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

of State Lands 

Preliminary Assessment of Channel Stability and BedMaterial Transport in the Tillamook Bay Tributaries and 

Nehalem River Basin, Northwestern Oregon

Open-File Report 2012–1187

U.S. Department of the Interior 

U.S. Geological Survey 
Cover: Donaldson Bar on the Wilson River. (Photograph by Krista Jones, U.S. Geological Survey, October 13, 2010) 
Preliminary Assessment of Channel Stability and BedMaterial Transport in the Tillamook Bay Tributaries and 

Nehalem River Basin, Northwestern Oregon

By Krista L. Jones, Mackenzie K. Keith, Jim E. O’Connor, 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 2012–1187

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

channel stability and bed-material transport in the Tillamook Bay tributaries and Nehalem River basin, northwestern Oregon: U.S. Geological Survey Open-File Report 2012–1187, 120 p. 

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endorsement by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual 

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

Contents

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

Tables ...........................................................................................................................................................................vii

Conversion Factors ...................................................................................................................................................... viii

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

Introduction .................................................................................................................................................................... 4

Locations and Reporting Units ....................................................................................................................................... 4

Study Basins .................................................................................................................................................................. 4

Geomorphic and Geologic Setting .............................................................................................................................. 7

Hydrology ................................................................................................................................................................. 11

Historical Channel Descriptions ................................................................................................................................16

Settlement and Land Ownership Patterns ................................................................................................................17

Natural and Anthropogenic Disturbances Affecting Bed-Material Dynamics ............................................................18

Mass Movements ..................................................................................................................................................19

Logging and Related Transportation Activities ......................................................................................................19

Fire ........................................................................................................................................................................21

Channel Alterations for Navigation and Flood Control ..........................................................................................23

Gravel Mining ........................................................................................................................................................25

Study Areas and Reaches ........................................................................................................................................26

Tillamook River .....................................................................................................................................................27

Trask River............................................................................................................................................................34

Wilson River ..........................................................................................................................................................34

Kilchis River ..........................................................................................................................................................38

Miami River ...........................................................................................................................................................40

Nehalem River ......................................................................................................................................................42

Approach and Key Findings .........................................................................................................................................42

Review of Existing Datasets .....................................................................................................................................45

Aerial and Orthophotographs ................................................................................................................................45

Historical Maps and Survey Data ..........................................................................................................................50

Previous Hydrologic and Geomorphic Studies .........................................................................................................50

Gravel-Operator Information and Surveys ................................................................................................................53

Bridge-Inspection Reports ........................................................................................................................................60

Specific Gage Analysis .............................................................................................................................................68

Delineation of Bars and Channel Features, 1939–2009 ...........................................................................................72

Distribution and Area of Bars, 2009 ......................................................................................................................75

Results for Repeat Bar and Channel Delineation, 1939–2009 ..............................................................................75

Discussion of Mapped Changes in Bar and Channel Features, 1939–2009 .........................................................80

Analyses of Bed-Material Particle Sizes .................................................................................................................101

Discussion and Synthesis ..........................................................................................................................................105
iv

Spatial Variation in Bar Conditions .........................................................................................................................105

Temporal Trends in Bar and Channel Conditions ...................................................................................................106

General Bed-Material Transport Conditions ...........................................................................................................108

Outstanding Issues and Possible Approaches ...........................................................................................................110

Bed-Material Transport Rates and Sediment Budget .............................................................................................110

Detailed Channel Morphology Assessment ............................................................................................................112

Legacy and Ongoing Effects of Land Use Activities ...............................................................................................113

Priority Reaches for Future Analysis.......................................................................................................................114

Acknowledgments ......................................................................................................................................................114

References Cited .......................................................................................................................................................115

Figures

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

linear reference systems, streamflow-gaging stations, and other features in the Tillamook, Trask, Wilson, Kilchis, 

and Miami River basins, northwestern Oregon......................................................................................................... 5

Figure 2. Map showing the stream network, basin and county boundaries, geologic provinces, study reaches, 

linear reference systems, streamflow-gaging stations, and other features in the Nehalem River basin, 

northwestern Oregon ................................................................................................................................................ 6

Figure 3. Diagrams showing the longitudinal profiles of the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem 

River basins, northwestern Oregon. ......................................................................................................................... 9

Figure 4. Graphs showing mean daily streamflow for U.S. Geological Survey and Oregon Water Resource 

Department streamflow-gaging stations on the Trask River above Cedar Creek near Tillamook, Oregon 

(14302480), Wilson River near Tillamook, Oregon (14301500), Miami River near Garibaldi, Oregon (14301300), 

and Nehalem River near Foss, Oregon (14301000), northwestern Oregon. ..........................................................13

Figure 5. Graphs showing annual peak streamflow for U.S. Geological Survey and Oregon Water Resource 

Department streamflow-gaging stations on the Trask River above Cedar Creek near Tillamook, Oregon 

(14302480), Wilson River near Tillamook, Oregon (14301500), Miami River near Garibaldi, Oregon (14301300), 

and Nehalem River near Foss, Oregon (14301000), northwestern Oregon. ..........................................................15

Figure 6. Historical photographs showing log drives on the Nehalem River circa 1915 and Trask River (date 

unknown). ...............................................................................................................................................................22

Figure 7. Historical photographs of the Tillamook Burn: the Wolf Creek subbasin of the Salmonberry River basin 

in 1932, a burned riparian corridor along the Wilson River, and students planting trees as part of the Tillamook 

Burn reforestation effort..........................................................................................................................................23

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

field reconnaissance photographs of the Tillamook River study area, northwestern Oregon. ................................32

Figure 9. Diagram showing longitudinal profiles for the study reaches on the Tillamook, Trask, Wilson, Kilchis, 

Miami, and Nehalem River basins, northwestern Oregon. .....................................................................................33

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

field reconnaissance photographs in the Trask River study area, northwestern Oregon. .......................................35
v 

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

field reconnaissance photographs in the Wilson River study area, northwestern Oregon. .....................................37

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

field reconnaissance photographs in the Kilchis River study area, northwestern Oregon. .....................................39

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

field reconnaissance photographs in the Miami River study area, northwestern Oregon. ......................................41

Figure 14. Map showing key locations, bars, and channel centerline delineated from 2009 orthophotographs and 

field reconnaissance photographs in the Fluvial Reach of the Nehalem River, northwestern Oregon. ..................43

Figure 15. Map showing key locations, bars, and channel centerline delineated from 2009 orthophotographs and 

field reconnaissance photographs in the Tidal Reach of the Nehalem River, northwestern Oregon. .....................44

Figure 16. Graphs showing reported estimates of deposited and mined gravel from 1999 to 2011 for instream 

mining sites along the Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. .......................57

Figure 17. Diagrams showing channel cross sections surveyed at RKM 11.5, 8.8, 6.4, and 1.3 along the 

Tillamook River, northwestern Oregon. ..................................................................................................................64

Figure 18. Diagrams showing channel cross sections surveyed at RKM 7.0 and 2.1 on the Trask River, 

northwestern Oregon. .............................................................................................................................................65

Figure 19. Diagrams showing channel cross sections surveyed at RKM 14.1, 6.3, and 2.8 on the Wilson River, 

northwestern Oregon. .............................................................................................................................................66

Figure 20. Diagrams showing channel cross sections surveyed at RKM 6.0, 4.2, 1.5, and 1.0 on the Kilchis River, 

northwestern Oregon. .............................................................................................................................................67

Figure 21. Diagrams showing channel cross sections surveyed at RKM 8.5, 2.7, and 0 on the Miami River, 

northwestern Oregon. .............................................................................................................................................69

Figure 22. Diagrams showing channel cross sections surveyed at RKM 18.8 and 10.6 on the Nehalem River, 

northwestern Oregon. .............................................................................................................................................70

Figure 23. Diagrams showing the stage-discharge rating curves for specific discharges for the U.S. Geological 

Survey streamflow-gaging stations on the Wilson River near Tillamook, Oregon (14301500) and Nehalem River 

near Foss, Oregon (14301000), northwestern Oregon. ..........................................................................................71

Figure 24. Graphs showing bar area by river kilometer as delineated from orthophotographs taken in 2009 for 

study areas on the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. ...........78

Figure 25. Graphs showing unit bar area, number of bars, channel centerline length, and average wetted channel 

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

Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. ...........................................................79

Figure 26. Images showing repeat bar and channel delineations in two sections (river kilometers 13.6–11.4 and 

11.6–10.0) of the Fluvial Tillamook Reach, northwestern Oregon. .........................................................................82

Figure 27. Images showing repeat bar and channel delineations near the Tillamook River mouth (river kilometer 

1.2–0) and pile structures and log booms (river kilometer 7.6–6.6) in the Tidal Tillamook Reach, northwestern 

Oregon.. ................................................................................................................................................................. 83

Figure 28. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar 

surfaces, and lateral channel migrations in two sections (river kilometers 15.6–14.0 and 13.0–11.8) of the Fluvial 

Trask Reach, northwestern Oregon. ......................................................................................................................84

Figure 29. Images showing repeat bar and channel delineations and vegetation growth and stabilization of bar 

surfaces in two sections (river kilometers 7.0–6.6 and 3.0–2.6) of the Tidal Trask Reach, northwestern Oregon.. 85
vi

Figure 30. Images showing repeat bar and channel delineations from river kilometer 14.0 to 13.4 in the Upper 

Fluvial Wilson Reach, northwestern Oregon. .........................................................................................................86

Figure 31. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar 

surfaces, and channel migrations from river kilometer 10.6 to 8.2 in the Lower Fluvial Wilson Reach, northwestern 

Oregon.. ................................................................................................................................................................. 87

Figure 32. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar 

surfaces, and channel simplification from river kilometer 8.0–6.4 in the Lower Fluvial Wilson Reach, northwestern 

Oregon.. ................................................................................................................................................................. 88

Figure 33. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar 

surfaces, and other changes from river kilometer 5.0 to 3.6 in the Tidal Wilson Reach, northwestern Oregon. .....89

Figure 34. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar 

surfaces, and channel migrations from river kilometer 6.4 to 4.8 in the Fluvial Kilchis Reach, northwestern Oregon.

...............................................................................................................................................................................90

Figure 35. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar 

surfaces, and channel migrations from river kilometer 4.0 to 2.8 in the Fluvial Kilchis Reach, northwestern Oregon.

...............................................................................................................................................................................91

Figure 36. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar 

surfaces, and channel migrations from river kilometer 2.6 to 1.8 in the Tidal Kilchis Reach, northwestern Oregon.

...............................................................................................................................................................................92

Figure 37. Images showing repeat bar and channel delineations, channel migrations, and vegetation changes 

from river kilometer 11.6 to 10.2 in the Upper Fluvial Miami Reach, northwestern Oregon. ...................................93

Figure 38. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar 

surfaces, and channel migrations from river kilometer 8.4 to 6.4 in the Lower Fluvial Miami Reach, northwestern 

Oregon. ..................................................................................................................................................................94

Figure 39. Images showing repeat bar and channel delineations and vegetation growth and stabilization of bar 

surfaces from river kilometer 5.4 to 3.8 in the Lower Fluvial Miami Reach, northwestern Oregon. ........................95

Figure 40. Images showing repeat bar and channel delineations and vegetation growth and stabilization of bar 

surfaces from RKM 1.4 to 0 in the Tidal Miami Reach, northwestern Oregon. .......................................................96

Figure 41. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar 

surfaces, and channel migrations from RKM 26.4 to 24.8 in the Fluvial Nehalem Reach, northwestern Oregon. 

[RKM, river kilometer] .............................................................................................................................................97

Figure 42. Images showing repeat bar and channel delineations and stable channel planform from RKM 31.4 to 

28.6 in the Fluvial Nehalem Reach, northwestern Oregon. ....................................................................................98

Figure 43. Images showing repeat bar and channel delineations from RKM 10.0 to 3.0 in the Tidal Nehalem 

Reach, northwestern Oregon. ................................................................................................................................99

Figure 44. Images showing repeat bar and channel delineations and planform changes from RKM 24.2 to 19.2 in 

the Tidal Nehalem Reach, northwestern Oregon. ................................................................................................100

Figure 45. Graphs showing distributions of surface and subsurface particle sizes for bed-material sampling sites 

along the Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. .........................................103
vii 

Tables

Table 1. Drainage characteristics of the Tillamook Bay subbasins and Nehalem River basin, northwestern 

Oregon.. ................................................................................................................................................................... 7

Table 2. Geologic province summary by percentage as generalized from Ma and others (2009) for the Tillamook 

Bay subbasins and Nehalem River basin, northwestern Oregon.. ........................................................................... 8

Table 3. Summary of streamflow-gaging station information for the Trask, Wilson, Miami, and Nehalem Rivers, 

northwestern Oregon. .............................................................................................................................................12

Table 4. Summary of land ownership for the Tillamook Bay subbasins and Nehalem River basin, northwestern 

Oregon. ..................................................................................................................................................................18

Table 5. Time periods of log drives and splash damming in the Tillamook Bay sub-basins and Nehalem River 

basin, northwestern Oregon. ..................................................................................................................................20

Table 6. Summary of floodplain modifications in the study areas of the Tillamook Bay sub-basins and Nehalem 

River basin, northwestern Oregon. .........................................................................................................................25

Table 7. Ongoing instream gravel mining permits in the Tillamook Bay subbasins and Nehalem River basin, 

northwestern Oregon.. ............................................................................................................................................26

Table 8. Summary of characteristics for study reaches on the Tillamook, Trask, Wilson, Kilchis, Miami, and 

Nehalem Rivers, northwestern Oregon. .................................................................................................................28

Table 9. Aerial photographs with coverage of the Tillamook Bay subbasins, northwestern Oregon. .....................46

Table 10. List of aerial photographs with coverage of the Nehalem River, northwestern Oregon. .........................48

Table 11. List of existing datasets reviewed for the Tillamook Bay subbasins and Nehalem River basin, 

northwestern Oregon. .............................................................................................................................................51

Table 12. Partial compilation of deposited and mined gravel volumes from 2003 to 2011 reported for instream 

mining sites along the Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. .......................54

Table 13. Partial compilation of deposited and mined gravel volumes from 1993 to 1997 at active and historical 

instream gravel mining reported in Stinson and Stinson (1998).. ...........................................................................55

Table 14. Summary of net changes measured from channel cross sections collected by the Oregon Department 

of Transportation in the six study areas in the Tillamook Bay subbasins and Nehalem River basin, northwestern 

Oregon. ..................................................................................................................................................................61

Table 15. Photograph rectification data for the Tillamook and Nehalem study areas, northwestern Oregon. ........73

Table 16. Streamflow during the acquisition of the aerial photographs used for repeat bar and channel feature 

delineation on the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon..............74

Table 17. Repeat bar attribute data as delineated from photographs taken in 1939, 1967, 2005, and 2009 for the 

Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. ..........................................76

Table 18. Unit bar area data for predominantly fluvial reaches from this study and prior studies in select Oregon 

coastal rivers. .........................................................................................................................................................77

Table 19. Repeat channel feature data as delineated from photographs taken in 1939, 1967, 2005, and 2009 for 

the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. ....................................80

Table 20. Bed-material data collected at sampling sites along the Trask, Wilson, Kilchis, Miami, and Nehalem 

Rivers, northwestern Oregon. ..............................................................................................................................102

Table 21. Armoring ratios reported from this and prior bed-material studies by the U.S. Geological Survey in 

select Oregon coastal rivers from north to south. ................................................................................................. 104
viii 

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 (m

2

) 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)

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. 
1 

Preliminary Assessment of Channel Stability and BedMaterial Transport in the Tillamook Bay Tributaries and 

Nehalem River Basin, Northwestern Oregon

By Krista L. Jones, Mackenzie K. Keith, Jim E. O’Connor, 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 

Tillamook (drainage area 156 square kilometers 

[km2]), Trask (451 km2), Wilson (500 km2), 

Kilchis (169 km2), Miami (94 km2), and Nehalem (2,207 km2

) Rivers along the northwestern 

Oregon coast. This study, conducted in cooperation with the U.S. Army Corps of Engineers and 

Oregon Department of State Lands to inform 

permitting decisions regarding instream gravel 

mining, revealed that: 

Study areas along the six rivers can be divided into reaches based on tidal influence and 

topography. The fluvial (nontidal or dominated by riverine processes) reaches vary in 

length (2.4–9.3 kilometer [km]), gradient 

(0.0011–0.0075 meter of elevation change 

per meter of channel length [m/m]), and bedmaterial composition (a mixture of alluvium 

and intermittent bedrock outcrops to predominately alluvium). In fluvial reaches, unit bar 

area (square meter of bar area per meter of 

channel length [m2/m]) as mapped from 2009 

photographs ranged from 7.1 m2/m on the 

Tillamook River to 27.9 m2/m on the Miami 

River. 

In tidal reaches, all six rivers flow over alluvial deposits, but have varying gradients 

(0.0001–0.0013 m/m) and lengths affected 

by tide (1.3–24.6 km). The Miami River has 

the steepest and shortest tidal reach and the 

Nehalem River has the flattest and longest 

tidal reach. Bars in the tidal reaches are generally composed of sand and mud. Unit bar 

area was greatest in the Tidal Nehalem 

Reach, where extensive mud flats flank the 

lower channel. 

Background factors such as valley and channel confinement, basin geology, channel 

slope, and tidal extent control the spatial variation in the accumulation and texture of bed 

material. Presently, the Upper Fluvial Wilson 

and Miami Reaches and Fluvial Nehalem 

Reach have the greatest abundance of gravel 

bars, likely owing to local bed-material 

sources in combination with decreasing 

channel gradient and valley confinement. 

Natural and human-caused disturbances such 

as mass movements, logging, fire, channel 

modifications for navigation and flood control, and gravel mining also have varying effects on channel condition, bed-material 

transport, and distribution and area of bars 

throughout the study areas and over time. 

Existing datasets include at least 16 and 18 

sets of aerial and orthophotographs that were 

taken of the study areas in the Tillamook Bay 

tributary basins and Nehalem River basin, respectively, from 1939 to 2011. These photographs are available for future assessments of 

long-term changes in channel condition, bar 
2 

area, and vegetation establishment patterns. 

High resolution Light Detection And Ranging (LiDAR) surveys acquired in 2007–2009 

could support future quantitative analyses of 

channel morphology and bed-material 

transport in all study areas. 

A review of deposited and mined gravel volumes reported for instream gravel mining 

sites shows that bed-material deposition 

tends to rebuild mined bar surfaces in most 

years. Mean annual deposition volumes on 

individual bars exceeded 3,000 cubic meters 

(m3) on Donaldson Bar on the Wilson River, 

Dill Bar on the Kilchis River, and Plant and 

Winslow Bars on the Nehalem River. Cumulative reported volumes of bed-material deposition were greatest at Donaldson and Dill 

Bars, totaling over 25,000 m3

per site from 

2004 to 2011. Within this period, reported 

cumulative mined volumes were greatest for 

the Donaldson, Plant, and Winslow Bars, 

ranging from 24,470 to 33,940 m3. 

Analysis of historical stage-streamflow data

collected by the U.S. Geological Survey on 

the Wilson River near Tillamook (14301500) 

and Nehalem River near Foss (14301000) 

shows that these rivers have episodically aggraded and incised, mostly following high 

flow events, but they do not exhibit systematic, long-term trends in bed elevation. 

Multiple cross sections show that channels 

near bridge crossings in all six study areas 

are dynamic with many subject to incision 

and aggradation as well as lateral shifts in 

thalweg position and bank deposition and 

erosion. 

In fluvial reaches, unit bar area declined a net 

5.3–83.6 percent from 1939 to 2009. The 

documented reduction in bar area may be attributable to several factors, including vegetation establishment and stabilization of formerly active bar surfaces, lateral channel 

changes and resulting alterations in sediment 

deposition and erosion patterns, and streamflow and/or tide differences between photographs. Other factors that may be associated 

with the observed reduction in bar area but 

not assessed in this reconnaissance level 

study include changes in the sediment and 

hydrology regimes of these rivers over the 

analysis period. 

In tidal reaches, unit bar area increased on 

the Tillamook and Nehalem Rivers (98.0 and 

14.7 percent, respectively), but declined a net 

24.2 to 83.1 percent in the other four tidal 

reaches. Net increases in bar area in the Tidal 

Tillamook and Nehalem Reaches were possibly attributable to tidal differences between 

the photographs as well as sediment deposition behind log booms and pile structures on 

the Tillamook River between 1939 and 1967. 

The armoring ratio (ratio of the median grain 

sizes of a bar’s surface and subsurface layers) 

was 1.6 at Lower Waldron Bar on the Miami 

River, tentatively indicating a relative balance between transport capacity and sediment supply at this location. Armoring ratios, 

however, ranged from 2.4 to 5.5 at sites on 

the Trask, Wilson, Kilchis, and Nehalem 

Rivers; these coarse armor layers probably 

reflect limited bed-material supply at these 

sites.

On the basis of mapping results, measured 

armoring ratios, and channel cross section 

surveys, preliminary conclusions are that the 

fluvial reaches on the Tillamook, Trask, 

Kilchis, and Nehalem Rivers are currently 

sediment supply-limited in terms of bed material—that is, the transport capacity of the 

channel generally exceeds the supply of bed 

material. The relation between transport capacity and sediment is more ambiguous for 

the fluvial reaches on the Wilson and Miami 

Rivers, but transport-limited conditions are 

likely for at least parts of these reaches. 

Some of these reaches have possibly evolved 

from sediment supply-limited to transportlimited over the last several decades in response to changing basin and climate conditions. 
3 

Because of exceedingly low gradients, all the 

tidal reaches are transport-limited. Bed material in these reaches, however, is primarily 

sand and finer grain-size material and probably transported as suspended load from upstream reaches. These reaches will be most 

susceptible to watershed conditions affecting 

the supply and transport of fine sediment. 

