

Examining temporal changes in unvegetated

and vegetated surfaces would allow a more 

quantitative assessment of channel migration, 

erosion, deposition, and vegetation establishment during different time periods and enable

a more complete description of processes and 

trends of bar changes. An assessment of overall bar status and trends would benefit from 

supplemental bar delineations from historical 

aerial photographs, such as those taken in 

1942, the 1950s, 1972, 1976, 1986, 1989, 

1990, 1995, and 2000 (table 4). 

2. Detailed mapping of channel features before 

and after major floods to assess the response 

of the channel to floods of different magnitudes and, ultimately, sediment flux and 

channel evolution in the Coquille River study 

area. Possible floods for focusing this effort 

include those of 1945, 1955, 1964, 1971, 

1981, 1996, and 2005 (fig. 4B).

3. Assessment of the potential relationship between channel migration, large wood, 

vegetation establishment, and peak flows. In 

the Umpqua and Chetco River basins, historical declines in bar area are associated with 

long-term decreases in flood magnitude (Wal-
79

lick and others, 2010; 2011). For the Coquille 

River, however, decreases in bar area do not 

appear to be correlated with a reduction in 

peak flows (fig. 4B). Other possible factors 

include changes in the type and volume of inchannel wood as well as changes in riparian 

vegetation conditions. Further characterization of hydrology patterns in the Coquille 

River basin and its linkages with climate factors related to flood peaks, such as the Pacific 

Decadal Oscillation, could support inferences 

of likely future changes in vegetation establishment and channel planform and profile.

1. Investigation of bed-elevation changes. 

Modern channel surveys could be compared to historical surveys, such as the 

USGS profile maps, cross sections at 

USGS cableways, flood profiles and bathymetric surveys in the Bandon Reach 

(table 5), to more systematically document spatial and temporal changes in bed 

elevation. Such analyses would complement detailed mapping of channel and 

floodplain characteristics and provide insights into the factors controlling the 

observed changes. Properly conducted and 

archived, such modern surveys could also 

serve as a basis for the long-term monitoring of vertical channel conditions. 

2. More detailed review of the data available 

for bridges. A review of the as-built surveys and construction plans for publicly 

owned bridges within the Coquille River 

study area may provide information sufficient to assess sediment thickness and 

changes in bed elevation. Investigations of 

construction plans and permits for countyand privately-owned bridges within the 

study area may also yield useful information. 

Legacy and Ongoing Effects of Land Use Activities

Anthropogenic activities, such as historical 

forestry practices (including log drives and splash 

damming), dredging and wood removal for navigation, and instream gravel mining, have likely 

affected sediment transport and deposition dynamics in the Coquille River study area. 

Quantitatively assessing the past and present effects of these factors on sediment dynamics 

would be challenging due to likely interactions 

among these factors as well as their interactions 

with the overarching physical controls on sediment dynamics such as basin topography, channel 

slope, geology, and hydrology. Further investigations of fine and coarse sediment inputs 

associated with land use activities may provide 

information on the relative fluxes of different 

clast sizes delivered to the study area and their 

temporal and spatial variations. An approach for 

investigating the relative importance of past activities on overall sediment dynamics would be 

to: 

1. Determine the distribution of areas of active 

gravel transport and deposition and analyze 

temporal trends in channel and floodplain 

morphology with respect to land-use disturbances.

2. Assess changes in bar area and channel planform near historical instream gravel mining 

sites with a detailed geomorphic analysis.

Priority Reaches for Future Analysis

Considering the large drainage area of the 

Coquille River basin and portion of the basin assessed in this study, addressing all the data gaps 

and analyses outlined above is probably not practical in the near future. Specific reaches, however, 

might warrant additional analysis because of 

overall geomorphic conditions and ongoing management and restoration as well as gravel mining 

activities.
80

The South Fork Coquille River, encompassing the Powers and Broadbent Reaches, would be 

a logical analysis area because it is an ecologically important segment of the Coquille River 

system. Information on coarse sediment fluxes 

and channel dynamics may be useful for ongoing 

management and restoration activities addressing 

riparian conditions, bank erosion, and local bed 

lowering within these reaches. Additionally, this 

section of the river, which drains the gravel-rich 

Klamath Mountains, has been subject to multiple 

anthropogenic disturbances. The Broadbent 

Reach, in particular, has been affected by voluminous instream gravel mining and is likely 

responsive to upstream basin disturbances as a 

result of its low gradient and unconfined floodplain. 

The tidal Bandon and Myrtle Point Reaches 

may also be logical reaches for in-depth analysis. 

In these reaches, the issues would pertain more to 

the deposition and transport of fine sediment (and 

associated channel and riparian conditions and 

processes) rather than coarse bed material. The 

preliminary bar mapping produced by this study 

may provide a baseline for more detailed mapping of geomorphic features and estuarine 

habitats for the tidal reaches. Since the legacy of 

land-use effects in the basin has probably substantially affected fine sediment transport and 

deposition, the transport-limited and unconfined 

character of these reaches makes them responsive 

to perturbations in sediment loads and river flow. 

Acknowledgments

The framework for this study was established 

with the guidance of Judy Linton of the Portland 

District of the U.S. Army Corps of Engineers. 

The study was administered by Judy Linton as 

well as by Bill Ryan, Pamela Konstant, and Cynthia Wickman of the Oregon Department of State 

Lands. Field assistance was provided by Xavier 

Rodriguez Lloveras, National Museum of Natural 

Science, Spanish National Research Council, 

Spain. Mike Flewelling of the Knife River Corporation provided access to the Seals Bar bedmaterial sampling site. Christy Leas, Oregon Department of State Lands, coordinated access to 

the gravel mining permit files housed at the Oregon Department of State Lands. Copies of the 

Benner (1991), Florsheim and Williams (1996), 

and Clearwater Biostudies, Inc. (2003) were graciously provided by Pamela Blake, Oregon 

Department of Environmental Quality. Mike 

McCabe, Oregon Department of State Lands,

provided a copy of the Coos Bay Times (1928) 

article, and Dolores Knight, Coos Bay Public Library, provided an electronic copy of the 

McGeorge Gravel Company’s site photo included 

in the article. The University of Oregon Map and 

Aerial Photography Library provided a summary 

of aerial photographs available for the Coquille 

River study area. Stephen Dow Beckham and 

Roxann Gess Smith permitted use of historical 

photographs showing splash dams and log jams in 

the Coquille River basin. Two colleagues provided insightful comments that improved this 

report.

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