Compared to basins on the southwestern Oregon coast, such as the Chetco and Rogue 

River basins, these six basins likely transport 

overall less gravel bed material. Although 

tentative in the absence of actual transport 

measurements, this conclusion is supported 

by the much lower area and frequency of 

bars and longer tidal reaches along all the 

north-coast rivers examined in this study. 

Previous studies suggest that the expansive 

and largely unvegetated bars visible in the 

1939 photographs are primarily associated 

with voluminous sedimentation starting soon 

after the first Tillamook Burn fire in 1933. 

However, USGS studies of temporal bar 

trends in other Oregon coastal rivers unaffected by the Tillamook Burn show similar 

declines in bar area over approximately the 

same analysis period. In the Umpqua and 

Chetco River basins, historical declines in 

bar area are associated with long-term decreases in flood magnitude. Other factors 

may include changes in the type and volume 

of large wood and riparian vegetation. Further characterization of hydrology patterns in 

these basins and possible linkages with climate factors related to flood peaks, such as 

the Pacific Decadal Oscillation, could support inferences of expected future changes in 

vegetation establishment and channel planform and profile. 

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 fluvial study 

areas on the Wilson, Kilchis, Miami, and 

Nehalem Rivers and relevant to several ongoing management and ecological issues pertaining to sand and gravel transport. Tidal 

reaches may also be logical subjects for indepth analysis where studies would be more 

relevant to the deposition and transport of fine sediment (and associated channel and riparian conditions and processes) rather than 

coarse bed material.
4 

Introduction

This report summarizes a reconnaissance 

level study of channel condition and bedmaterial transport relevant to the permitting of 

instream gravel mining in six basins—the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem River basins—on the northwestern Oregon 

coast (figs. 1 and 2). The Tillamook, Trask, Wilson, Kilchis, and Miami River basins are collectively referred to as the Tillamook Bay subbasins 

in this report. The study included a review of existing datasets (such as channel cross sections 

and instream gravel mining records), delineation 

of bars and wetted channels from aerial and orthophotographs spanning 1939–2009, and field 

observations and bed-material measurements 

made in October 2010. From these efforts, we 

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

transport, and the potential effects of instream 

gravel mining on both; assessed vertical and lateral channel stability; and made preliminary conclusions regarding the relation between sediment 

supply and transport capacity for the six study 

areas. This reconnaissance level study is a 

“Phase I” assessment similar to those completed 

for the Umpqua River (O'Connor and others, 

2009), Rogue River (Jones and others, 2012a), 

Coquille River (Jones and others, 2012b), and 

Hunter Creek (Jones and others, 2011) 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. 

Locations and Reporting Units

Locations within the six study areas (described below) are referenced to river kilometers 

(RKM). To develop this reference system, centerlines were digitized for the wetted channel of 

each river starting at locations indicated on figures 1 and 2 using orthoimagery acquired 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, and the values increase in the upstream direction. After accounting for the conversion between river kilometers 

and river miles (RM), this reference system differs slightly from RM shown on recent U.S. 

Geological Survey (USGS) topographic quadrangle maps (1984–1986 for the Tillamook Bay 

subbasins; 1984–1985 for the Nehalem River). 

The discrepancies probably owe to factors such 

as slightly different starting points of the reference systems, recent changes in channel positions, and resolution at which they were mapped 

(figs. 1 and 2). 

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

data reported by other sources in metric (International System) units. Conversions to inch-pound 

(English) units are provided in the front matter of 

the report. 

Study Basins

The Tillamook, Trask, Wilson, Kilchis, and 

Miami Rivers flow into Tillamook Bay near the 

towns of Tillamook and Garibaldi (fig. 1). In total, the five Tillamook Bay rivers have a drainage area of 1,369 km2

and over 930 km of 

mapped streams (table 1). The Wilson and Trask 

River basins cover the largest areas (500 and 451 

km2, respectively) whereas the Tillamook and 

Kilchis Rivers encompass similar sized areas 

(156 and 169 km2, respectively) and the Miami 

River the smallest area (94 km2). The length of 

river affected by tide increases clockwise around 

the bay, with tidal river segments beginning at 

RKM 1.3 on the Miami River and RKM 10.2 on 

the Tillamook River (Oregon Department of 

State Lands, 2007). The five Tillamook Bay 

subbasins are within Tillamook, Washington, 

and Yamhill Counties. They are bordered by the 

Nehalem River basin to the north, Tualatin River 

basin to the east, Yamhill River basin to the 

southeast, and Nestucca River basin to the south. 
5

Figure 1. Map showing the stream network, basin and county boundaries, geologic provinces, study reaches, linear reference systems, streamflow-gaging 

stations, and other features in the Tillamook, Trask, Wilson, Kilchis, and Miami River basins, northwestern Oregon
6

Figure 2. Map showing the stream network, basin and county boundaries, geologic provinces, study reaches, linear reference systems, streamflow-gaging 

stations, and other features in the Nehalem River basin, northwestern Oregon
7 

To the north of the Tillamook Bay subbasins, the larger Nehalem River (2,207 km2

) 

flows into Nehalem Bay near the towns of Nehalem and Brighton (fig. 2) and has nearly 1,500 

km of mapped streams (table 1). Tide affects a 

substantially longer section (24.6 km) of the Nehalem River compared to the Tillamook Bay 

subbasins. The Nehalem River basin is bordered 

to the northwest by the Necanicum River basin, 

to the north and east by tributaries to the Columbia River, and to the south by the Tualatin, Wilson, Kilchis, and Miami River basins. The Nehalem River flows through Tillamook, Washington, Columbia, and Clatsop Counties. 

Geomorphic and Geologic Setting 

All six basins have rugged uplands, which 

abruptly transition downstream to lowland 

floodplains that make up relatively smaller portions of the basins (figs. 1 and 2). The steep uplands are chiefly underlain by Eocene volcanic 

and sedimentary rocks (Walker, 1991). These 

areas are extensively affected by mass movements, including shallow landslides, debris 

flows, and deeper earthflows and landslides 

(Tillamook Bay Taskforce and others, 1978; 

Johnson and Maser, 1999; Snyder and others, 

2001; Snyder and others, 2003; Duck Creek 

Associates, 2008; 

Reckendorf, 2008a). The valleys are mainly 

carved into the softer sedimentary rocks and are 

locally flanked by Quaternary alluvium as well 

as marine terraces and dunes near the coast. 

Bedrock palisades on the Wilson River upstream 

of the study area. 

Table 1. Drainage characteristics of the Tillamook Bay subbasins and Nehalem River basin, northwestern Oregon. Data determined at the mouth of the rivers.

[km2, square kilometer; km, kilometer; RKM, river kilometer]

Attribute

River basin 1

Drainage area (km2)

1Mapped stream 

length (km)

1

Drainage density 

(km/km2)

2

Head of tide (RKM)

Tillamook 156 132 0.8 10.2

Trask 451 328 0.7 7.0

Wilson 500 320 0.6 5.0

Kilchis 169 94 0.6 2.7

Miami 94 56 0.6 1.3

Nehalem 2,207 1,498 0.7 24.6

1 Derived from StreamStats (http://water.usgs.gov/osw/streamstats /oregon.html) for the area upstream of RKM 0

2 Derived from Oregon Department of State Lands (2007)
8 

The proportions and distributions of geologic provinces, particularly the Coast Range sedimentary and volcanic subdivisions, differ between the six basins (table 2; figs 1 and 2). The 

Trask, Wilson, and Miami River basins are 

roughly 20 percent sedimentary rocks and 70 

percent volcanic rocks. Both types of rocks are 

dispersed throughout the Trask and Wilson basins. In the Miami River basin, volcanic rocks 

dominate the headwaters and eastern portion of 

the lower basin, whereas sedimentary rocks encompass the western portion of the lower basin. 

The Tillamook and Nehalem River basins have 

more than half of their areas underlain by Coast 

Range sedimentary rocks, and 27 percent or less 

by volcanic rocks. The headwaters and mainstem 

of the Tillamook River drain sedimentary rocks, 

whereas its tributaries in the eastern portion of 

the basin drain volcanic rocks. In the Nehalem 

River basin, sedimentary rocks encompass the 

headwaters and majority of the mainstem, but 

volcanic rocks dominate the basin downstream 

of the town of Elsie and tributaries such as Cronin and Cook Creeks and the Salmonberry River. 

Unlike the others, the Kilchis River basin is 93 

percent Coast Range volcanic rocks, with sedimentary rocks near the mouth making up only 3 

percent of the basin’s geology. 

The distribution of volcanic and sedimentary 

rocks probably exerts substantial influence on 

the volume and distribution of bed material in 

these basins. Although both rock types likely 

contribute considerable bed material in highrelief headwater areas, ongoing analyses of 

downstream transport and particle attrition indicate that sedimentary rocks rapidly disaggregate 

into sand and silt, and thus are more likely to be 

transported as part of the suspended sediment 

load than as gravel-size bed material (Mangano 

and others, 2011; Wallick and others, 2011). 

Upstream of the heads of tide, water-surface 

gradients are variable and locally steep in the 

headwaters of each basin (fig. 3A–F). Generally, 

water-surface gradients decline relatively 

smoothly (with the exception of small convex 

segments that may indicate slope discontinuities 

caused by mass movement-related sediment inputs) as the Trask, Wilson, Kilchis, and Miami 

Rivers approach the Tillamook Bay (fig. 3B–E). 

Differences in bed-material transport rates 

associated with the varying geological environments may explain the different lengths of the 

rivers affected by tide (table 1; fig. 3A–F). The 

long, tidally affected reaches of the Tillamook, 

Trask, and Nehalem Rivers (7.0–24.6 km) indicate that coarse bed-material supply in these basins primarily underlain by sedimentary rocks is 

surpassed by Holocene sea-level rise, resulting in 

partly drowned river valleys near the present 

coast lines (Komar, 1997). In contrast, the shorter tidal reaches of the Wilson, Kilchis, and Miami Rivers are likely a consequence of relatively 

greater long-term supplies of bed material filling 

their valleys as sea level has risen over the last 

10,000 years.

Table 2. Geologic province summary by percentage as generalized from Ma and others (2009) for the 

Tillamook Bay subbasins and Nehalem River basin, northwestern Oregon. Data determined at the mouth 

of the rivers.

Geologic province

River basin 

Coast Range 

(sedimentary)

Coast Range 

(volcanic)

Columbia River 

basalts

Quaternary 

deposits

Tillamook 47.8 25.1 0.4 26.7

Trask 19.3 69.0 0 11.7

Wilson 22.4 70.8 0 6.8

Kilchis 2.8 93.1 0 4.1

Miami 18.9 71.7 0.8 8.6

Nehalem 63.7 27.1 4.3 4.9
9 

Figure 3. Diagrams showing the longitudinal profiles of the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem 

River basins, northwestern Oregon. Profiles determined from the U.S. Geological Survey 10-m Digital Elevation 

Model along the channel centerlines 
10

Figure 3 (continued). Diagrams showing the longitudinal profiles of the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem River basins, northwestern Oregon. Profiles determined from the U.S. Geological Survey 

10-m Digital Elevation Model along the channel centerlines.
11

Hydrology 

Since the 1930s, the USGS has measured 

streamflow at stations in the Trask, Wilson, and 

Nehalem River basins (table 3). As of 2011, the 

USGS measures stage and streamflow on the 

Trask (Trask River above Cedar Creek, 

14302480), Wilson (Wilson River near Tillamook, 14301500), and Nehalem (Nehalem River 

near Vernonia, 14299800; Nehalem River near 

Foss, 14301000) Rivers. Additionally, the Oregon Water Resources Department (OWRD) has 

measured stage and streamflow on the Miami 

River periodically since the 1970s (Miami River 

near Garibaldi, 14301300; 

http://www.wrd.state.or.us/OWRD/SW/index.sht

ml). Neither agency currently measures streamflow in the Tillamook and Kilchis River basins. 

The hydrology of these rivers is driven by 

seasonal precipitation that falls predominately as 

rain from October to March. Mean annual precipitation ranges from 229 centimeters per year 

(cm/yr) near the town of Tillamook (Tillamook 

Bay National Estuary Project, 1998) to 241 

cm/yr near Nehalem Bay to 508 cm/yr in the 

Salmonberry River basin (State Service Center 

for GIS [1996] as cited in Johnson and Maser 

[1999]). Mean annual streamflows range from 

6.4 m3/s on the Miami River to 75.0 m3

/s on the 

Nehalem River near Foss (table 3; fig. 4A–D). 

Mean January monthly flows are approximately 

20–100 times those of mean August flows. 

Greater rainfall is most common from November 

to January in the Tillamook Bay subbasins 

(Tillamook Bay National Estuary Project, 1998) 

with flash flooding and mud flows frequent in 

the steep tributaries where thin soils cover bedrock (Coulton and others, 1996). Flooding is 

common in the lower mainstems of the Tillamook Bay subbasins because the capacity of the 

channels to convey floods has presumably been 

reduced (U.S. Army Corps of Engineers, 2005). 

Although rare, rain-on-snow events have triggered some floods in the basins, including those 

of 1955, 1964, and 1996 (Johnson and Maser, 

1999; Snyder and others, 2003). 

For select streamflow-gaging stations with 

15 or more years of recent data collection, we 

identified peak flows from the gaging records 

because these flows in part drive bed-material 

transport. Peak flows reached 1,093 m3/s on November 16, 2006, on the Wilson River, 730 m3

/s 

on February 8, 1996, on the Trask River, 220 

m

3

/s on November 12, 2008, on the Miami River, and 1,991 m3

/s on February 8, 1996, on the 

Nehalem River near Foss (table 3; fig. 5A–D). 

Since the December 1964 flood, the number of 

10-year or greater recurrence-interval events on 

the Wilson River and 5-year or greater events on 

the Nehalem River has increased slightly. (The 

recurrence interval is the average frequency, in 

years, with which a flood of certain magnitude 

would be expected to occur. A 10-year recurrence interval flood, for example, has a 10 in 

100, or 10 percent, chance of occurring in any 

particular year.) The ranking for the 1964 flood 

on the Trask River illustrates this shift in peak 

flow patterns; this flood on the Trask River was 

ranked as approximately a 90-year event in the 

1960s, but is currently ranked as less than a 25-

year event because of frequent floods in more 

recent years (Coulton and others, 1996). See 

Coulton and others (1996) and Johnson and Maser (1999) for summaries of historical peak 

floods in the Tillamook Bay area and Nehalem 

River basin, respectively. 
12

Table 3. Summary of streamflow-gaging station information for the Trask, Wilson, Miami, and Nehalem Rivers, northwestern Oregon. Data from 

U.S. Geological Survey (2011) and Oregon Water Resources Department (2011).

[~, approximately; km, kilometer; RKM, river kilometer; km2, square kilometer; WY, water year; m3/s, cubic meter per second; --, data not available]

River Station name Station ID

Study 

reach Location

Nearest 

bridge

Drainage 

area 

(km2) Period of record

Mean 

annual 

flow 

(m3/s)

Mean 

January 

flow 

(m3/s)

Mean 

August 

flow 

(m3/s)

Peak flow 

(m3/s)

Date of peak 

flow event

Trask

Trask River 

above Cedar 

Creek, near 

Tillamook1

14302480 -- ~1.8 km 

above 

study area

~6.4 km 

downstream

404 4/1996–present 27.6 64.0 3.1 637.0 11/25/1999

Trask 

River near 

Tillamook

14302500 -- ~0.9 km 

above 

study area

5.4 km 

downstream

376 7/1931–36/1972 27.4 62.0 3.0 730.5 22/8/1996

Wilson

Wilson 

River near 

Tillamook

14301500 -- ~0.1 km 

above 

study area3

1.2 km 

downstream

417 10/1914–19/1915; 

8/1916–11/1916; 

7/1931–present

4

33.3 72.4 3.0 1,092.9 11/6/2006

Wilson River 

at Sollie 

Smith Bridge 

at Tillamook5

14302020 Lower

Fluvial

Wilson

RKM 6.3 At station 490 7/2008–present -- -- -- Only stage 

data available

11/12/2008

Miami

Miami River 

near Garibaldi

14301300 Tidal 

Miami

RKM 2.7 At station 73 10/1973–9/1995; 

10/2008–present

6.5 13.7 0.8 220.0 11/12/2008

Nehalem

Nehalem 

River near 

Vernonia

14299800 -- ~140 km 

above 

study area

At station 181 7/2001–present 6.4 19.9 0.2 498.4 12/3/2007

Nehalem 

River near 

Foss

14301000 -- ~0.4 km 

above 

study area

2.6 km upstream1,728 10/1939–present 75.0 176.7 4.2 1,990.7 2/8/1996

1

Streamflow measurements are made at Long Prairie Road Bridge, RKM 11.6 (~6.4 km downstream of the current gage location). USGS (2011) calculates the 

gage's drainage area at the discharge measurement location. Drainage area at the gage is 373 km2as measured from StreamStats.

2 Flow was estimated based on flood marks

3 Location of gage has changed over time

4 Mean annual flow reported for water years 1932–2010

5 Gage heights only; no streamflow data collected at this station
13

Figure 4. Graphs showing mean daily streamflow for U.S. Geological Survey and Oregon Water Resource Department streamflow-gaging stations on the (A) Trask River above Cedar Creek near Tillamook, Oregon 

(14302480), (B) Wilson River near Tillamook, Oregon (14301500), (C) Miami River near Garibaldi, Oregon 

(14301300), and (D) Nehalem River near Foss, Oregon (14301000), northwestern Oregon. [km, kilometer; km2, 

square kilometer; RKM, river kilometer] 
14

Streamflow alterations in the study basins 

include water withdrawals for agricultural, municipal, and domestic uses primarily in the 

floodplains of the Tillamook Bay subbasins and 

Nehalem River basin and near several towns 

along the Nehalem River (figs. 1 and 2). Additionally, small dams are in the headwaters of the 

Trask and Tillamook Rivers and on Fishhawk 

Creek, a tributary to the Nehalem River. The 

dam forming Skookum Lake Reservoir on Fawcett Creek, a tributary to the Tillamook River, 

was built in 1965 to provide the city of Tillamook with municipal drinking water (City of 

Tillamook, 2011). At the Barney Reservoir on 

the Middle Fork of the North Fork Trask River, 

water is diverted to the headwaters of the Tualatin River (U.S. Geological Survey, 2011) for use 

by the cities of Beaverton, Hillsboro, and Forest 

Grove. Fishhawk Lake is a private recreational 

lake on Fishhawk Creek north of the town of 

Birkenfeld. Historically, several small dams that 

no longer exist were operated for hydropower, 

fire control, and logging activities throughout the 

Nehalem River basin (Johnson and Maser, 

1999). Effects of existing dams on overall bedmaterial flux are likely limited because these 

dams are small and affect 5 percent or less of 

these basins.

A flood on December 3, 2007, undermined bridge 

piers and railroad tracks adjacent to the Salmonberry 

River near its confluence with the Nehalem River (Oregon Department of Forestry). 

Bridge pier blocking large wood on the North Fork 

Trask River near its confluence with the South Fork 

Trask River. 
15

Figure 5. Graphs showing annual peak streamflow for U.S. Geological Survey and Oregon Water Resource Department streamflow-gaging stations on the (A) Trask River above Cedar Creek near Tillamook, Oregon 

(14302480), (B) Wilson River near Tillamook, Oregon (14301500), (C) Miami River near Garibaldi, Oregon 

(14301300), and (D) Nehalem River near Foss, Oregon (14301000), northwestern Oregon. Reported flow recurrence intervals from Cooper (2005). [km, kilometer; km2

, square kilometer; m3/s, cubic meter per second; RKM, 

river kilometer; * above peak in “A” (Trask River) is from field measurement]
16

Historical Channel Descriptions 

Historical observations of river channels are 

useful counterpoints for comparing present 

channel conditions. Although most historical accounts describe conditions within the bays and in 

relation to navigation and trade development, 

some describe general channel characteristics, 

channel planform changes, and transport of sediment and large wood in the rivers. Coulton and 

others (1996) describe historical changes in 

Tillamook Bay. 

Early accounts by the Corps of Engineers 

described the region’s suitability for future land 

uses. In 1886, Lieutenant Edward Burr noted 

that, “There are large quantities of spruce, fir, 

and cedar timber on the streams tributary to the 

bay, and the winter freshets on these streams fit 

them for the driving of logs” (U.S. Congress, 

1889). In 1888, Captain Charles F. Powell reported, “The rivers are mountain streams in the 

upper part of their course and tidal sloughs in the 

lower portion. The best country, grazing and 

farming, of the region is on these rivers and 

around the head of the bay; higher up the rivers 

are timber lands” (U.S. Congress, 1889). Powell 

added, “Tillamook River is by far the best stream 

for navigation, but its banks are low and overflowed for miles, affording at no place on its 

navigable part, it is judged, a suitable landing, 

nor a convenient and accessible point for the 

trade of the settled country. Neither is such a 

point found along the north or south channels of 

the bay on account of the little room at the foot 

of the steep bluffs there and the absence of ordinarily practicable land routes to the settled country” (U.S. Congress, 1889). These historical observations indicate overbank flooding on the 

Tillamook River, seasonal high flows on the 

bay’s tributaries, and future distributions of land 

uses owing to the mountainous uplands and limited floodplain lands. 

Coulton and others (1996) summarized historical accounts of channel width, bed-material 

composition, and channel planform changes for 

the Tillamook Bay rivers, from which the following observations were extracted. The Tillamook River was described as a “river one hundred yards [approximately 90 m] wide, has no 

falls, and no difficult rapids” in an 1830 publication (Holman, 1910). Later in 1857, Samuel D. 

Snowden, a General Land Office (GLO) surveyor, described the Kilchis River as “3 feet [approximately 0.9 m] deep, gravel bottom” near 

RKM 12.6 (Township 1 North, Range 9 West 

section line) (General Land Office, 1856-57). 

Downstream at approximately RKM 6.5 (the intersection of the north boundary of Township 1 

South, Range 9 West, Section 5), Snowden noted 

the “[f]ast current, gravelly bottom, 100 links [66 

ft or 20 m] wide” channel of the Kilchis River 

(General Land Office, 1856-57). As summarized 

by Coulton and others (1996), Henry Meldrum, 

another GLO surveyor, revisited this location in 

1884 and recorded that “[t]he Kilchis River has 

changed its bed at this point, about 3.50 chains 

[230 ft or 70 m] north of [the] old channel which 

has filled with gravel, sand, [and other material].” Coulton and others (1996) also reported the 

Wilson River channel migrated at about river 

mile 5 (RKM 8.2) between the GLO surveys of 

the 1850s and 1939 aerial photographs. These 

descriptions are comparable with current conditions, particularly the planform changes on the 

Kilchis and Wilson Rivers (described later in this 

report).

Some historical accounts noted by Coulton 

and others (1996) document sediment transport 

in the Tillamook Bay rivers and along the Oregon coast. The Corps of Engineers reported in 

1902 and 1907 that “a considerable quantity of 

gravel, sand, and mud is annually deposited in 

the [Tillamook] bay and channels by tributary 

streams” (Gilkey, 1974). In 1896, Assistant Engineer David B. Ogden noted some difficulty 

driving piles approximately 3.7 m into the 

streambed for the dikes at the Wilson River 

mouth owing to sand and gravel (U.S. Army 

Corps of Engineers, 1896). On the Oregon coast 

north of the Nehalem River, during the winter 

1805–1806, explorer William Clark chronicled 

the occurrence of landslides where “fifty or a 
17

hundred acres at a time give way and a great 

proportion of an instant precipitated into the 

ocean” (Bancroft, 1884), illustrating the likely 

contributions of landslides to sediment fluxes in 

Oregon coastal rivers. 

Likewise, GLO surveyors and the Corps of 

Engineers described the occurrence and transport 

of large wood in the Tillamook region, as summarized by Coulton and others (1996). Surveyors noted in 1857 that “...the Tillamook River is 

navigable from section 7 to the ocean—and 

would be so for small steamboats if cleared of 

drift” (General Land Office, 1856–57). The Wilson River had jams over 200 m long (General 

Land Office, 1856–57). The GLO surveyed the 

Kilchis River “to a point where the river becomes shallow and obstructed by drift [and] it 

was thought useless to meander [survey] it any 

further up” (General Land Office, 1856–57). 

Later, the Corps of Engineers (1895) noted, 

“[t]he first mouth [of the Trask River], locally 

known as the North Fork, has become clogged 

up so with timber jams as to divert most of the 

water into the South Fork. It is proposed to remedy the evil by building a dike across the head of 

the South Fork and removing the jams from the 

North Fork” (U.S. Army Corps of Engineers, 

1895). The following year, the Corps of Engineers reported that, “Now that the South Fork 

has been diverted, the jams in the North Fork [or 

mainstem Trask channel near mouth] should be 

removed, banks trimmed, and sunken logs removed to permit it to carry the flood waters 

without flooding the farm lands” (U.S. Army 

Corps of Engineers, 1897). Summarizing the accumulation of wood in Tillamook Bay, the Corps 

of Engineers noted, “One of the most serious 

troubles with this bay is caused by the large 

number of snags and fallen trees that are carried 

in on floods, and which eventually sink on the 

shoals and become buried in the same” (U.S. 

Army Corps of Engineers, 1897). 

We found fewer historical accounts for the 

Nehalem River. Of these, two accounts highlight 

the Nehalem River’s potential for transporting 

timber (owing likely to its steep gradient and 

high winter flows) above the head of tide. In 

1884, J. L. Barnard traveled down the Nehalem 

River to assess logging prospects. Barnard reported, “[he] found only one piece of slab-wood 

lodged in the bed of the river from Browse's Mill 

[approximately 161 km from the mouth of the 

Nehalem River] to tide-water, with one lodgement of driftwood on top of a rock about 20 feet 

[6.1 m] high in the middle of the river, left there 

during some freshet, showing that it is a beautiful stream to run logs down, for 100 miles [160 

km] or more, to tide-water, furnishing an almost 

inexhaustible supply of timber” (as cited in Farnell, 1981). In 1889, J.S. Polhemus of the Corps 

of Engineers reported, “For 20 miles at least 

above the head of tide to the Middle Nehalem [a 

settlement near the three Fish Hawk Creeks, or 

between the towns of Birkenfeld and Jewell; fig. 

2], the river flows as a rapid stream over a rocky 

bottom between steep hills all covered with fine 

timber. It is not navigable, but I have been informed by old settlers, that it offers good facilities for driving logs for 70 or 80 miles, being 

particularly free from drift and other obstructions” (U.S. Congress, 1890). 

Other historical accounts of the Nehalem 

River document sediment transport. In 1889, 

Gwynn A. Lyell noted, “The [Nehalem] river 

was surveyed from the entrance to the islands 

above Kinney's cannery [near Wheeler, Oregon]. 

The channel at the islands is obstructed by gravel 

bars formed by accumulated drift. Above the islands the banks of the river are low and the width 

contracted deeper water than that below the islands” (U.S. Congress, 1890). Lyell also reported 

that “[t]he inner shore of the river opposite the 

entrance, and up to Fishery Point, is composed of 

sand, gravel, and cobble stones” (U.S. Congress, 

1890). 

Settlement and Land Ownership Patterns 

The Tillamook and Nehalem tribes inhabited 

the basins prior to Euro-American settlement 

(Coulton and others, 1996; Tillamook Bay National Estuary Project, 1998; Johnson and Maser, 

1999). John Meares and other explorers came to 
18

the Tillamook Bay area in the 1770s–1780s 

(Coulton and others, 1996), nearly 80 years before Euro-American settlers came to “fish, farm, 

and raise milk cows on the rich coastal plain” of 

the Tillamook Bay in 1851 (Wells, 1999). Many 

settlers built farms in the Kilchis and Wilson 

River valleys (Coulton and others, 1996). The 

Nehalem basin had its first Euro-American settler nearly 17 years later in 1866 and its towns of 

Wheeler and Nehalem established in 1868 

(Johnson and Maser, 1999). Basin land use initially focused on farming, dairies, and fishing 

and later included forestry (Coulton and others, 

1996; Johnson and Maser, 1999). 

Land use patterns vary some among the basins (table 4) (Oregon Natural Heritage Program, 

1999). Approximately 58–89 percent of the 

Trask, Wilson, Kilchis, and Miami River basins 

are managed largely as the Tillamook State Forest by the State of Oregon. The State managed 

Tillamook and Clatsop State Forests make up 

nearly a third of the Nehalem River basin. Most 

of these lands were transferred to the Oregon 

State Board of Forestry after the Tillamook Burn 

(Coulton and others, 1996; Johnson and Maser, 

1999). Private lands account for 98 and 68 percent of the Tillamook and Nehalem River basins, 

respectively, with a large proportion managed for 

timber in the Nehalem River basin (Johnson and 

Maser, 1999). Federal and county holdings are 

less than 5 percent of these basins. State managed lands dominate the headwaters and upper 

portions of the Tillamook Bay subbasins, whereas private lands used for residential, agriculture, 

and other purposes dominate the lowlands. In the 

Nehalem basin, State managed lands are in the 

basin’s headwaters to approximately the town of 

Timber, on south-flowing tributaries entering the 

mainstem between the towns of Birkenfeld and 

Jewell, lands draining to the mainstem from approximately Cronin to Foley Creeks, and most of 

the Cook Creek and Salmonberry River basins 

(fig. 2). Agriculture and other developed lands 

are near the towns of Vernonia, Mist, Birkenfeld, 

Jewell, Vinemaple, and Mohler. These land use 

distributions in combination with geology and 

valley topography likely have considerable influence on bed-material dynamics (as discussed below). 

Table 4. Summary of land ownership for the 

Tillamook Bay subbasins and Nehalem River 

basin, northwestern Oregon.

[%, percent]

Land ownership (%)

River basin Federal State County Private

Tillamook 1.0 0.8 0 98.2

Trask 4.8 62.1 0 33.0

Wilson 1.2 88.6 0.2 10.1

Kilchis 1.5 84.2 2.6 11.7

Miami 0 57.8 0 42.2

Nehalem 0.9 30.8 0 68.3

Determined from Oregon Natural Heritage Program 

(1999)

Natural and Anthropogenic Disturbances Affecting Bed-Material Dynamics 

Several natural and human-related disturbances have had substantial effects on sediment 

yield and transport and channel morphology in 

the Tillamook Bay subbasins and Nehalem River 

basin. Logging, channel alterations for navigation, flood control, and gravel mining are some 

human activities that can affect channel and bedmaterial conditions. Fire and mass movements 

are natural processes affecting sediment yield 

and transport, but both processes have likely 

been affected by human activities. Although 

streambank erosion is another natural process 

that is influenced by human actions, it was outside the scope of this study because it primarily 

increases fine sediment inputs rather than bedmaterial inputs. 
19

Bank erosion on the Wilson River, 1922 (Oregon 

State University Archives, 1238972454917) 

Mass Movements 

Mass movements and debris flows are probably the primary mechanisms that introduce bed 

material from hillslopes into the Tillamook Bay 

rivers and Nehalem River. Alluvial reworking of 

debris fans and accumulated terrace gravels further contributes bed material to the channels. In 

general, the steep headwater gradients, weathered sedimentary and volcanic rocks, and episodically intense rains promote abundant landslides 

and debris flows (Tillamook Bay Taskforce and 

others, 1978; Johnson and Maser, 1999; Snyder 

and others, 2001, Snyder and others, 2003; Duck 

Creek Associates, 2008; Reckendorf, 2008a). For 

example, the Oregon Department of Geology and 

Mineral Industries (DOGAMI, 1973) reported 

that “Throughout the Tillamook drainage at the 

height of the [January 1972] flooding, many 

small creeks, some too small to be shown on a 

map, turned into rivers of flowing mud, rocks 

and wood debris.” 

Mass movements also sometimes briefly 

dam the rivers. For instance, the Wilson River 

was dammed completely by a debris flow 

stretching over 120 m across the channel on January 31, 1965 (Levesque, 1980) and a landslide 

that moved over 383,000 m3

of material on April 

4, 1991 (Burns, 1998; Preiffer and others, 1998). 

During field reconnaissance, we visited a debris 

flow site near RKM 30.7 that probably resulted 

from the storm on December 2–3, 2007, and appears to contribute sediment and wood in mainstem Nehalem River. The volume and character 

of sediment delivered to streams may vary with 

the specific delivery process, geology, and disturbance factors. In particular, coarse bed material delivered from volcanic rocks may be a more 

considerable source of bed material because of 

these rocks have much greater resistance to abrasion than sedimentary rocks (Mangano and 

others, 2011). As described below, the frequency 

and character of mass movements can be affected by natural and human related disturbances. 

Logging and Related Transportation Activities 

Timber harvests can have many effects on 

terrestrial and aquatic ecosystems, including reducing vegetation cover and increasing surface 

water and sediment run-off to nearby rivers. Settlers initially harvested forests in the valleys and 

riparian areas of these six basins to establish 

fields and dairy pastures and for local construction needs (Coulton and others, 1996; Johnson 

and Maser, 1999). By the beginning of the 20th

century, industrial logging was widespread 

throughout the basins. In the Tillamook area, 

logging peaked in 1952, when salvage logging 

operations removed 609,624 board feet from the 

Tillamook Burn (Snyder and others, 2003; 

Andrews and Kutara, 2005). In the Nehalem 

River basin, timber harvests peaked during the 

1920–1940s, with the last old growth forests 

harvested in 1945 (Johnson and Maser, 1999). 

Harvests continue in these basins, and may increase in coming years as forests replanted after 

the Tillamook Burn reach harvestable ages 

(Snyder and others, 2003) and trees are harvested 

and thinned to combat Swiss Needle Cast, a forest pathogen infecting the region’s Douglas fir 

stands (Follansbee and Stark, 1998b; Johnson 

and Maser, 1999; Snyder and others, 2003; 

Jenkins and others, 2005). 

Transportation of timber can also affect the 

hydrology and sediment fluxes of nearby rivers. 

Log drives (the floating of logs during naturally 
20

occurring flood events; fig. 6A–B) and splash 

damming (log drives coupled with managed and 

repeated dam releases) were early transportation 

methods. Log drives occurred on all six rivers 

(table 5) and several tributaries (Farnell, 1980, 

1981; Miller, 2010). The longest log drives were 

on the Nehalem River and ran approximately 140 

km from the East Fork Nehalem River to the bay 

(Farnell, 1981). Later, splash dams were constructed on Bewley Creek (a tributary to the 

Tillamook River), North Fork Nehalem River, 

and Humbug Creek (a tributary to the Nehalem 

River; Farnell, 1980, 1981; Miller, 2010). Millions of logs were floated down the Nehalem 

River and tributaries, such as the North Fork Nehalem River, Humbug Creek, and Salmonberry 

River (Farnell, 1981). Log drives and splash 

damming may have increased flood frequency 

and magnitude, sediment fluxes, and streambed 

scouring (possibly to bedrock in some locations).

For example, floods caused by splash damming 

probably exceeded 100-year flood events in 

headwater areas, and equaled 100-year flood 

events in downstream areas in basins south of the 

Tillamook basin (Phelps, 2011). As suggested 

for the Coquille basin (Benner, 1991), riparian 

vegetation and instream wood and boulders were 

probably removed to maximize log transport efTable 5. Time periods of log drives and 

splash damming in the Tillamook Bay subbasins and Nehalem River basin, northwestern Oregon. [Source: Farnell 

(1980,1981)]

[~, approximately]

Activity River/Creek Time period

Log 

drive

Tillamook 1887–1915

Trask 1879, 1890–

1915

Wilson 1893–1908

Kilchis 1872–1915

Miami 1900–1920

Nehalem 1901–1926

Splash 

damming

Bewley 1892–1915

North Fork 

Nehalem

~1923–1926

Humbug 1916–1923

ficiency; such changes may have increased sediment fluxes and bank instability in these rivers. 

Timber transport shifted from log runs and 

splash dams in the 1870s–1920s (table 5) to railroads in the early 1900s and to trucks in the 

1940s (Coulton and others, 1996; R2 Resource 

Consultants, Inc., 2005). Recent forest road estimates include approximately 1,840 km of roads 

on Oregon Department of Forestry (ODF) lands 

in the Tillamook Bay subbasins (Snyder and others, 2001) and over 1,910 km of forest roads in 

the Nehalem River basin (Portland State University [2000] as cited in R2 Resource Consultants, 

Inc. [2005]). Roads on steep slopes in conjunction with timber harvests can increase the magnitude and frequency of mass movements 

(Swanson and Dyrness, 1975; Beschta, 1978; 

Amaranthus and others, 1985; Harden and 

others, 1995), particularly in regions naturally 

prone to mass movements like the Coast Range. 

As described by Coulton and others (1996), 

roads and culvert failures are likely substantial 

contributors to mass wasting and sediment inputs 

in the Tillamook Bay subbasins. Roads are also 

cited as “the principal cause of human-induced 

landslides in the forests” of the Tillamook Bay 

subbasins (Tillamook Bay National Estuary Project, 1998). 

Nehalem River along the Pacific Railway & Navigation 

Company, 1910 (Oregon State University, 

1238951456889). 
21

Several studies reinforce the abundance of 

road related landslides on forestlands in these 

basins. In 1978, 240 natural landslides and 4,440 

human related landslides were reported in the 

Tillamook Bay subbasins, with the number of 

landslides greatest in the Trask and Wilson River 

basins and lowest in the Tillamook River basin 

(Benoit, 1978). Reported landslides are likely 

lowest in the Tillamook basin where the effects 

of the Tillamook Burn and subsequent salvage 

logging were minimal. In the Kilchis River basin, 57 landslides were documented after the 

storms of 1995–1996, primarily near forest roads 

in use since 1972 (Mills, 1997). Additionally, 

over half of the ODF roads in the Tillamook Bay 

subbasins likely “pose a moderate or high risk of 

contributing sediment to a stream if a roadrelated landslide was to occur” with high-risk 

sites occurring about every 2 miles along ODF 

roads (Snyder and others, 2001). In the Upper 

Nehalem River basin, R2 Resource Consultants, 

Inc. (2005) reported that the highest landslide 

density coincided with roads. 

Fire 

Before and after Euro-American settlement, 

fires burned the Tillamook Bay subbasins and 

Nehalem River basin, reducing vegetation cover 

and soil moisture and episodically increasing 

sediment fluxes to nearby rivers. Native American tribes regularly burned the valleys and upland prairies in late fall to improve hunting, resource gathering, and visibility (Morris, 1934; 

Coulton and others, 1996). In approximately 

1800 and prior to Euro-American settlement, a 

large fire occurred south of the town of Mist in 

the Nehalem River basin (Johnson and Maser, 

1999). The Great Fire of 1845 was started by settlers on the western edge of the Willamette Valley and then crossed the Coast Range, affecting 

approximately 6,070 km2from Tillamook to 

Newport (Morris, 1934; Coulton and others, 

1996). An 1868 fire moved south from Clatsop 

County, burning the higher elevations of the 

Coast Range (Coulton and others, 1996) and 

likely portions of the Nehalem River basin and 

Tillamook Bay subbasins. Notes and maps from 

a timber cruise in 1908 indicated prior fires in 

most of the Trask, Wilson, and Kilchis valleys, 

particularly near the mainstems and major wagon 

roads (Coulton and others, 1996). 

More recently, the Tillamook Burn, a series 

of several fires between 1933 and 1951, and the 

Salmonberry Fire on the Nehalem and Salmonberry Rivers in 1945 destroyed a total of 1,436 

km2and over 13 million board feet of timber in 

the Trask, Wilson, Kilchis, Miami, and Nehalem 

River basins (Oregon State Department of 

Forestry, 1983). Historical photographs illustrate 

the effects of these fires and subsequent replanting efforts (fig. 7A–C). During the first fire, the 

caretaker at the Wilson River streamflow-gaging 

station noted, “During August there occurred the 

most disastrous fire in Oregon in many years, 

perhaps in history. The fire covered heavy stands 

of timber over almost the entire Wilson River 

watershed, burning down nearly to the gaging 

station. It reached a climax of intensity on Aug. 

25–26 forcing the gage reader to leave his home. 

Shortly afterwards, gentle showers enabled 

fighters to place the fire under control” (from 

records for 14301500 housed at the USGS Oregon Water Science Center). These 1933–1951 

fires repeatedly burned some areas in the Trask, 

Wilson, Miami, and Salmonberry River basins. 

Sediment from these affected lands was eroded 

and delivered to the rivers until reforestation efforts from 1949 to 1970 reduced erosion rates 

(Coulton and others, 1996). Today, most of lands 

affected by the Tillamook Burn and Salmonberry 

Fire are managed as the Tillamook and Clatsop 

State Forests. 
22

Figure 6. Historical photographs showing log drives on the (A) Nehalem River circa 1915 [Oregon State University Archives, LLID 1238951456889] and (B) Trask River (date unknown) [Oregon Historical Society bb009090]. 

The Oregon State University Archives and Oregon Historical Society granted permission to use these photographs. 
23

Figure 7. Historical photographs of the Tillamook Burn: (A) the Wolf Creek subbasin of the Salmonberry River 

basin in 1932 [Tillamook County Pioneer Museum], (B) a burned riparian corridor along the Wilson River [Oregon 

Historical Society bb009089], and (C) students planting trees as part of the Tillamook Burn reforestation effort 

[Oregon Department of Forestry]. The Tillamook County Pioneer Museum, Oregon Historical Society, and Oregon 

Department of Forestry granted permission to use these photographs. 

Channel Alterations for Navigation and Flood 

Control 

Before highways, waterways connected this 

region with nearby markets. The Corps of Engineers constructed and maintained jetties at the 

Tillamook Bay entrance since approximately 

1914 (Willingham, 1983; Coulton and others, 

1996), and completed two jetties at the Nehalem 

River mouth in 1918 (Willingham, 1983). As 

noted by Coulton and others (1996), the Corps of 

Engineers regularly dredged littoral sands from 

the Tillamook Bay’s entrance and main navigation channel from the late 1880s to the mid1970s (U.S. Army Corps of Engineers, 1975). 

On average, nearly 24,000 m3per year (a total of 

approximately 1.2 million m3) was removed and 

disposed of offshore from 1929 to 1979 

(Tillamook Bay National Estuary Project, 1998). 

Farther upstream, the Corps of Engineers maintained a navigation channel to the town of Tillamook from approximately 1890 to the 1920s 

(Farnell, 1980; Tillamook Bay National Estuary 

Project, 1998). Also, emergency dredging to reduce flooding during the winter of 1971–1972 

removed over 82,570 m3from the mouths of the 
24

Wilson and Trask Rivers and disposed of that 

material on their deltas (Follansbee and Stark, 

1998a). On the Nehalem River, Federal entities 

dredged approximately 9,500 m3of sand from 

the bay during 1932–1933 (Ferdun, 2010). The 

Corps of Engineers, however, does not presently 

dredge the Nehalem River because of the absence of a Federal navigation channel (Katharine 

Groth, U.S. Army Corps of Engineers, written 

commun., 2010).

Upstream, Federal entities and local diking 

districts built levees and dikes for channel 

maintenance and flood prevention starting in the 

early 1900s in the Tillamook Bay area and Nehalem basin (Coulton and others, 1996; Ferdun, 

2010). As described above, the Corps of Engineers built dikes, such as those near the Trask 

River mouth in 1896–1897 and on the historical 

Wilson River channel in 1900–1901 to reduce 

the amount of large wood and sediment blocking 

the channels and prevent flooding. Additionally, 

the Corps of Engineers “constructed dikes to redirect and direct water in an attempt to reduce 

the deposition of gravel and sand in the navigation channel” (Coulton and others, 1996). In the 

1920s, a dike was built to direct flow and logs to 

the sawmill near Wheeler on the Nehalem River 

(Johnson and Maser, 1999). Many of the historical levees and dikes in the lowland and tidal 

channels of the Tillamook Bay were constructed 

directly on both river banks (Phillip Williams & 

Associates, 2002). During the 20th and early 

21st centuries, flood control structures in the 

Tillamook and Nehalem areas have undergone 

frequent repairs and modifications (Coulton and 

others, 1996; Jenkins and others, 2005; U.S. 

Army Corps of Engineers, 2005; Ferdun, 2010). 

An inventory of levees and dikes in tidal areas along the Oregon coast (Oregon Coastal 

Management Program, 2011) indicates that 

floodplain modifications (or levees, dikes, and 

naturally formed levees reinforced with nonerodible materials) border over 70 percent of the 

mainstem in the Tidal Tillamook, Trask, and 

Wilson Reaches and approximately 30 percent of 

the mainstem in the Tidal Kilchis, Miami, and 

Nehalem Reaches (table 6). This inventory also 

included some modifications along the channels 

in the Fluvial Trask and Kilchis Reaches and the 

Lower Fluvial Reaches on the Wilson and Miami 

Rivers. These levees, dikes, and other bank protection features have probably affected hydrology and sediment fluxes, reduced channel migration, locally increased channel scour, and increased sediment deposition in downstream areas.

Large wood also has been removed from 

these river systems. As described in Coulton and 

others (1996), the Corps and Engineers and the 

Port of Tillamook removed over 9,300 snags 

from the Tillamook Bay channels during 1890–

1920 to improve navigation (Benner and Sedell, 

1987). Wood was mainly removed from areas 

near the mouth of the Tillamook River to the 

town of Tillamook and the lower Trask channels 

(Coulton and others, 1996). Upstream, wood 

jams were documented on all Tillamook Bay rivers (as described previously) and were so prevalent on the Wilson River that log jams were often 

broken up using dynamite at river mile 16, approximately 1.6 km upstream of the Wilson River study area (Coulton and others, 1996). Judging from the well documented activities on the 

Coquille River (Benner, 1991), many wood jams 

were likely removed during the period of log 

drives and splash dam operations. After the 

Tillamook Burn, wood removal (or “stream 

cleaning”) occurred until the 1960s and early 

1970s to improve fish passage in the Wilson 

River, upper Miami River and several tributaries, 

and the upper and lower Nehalem River and several of its tributaries (Johnson and Maser, 1999; 

Jenkins and others, 2005; R2 Resource 

Consultants, 2005; Duck Creek Associates, 

2008). Reductions in large wood possibly contributed to simplification of channel morphology 

and instream habitats and likely affected channel 

processes, including rates of bank erosion and 

sediment storage.
25

Table 6. Summary of floodplain modifications in the study areas of the Tillamook Bay sub-basins and 

Nehalem River basin, northwestern Oregon. Data derived from the Oregon Coastal Management 

Program (2011).

River Reach

Wetted channel 

perimeter 

(meters)

1

Estimated length 

of floodplain 

modifications 

(meters)

Channel 

bordered by 

floodplain

modifications 

(percent)

Figure in this 

report

Tillamook Fluvial 8,140 0 0 9

Tidal 20,670 15,830 77 9

Trask Fluvial 19,240 1,100 6 10

Tidal 14,280 10,170 71 10

Wilson Upper Fluvial 5,690 0 0 11

Lower Fluvial 16,040 5,560 35 11

Tidal 10,190 7,860 77 11

Kilchis Fluvial 10,760 400 4 12

Tidal 5,420 1,810 33 12

Miami Upper Fluvial 4,850 0 0 13

Lower Fluvial 16,240 1,680 10 13

Tidal 2,770 960 34 13

Nehalem Fluvial 15,320 0 0 14

Tidal 59,500 16,670 28 15

1 Total bank length for each reach is approximated using wetted channel perimeter.

Gravel Mining 

Instream gravel mining can potentially lead 

to lowering of the channel bed, changes in cross 

sections, increased turbidity, armoring of bar surfaces, and reductions in downstream bedmaterial fluxes (Kondolf, 1994). These geomorphic changes may correspond to changes in 

the frequency and geometry of pools and riffles, 

scouring of salmon redds, filling of interstitial 

spaces (spaces between sand grains or gravel) 

with fine sediment, and declines in macroinvertebrates (Kondolf and others, 2002). Other biological effects may include dewatering of salmon 

redds built on mined bar surfaces during higher 

flows. Bed material has been mined from the 

Wilson and the Trask Rivers since at least the 

early 1900s to support local construction needs 

and build levees (Coulton and others, 1996) and 

from the Kilchis River since at least the 1940s 

(Follansbee and Stark, 1998a). Gravel was also 

mined from the Miami River near Peterson and 

Stuart Creeks in the 1960s–1970s (Jenkins and 

others, 2005) and the mainstem Nehalem River 

to build Highway 26 (Johnson and Maser, 1999; 

R2 Resource Consultants, 2005). Reports from 

1991 indicated that over 44,000 m3 of gravel 

were removed annually from the Trask, Wilson, 

Kilchis, and Miami Rivers and nearby Nestucca 

River (Tillamook County, 2000). 

Owing to possible adverse effects of instream gravel mining on local chum salmon 

populations, the Tillamook Gravel Mediated 

Agreement was developed in 1992 to halt com-
26

mercial instream gravel mining above the head 

of tide on the Trask, Wilson, Kilchis, and Miami 

Rivers by October 1, 1997 (Tillamook County, 

2000). After this termination date, instream 

gravel mining was only permitted to prevent 

bank erosion and for noncommercial purposes 

(Tillamook County, 2000), with the exception of 

existing commercial gravel mining permits 

(Robert Lobdell, Oregon Department of State 

Lands, oral commun., 2012). After October 

1997, Tillamook County (2000) noted the building of gravel bars (partly in association with sedimentation during the February 1996 flood) and 

severe bank erosion opposite of gravel bars by

the winter of 1998–1999. These concerns resulted in modifications to the 1992 agreement, including a pilot project to reduce bank erosion 

opposite of Bush (Trask, RKM 12.2), Tannler 

(Wilson, RKM 6.6), Upper Landolt (Kilchis, 

RKM 5.3), and Gomes (Kilchis, RKM 4.8) Bars. 

These modifications also clarified that gravel 

mining in tidal reaches was excluded from this 

agreement since Federal, State and local laws 

and requirements address it. 

As of 2011, active instream mining permits 

are located on the Trask, Wilson, Kilchis, Miami, and Nehalem Rivers with annual limit removal limits ranging from 2,000 to 11,000 m3

per site (table 7; Judy Linton, U.S. Army Corps 

of Engineers, written commun., 2010; Robert 

Lobdell, Oregon Department of State Lands, 

written commun., 2011). A permitted mining site 

on the South Fork Nehalem River with an annual 

mining limit of 11,470 m3 was not included in 

this study because it is located in the upper portion of the basin, where narrow canyon walls 

preclude geomorphic mapping from photographs. Dill Bar on the Kilchis River was excluded from the mapping because it is 1.1 km 

upstream of the Kilchis River study area, but was 

included in the compilation of reported deposited 

and mined gravel volumes. All ongoing mining 

sites are above the head of tide (see maps of 

study reaches below). Refer to the “GravelOperator Information and Surveys” section for 

more details. 

Like instream gravel mining, floodplain 

mining can also affect channel condition and 

bed-material transport. The most recent USGS 

topographic quadrangles from 1984 to 1986 

(which are based on aerial photographs from 

1980) denote gravel mining sites on the Trask 

River floodplain. Although not specifically assessed in this study, the active channel near 

floodplain mining sites is commonly channelized, levied, and armored to prevent avulsions 

(channel excursions) into floodplain excavations, 

which can result in a diversion of the river into 

the mine pit (pit capture) and channel incision 

(Kondolf and others, 2002). 

Table 7. Ongoing instream gravel mining permits in the 

Tillamook Bay subbasins and Nehalem River basin, 

northwestern Oregon. Data from Judy Linton (U.S. Army Corps of Engineers, written commun., 2010) and 

Robert Lobdell (Oregon Department of State Lands, 

written commun., 2011).

[RKM, river kilometer; km, kilometer]

River Bar Approximate 

locations

Permitted limit on

annual mining volume 

(cubic meters)

Trask Bush RKM 12.2 4,330

Wilson

Donaldson RKM 10.4 6,000

Barker RKM 6.9 2,100

Kilchis

Dill ~0.1 km 

upstream 5,500

Gomes RKM 4.8 3,000

Miami Waldron RKM 4.8 2,000

Nehalem

Plant RKM 25.8 1

11,000

Winslow RKM 24.8

South 

Fork

Nehalem

Unknown

Near the 

town of 

Cochran

11,000

1Limit is combined for Plant and Winslow Bars

Study Areas and Reaches 

For the purposes of this study, we identified 

14 study reaches encompassing the major alluvi-
27

al portions of 6 river systems, including the lowermost 14.1 km of the Tillamook River, 16.3 km 

of the Trask River, 15.2 km of the Wilson River, 

7.8 km of the Kilchis River, 11.6 km of the Miami River, and 31.4 km of the Nehalem River 

(figs. 1 and 2). These mainstem corridors contain 

most of the alluvial deposits and historical and 

ongoing instream gravel mining sites within the 

basins. The 6 study areas were subdivided into 

12 reaches based primarily on tidal extent and 

topography. 

Tillamook River 

The Tillamook River begins east of the Cape 

Lookout State Park and flows eastward for 9.5 

km and then northward for 6.7 km, gaining tributaries that drain Coast Range sedimentary rocks 

and Quaternary deposits to the west but also 

Coast Range volcanic rocks to the east (fig. 1). 

Larger tributaries like Munson (8.3 km2), Simmons (11.0 km2

), Fawcett (16.2 km2

), and 

Killam (15.4 km2) Creeks draining Coast Range 

volcanic rocks to the east probably provide most 

of the bed material to the Fluvial Tillamook 

Reach. The Tillamook River study area begins 

downstream of Killam Creek at RKM 14.1 (fig. 

8). From here, the Tillamook River generally 

continues northwestward for 14.1 km, augmented by several small tributaries like Bewley 

(RKM 11.1; 15.8 km2), Sutton (RKM 8.7; 6.5 

km2), Beaver (RKM 8.0; 13.7 km2), Anderson 

(RKM 7.2; 6.5 km2), and Esther (RKM 1.5; 3.4 

km2) Creeks. The South Branch Trask River 

connects the Tillamook and Trask Rivers at 

RKM 1.8. The study area for the Tillamook River was divided at the head of tide (table 8) into 

the Fluvial Tillamook (RKM 14.1–10.2) and 

Tidal Tillamook (RKM 10.2–0) Reaches. Upstream of the study area, the Tillamook River 

contains a few, small gravel bars. No permits for 

ongoing instream gravel mining exist along the 

Tillamook River. 

In the Fluvial Tillamook Reach (RKM 14.1–

10.2), the Tillamook River has a drainage area 

that increases from 89 km2near its upstream 

boundary to 110 km2

at the head of tide and a 

concomitant increase in floodplain width from 

50 to 720 m (table 8; fig. 8). The channel is 

largely unconfined, but flows against valley 

walls to the southwest near RKM 14.1, 12.9–

12.5, and 11.1–10.8 in addition to Highway 101 

on the east bank near RKM 11.8–11.6. The gradient of the Fluvial Tillamook Reach is 0.0022 

m/m (table 8; fig. 9). The active channel, encompassing the wetted channel area and flanking 

gravel bars, ranges in width from 17 to 27 m, and 

contains elongated lateral and point bars (up to 

5,160 m2

in 2009 photographs) composed of 

gravel and finer grained sediments. The channel 

flows over cobble and fine grained alluvial deposits within this reach. 

The head of tide is at about RKM 10.2 (table 

1), and marks the transition to the Tidal Tillamook Reach, where the channel continues to 

flow over alluvial deposits and against western 

valley walls in several locations, such as near 

RKM 8.8, 7.9–7.6, 5.8, and 2.8–1.8 (table 8; fig. 

8). In this reach, gradient declines to 0.0002 m/m 

(table 8; fig. 9) and bars are scarce except for 

near RKM 0 where large (up to 119,610 m2) bars 

line the channel. The width of the active channel 

ranges from 15 to 137 m and the width of the 

floodplain ranges from 720 to 4,300 m, reaching 

its greatest width at the downstream end of the 

reach where the Tillamook and Trask Rivers 

share the floodplain. The drainage area of the 

Tillamook River is 156 km2at RKM 0. A 

noncomprehensive inventory of levees and dikes 

in tidal areas along the Oregon coast (Oregon 

Coastal Management Program, 2011) shows that 

almost the entirety of the Tillamook River from 

RKM 8.8 to 0 has either been diked or reinforced 

along its natural levees except for a short segment near RKM 2.2 (table 6; fig. 8 ). On current 

USGS quadrangle maps, roads near RKM 10.2–

8.8 border the Tillamook River. Piling remnants 

likely installed to concentrate streamflows and 
28

Table 8. Summary of characteristics for study reaches on the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon.

—continued

[m/m, meter change in elevation per meter of channel length; km2; square kilometers; m, meter; RKM, river kilometer; Hwy, highway; LiDAR, Light Detection 

And Ranging]

River Reach Channel description

Reach 

gradient2

(m/m)

Drainage 

area 

(km2)

Active 

channel 

width (m) Floodplain description

Background 

sediment drivers

River corridor 

modifications and 

disturbances

Tillamook

Fluvial; 

RKM 14.1–

10.2

Largely unconfined channel 

flows on alluvium and periodically against valley wall 

on west bank; lateral and 

point bars throughout reach

0.0022 89–110 17–27 Progressively widening 

floodplain; width 50–

720 m

Inputs from tributaries and other 

upstream sources 

such as eroded 

bank material

Bordered by Hwy 101 

from RKM 11.1

to10.8; log drives and 

splash dams

Tidal; 

RKM 10.2–0

Tidally affected channel 

flows on alluvium and periodically against valley wall 

on west bank; fewer and 

smaller bars

0.0002 110–156 15–137 Wide floodplain; width 

1,500–4,300 m and 

shared with Trask River

Low–gradient promotes deposition of 

bed and suspended 

loads from upstream sources

Confined by levees 

and dikes in lower 8.8 

km; pile structures 

and log boom remnants in channel; log 

drives and splash 

dams

Trask

Fluvial; 

RKM 16.3–

7.0

Channel flows on alluvium; 

confined in upper 2 km; 

flows between north and 

south valley walls; lateral, 

medial, and point bars 

throughout reach

0.0016 378–425 28–56 Narrow valley in upper 

2 km that progressively 

widens; width 100–

1,530 m

Inputs from tributaries and other 

upstream sources 

such as eroded 

bank material, debris flows, and 

landslides

Intermittently confined by levees and 

dikes from RKM 10.6

to 7.0; historical and 

ongoing gravel mining; floodplain mining of unknown status; log drives

Tidal; 

RKM 7.0–0

Tidally affected channel on 

alluvium; sparse lateral and 

point bars

0.0001 425–451 26–66 Wide floodplain; width 

1,500–4,300 m and 

shared with Tillamook 

River

Low-gradient promotes deposition of 

bed and suspended 

loads from upstream sources

Entire reach confined 

by levees and dikes; 

log drives
29

Table 8. Summary of characteristics for study reaches on the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon.

—continued

[m/m, meter change in elevation per meter of channel length; km2; square kilometers; m, meter; RKM, river kilometer; Hwy, highway; LiDAR, Light Detection 

And Ranging]

River Reach Channel description

Reach 

gradient2

(m/m)

Drainage 

area 

(km2)

Active 

channel 

width (m) Floodplain description

Background 

sediment drivers

River corridor 

modifications and 

disturbances

Wilson

Upper Fluvial; 

RKM 15.2–

12.6

Largely confined channel 

flows on alluvium plus intermittent bedrock in and 

along channel; lateral and 

point bars throughout reach

0.0017 417–474 42–66 Narrow valley that 

peaks in width at Little 

North Fork Wilson River confluence; width 

110–150 m

Inputs from tributaries and other 

upstream sources 

such as eroded 

bank material, debris flows, and 

landslides

Log drives

Lower Fluvial; RKM 

12.6–5.0

Channel flows on alluvium 

and periodically against valley walls along north and 

south banks; lateral and 

point bars throughout reach

0.0011 474–492 50–58 Progressively widening 

to head of tide; width 

150–2,200 m

Inputs from tributaries and other 

upstream sources 

such as eroded 

bank material, debris flows, and 

landslides

Intermittently confined by levees and 

dikes (RKM 12.4–

5.0) and roads (RKM 

6.3–5.0); historical 

and ongoing gravel 

mining; log drives

Tidal; 

RKM 5.0–0

Tidally affected channel on 

alluvium; sparse lateral, 

point, and medial bars in 

upper ~1.8 km

0.0002 492–500 30–42 Wide floodplain; width 

2,200–3,000 m

Low-gradient promotes deposition of 

bed and suspended 

loads from upstream sources

Confined by levees 

and dikes (RKM 5.0–

0) and roads (RKM 

5.0–4.8, 2.8–2.2, 1.7–

0.2); log drives

Kilchis

Fluvial; 

RKM 7.8–2.7

Channel flows on alluvium; 

flows through narrow valley 

and periodically against valley walls along south and 

east banks; medial, lateral, 

and point bars throughout 

reach

0.0015 149–162 27–42 Progressively widening 

to head of tide; width 

110–1,040 m

Inputs from tributaries and other 

upstream sources 

such as eroded 

bank material, debris flows, and 

landslides

Confined by levees 

and dikes (RKM 4.0–

3.7); historical and 

ongoing instream 

gravel mining; log 

drives
30

Table 8. Summary of characteristics for study reaches on the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon.

—continued

[m/m, meter change in elevation per meter of channel length; km2; square kilometers; m, meter; RKM, river kilometer; Hwy, highway; LiDAR, Light Detection 

And Ranging]

River Reach Channel description

Reach 

gradient2

(m/m)

Drainage 

area 

(km2)

Active 

channel 

width (m) Floodplain description

Background 

sediment drivers

River corridor 

modifications and 

disturbances

Kilchis (cont.)

Tidal; 

RKM 2.7–0

Tidally affected channel on 

alluvium; larger lateral and 

point bars in upper ~1 km; 

flows periodically against 

valley wall along east bank

0.0007 162–169 23–42 Wide floodplain; width 

800–2,500 m

Low-gradient promotes deposition of 

bed and suspended 

loads from upstream sources

Confined by levees 

and dikes (RKM 2.0–

0) and roads (such as 

near RKM 1.5–0.8); 

log drives

Miami

Upper Fluvial; 

RKM 11.6–

9.2

Channel flowing on alluvium through narrow valley; 

alternates between valley 

walls; large alternating, 

channel flanking bars

0.0075 32–45 32–41 Narrow floodplain; 

width 150–170 m

Inputs from tributaries and other 

upstream sources 

such as eroded 

bank material, debris flows, and 

landslides

Potential log drives

Lower Fluvial; RKM 9.2–

1.3

Channel flowing on alluvium; alternates against valley 

walls; medial, lateral, and 

point bars throughout reach 

with bars larger and more 

numerous downstream of 

tributaries and where mainstem crosses floodplain

0.0030 45–86 18–32 Progressively widening 

floodplain that narrows 

briefly at RKM 8.8, 8.1, 

7.4, 3.6; width 170–390 

m

Inputs from tributaries and other 

upstream sources 

such as eroded 

bank material, debris flows, and 

landslides

No levees on quads, 

but natural or anthropogenic levee evident 

in LiDAR from RKM 

5.6 to 5.4 and 3.6 to 

2.2; bermed, ditched 

or riprapped (RKM 

3.2–1.3); historical 

and ongoing instream 

gravel mining; log 

drives

Tidal; 

RKM 1.3–0

Tidally affected channel on 

alluvium; flows against 

northwest valley wall; sparse 

lateral and point bars

0.0013 86–93 15–20 Narrower floodplain 

than other rivers; width 

390–520 m

Low-gradient promotes deposition of 

bed and suspended 

loads from upstream sources

Bermed, ditched, or 

riprapped (RKM 1.3–

1.2) and leveed 

(RKM 0.6–0); log 

drives
31

Table 8. Summary of characteristics for study reaches on the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon.

—continued

[m/m, meter change in elevation per meter of channel length; km2; square kilometers; m, meter; RKM, river kilometer; Hwy, highway; LiDAR, Light Detection 

And Ranging]

River Reach Channel description

Reach 

gradient2

(m/m)

Drainage 

area 

(km2)

Active 

channel 

width (m) Floodplain description

Background 

sediment drivers

River corridor 

modifications and 

disturbances

Nehalem

Fluvial; 

RKM 31.4–

24.6

Channel flows mostly on 

alluvium with some bedrock 

on margins and in channel 

such as near RKM 31.2, 

30.8, 30.2; confined by valley from RKM 31.4–29.6 

and unconfined from RKM 

29.6–24.6; flows periodically against valley walls; 

point, medial, and lateral 

bars throughout reach that 

increase in area in lower 1.6 

km

0.0013 1,821–

1,847

54-254 Narrow floodplain from 

RKM 31.4–29.6; widens 

then toward head of 

tide; width 170–490 m

Inputs from tributaries and other 

upstream sources 

such as eroded 

bank material, debris flows, and 

landslides

Historical and ongoing instream gravel 

mining; log drives 

and splash dams

Tidal; RKM 

24.6–0

Tidally affected channel on 

alluvium with confined and 

unconfined segments; flows 

against valley wall at RKM 

24.4-22.6; bars present in 

upper 5.8 km; large tidal 

flats and islands near mouth

0.0001 1,847–

2,207

47–2,190 Confined near RKM 

24.6–18.8, RKM 9.8 

(Dean Point), and RKM 

4.6 (Fishery Point) to 

mouth; width 340 to 

4,720 m

Low-gradient promotes deposition of 

bed and suspended 

loads from upstream sources

Leveed, diked, or 

riprapped along channel (RKM 24–23.1, 

20.2-19.6,18.8–9.0) 

and intermittently 

throughout Nehalem 

Bay; jetties at the 

mouth of bay; historical dredging; log 

drives and splash 

dams
32

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

field reconnaissance photographs of the Tillamook River study area, northwestern Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally formed levees reinforced with nonerodible materials 

(source: Oregon Coastal Management Program, 2011). 
33

Figure 9. Diagram showing longitudinal profiles for the study reaches on the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem River basins, 

northwestern Oregon. Profiles derived from 1-m Light Detection And Ranging (LiDAR) topographic surveys acquired from 2007 to 2009 along channel centerlines. Profile steps in the tidal reaches probably reflect LiDAR acquisition at different tide stages.
34

transport logs are present in this reach (fig. 8) 

and likely affect fine sediment deposition. 

Trask River

The headwaters and most of the Trask River 

flow through the Tillamook State Forest. The 

mainstem begins at the confluence of the North 

and South Forks of the Trask River (20.7 and 

135.4 km2, respectively) and generally flows 

westward for approximately 30.7 km toward 

Tillamook Bay and the town of Tillamook (fig. 

1). In the upper watershed, the mainstem flows 

over bedrock, such as near the confluence of the 

North and South Forks of the Trask River, and 

through a bedrock canyon near the town of 

Trask. The South Fork Trask River contributes 

gravel to the mainstem, as evidenced by a gravel 

delta at its mouth. The channel of the North Fork 

Trask River has bedrock and large boulders at its 

confluence with the South Fork Trask River, indicating that less bed material emanates from this 

tributary. Upstream of the study area, bedmaterial sediment is present along the Trask River, primarily as a thin veneer over bedrock and 

boulders, at high amplitude bends, or as lateral 

and point bar features near the confluence of 

Samson Creek and the Trask River. The study 

area begins at RKM 16.3, upstream of Gold 

Creek (RKM 16.2; 17.3 km2), which contributes 

some bed material to the mainstem, based upon 

deposits evident in the aerial and orthophotographs from 1939, 2005, and 2009. Within the 

study area, the Trask River gains Hanenkrat 

(RKM 15.5; 1.2 km2), Green (RKM 12.2; 3.4 

km2), and Mill (RKM 8.7; 12.3 km2) Creeks and 

the tidal Dougherty (RKM 1.0) and Hoquarten 

(RKM 1.0) Sloughs (fig. 10). The South Branch 

Trask River (RKM 2.6) connects the Trask and 

Tillamook Rivers. The study area for the Trask 

River was divided into the Fluvial Trask (RKM 

16.3–7.0) and Tidal Trask (RKM 7.0–0) Reaches 

at the head of tide (table 8). 

In the Fluvial Trask Reach (RKM 16.3–7.0), 

the drainage area of the Trask River ranges from 

378 to 425 km2

(table 8; fig. 10). The valley is 

narrow ( approximately100 m wide) in the upper 

2 km of this reach, but then progressively increases to 1,530 m in width at the head of tide. 

Likewise, the width of the active channel ranges 

from 28 to 56 m wide. Downstream of the confined, upper 2 km, the Trask River crosses the 

floodplain multiple times after flowing against 

the floodplain boundary near RKM 13.2, 11.8–

11.4 and 9.2. The Trask River has a gradient of 

0.0016 m/m (table 8; fig. 9), flows over alluvial 

deposits, and contains lateral, medial, and point 

bars (up to 21,840 m2

in 2009) throughout this 

reach. Levees intermittently border the Trask 

River from RKM 10.6 to 7.0 (table 6; fig. 10) 

(Oregon Coastal Management Program, 2011). 

Key locations in this reach include the active instream gravel mining site at RKM 12.2 (Bush 

Bar) and floodplain mining sites of unknown status are denoted near RKM 14.8, 13.4, and 12.8 

on USGS topographic quadrangles produced 

from 1984 to 1986. 

Within the Tidal Trask Reach (RKM 7.0–0), 

the Trask River decreases in gradient to 0.0001 

m/m as it enters the wide coastal plain shared 

with the Tillamook River (approximately 1,500–

4,300 m wide; table 8; fig. 10). At RKM 0, the 

drainage area of the Trask River is 451 km2. The 

width of the active channel ranges from 26 to 66 

m in this tidally influenced reach. Here, the 

Trask River flows over alluvial deposits, but 

contains fewer lateral and point bars (up to 8,970 

m

2

in 2009) relative to the Fluvial Trask Reach. 

As shown in figure 10, levees including natural 

to man-made dikes discontinuously line the 

Trask River from RKM 7.0 to 2.6 and at RKM 

0.8 (table 6). 

Wilson River

The mainstem Wilson River begins east of 

the town of Lees Camp at the confluence of the 

South Fork of the Wilson River and Devils Lake 

Fork, which drain 41.3 and 68.6 km2, respectively (fig. 1). The Wilson River then continues in a 

southwestward direction for 38.5 km gaining 

tributaries such as the North Fork Wilson River 

(69.9 km2), Cedar (24.5 km2

), Jordan (64.4 km2), 

and Fall (11.9 km2) Creeks before its confluence 
35

Figure 10. Map showing key locations, bars, and channel centerline delineated from 2009 orthophotographs and field reconnaissance photographs 

in the Trask River study area, northwestern Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally formed levees 

reinforced with nonerodible materials (source: Oregon Coastal Management Program, 2011). 
36

with the Little North Fork Wilson River (RKM 

13.9; 51.1 km2). The Wilson River then continues westward for approximately 13.6 km toward 

the Tillamook Bay. Like the Trask River, the 

headwaters, forks, and mainstem of the Wilson 

River upstream of RKM 11.6 are chiefly within 

the Tillamook State Forest. The Wilson River 

study area begins at RKM 15.2, upstream of the 

confluence of the Wilson and Little North Fork 

Wilson River (fig. 11). Tributaries like the Little 

North Fork Wilson River deliver bed material to 

the mainstem as indicated by gravel deposits and 

overbank deposition at its mouth (fig. 11). Upstream of the study area, the Wilson River intermittently flows through some wider sections 

containing large gravel bars (such as the 3 km 

long segment near Sylvan Creek) and confined 

gorges and basalt palisades and over bedrock 

outcrops that provide lateral and vertical channel 

stability. 

The study area on the Wilson River was divided into three reaches—the Upper Fluvial Wilson (RKM 15.2–12.6), Lower Fluvial Wilson 

(RKM 12.6–5.0), and Tidal Wilson (RKM 5.0–

0) Reaches (table 8; fig. 11). The fluvial section 

of the Wilson River was divided into the Upper 

and Lower Fluvial Reaches because the river is 

confined from RKM 15.2 to 12.6 and has a much 

wider floodplain from RKM 12.6 to 5.0. In the 

Upper Fluvial Wilson Reach (RKM 15.2–12.6), 

the Wilson River flows over alluvial deposits as 

well as intermittent bedrock outcrops in and 

along the channel (table 8; fig. 11). Here, the 

Wilson River has a gradient of 0.0017 m/m (table 8; fig. 9), and contains lateral and point bars 

(up to 14,930 m2

in 2009) throughout the reach. 

The channel is confined by a narrow (approximately 110 m wide) valley that increases in 

width (150 m) at the confluence of the Wilson 

and Little North Fork Wilson Rivers (RKM 13.9; 

fig. 11), and has an active channel 42–66 m 

wide. The drainage area of the Wilson River 

ranges from 417 to 474 km2

in this reach. No

instream gravel mining permits are active in this 

reach. 

In contrast, the channel in the Lower Fluvial 

Wilson Reach (RKM 12.6–5) flows predominately over alluvial deposits and through a valley 

that increases from 150 to 2,200 m in width toward the head of tide (table 8; fig. 11). The relatively lower gradient (0.0011 m/m; fig. 9) channel flows against valley walls to the south at 

RKM 12.4–12.2 and to the north at RKM 12.0–

11.6, 9.6–8.2, and 6.2, and ranges from 50 to 58 

m in active width. Bar deposits (up to 16,830 m2

in 2009) are most abundant in the upper 4.4 km 

of this reach. The Wilson River is bordered by 

levees intermittently along RKM 12.6–7.0 and 

almost continually along RKM 7.0–5.0 (table 6; 

fig. 11) and by roads (such as along RKM 6.3–

5.0) on current USGS quadrangles. The drainage 

area of the Wilson River is 492 km2

at the downstream boundary of the Lower Fluvial Wilson 

Reach. Instream gravel mining sites are active at 

Donaldson (RKM 10.4) and Barker (RKM 6.9) 

Bars. Stinson and Stinson (1998) noted also instream gravel mining at Widmer (RKM 12.2) 

and Tannler (RKM 6.6) Bars (see the GravelOperator Information and Surveys section below).

Downstream in the Tidal Wilson Reach, the 

channel continues to flow over alluvial deposits, 

but declines in gradient to 0.0002 m/m (table 8; 

figs. 9 and 11). Sparse lateral, point, and medial 

bars (up to 1,010 m2in 2009) are primarily in the 

reach’s upper 1.8 km. Near the Tillamook Bay, 

the width of the valley increases to 3,000 m and 

the river has a total drainage area of 500 km2at 

RKM 0. The active channel ranges from 30 to 42 

m wide. Roads shown on current USGS quadrangles border the river near RKM 5.0–4.8, 2.8–

2.2, and 1.7–0.2, whereas levees are present 

along one or both banks for most of the reach 

(table 6; fig. 11). 
37

Figure 11. Map showing key locations, bars, and channel centerline delineated from 2009 orthophotographs and field reconnaissance photographs 

in the Wilson River study area, northwestern Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally formed levees reinforced with nonerodible materials (source: Oregon Coastal Management Program, 2011). 
38

Kilchis River 

Much of the Kilchis River basin upstream of 

RKM 9.2 is within the Tillamook State Forest. 

The North and South Forks of the Kilchis River 

(41.4 and 26.6 km2, respectively) drain opposite 

flanks of Sawtooth Ridge, and form the mainstem at their confluence (fig. 1). The mainstem 

then flows in southwestward for 4.5 km to Tilton 

Creek (4.2 km2) and then continues generally 

southward for 6.8 km to the Little South Fork 

Kilchis River (30.9 km2). In its final 10.1 km to 

the Tillamook Bay, the Kilchis River flows 

southwestward, and gains several tributaries, 

such as Clear Creek (RKM 9.2; 11.7 km2). The 

study area, beginning at RKM 7.8 and approximately 1.2 km downstream of Clear Creek, was 

subdivided into two reaches at the head of tide 

(Fluvial Kilchis, RKM 7.8–2.7; Tidal Kilchis, 

RKM 2.7–0; table 8; fig. 12).

Outside the study area, the channel flows 

over bedrock in several locations like near the 

confluence of the North and South Forks of the 

Kilchis River, but contains intermittent lateral 

and point bars downstream of the confluence of 

the North and South Forks of the Kilchis River. 

Stream barbs were installed in the channel in the 

late 1990s to reduce bank erosion at Bruck Bar 

(approximately 2.3 km downstream of the NorthSouth Forks of the Kilchis River confluence), but 

were not included in the Oregon Coastal Management Program (2011) dataset which primarily 

focused on tidal areas. Gravel was mined historically at Bruck Bar (Stinson and Stinson, 1998), 

and is actively mined at Dill Bar (approximately 

0.1 km upstream of the study area; Judy Linton, 

U.S. Army Corps of Engineers, written commun., 2010; Robert Lobdell, Oregon Department 

of State Lands, written commun., 2011). 

Throughout the Fluvial Kilchis Reach 

(RKM 7.8–2.7), the Kilchis River flows over 

gravel and other alluvial deposits and contains 

lateral, medial, and point bars (up to 5,050 m2

in 

2009; table 8; fig. 12). The channel has a gradient of 0.0015 m/m (table 8; fig. 9), and flows 

through a confined valley (approximately 110 m 

wide) and against valley walls to the south along 

RKM 7.8–6.4. At RKM 6.0, the Kilchis River is 

restricted by the valley wall to the west and a 

road to the east. In this confined reach, the active 

channel is 27 to 42 m wide. Downstream of 

RKM 6.0, the valley progressively widens to 

1,040 m near the head of tide. The drainage area 

of the Kilchis River ranges from 149 to 162 km2

in this reach. Between RKM 4.0 and 3.7, the levees constrain the Kilchis River (table 6; fig. 12). 

Active instream gravel mining occurs at Gomes 

(RKM 4.8) Bar whereas historical mining sites 

were present throughout the reach (see the Gravel-Operator Information and Surveys section below). 

In the Tidal Kilchis Reach (RKM 2.7–0), the 

river continues to flow over alluvial deposits that 

are mostly sand and gravel, but declines in gradient to 0.0007 m/m (fig. 9), and contains larger 

lateral and point bars (up to 12,670 m2in 2009) 

in the reach’s upper 1 km (table 8; fig. 12). Although the channel flows through a wide (800–

2,500 m) valley, it flows against valley walls to 

the east at RKM 2.6 and to the south at RKM 

1.9–1.6. The active channel ranges from 23 to 42 

m wide. Current USGS quadrangles show roads 

near RKM 1.5–0.8 whereas levees border the 

Kilchis River from RKM 2.0–0 (table 6; fig. 12). 

The drainage area of the Kilchis River at RKM 0 

is 169 km2. 

Measurement transect at Bruck Bar. 
39

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

field reconnaissance photographs in the Kilchis River study area, northwestern Oregon. Floodplain modifications 

identified in the map include dikes, levees, and naturally formed levees reinforced with nonerodible materials 

(source: Oregon Coastal Management Program, 2011). 
40

Miami River 

The Miami River begins in the Tillamook 

State Forest and flows southwestward for approximately 24.5 km to the north end of the 

Tillamook Bay near town of Garibaldi (fig. 1). 

The study area on the Miami River begins at 

RKM 11.6, approximately 2.3 km upstream of 

the Miami River and Prouty Creek confluence. 

Within the study area, the Miami River is supplemented by Stuart (RKM 9.5, 3.0 km2

), Prouty 

(RKM 9.3; 3.1 km2), Peterson (RKM 7.2, 7.1 

km2), and Moss (RKM 2.2, 11.6 km2

) Creeks 

(fig. 13). The Miami River study area was divided into three reaches—the Upper Fluvial Miami 

(RKM 11.6–9.2), Lower Fluvial Miami (RKM 

9.2–1.3), and Tidal Miami (RKM 1.3–0) Reaches (table 8; fig. 13). 

Flowing on alluvial deposits through a narrow valley (150–170 m wide), the Miami River 

in the Upper Fluvial Reach (RKM 11.6–9.2) 

contains large (up to 11,840 m2in 2009) alternating, channel flanking bars (table 8; fig. 13). Field 

observations from the October 2010 reconnaissance trip indicate that large wood may contribute to bar formation in this reach. This channel 

has the highest gradient in this study (0.0075 

m/m; fig. 9) and ranges from 32 to 41 m in active 

channel width. The channel swings between valley walls to the south (RKM 11.6, 11.3, 10.4, 

and 10.1), north (RKM 11, and 10.8), and west 

(RKM 9.8, 9.6, and 9.3–9.2). The basin area of 

the Miami River ranges from 32 to 45 km2in this 

reach. 

In the Lower Fluvial Reach (RKM 9.2–1.3), 

the Miami River continues to flow on alluvial 

deposits and has medial, lateral, and point bars 

that are larger and more numerous downstream 

of tributaries and where the mainstem crosses the 

floodplain (table 8; fig. 13). The bars in this 

reach are generally smaller (up to 5,790 m2

in 

2009) than those in the Upper Fluvial Reach. 

Here, channel gradient declines to 0.0030 m/m 

(fig. 9). The width of the floodplain increases 

from 170 to 390 m, but narrows locally at RKM 

8.8, 8.1, 7.4, and 3.6. The river continues to alternate between valley walls, flowing against 

them to the north (RKM 9.2–8.6 and 1.5), south 

(RKM 8.1), west (RKM 7.2, 6.8, and 6.1–5.5) 

and east (RKM 6.5–6.4, 4.8, 4.4, and 3.7). The 

active channel varies from 18 to 32 m in width. 

The Miami River has a drainage area of 86 km2 

at the reach’s downstream boundary. Although 

no roads are shown along the river on current 

USGS quadrangles, natural or anthropogenic 

levees are evident in the 2008 LiDAR survey 

between RKM 5.6–5.4 and 3.6–2.2 (fig. 13). The 

east bank has been intermittently bermed, 

ditched, or riprapped between RKM 3.2–1.2 (table 6; fig. 13). Gravel is actively mined at Waldron Bar (Judy Linton, U.S. Army Corps of Engineers, written commun., 2010; Robert Lobdell, 

Oregon Department of State Lands, written 

commun., 2011). Historically, at least four other 

sites were mined for gravel (see the GravelOperator Information and Surveys section below). 

In the Tidal Miami Reach (RKM 1.3–0), the 

shortest and steepest tidal reach in this study (table 1; fig. 9), the Miami River flows on alluvial 

deposits, against the northwest valley wall from 

RKM 1.2 to 1.0, and through a narrower floodplain (390–520 m wide) relative to the other five 

rivers (table 8; fig. 13). Here, the river contains 

fewer lateral and point bars (up to 1,530 m2

in 

2009) relative to its upstream reaches. The active 

channel ranges from 15 to 20 m in width. Levees 

are present from RKM 0.6 to 0 (table 6; fig. 13). 

The total drainage area of the Miami River is 93 

km2. 

Large wood jams trapping sediment above 

the Miami River study 

area.
41

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

field reconnaissance photographs in the Miami River study area, northwestern Oregon. Floodplain modifications 

identified in the map include dikes, levees, and naturally formed levees reinforced with nonerodible materials 

(source: Oregon Coastal Management Program, 2011). 
42

Nehalem River 

The headwaters of the Nehalem River begin 

in the Tillamook and Clatsop State Forests near 

Giveout Mountain (827 m). The mainstem flows 

southeast a short distance before it is joined by 

the South Fork Nehalem River (3.2 km2; fig. 2) 

and then continues northeastward for 53 km to

the East Fork Nehalem River (83.4 km2), acquiring Lousignont (27.3 km2

), Wolf (43.7 km2), 

Clear (33.2 km2), Beaver (32.8 km2), Rock 

(161.9 km2), and Pebble (56.2 km2) Creeks. 

From the East Fork Nehalem River to Salmonberry River (183.9 km2

), the mainstem cuts a 

counter clockwise path for 99 km through the 

Coast Range, picking up Crooked (32.6 km2),

Fishhawk (60.3 km2), Deep (58.8 km2), Beneke 

(129.1 km2), Humbug (75.0 km2), and Cronin 

(33.1 km2) Creeks. The river then flows west for 

11 km to Fall Creek and then south for 4 km 

gaining Lost Creek (19.9 km2) and Cook Creek 

(76.3 km2). The confluence of the Nehalem River and Cook Creek marks the beginning of the 

Nehalem River study area. Within the study area, 

the Nehalem River continues west for 10 km to 

Foley Creek (RKM 21.9; 44.0 km2) and then 

north for 8 km until its confluence with the 

southwestward flowing North Fork Nehalem 

River (RKM 13.5; 250.5 km2). The mainstem 

then continues for 6 km until it reaches the Pacific Ocean near the town of Brighton. The study 

area was divided into two reaches—the Fluvial 

Nehalem (RKM 31.4–24.6; fig. 14) and Tidal 

Nehalem Reaches (RKM 24.6–0; fig. 15).

The Nehalem River in the Fluvial Reach 

(RKM 31.4–24.6) flows predominantly over alluvial deposits as well as locally on bedrock in 

and along the channel in the upper part of the 

reach (table 8; fig. 14). With a gradient of 0.0013 

m/m (fig. 9), the channel has lateral, medial, and 

point bars (up to 18,880 m2 in 2009), but their 

area is greatest in the reach’s lower 1.6 km. The 

channel is relatively confined by its narrow (170 

m wide) valley from RKM 31.4–29.6. Downstream of RKM 29.6, the floodplain progressively widens to 490 m toward the head of tide. The 

channel flows against valleys walls to the south 

(RKM 29.2, 28.4–27.6, 26.5–26.2), north (RKM 

25.8–25.4), and west (RKM 25.0–24.8), and has 

an active width that ranges from 54 to 254 m.

The drainage area of the Nehalem River increases from 1,821 to 1,847 km2 in the Fluvial Nehalem Reach. Levees flank the channel near RKM 

27.2–26.2 (table 6; fig. 14). Gravel mining permits are active for Plant and Winslow Bars at 

RKM 25.8 and 24.8, respectively (Judy Linton, 

U.S. Army Corps of Engineers, written commun., 2010; Robert Lobdell, Oregon Department 

of State Lands, written commun., 2011).

In the Tidal Nehalem Reach (RKM 24.6–0), 

the river flows over alluvial deposits and through 

unconfined and confined segments (table 8; fig. 

15). The low gradient channel (0.0001 m/m; fig. 

9) is confined from RKM 24.6 to 18.8, at Dean 

Point (RKM 9.8), and from Fishery Point (RKM 

4.6) to the mouth. The Nehalem River also flows 

against a valley wall to the northeast near RKM 

24.4–22.6. The width of the floodplain throughout this reach ranges from 340 to 4,720 m. A few 

small bars (up to 0.09 km2in 2009) flank the 

channel in the upper section of this reach, whereas large tidal flats and islands (up to 4.7 km2

in 

2009) occur in the Nehalem Bay. On the current 

USGS quadrangles, roads may constrain a few 

small segments (such as near RKM 17.6–17.4, 

17.0–16.2, 15.2–14, and 10.8–9.6). Riprap and 

human-made dikes and natural levees are near 

RKM 24.0–23.1, 20.2–19.6, and 18.8–9.0 and 

within the Nehalem Bay (table 6; fig. 15). 

Approach and Key Findings

For this study, we reviewed existing datasets 

and studies relevant to channel condition and 

bed-material transport in the Tillamook Bay subbasins and Nehalem River basin, applied reconnaissance-level geographic information system 

(GIS) analyses, and made field observations and 

particle size measurements in October 2010. The 

objectives of these efforts were to (1) identify 

existing datasets that would support more detailed analyses of bed-material transport and 

channel condition, (2) summarize reported
43

Figure 14. Map showing key locations, bars, and channel centerline delineated from 2009 orthophotographs and field reconnaissance photographs 

in the Fluvial Reach of the Nehalem River, northwestern Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally 

formed levees reinforced with nonerodible materials (source: Oregon Coastal Management Program, 2011).
44

Figure 15. Map showing key locations, bars, and channel centerline delineated from 2009 orthophotographs and 

field reconnaissance photographs in the Tidal Reach of the Nehalem River, northwestern Oregon. Floodplain 

modifications identified in the map include dikes, levees, and naturally formed levees reinforced with nonerodible 

materials (source: Oregon Coastal Management Program, 2011). 
45

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

broad-scale bar and channel patterns using aerial 

and orthophotographs spanning 1939–2009, (4) 

identify locations where the channels may be aggrading, incising, prone to migration, or stable, 

and (5) assess the transport capacity and sediment supply relation for each reach. Overall, this 

study provides a preliminary review of channel 

condition and bed-material transport in these rivers, 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 for the Tillamook Bay subbasins and Nehalem River basin that could be used to evaluate 

channel condition and bed-material transport. 

This search focused primarily on aerial and orthophotographs, but included other geospatial 

datasets, such as LiDAR topographic data, geologic maps, General Land Office (GLO) surveys, 

and navigation surveys. 

Aerial and Orthophotographs 

We reviewed aerial and orthophotography 

coverages of the Tillamook Bay subbasins and 

Nehalem River basin available from the U.S. 

Army 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 public, 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. 

The entire study areas in the Tillamook Bay 

subbasins and Nehalem River basin were photographed at least 12 and 15 times, respectively, 

between 1939 and 2011 (table 9; table 10). Several additional sets of aerial photographs provide 

nearly complete coverage of the study areas (tables 9 and 10). Of the Tillamook Bay subbasins, 

study areas along the Tillamook, Trask, and Wilson Rivers were photographed most frequently 

(table 9). Of the two Nehalem River reaches, the 

Tidal Nehalem Reach was photographed more 

frequently (table 10). At least 16 photograph sets 

in table 9 and 18 sets of photograph sets in table 

10 provide comprehensive coverage of all or 

most of the study areas and were taken at scales 

of 1:24,000 or greater. These sets would be suitable for use in future studies assessing long-term 

changes in channel attributes, bar frequency and 

area, and vegetative cover throughout the study 

areas. 

For bar and channel delineations in the six 

study areas, we used aerial photographs taken in 

1939 and 1967 and orthophotographs taken in 

2005 and 2009 (tables 9 and 10, described below). At the time of this study, the 2009 photographs were the most recent and were chosen to 

represent relatively recent bar and channel conditions throughout the study areas. The 1939, 

1967, and 2005 photographs were selected so we 

could compare data between this and completed 

studies in the Chetco (Wallick and others, 2010), 

Umpqua (Wallick and others, 2011), Rogue 

(Jones and others, 2012a), and Coquille (Jones 

and others, 2012b) River basins and Hunter 

Creek basin (Jones and others, 2011). The 1939 

photographs are the earliest photographs of the 

study areas (table 9; table 10) and the 1967 photographs provide coverage of the study areas following the December 22, 1964 flood, which exceeded a 10-year flood event on the Wilson, Miami, and Nehalem Rivers (fig. 5B–D). 
46

Table 9. Aerial photographs with coverage of the Tillamook Bay subbasins, northwestern Oregon.—continued

[Aerial photographs shown in bold were used to delineate bar and channel features in this study. --, data unavailable; 

USACE, U.S. Army Corps of Engineers; UO, University of Oregon Map and Aerial Photography Library; RKM, river 

kilometer; USC&GS, U.S. Coast and Geodetic Survey; ODF, Oregon Department of Forestry; USDA, U.S. Department of 

Agriculture; WAC, Western Aerial Contractor; ODR, Oregon Department of Revenue; AM; Aerial Mapping; USGS, U.S. 

Geological Survey; m, meter]

Full coverage of 

study area(s) Partial coverage of study area(s) Year

Collection 

month/day Scale

Collection 

entity Repository

All -- 1939 5/8, 5/12, 

7/20

1:10,200 USACE USACE1

-- Miami, RKM 5-0 1944 5/3 1:30,000 USACE

Trask, Kilchis Partial coverage of Tillamook, Wilson, and Miami1945 -- 1:6,000 USACE UO

Tillamook Wilson, RKM 9-0; Trask, 

RKM 14-0

1946 8/9 1:10,000 USC&GS USACE

All except Tillamook-- 1951 -- 1:12,000 ODF UO

Tillamook; Trask; 

Wilson

-- 1952 5/17; 5/22 1:25,000 USC&GS USACE

All -- 1954 -- 1:12,000 USDA; 

ODF

UO

-- Tillamook, RKM 11-0; 

Trask, RKM 6-0; Wilson, 

RKM 5.5-0; Kilchis, 2.5-0; 

Miami, RKM 5-0

1955 8/26-27 1:9,600 USACE USACE

Tillamook; Kilchis Trask, RKM 10-0; Wilson, 

RKM 9-0 

1962 3/13 1:14,700 USACE USACE

-- Trask, RKM~2-0; Wilson, 

RKM ~3-0; Miami, RKM 10-

0

1964 8/20 1:22,000 USACE USACE

All -- 1965 4/26 1:12,000 USACE USACE

-- Miami, RKM 10-0 1966 8/17 1:30,000 USACE USACE

All -- 1967 2/19 1:20,000 USDA UO

All -- 1969 7/18 1:48,000 WAC USACE

All -- 1970 -- 1:12,000 ODF UO

-- Tillamook, RKM 14-0; 

Trask, RKM 7.5-0; Wilson, 

RKM 4-0

1972 7/3 1:30,000 Delano USACE

Tillamook; Trask; 

Wilson

-- 1974 -- 1:12,000 ODR UO

Tillamook Trask, RKM 9-0; Wilson, 

RKM 10-0; Kilchis, RKM 2-

0 

1978 3/2 1:12,000 Aerial 

Mapping

USACE

Tillamook Trask, RKM 9-0; Wilson, 

RKM 11-0; Kilchis, RKM 

7.5-0

1978 10/2 1:24,000 WAC USACE

Tillamook Trask, RKM 14-0; Wilson, 

RKM 15-0; Kilchis, RKM 

7.5-0

1978 10/12-13 1:24,000 AM USACE
47

Table 9. Aerial photographs with coverage of the Tillamook Bay subbasins, northwestern Oregon.—continued

[Aerial photographs shown in bold were used to delineate bar and channel features in this study. --, data unavailable; 

USACE, U.S. Army Corps of Engineers; UO, University of Oregon Map and Aerial Photography Library; RKM, river 

kilometer; USC&GS, U.S. Coast and Geodetic Survey; ODF, Oregon Department of Forestry; USDA, U.S. Department of 

Agriculture; WAC, Western Aerial Contractor; ODR, Oregon Department of Revenue; AM; Aerial Mapping; USGS, U.S. 

Geological Survey; m, meter]

Full coverage of 

study area(s) Partial coverage of study area(s) Year

Collection 

month/day Scale

Collection 

entity Repository

-- Tillamook, RKM 11–0; 

Trask, RKM 8–0; Wilson, 

RKM 8.5–0

1980 7/7 1:12,000 AM USACE

Tillamook; Kilchis; 

Miami

Trask, RKM 11–0; Wilson, 

RKM 11–0

1982 3/23–24 1:48,000 WAC USACE

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

Tillamook; Trask; 

Wilson

-- 1986 7/11 1:48,000 WAC USACE

All except Miami Miami, RKM 4–0 1989 10/31 1:24,000 Bergman USACE

All -- 1994 5/30; 7/18; 

9/4; 6/27

1:24,000 USGS USGS, 

UO

-- Tillamook, RKM 11–0; 

Trask, RKM 6–0; Wilson, 

RKM 5.5–0; Kilchis, RKM 

2.5–0; Miami, RKM 5–0

1999 9/29 1:6,000 Earth Data USACE

Kilchis Trask, RKM 2–0; Wilson, 

RKM 8–0

2000 5/24 1:6,000 Bergman USACE

All except Trask Trask, RKM 16–0 2000 9/12 1:6,000 Bergman USACE

All -- 2000 7/30; 8/8; 

8/16–17; 

8/22

1:24,000 USGS USGS

Tillamook; Trask; 

Wilson

-- 2001 5/11; 5/20 1:24,000 WAC USACE

All -- 2005 7/17; 7/19–

20

1 pixel = 

0.5 m USDA USGS

All -- 2009 6/23; 6/27 1 pixel = 

1 m USDA USGS

All -- 2011 7/2; 7/5 1 pixel = 

1 m

USDA USDA

1 Limited coverage of the study area available from UO

Donaldson Bar on the Wilson River. 
48

Table 10. List of aerial photographs with coverage of the Nehalem River, northwestern Oregon.—continued

[--, data not available; USACE, U.S. Army Corps of Engineers; UO, University of Oregon Map Library; RKM, river kilometer; ODF, Oregon Department of Forestry; USGS, U.S. Geological Survey; USDA, U.S. Department of Agriculture; 

ODR, Oregon Department of Revenue; WAC, Western Aerial Contractor; AM; Aerial Mapping; m, meter]

Full coverage of 

reach(es) Partial coverage of reach(es) Year

Collection 

month/day Scale

Collection 

entity Repository

All -- 1939 5/8; 5/12 1:10,200 USACE USACE, 

UO

Fluvial Nehalem Tidal Nehalem, RKM 24.6–

8.2

1951 -- 1:12,000 ODF UO

All -- 1953 -- 1:37,400 USGS UO

-- Tidal Nehalem, RKM 8.2–0 1954 -- 1:20,000 USDA UO

Fluvial Nehalem Tidal Nehalem, RKM 24.6–

8.2

1954-

55

-- 1:12,000 ODF UO

All -- 1960 -- 1:12,000 ODR UO

-- Tidal Nehalem, RKM 13–0 1962 3/13 1:12,000 USACE USACE

-- Tidal Nehalem, RKM 14–0 1963 5/28 1:18,000; 

1:16,200

USACE USACE

-- Tidal Nehalem, RKM 17–0 1964 8/20 1:22,000 USACE USACE

Tidal Nehalem Fluvial Nehalem, RKM 29-

24.6

1965 4/26 1:12,000 USACE USACE

-- Tidal Nehalem, RKM 24–0 1965 7/13–14; 

7/23

1:24,000 USACE USACE

-- Tidal Nehalem, RKM 11–0 1966 8/17 1:30,000 USACE USACE

All -- 1967 2/19 1:20,000 USDA UO

Tidal Nehalem, RKM 23.5–0 1969 7/18 1:48,000 WAC USACE

All -- 1970 -- 1:12,000 ODF UO

-- Tidal Nehalem, RKM 18–0 1972 7/3 1:12,000 Delano USACE

-- Tidal Nehalem, ~RKM 22.6–

0

1974 -- 1:12,000 ODR UO

-- Tidal Nehalem, ~RKM 8–0 1977 10/17 1:36,000 WAC USACE

-- Tidal Nehalem, ~RKM 8–0 1977 12/26 1:24,000 WAC USACE

Tidal Nehalem Fluvial Nehalem, RKM 25–

24.6

1978 3/2 1:12,000 AM USACE

-- Tidal Nehalem, RKM 23–0 1978 10/2 1:24,000 WAC USACE

-- Tidal Nehalem, RKM 22.5–0 1978 10/12 1:24,000 AM USACE

-- Tidal Nehalem, ~RKM 8–0 1980 4/2 1:24,000 WAC USACE

Tidal Nehalem Fluvial Nehalem, RKM 25–

24.6

1980 7/7 1:12,000 AM USACE

All -- 1980 -- 1:24,000 USGS UO

All -- 1982 3/24 1:48,000 WAC USACE

-- Tidal Nehalem, RKM 21-0 1983 9/28 1:48,000 WAC USACE

All -- 1986 6/11 1:48,000 WAC USACE

All -- 1989 10/31 1:24,000 Bergman USACE

All -- 1994 5/30; 7/18; 

8/30; 9/4

1:24,000 USGS UO, 

USGS
49

Table 10. List of aerial photographs with coverage of the Nehalem River, northwestern Oregon.—continued

[--, data not available; USACE, U.S. Army Corps of Engineers; UO, University of Oregon Map Library; RKM, river kilometer; ODF, Oregon Department of Forestry; USGS, U.S. Geological Survey; USDA, U.S. Department of Agriculture; 

ODR, Oregon Department of Revenue; WAC, Western Aerial Contractor; AM; Aerial Mapping; m, meter]

Full coverage of 

reach(es) Partial coverage of reach(es) Year

Collection 

month/day Scale

Collection 

entity Repository

All -- 2000 7/30; 8/8; 

8/22

1:24,000 USGS USGS

All -- 2001 5/11 1:24,000 WAC USACE

All -- 2005 07/17; 8/3 1 pixel = 0.5 

m

USDA USGS

All -- 2009 6/27 1 pixel = 1 m USDA USGS

All -- 2011 7/2; 7/5 1 pixel = 1 m USDA USDA

Confluence of Cook Creek and the Nehalem River.
50

Historical Maps and Survey Data 

We reviewed historical maps and survey data that are available from several sources for the 

six study areas. The purpose of this review was 

to identify datasets with information on channel 

condition, bar distribution and area, and channel 

morphology and bed elevations that could support assessments of channel change in future 

studies. For the Tillamook Bay subbasins, we 

focused on our study areas; see Coulton and others (1996) for datasets relevant to the Tillamook 

Bay. 

The GLO conducted the earliest surveys of 

the six study areas from 1857 to 1858 and 1858 

to 1884, respectively (table 11). The main purpose of these surveys was to establish the Township, Range and Section lines of the Public Land 

Survey System (PLSS) (Atwood, 2008). Along 

the lower sections of the Tillamook, Trask, Wilson, and Kilchis Rivers and entire Nehalem River study area, channel edges were surveyed (a 

process typically described as “meandering”), 

thereby providing an accurate planview depiction 

of channel geometry at the time of the survey. 

Future reviews of the GLO maps and accompanying surveyor notes would help determine if 

surveyors recorded channel and vegetation descriptions that would be useful for assessing historical changes in channel morphology or bedmaterial transport. Existing GLO reconstructions 

have focused primarily vegetation communities, 

swamps, and marshes in the Tillamook Bay area 

(Coulton and others, 1996) and saltwater marshes and freshwater wetlands in the lower Nehalem 

River (Christy, 2004). 

Other datasets include nautical charts showing bathymetry for multiple times for the lower 

Nehalem, Tillamook, and Trask Rivers by the 

National Ocean Survey (table 11). The USGS 

surveyed the position and profile of the Wilson 

and Trask Rivers in 1953 and Nehalem River in 

1936 (table 11). The Oregon Department of Geology and Mineral Industries (DOGAMI) is the 

source for recent, high-resolution (1-m) LiDAR 

data as well as maps of the major geologic units 

and geomorphic divisions for the study areas (table 11). Maps of the Nehalem River’s shoreline 

from 1954 and estuary habitats from 1978 are 

also available (table 11). Other datasets that may 

be useful for assessing longitudinal profile 

changes (but not included in table 11) are flood 

insurance maps and data from the Federal Emergency Management Agency and Corps of Engineers. 

Previous Hydrologic and Geomorphic Studies 

For the Tillamook Bay subbasins, issues related to sedimentation, flooding, water quality, 

aquatic habitat, and instream gravel mining have 

motivated several studies of hydrology and geomorphology. The number and scope of these 

studies contrasts with the Nehalem River basin 

for which we found no such studies. Based on 

our literature review, the only available studies 

for the Nehalem River basin are two general watershed studies (Johnson and Maser, 1999; R2 

Resource Consultants, 2005). 

Relevant studies of river geomorphology in

the Tillamook Bay subbasins include (1) a basin 

erosion and sediment study by the Tillamook 

Bay Task Force and others (1978), (2) an environmental history of the estuary and surrounding 

watersheds by Coulton and others (1996), (3) an 

analysis of the effects of gravel bar mining on 

the Wilson, Kilchis, and Miami Rivers by Stinson and Stinson (1998), and (4) a geomorphic 

analysis of Tillamook Bay rivers by Pearson 

(2002). Additional sources include watershed 

assessments and analyses for the Trask 

(Follansbee and Stark, 1998b; Snyder and others, 

2003), Wilson (Duck Creek Associates, 2008), 

Kilchis (Follansbee and Stark, 1998a), and Miami (Snyder and others, 2001; Jenkins and 

others, 2005) River basins as well as several reports on bar gravel mining in the Tillamook area, 

such as those by Reckendorf (2006, 2008a,b). 

Key findings from these studies will be noted in 

relation to the findings of our analyses presented 

in subsequent report sections. 
51

Table 11. List of existing datasets reviewed for the Tillamook Bay subbasins and Nehalem River basin, northwestern Oregon.

[BLM, Bureau of Land Management; RKM, river kilometer; NOS, National Ocean Survey; NOAA, National Oceanic and Atmospheric Administration; USGS, 

U.S. Geological Survey; NA, not available; OCA: Oregon Coastal Atlas; ODFW, Oregon Department of Fish and Wildlife; OSU, Oregon State University; 

LiDAR, Light Detection and Ranging; m, meter; DOGAMI, Oregon Department of Geology and Mineral Industries; Oregon GEO; Oregon Geospatial Enterprise Office]

Dataset Study Area(s) Scale Date(s) Source Depository Description

General Land 

Office (GLO) 

survey

Tillamook, 

Trask, Wilson, 

Kilchis, and 

Miami

~1:31,680 1857–87 GLO maps BLM1 Earliest surveys conducted between 1857 and 1858; meander surveys conducted in 1858 for Tillamook (RKM 6.4-0), Trask (RKM 3.3–0), Wilson 

(RKM 3-0), and Kilchis (RKM 1.6–0) Rivers; surveys not meandered for 

Miami River; maps show plan view of channels and surrounding lands; 

limited details on river features

Nehalem ~1:31,680 1858–84 GLO maps BLM1 Earliest surveys conducted in 1858; meander surveys conducted in 1858, 

1873, 1882 and 1884 for the entire study area on the Nehalem River (RKM 

31.4–0); maps show planview of channel and surrounding lands; limited 

details on river features

Nautical 

chart

Nehalem 1:20,000 Multiple 

years2

NOS NOAA3 Bathymetric map of ~RKM 9.5–0 of the Nehalem River in 1891 and 1947 

and ~RKM 13.4–0 in subsequent years

Tillamook, 

Trask

1:20,000 Multiple 

years4

NOS NOAA3 Bathymetric map of Tillamook (~RKM 1.6–0 in 1928 and 1948; ~RKM 3–

0 in subsequent years) and Trask (~RKM 2–0) Rivers

Plan and profileNehalem 1:24,000 1936 USGS USGS Contour map of Nehalem River from ~RKM 31.4–18.8; includes profiles; 

published in 1939

Trask, Wilson 1:24,000 1953 USGS USGS Contour map of Trask (RKM 16.3–11.7) and Wilson (RKM 20.7–10.2) 

Rivers; includes profiles

Shoreline 

map

Nehalem 1:5,000 1954 NOS OCA5 Vectorized Nehalem River shoreline from 1954 and ~RKM 21–0.4

Estuary habitat map

Tillamook, 

Trask, Miami

NA 1978 ODFW OSU6 Map of estuary categorized by tidal inundation, habitat type, vegetation, 

and sediment for Tillamook (~RKM 1.4–0), Trask (~RKM 1.8–0), and 

Miami (RKM 0.4–0) Rivers

Nehalem NA 1978 ODFW OSU6 Map of estuary categorized by tidal inundation, habitat type, vegetation, 

and sediment for ~RKM 21.4–0

LiDAR

Tillamook, 

Trask, Wilson, 

Kilchis, and 

Miami

~1 m 2007–09 DOGAMI DOGAMI7 High resolution topographic survey of all study areas

Nehalem ~1 m 2009 DOGAMI DOGAMI7 High resolution topographic survey of entire study area

Geologic 

map

All study 

areas

1:12,000 to 

1:500,000

2009 DOGAMI Oregon GEO8 Digital compilation of geologic maps in Oregon (Ma and others, 2009); 

complete coverage of all study areas
Table 11 footnotes

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

2

1860, 1947, 1970, 1973, 1978, 1982, 1990, 2006; other years likely

3 NOAA: http://historicalcharts.noaa.gov/; http://www.charts.noaa.gov/OnLineViewer/PacificCoastViewerTable.shtml

4

Such as 1969, 1971, 1973, 1975, 1977, 1979, 1984, 1990, 2006; other years likely

5 OCA: http://www.coastalatlas.net/index.php?option=com_custompages&e=3&Itemid=68

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

7 DOGAMI Oregon LiDAR Consortium: http://www.oregongeology.org/sub/projects/olc/

8 Oregon Geospatial Enterprise Office: http://www.oregon.gov/DAS/EISPD/GEO/sdlibrary.shtml

General Land Office map of the Tillamook Bay, circa 1874 (Courtesy of the Bureau of Land Management).
Gravel-Operator Information and Surveys 

In August 2011, we reviewed permit files at 

the Oregon Department of State Lands to obtain 

estimates of deposited and mined volumes of 

bed-material reported for the active instream 

gravel mining sites in the Tillamook Bay subbasins and Nehalem River basin. Coastwide 

Ready-Mix provided copies of surveys taken in 

2009 at Donaldson, Barker, Dill, and Gomes 

Bars (Dennis Johnson, Coastwide Ready-Mix, 

written commun., 2010) and Mohler Sand and 

Gravel, LLC provided copies of surveys taken in 

2010 at Plant Bar (Brian Mohler, Mohler Sand 

and Gravel, LCC, written commun., 2010). From 

the permit files and surveys, we derived partial 

estimates of deposited and mined gravel volumes, primarily from repeat topographic surveys, 

for eight instream gravel-mining sites (table 12; 

figs. 10–14). Stinson and Stinson (1998) also 

compiled deposited and mined gravel volumes 

for mined and unmined sites from 1993 to 1997 

(tables 12 and 13). Because these data compilations are incomplete, actual volumes of mined 

and deposited bed material were probably greater 

than reported here. 

Although the compilations are incomplete, 

some patterns emerge from the available measurements. From 1993 to 1997, operators reported 

removal of 40,040 m3and 71,910 m3of gravel 

from the Wilson and Kilchis Rivers, respectively, whereas 6,160 m3

of gravel were taken from 

the Miami River for the same period (table 13). 

From 2004 to 2011, the reported cumulative volumes of bed-material deposition were also greatest for the Wilson and Kilchis Rivers, where 

deposition volumes totaled over 25,000 m3at

Donaldson and Dill Bars, respectively (table 12). 

Mean annual volumes of deposition on individual bars exceeded 3,000 m3

for Donaldson and 

Dill Bars and both bars on the Nehalem River. 

From 2003 to 2011, reported cumulative mined 

volumes per site was greatest for Donaldson, 

Plant, and Winslow Bars, ranging from 24,470 to 

33,940 m3(table 12). For most years and sites 

with volumes of deposited and mined sediment, 

bar deposition matched or exceeded mined volumes (fig. 16A–I). The greatest surveyed deposition volume, 8,950 m3 on Donaldson Bar on the 

Wilson River, followed a flood on November 6, 

2006 that exceeded a 50-year event (fig. 5B), 

which is consistent with the relation between 

discharge and deposition volumes noted for other 

rivers on the Oregon coast (Wallick and others, 

2010; Jones and others, 2011; Wallick and 

others, 2011; Jones and others, 2012a, b). 

Although the limited dataset hinders comparison of decadal trends in bed-material recruitment, deposition volumes from 1995, as reported by Stinson and Stinson (1998), were 

comparable to deposition volumes reported from 

2003 to 2010 for Dill and Gomes Bars on the 

Kilchis River and Waldron Bar on the Miami 

River (table 12). Because gravel mining likely 

creates preferential depositional areas on mined 

bar surfaces, deposition estimates at individual, 

mined bars cannot be reliably extrapolated to assess overall deposition rates for all bars along 

these rivers, but they do provide evidence of 

minimum annual bed-material flux rates (Wallick and others, 2012). 
54

Table 12. Partial compilation of deposited and mined gravel volumes from 2003 to 2011 reported for instream mining sites along the Trask, Wilson, 

Kilchis, Miami, and Nehalem Rivers, northwestern Oregon.

[Original data reported in cubic yards. Reported annual values were converted to cubic meters, and rounded to the nearest 10. Mean and cumulative values based 

on rounded annual values. Mean values calculated using sum and number of rounded annual estimates owing to data gaps. m3, cubic meter; RKM, river kilometer; ~, approximately; Dep, deposited volume; Mined, mined volume; --, data gap; data compiled from permits files housed at Oregon Department of State Lands 

(accessed August 2011)]

River Trask Wilson Kilchis Miami Nehalem

Reach Fluvial Lower Fluvial Fluvial Lower Fluvial Fluvial

Bar Bush Donaldson Barker Dill Gomes Waldron Plant Winslow

RKM 12.2 10.4 6.9

~0.1 km upstream 

of study area 4.8 4.8 25.8 24.8

Bar change Dep Mined Dep Mined Dep Mined Dep Mined Dep Mined Dep Mined Dep Mined Dep Mined

2003 -- -- -- 4,790 -- -- -- -- -- 2,120 -- -- -- 2,330 -- 0

2004 -- -- -- 0 2,580 1,780 3,480 3,430 1,150 -- -- -- -- 860 -- 5,240

2005 -- 910 4,950A

2,320 1,020 1,090 4,720 3,680 -- -- 1,240 1,160 -- 3,960 -- 4,290

2006 -- 2,780 4,260 3,960 1,100 1,640 4,160 3,160 4,140 2,190 2,380 1,010 -- 7,860 -- 6,810

2007 -- 2,680 8,950 5,660 1,290 810 3,070 2,010 1,430 1,350 1,380 1,310 -- 7,140 -- 6,750

2008 -- 2,690 3,060 2,980 1,890 900 1,880 1,840 880 830 -- -- -- 4,650 6,420 3,250

2009 -- 1,150 4,780 4,760 1,550 1,540 4190B

4,150 1,100B1,090 -- 0 6,350 5,610 8,410 4,840

2010 -- NRC

-- 0 -- 0 -- 0 -- 0 -- 0 4,820 1,530 -- 0

B

2011 -- -- 4,160A

-- -- -- 3,890A-- -- -- -- -- -- -- -- --

Mean annual 

volume by 

siteD

-- 2,040 3,770 4,080 1,570 1,290 3,170 3,050 1,740 1,520 1,670 1,160 5,590 4,240 7,420 5,200

Cumulative 

volumes by 

site

-- 10,210 30,160 24,470 9,430 7,760 25,390 18,270 8,700 7,580 5,000 3,480 11,170 33,940 14,830 31,180

Cumulative 

volumes by 

river

-- 10,210 39,590 32,230 34,090 25,850 5,000 3,480 26,000 65,120

A Deposition estimate is cumulative for year indicated and previous year

B Operator provided information on 2010 mining activities

C Mined volume not included in permit file; field observations indicate mining

D Mean values calculated using number of estimates listed in table
55

Table 13. Partial compilation of deposited and mined gravel volumes from 1993 to 1997 at active and historical instream gravel mining reported in 

Stinson and Stinson (1998).—continued

[Locations approximated using drawings in report. Original data reported in cubic yards. Reported annual values were converted to cubic meters, and rounded 

to the nearest 10. Cumulative values for each river basin based on rounded annual values. RKM, river kilometer; C, control site; M, mining site; Dep, deposited 

volume; Mined, mined vol-ume; --, data gap; ~, approximately; km, kilometer; NA, unavailable]

River Bar

Site 

Type

Approximate

location

Estimate 

type

Volume measured by Stinson and 

Stinson (1998)

Volume estimated by operator and reported 

in Stinson and Stinson (1998)

Total mined 

volume per river 

basin

reported by 

1993 1994 1995 1996 1993 1994 1995 1996 1997 operator

Wilson Jacob C RKM 12.4 Dep

Mined

--

800

--

270

--

--

--

--

--

490

--

380

--

--

--

--

--

--

40,040

Widmer M RKM 12.2 Dep

Mined

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

3,290

Upper 

Donaldson1

C RKM 10.4 Dep

Mined

--

3,080

--

--

--

--

--

--

--

2,490

--

2,980

--

2,700

--

10,470

--

6,290

Lower 

Donaldson

M RKM 10.0 Dep

Mined

--

1,500

--

--

--

--

--

--

--

1,700

--

--

--

--

--

--

--

--

Barker2 M RKM 6.9 Dep

Mined

--

790

--

--

--

--

--

--

--

800

--

550

--

1,180

--

1,450

--

--

Tannler M RKM 6.6 Dep

Mined

--

540

--

--

--

470

--

--

--

870

--

930

--

710

--

1,530

--

1,230

Kilchis Bruck M ~0.6 km 

above study 

area

Dep

Mined

--

3,240

--

--

--

4,420

--

NA

--

2,230

--

1,840

--

4,290

--

--

--

4,260

71,910

Bay City3 M ~0.1 km 

above study 

area

Dep

Mined

--

1,400

--

940

5,300

5,430

--

--

--

1,090

--

1,430

--

4,820

-- --

8,450 3,170

Lower Bay 

City

M RKM 7.8 Dep

Mined

--

--

--

250

--

--

--

--

--

--

--

--

--

--

--

--

--

--

Darby M RKM 6.8 Dep

Mined

--

100

--

270

610

550

--

--

--

270

--

330

--

780

--

710

--

470

Crusher M RKM 5.8 Dep

Mined

--

--

--

300

420

490

--

NA

--

--

--

--

--

780

--

--

--

2,980

Upper

Landolt

M RKM5.3 Dep

Mined

--

430

--

460

2,010

830

--

--

--

760

--

930

--

970

--

5,860

--

950
56

Table 13. Partial compilation of deposited and mined gravel volumes from 1993 to 1997 at active and historical instream gravel mining reported in 

Stinson and Stinson (1998).—continued

[Locations approximated using drawings in report. Original data reported in cubic yards. Reported annual values were converted to cubic meters, and rounded 

to the nearest 10. Cumulative values for each river basin based on rounded annual values. RKM, river kilometer; C, control site; M, mining site; Dep, deposited 

volume; Mined, mined vol-ume; --, data gap; ~, approximately; km, kilometer; NA, unavailable]

River Bar

Site 

Type

Approximate

location

Estimate 

type

Volume measured by Stinson and 

Stinson (1998)

Volume estimated by operator and reported 

in Stinson and Stinson (1998)

Total mined 

volume per river 

basin

reported by 

1993 1994 1995 1996 1993 1994 1995 1996 1997 operator

Kilchis

(cont,)

Lower 

Landolt4

M RKM 4.8 Dep

Mined

--

--

--

1,680

2,190

2,060

--

--

--

360

--

1,360

--

2,330

--

--

--

870

Curl C RKM 4.4 Dep

Mined

--

--

--

--

50

--

--

NA

--

--

--

--

--

--

--

--

--

--

Bosch C RKM 4.1 Dep

Mined

--

--

--

--

--

--

--

NA

--

--

--

--

--

--

--

--

--

--

Averill M RKM 2.9 Dep

Mined

--

820

--

1,780

6,120

6,380

--

--

--

1,610

--

2,970

--

6,500

--

6,380

--

2,160

Miami Wald C RKM 6.1 Dep

Mined

--

--

--

NA

--

--

--

--

--

NA

--

NA

--

NA

--

NA

--

NA

6,160

Upper 

Waldron5

M RKM 4.8 Dep

Mined

--

--

--

480

770

--

--

--

--

--

--

--

--

--

--

4,590

--

900

Middle 

Waldron

M RKM 4.6 Dep

Mined

--

--

--

600

310

--

--

--

--

--

--

--

--

--

--

--

--

--

Lower 

Waldron

M RKM 4.4 Dep

Mined

--

--

--

210

280

--

--

--

--

--

--

--

--

--

--

--

--

670

Filosi M RKM 2.3 Dep

Mined

--

100

--

50

750

560

--

--

--

--

--

--

--

--

--

--

--

--

1 Ongoing mining site under the name Donaldson Bar

2 Ongoing mining site

3 Ongoing mining site under the name Dill Bar

4 Ongoing mining site under the name Gomes Bar

5 Ongoing mining site under the name Waldron Bar
57

Figure 16. Graphs showing reported estimates of deposited and mined gravel from 1999 to 2011 for instream 

mining sites along the Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. Data compiled 

from permit files housed at Oregon Department of State Lands (accessed August 2011). [RKM, river kilometer; 

NA, data not available] 
58

Figure 16 (continued). Graphs showing reported estimates of deposited and mined gravel from 1999 to 2011 

for instream mining sites along the Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. 

Data compiled from permit files housed at Oregon Department of State Lands (accessed August 2011). 

[RKM, river kilometer; NA, data not available]—continued 
59

Figure 16 (continued). Graphs showing reported estimates of deposited and mined gravel from 1999 to 2011 

for instream mining sites along the Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. 

Data compiled from permit files housed at Oregon Department of State Lands (accessed August 2011). 

[RKM, river kilometer; NA, data not available. 
60

Despite little evidence of systematic change 

in bar volume or particle-size distribution (Stinson and Stinson, 1998) at mined sites, repeat bar 

and channel delineations show that several 

mined bars have changed in size, shape, or position relative to the main channel from 1939 to 

2009 (see the “Delineation of Bar and Channel 

Features, 1939–2009” section). Detailed analyses 

of bed-material flux and morphological changes 

along the Trask, Wilson, Kilchis, Miami, and 

Nehalem Rivers would enable more quantitative 

assessments of changes in bar replenishment and 

morphology in relation to peak flows as well as 

support the evaluation of the possible effects of 

gravel mining on overall bed-material flux and 

downstream channel conditions. Photographs, 

such as those taken in 1994, 2000, 2005, 2009, 

and 2011 of the Trask, Wilson, Kilchis, and Miami Rivers (table 9) and in 1994, 2000, 2001, 

2005, 2009, and 2011 of the Nehalem River (table 10), would likely support detailed geomorphic assessments. 

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 21 bridges in the six study 

areas (Oregon Department of Transportation, 

written commun., 2011; table 14). ODOT has 

resurveyed channel cross sections at 18 bridges, 

with at least two survey locations within each 

study area and at least one survey in a fluvial 

reach in four of the six study areas (repeat cross 

sections were unavailable for the fluvial reaches 

on the Trask and Nehalem Rivers). The surveys 

span 1926–2010 and include as many as four 

surveys at some locations (table 14). We also 

examined the supplemental data accompanying 

the survey reports, including inspection and underwater reports, photographs, and scour assessments that may assist in assessing channel 

and bed-material conditions adjacent to the 

bridges. 

The most recent inspection surveys and underwater reports include some descriptions of 

bed material, wood accumulation, and bridge 

infrastructure scour (table 14). The streambeds 

were described as soft silt on the Tillamook River (RKM 6.4), sandy silt on the Trask River 

(RKM 2.1), gravel and silt bordered by a bedrock outcrop to the south on the Wilson River 

(RKM 14.1), gravel and sand on the Kilchis River (RKM 4.2), cobble and gravel and then sand 

and gravel at RKM 8.5 and 0, respectively, on 

the Miami River, and sand and silt on the Nehalem River (RKM 18.8 and 10.6). Several inspection reports document the accumulation of large 

wood near bridges on the Tillamook (RKM 

11.5), Trask (RKM 7.0 and 2.1), Wilson (RKM 

2.8), Kilchis (RKM 4.2), Miami (RKM 0), and 

Nehalem (RKM 22.4, 18.8, and 10.6) Rivers. 

These reports also note bank slumping, erosion 

of bank protection, undermining of channel protection, or “minor channel damage” (as stated in 

ODOT reports) on the Tillamook (RKM 11.5 

and 8.8), Trask (RKM 11.6, 7.0, 3.8, and 2.1), 

Wilson (RKM 14.1 and 6.3), Kilchis (RKM 6.0, 

4.2, 1.5, and 1.0), Miami (RKM 8.5, 2.7, and 0), 

and Nehalem Rivers (RKM 22.4 and 18.8). 

ODOT documented scour of bridge infrastructure at six of these locations (Trask RKM 7.0, 

Wilson RKM 14.1 and 6.3, Kilchis RKM 1.0, 

Miami RKM 8.5, and Nehalem RKM 22.4) plus 

one other location (Tillamook RKM 6.4).

The repeat cross sections show that channels 

near bridge crossings in all study areas are dynamic with many subject to incision and aggradation as well as lateral shifts in channel position 

(table 14). Thalweg elevation changes included a 

mixture of incision and aggradation on the 

Tillamook and Trask Rivers (figs. 17A–D and 

18A–B). The thalweg of the Tillamook River 

incised a net 0.5 to 2.6 m at three locations 

(RKM 11.5, 8.8, and 1.3) over different survey 

periods, but aggraded 3.1 m near RKM 6.4 from 

1996 to 2004. Likewise, the Trask River thalweg 

incised a net 2.3 m at RKM 7.0 primarily from 

1998 to 2004, but aggraded 0.5 m downstream at 

RKM 2.1 from 2003 to 2004. Thalweg position 
 

61

Table 14. Summary of net changes measured from channel cross sections collected by the Oregon Department of Transportation (ODOT, written 

commun., 2011) in the six study areas in the Tillamook Bay subbasins and Nehalem River basin, northwestern Oregon.—continued

[RKM, river kilometer; USGS, U.S. Geological Survey; Rd, Road; NA, unavailable; Hwy, highway]

Study 

area Bridge Reach RKM

ODOT 

bridge 

ID

Survey 

years

Net thalweg 

elevation 

change 

(meters)

Maximum net 

erosion

(meters)

Maximum net 

deposition

(meters)

ODOT notes (USGS notes)

Left 

bank

Right 

bank

Left 

bank

Right 

bank

Tillamook

Bewley 

Creek Rd

Fluvial 11.5 18538 1999, 

2004

-0.6 -1.0 -1.3 +0.7 0.0 Eroded bank protection; wood in span

Tillamook 

River Rd

Tidal 8.8 19625 2004a, 

2004b1

-0.5 -1.0 -0.3 0 +0.4 Minor channel damage

Burton Tidal 6.4 01594A 1996, 

2004

+3.1 0 -0.1 +2.7 +2.1 Unstable scour of infrastructure; channel over soft silt 

bed and protected (secondary thalweg aggrades 1.8 m 

from 1996 to2004)

Hwy 131 Tidal 1.3 01345C 1961, 

1998, 

2004

-2.6 -2.1 -2.2 +1.7 0 Channel protected (net changes likely greater owing to 

limited data in 1961 survey)

Trask

Long Prairie RdFluvial 11.6 20306 NA -- -- -- -- -- 23 m of bank slumping downstream of bent and minor 

bank erosion

Hwy 9 Tidal 7.0 07147 1948, 

1998, 

2004, 

2008

-2.3 -1.9 -0.7 +1.3 +3.7 Unstable scour of infrastructure; bank protection and 

north and south stream banks eroded; drift in bent

Tillamook 

River Rd

Tidal 3.8 17929 2004 -- -- -- -- -- Minor channel damage

Stillwell Tidal 2.1 05640A 2003, 

2004

+0.5 0 0 +1.5 +0.4 Bank slumping; some erosion around piles after 1996 

flood; sandy silt streambed; old trees lodged in channel
 

62

Table 14. Summary of net changes measured from channel cross sections collected by the Oregon Department of Transportation (ODOT, written 

commun., 2011) in the six study areas in the Tillamook Bay subbasins and Nehalem River basin, northwestern Oregon.—continued

[RKM, river kilometer; USGS, U.S. Geological Survey; Rd, Road; NA, unavailable; Hwy, highway]

Study 

area Bridge Reach RKM

ODOT 

bridge 

ID

Survey 

years

Net thalweg 

elevation 

change 

(meters)

Maximum net 

erosion

(meters)

Maximum net 

deposition

(meters)

ODOT notes (USGS notes)

Left 

bank

Right 

bank

Left 

bank

Right 

bank

Wilson

Mills Upper 

Fluvial

14.1 01868 1939, 

1996, 

2004, 

2008

+0.4 -1.4 -1.9 +0.6 0 Unstable scour of bridge infrastructure; minor channel 

damage; gravel and silt streambed; pier on bedrock 

outcrop on south bank

Sollie 

Smith

Lower 

Fluvial

6.3 57C23 1996, 

2004

+2.1 0 -0.7 +2.0 +1.5 Unstable scour of bridge infrastructure; minor channel 

damage

Hwy 9 Tidal 2.8 01499 1930, 

1998, 

2004, 

2008

+0.4 -2.9 -1.2 +1.3 0 Bank slumping; wood build-up causing scour

Kilchis

Kilchis 

River Rd

Fluvial 6.0 20999 2008, 

2010

-0.4 -1.2 -1.0 +2.5 0 Bank slumping

Curl Rd Fluvial 4.2 57C20 1996, 

2004

0 -0.1 -0.7 +0.6 +0.6 Minor channel damage; gravel and sand streambed; 

some wood build-up

Alderbrook 

Loop

Tidal 1.5 00455A 1996, 

2004

-0.2 -0.5 -0.3 0 +0.3 Bank slumping

Kilchis 

River and 

Possetti Rd2

Tidal 1.0 07424 1951, 

1998, 

2004, 

2008 

-0.5 -0.7 -0.2 +1.9 +0.9 Unstable scour of bridge infrastructure; erosion of bank 

protection and south bank
 

63

Table 14. Summary of net changes measured from channel cross sections collected by the Oregon Department of Transportation (ODOT, written 

commun., 2011) in the six study areas in the Tillamook Bay subbasins and Nehalem River basin, northwestern Oregon.—continued

[RKM, river kilometer; USGS, U.S. Geological Survey; Rd, Road; NA, unavailable; Hwy, highway]

Study 

area Bridge Reach RKM

ODOT 

bridge 

ID

Survey 

years

Net thalweg 

elevation 

change 

(meters)

Maximum net 

erosion

(meters)

Maximum net 

deposition

(meters)

ODOT notes (USGS notes)

Left 

bank

Right 

bank

Left 

bank

Right 

bank

Miami

New Miami 

River Rd

Lower 

Fluvial

8.5 57C59 1996, 

2004

-0.6 -0.6 -0.2 +0.3 +0.7 Extensive scour of bridge infrastructure; channel protection undermined; cobble and gravel streambed

Moss Creek 

Rd

Lower 

Fluvial

2.7 57C12 1996, 

2004

-0.6 -0.5 -0.4 0 +0.3 Minor channel damage; some bank erosion under span

Hwy 9/101 Tidal 0 01226A 1990, 

1997, 

2005

-0.5 -3.1 -0.1 +0.8 +1.5 Minor channel damage; large debris in channel; sand 

and gravel bed

Nehalem

Miami Foley RdTidal 22.4 01362A NA -- -- -- -- -- Extensive scour of bridge infrastructure; bank slumping 

and erosion; large build-up of drift at bents

Hwy 463 Tidal 18.8 01217 1926, 

1997, 

2003, 

2007

+1.2 -1.5 0 +2.4 +0.9 Bank slumping; sand and silt streambed; large debris in 

channel and surrounding piers; some scour at toe of 

embankments; wood in channel

Hwy 9 Tidal 10.6 00574F 1980, 

2001, 

2005, 

2009 

+2.2 0 -0.2 +1.2 +0.8 Channel protected; large wood and debris in channel; 

sand and silt streambed

1 2004a surveyed on 3/11/04; 2004b surveyed on 9/10/04

2 1951 cross section derived from bridge plans

3 ODOT report indicates the 1926 survey may be derived from bridge plans or cross section survey.
 

64

Figure 17. Diagrams showing channel cross sections surveyed at RKM 11.5, 8.8, 6.4, and 1.3 along the Tillamook River, northwestern Oregon. Data provided by the Oregon Department of Transportation (written commun., 

2011). [RKM, river kilometer] 
 

65

Figure 18. Diagrams showing channel cross sections surveyed at RKM 7.0 and 2.1 on the Trask River, northwestern Oregon. Data provided by the Oregon Department of Transportation (written commun., 2011). [RKM, river 

kilometer] 

was relatively stable between surveys except 

where the thalweg shifted laterally 19.0 and 

8.1 m toward the left banks at Tillamook RKM 

1.3 and Trask RKM 7.0, respectively, from 1998 

to 2004. In addition to aggradation, incision, and 

some lateral shifting of channel position, banks 

at all cross sections on the Tillamook and Trask 

Rivers experienced 1 m or more of lateral deposition and/or erosion. 

Along the Wilson River, the thalweg episodically aggraded and incised, resulting in net elevation increases of 0.4 m at RKM 14.1 and 2.8 

from the 1930s to 2008 (table 14; fig. 19A, C). 

The thalweg also aggraded 2.1 m at RKM 6.0 

from 1996 to 2004 (fig. 19B). All three cross 

sections exhibited almost 2 m or more of local 

bank deposition and erosion as well as lateral 

changes in thalweg position. For example, the 

thalweg shifted towards the right bank approximately 23.0 m at RKM 14.1 from 1939 to 1996, 

and 11.0 m at RKM 2.8 from 1930 to 1998 (fig. 

19A,C), but later returned to its earliest surveyed 

location at both sites. 

Along the Kilchis River, cross sections at 

RKM 4.2 and 1.5 show either minimal (0.2 m) 

incision or no detectable change in thalweg elevation and less than 1 m of bank deposition and 

erosion (table 14; fig. 20A–D). Meanwhile, the 

upstream cross section at RKM 6.0 experienced 

more than 2 m of deposition along the left bank 
 

66

Figure 19. Diagrams showing channel cross sections surveyed at RKM 14.1, 6.3, and 2.8 on the Wilson River, 

northwestern Oregon. Data provided by the Oregon Department of Transportation (written commun., 2011). 

[RKM, river kilometer] 
 

67

Figure 20. Diagrams showing channel cross sections surveyed at RKM 6.0, 4.2, 1.5, and 1.0 on the Kilchis River, 

northwestern Oregon. Data provided by the Oregon Department of Transportation (written commun., 2011). 

[RKM, river kilometer] 
 

68

as the thalweg shifted towards the right bank and 

lowered 0.4 m from 2008 to 2010 (fig. 20A). At 

RKM 1.0, the channel switched from flowing 

against the right to the left bank from 1951 to 

1988, incised a net 0.5 m, and had some bank 

deposition and erosion (fig. 20D). 

The thalweg of the Miami River generally 

incised over the survey periods (table 14; fig. 

21A–C). At RKM 8.5, the thalweg incised 0.6 m, 

but remained in approximately the same location 

from 1996 to 2004 (fig. 21A). Over the same period, the thalweg incised 0.6 m and shifted toward the left bank at RKM 2.7 (fig. 21B). The 

banks at RKM 8.5 and 2.7 experienced some 

erosion and deposition from 1996 to 2004. 

Downstream at RKM 0, the channel shifted leftward and aggraded 0.2 m from 1990 to 1997, but 

then shifted further towards the left bank and incised 0.6 m from 1997 to 2005, resulting in a net 

incision of approximately 0.5 m (fig. 21C). The 

banks at RKM 0 experienced greater erosion and 

deposition than those at the upstream sites. 

The thalweg of the Nehalem River aggraded 

over the survey period at two bridge crossings 

(RKM 18.8 and 10.6; table 14; fig. 22A–B). At 

RKM 18.8, the thalweg aggraded a net 1.2 m 

primarily from 1926 to 1997 while the banks experienced a net 1.5 m of erosion on the left and 

2.4 m of deposition on the right. The thalweg at 

RKM 18.8 has also shifted laterally, sometimes 

exceeding 15 m between surveys from 1926 to

2007 (fig. 22A). At RKM 10.6, the thalweg aggraded a net 2.2 m between 1980 and 2009 with 

the greatest elevation increase (approximately 

1.5 m) occurring from 2005 to 2009 (fig. 22B).

The thalweg shifted towards the left bank from 

1980 to 2001, but then remained in a similar 

overall position in subsequent surveys. The 

channel banks at RKM 10.6 reflect the overall 

pattern of channel shifting and aggradation, as 

they experienced less than 0.2 m of erosion from 

1980 to 2009, but nearly 1 m of deposition from 

2005 to 2009 (table 14; fig. 22B).

Specific Gage Analysis 

Another approach to evaluating vertical adjustments in channel elevation are specific gage 

analyses (Klingeman, 1973), which enable detection of changes in streambed elevation by assessing variations in water elevation (stage) over 

time for specific discharge values. At each 

USGS streamflow-gaging station, discharge is 

related to stage by a stage–discharge rating 

curve, which is based on multiple, paired stage 

and discharge measurements made 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 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. 

We conducted specific gage analyses for the 

streamflow-gaging stations on the Wilson River 

near Tillamook (14301500; approximately 0.1 

km upstream of Wilson River study area; table 3; 

fig. 1) and Nehalem River near Foss (14301000; 

approximately 0.4 km upstream of Nehalem 

River study area; table 3; fig. 2). We selected the 

Wilson and Nehalem stations for specific gage 

analyses because they have long-term periods of 

record and were operational as of 2011 (table 3). 

The Wilson River gage is in a section where the 

channel flows over alluvial deposits and intermittent bedrock. The Nehalem River gage is situated near where the channel transitions from 

flowing primarily on bedrock to alluvial deposits. Changes in stage were assessed for low to 

moderate flows (2.0–124.6 m3/s on the Wilson 

River and 2.8–283.1 m3/s on the Nehalem River) 

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. 
 

69

Figure 21. Diagrams showing channel cross sections surveyed at RKM 8.5, 2.7, and 0 on the Miami River, northwestern Oregon. Data provided by the Oregon Department of Transportation (written commun., 2011). [RKM, river 

kilometer]
 

70

Figure 22. Diagrams showing channel cross sections surveyed at RKM 18.8 and 10.6 on the Nehalem River, 

northwestern Oregon. Data provided by the Oregon Department of Transportation (written commun., 2011). 

[RKM, river kilometer] 

Although the gaging record for the Wilson 

River station begins in 1914, the specific gage 

analysis for this station uses data from July 1931 

to January 2010 because the datum for stage 

measurements made from 1914 to 1916 is unknown and measurements were not made from 

1916 to 1931. During the analysis period, the 

gage was moved four times (resulting in essentially five analysis “windows”), with datum 

shifts made in 1937 and 2003 (fig. 23A). Stage 

decreased a net 0.02–0.08 m over 1931–1937, 

0.10–0.27 m over 1937–1967, and 0.06–0.26 m 

over 1973–2003. Net increases in stage, however, ranged from 0.47 to 0.63 m over 1976–1973 

and 0.03 to 0.12 m over 2003–2010. This analysis indicates that the channel experiences episodic periods of aggradation followed by incision, 

particularly following some floods, such as those 

exceeding a 10-year return period (December 21, 

1933; December 22, 1964) and a 25-year return 

period (January 20, 1972; February 8, 1996; fig. 

5B). However, some larger floods like those exceeding a 50-year event (November 6, 2006) and 

almost a 25-year event (December 3, 2007) do 

not appear to trigger stage changes; this lack of 

response in the stage-discharge relation may be 

attributable to differences in flood duration and 

deposition dynamics at the gage. The small 

(0.03–0.12 m) increase in stage from 2009 to 

2010 does not correspond with a flood event and 

may indicate changes in cross section controls 
 

71

Figure 23. Diagrams showing the stage-discharge rating curves for specific discharges for the U.S. Geological 

Survey streamflow-gaging stations on the Wilson River near Tillamook, Oregon (14301500) and Nehalem River 

near Foss, Oregon (14301000), northwestern Oregon. The source data are station records housed at the Oregon 

Water Science Center, U.S. Geological Survey, Portland, Oregon. [km, kilometer] 
 

72

(Klingeman, 1973) or sediment delivery to the 

section following the 2006 and 2007 floods. 

On the Nehalem River, the stage-discharge 

relations for the five analyzed discharges show 

stage changes spanning as much as 0.92 m between ratings from October 1939 to January 

2010 (fig. 23B). Stage decreased a net 0.18 and 

0.09 m for the two lowest discharges, but increased a net 0.09 to 0.15 m for three highest 

discharges. These differences may be attributable 

to changes in the geometry of the high and low 

flow portions of the cross section, causing water 

levels to increase during elevated discharges and 

decrease at low discharges. For all analysis discharges, stage exhibited short, periodic rises (that 

increase in magnitude and duration with discharge), particularly over 1963–1964, 1979–

1983, and 1992–1999. These episodes coincide 

with multiple flood events (such as those on January 25, 1964, December 23, 1964, and February 

8, 1996; fig. 5D), and perhaps indicate increases 

in bed-material transport and channel aggradation following relatively large flows and bedmaterial erosion in other years. Counter to this, 

however, the December 3, 2007 flood event was 

greater in magnitude than the 25-year event, but 

does not appear to have affected the stagedischarge relation, indicating variation in local 

channel responses to flooding. Future review and 

analysis of station notes, historical cableway 

surveys, and individual discharge measurements 

could provide additional data on channel geometry and bed-material trends at both streamflowgaging stations. 

Delineation of Bars and Channel Features, 

1939–2009 

For this reconnaissance-level study, we mapped: 

1. Channel centerlines for the six study areas using orthophotographs taken in 2009 

(tables 9 and 10) to develop the linear 

reference system for this study, and 

2. Bars, channel centerlines, and wetted 

channel edges for the six study areas using aerial and orthophotographs taken in 

1939, 1967, 2005, and 2009 (tables 9 and 

10) to assess temporal changes in the location and areal coverage of bars as well 

as the length and wetted width of the 

channel. 

For both efforts, we delineated lateral and 

medial bars greater than 200 m2in area from aerial and orthophotographs at a scale of 1:2,000 for 

Tillamook Bay study areas and upstream of 

RKM 19.0 on the Nehalem River and at 1:10,000 

downstream of RKM 19.0 on the Nehalem River. Bar and channel delineations were done using 

the Geographic Information System (GIS) program ESRI ArcMap 9.3.1 and 10.0.3. Although 

bars were not classified by grain size, field observations made in October 2010 indicated that 

most bars in the fluvial reaches were composed 

of gravel and finer particles. Most bars in the tidal reaches were composed of sand and mud. Fine 

sediment deposits that flank the channel in the 

Tidal Tillamook Reach are apparent in the 1969, 

2005, and 2009 photographs, but because these 

surfaces are not obvious bars, they were not 

mapped in this study. Most mapped bars had little to no vegetation, although some had areas that 

were partly or wholly covered by grasses, 

shrubs, and (to a lesser extent) mature trees; 

however, vegetation or habitat types were not 

specifically mapped by this effort. 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).

The quality of underlying photographs and 

errors introduced by georeferencing 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). As described above, we selected photographs taken in 

1939, 1967, 2005, and 2009 for mapping bars, 

channel centerlines, and wetted channel edges in 

the six study areas (tables 9 and 10). Scanned 

copies of the black and white photographs taken 

in 1939 and 1967 were acquired from the Corp 
 

73

of Engineers aerial photograph library and University of Oregon Map and Aerial Photography 

Library, respectively. These photographs were 

generally of adequate resolution and free of glare 

and shadow to facilitate detailed mapping of bars 

and channel features with the exception of some 

glare and shadow or low resolution along the upper portions of the Tillamook Bay Rivers, particularly in the 1967 photographs of the Upper Fluvial Wilson and Miami Reaches and Fluvial 

Trask Reach. 

The 1939 and 1967 photographs of the six 

study areas were georectified (table 15) using 

methods similar to Wallick and others (2011). 

The total Root Mean Square Error (RMSE) of 

rectified photographs, an indicator of the horizontal position uncertainties owing to the georectification process, was less than 4.9 m for all 

study areas. Generally, ground-control points for 

georectification were located near the mainstem 

channels so that positional errors for channel features should be less than the RMSE reported for 

individual photographs. Although land use and 

land cover change limited the number of groundcontrol points for the 1939 photographs of the 

Nehalem River study area, RMSE values for 

these rectified photographs are similar to those 

reported for rectified 1939 and 1967 photographs 

of the Coquille River (Jones and others, 2012b) 

and 1967 photographs of the Rogue River (Jones 

and others, 2012a) on the southwestern Oregon 

coast. 

Streamflow during photograph acquisition 

may affect bar exposure, influencing the mapped 

bar and wetted channel areas (table 16). Streamflow data from the long-term Wilson River gage 

(14301500) was used to assess relative flow 

conditions for the ungaged Tillamook Bay rivers. 

From these records, streamflows were generally 

lowest during the collection of the 2009 photographs (1.3–9.5 m3

/s), and slightly greater in the 

1939 (4.6–5.9 m3/s) and 2005 (5.0–10.0 m3/s) 

photographs. Streamflow during the collection of 

the 1967 photographs was substantially greater 

than during the other collections, and ranged 

from 65.7 to 199.3 m3/s at the Wilson and Nehalem gages, respectively. The higher streamflows 

in the 1967 photographs likely reduced the area 

of mapped bars and increased the mapped area of 

wetted channel width in 1967 relative to the other years. 

Table 15. Photograph rectification data for the Tillamook and Nehalem study areas, northwestern Oregon.

Polynomial transformation applied to photographs

Study areas

Year of 

photograph 

coverage

First order transformation Second order transformation

Study area 

coverage 

(percent)

Average 

number of 

ground control 

points

Root Mean 

Square Error 

(meters)

Study area 

coverage 

(percent)

Average 

number of 

ground control 

points

Root Mean 

Square Error 

(meters)

Tillamook 

(all)

1939 0 -- -- 100 11 1.2–4.4

1967 0 -- -- 100 12 2.0–4.9

Nehalem 1939 18 6 3.0–4.5 82 12 0.9–4.4

1967 0 -- -- 100 11 1.7–4.7
 

74

Table 16. Streamflow during the acquisition of the aerial photographs used for repeat bar and 

channel feature delineation on the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon.

[m3/s, cubic meter per second; --, same as main streamflow; NA, gage inactive; USACE, U.S. Army 

Corps of Engineers; USGS, U.S. Geological Survey]

Year River Flight dates1

Mean daily discharge (m3/s)2

Minimum Maximum Main

1939 Tillamook 5/8; 5/12; 7/20 4.6 5.9 5.9

Trask 5/8; 5/12 5.2 5.9 5.2

Wilson 5/8; 5/12 5.2 5.9 5.2

Kilchis 5/8; 5/12 5.2 5.9 5.2

Miami 5/12 -- -- 5.2

Nehalem 5/8; 5/12 NA -- --

1967 Tillamook 2/19 -- -- 65.7

Trask 2/19 -- -- 65.7

Wilson 2/19 -- -- 65.7

Kilchis 2/19 -- -- 65.7

Miami 2/19 -- -- 65.7

Nehalem 2/19 -- -- 199.3

2005 Tillamook 7/17; 7/19 5.3 6.1 5.3

Trask 7/19–20 4.9 5.0 35.0

Wilson 7/19–20 5.1 5.3 45.1, 5.3

Kilchis 7/19 5.3 5.3 5.3

Miami 7/17; 7/19 5.3 6.1 5.3

Nehalem 7/17; 8/3 5.6 10.0 45.6, 10.0

2009 Tillamook 6/23; 6/27 5.1 5.5 5.1

Trask 6/27 -- --

3

5.0

Wilson 6/27 -- -- 5.1

Kilchis 6/27 -- -- 5.1

Miami 6/27 -- --

5

1.3

Nehalem 6/27 -- -- 9.5

1 1939 dates derived from photographs at USACE library

2 Discharge from USGS streamflow-gaging station 14301500 Wilson River near Tillamook, Oregon for 

the Miami, Kilchis, Wilson, Trask, and Tillamook Rivers; discharge from USGS streamflow-gaging 

station 14301000 Nehalem River near Foss, Oregon for the Nehalem River. 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. 

3Discharge from USGS streamflow-gaging station 14302480 Trask River above Cedar Creek

4 Areal coverage is approximately equal for both dates

5 Data from OWRD streamflow-gaging station Miami River near Garibaldi, Oregon
 

75

Distribution and Area of Bars, 2009 

In 2009, unit bar area, or the total area of 

bars per meter of channel length (m2/m), ranged 

from 7.1 to 27.9 m2/m in the fluvial reaches and 

0.7 to 262.0 m2

/m in the tidal reaches (table 17). 

Of the fluvial reaches, the Upper Fluvial Miami 

Reach had the greatest unit bar area (27.9 m2

/m). 

Of the tidal reaches, the Nehalem Tidal Reach 

had the greatest unit bar area (262.0 m2

/m), owing to extensive mud flats and tidal wetlands between RKM 9.6 and 3.0 where the floodplain 

widens to 2.9 km (fig. 15). The unit bar values 

on the Wilson, Miami, and Nehalem Rivers are 

similar to rivers along the southwestern Oregon 

coast, such as Hunter Creek and the Chetco River that drain the gravel-rich Klamath Mountains 

(table 18). 

In fluvial reaches, bar area was generally 

greatest where declining gradients and widening 

channels promoted the deposition of sediment 

received from the contributing watersheds or 

where channels were relatively unconfined 

throughout the fluvial reaches (fig. 24A–F). For 

instance, bar area peaked on the Tillamook River 

near RKM 12.0 and Trask River near RKM 14.0 

where the floodplains and active channels begin 

to widen, permitting sediment storage, and then 

generally diminished downstream (figs. 8, 10, 

and 24A–B). Similarly, bar area fluctuated longitudinally, but still increased considerably in relatively unconfined sections near RKM 10.0 on the 

Wilson River and RKM 10.0 and 4.0 on the Miami River. In contrast, bar area on the Kilchis 

and Nehalem Rivers peaked near or at the downstream boundary of the fluvial reaches, coinciding with the head of tide and channel gradient 

reductions. These distributions of bar area relate 

to the relation between transport capacity and 

sediment supply (as discussed below) and background drivers, such as valley confinement and 

channel gradient. 

Results for Repeat Bar and Channel Delineation, 

1939–2009 

Mapping of bars from aerial and orthophotographs dating from 1939 to 2009 shows that 

unit bar area decreased during this time period 

for all reaches except for tidal reaches on the 

Tillamook (98.0 percent increase) and Nehalem 

(14.7 percent increase) Rivers (table 17; fig. 25). 

In all other reaches, reductions in unit bar area 

ranged from 5.3 to 83.6 percent in fluvial reaches 

and 24.2 to 83.1 percent in tidal reaches. 

From 1939 to 2009, net changes in the number (fig. 25) and average area of mapped bars 

(table 17) varied by reach. Overall, bars became 

less numerous and smaller in average area in six 

reaches (Fluvial Tillamook, Fluvial and Tidal 

Trask, Tidal Wilson, and Lower Fluvial and Tidal Miami Reaches), less numerous but larger in 

average area in three reaches (Upper Fluvial 

Wilson, Tidal Kilchis, and Tidal Nehalem 

Reaches), and more numerous but smaller in average area in four reaches (Tidal Tillamook, 

Lower Fluvial Wilson, Lower Fluvial Miami, 

Fluvial Nehalem Reaches). The Fluvial Kilchis 

Reach was the only reach to maintain the same 

number of bars even though average area decreased from 1939 to 2009. 

Channel centerline length changed 1 percent 

or less in the Tidal Trask, Wilson, and Miami 

Reaches, Fluvial Kilchis Reach, and Nehalem 

River study area from 1939 to 2009 (table 19; 

fig. 25). Channel length decreased in the Fluvial 

Trask (4 percent; 390 m), Lower Fluvial Wilson 

(1.9 percent; 150 m), and Lower Fluvial Miami 

(1.4 percent; 110 m) Reaches and increased on 

the Tillamook River (2.3 percent or 90 m in the 

fluvial reach; 1.4 percent or 140 m in the tidal 

reach) and in the Upper Fluvial Wilson (1.2 percent; 30 m), Tidal Kilchis (1.1 percent; 30 m), 

and Upper Fluvial Miami (4.8 percent; 110 m) 

Reaches. Sections with substantial channel planform changes are discussed below.
 

76

Table 17. Repeat bar attribute data as delineated from photographs taken in 1939, 1967, 2005, and 2009 for the Tillamook, Trask, Wilson, Kilchis, 

Miami, and Nehalem Rivers, northwestern Oregon.

[m

2

/m, square meter of bar area per meter of channel length; m, meter; %, percent]

Unit bar area (m2/m) Number of bars Average bar area (m2)

River Reach 1939 1967 2005 2009

Net % 

change 1939 1967 2005 2009

Net % 

change 1939 1967 2005 2009

Net % 

change

Tillamook Fluvial 21.1 7.2 7.3 7.1 -66.4 21 14 25 17 -19.0 3,800 1,940 1,140 1,650 -56.6

Tidal 7.3 11.2 14.1 14.5 98.0 3 11 10 11 266.7 24,450 10,140 14,290 13,370 -45.3

Trask Fluvial 58.9 38.8 9.9 9.7 -83.6 46 22 44 41 -10.9 11,660 16,070 2,090 2,190 -81.2

Tidal 7.7 2.7 2.1 2.3 -70.4 17 8 5 7 -58.8 3,140 2,380 2,910 2,260 -28.0

Wilson Upper 

Fluvial

19.7 11.7 16.0 18.6 -5.3 15 8 14 12 -20.0 3,330 3,710 3,040 4,060 21.9

Lower 

Fluvial

52.2 27.3 12.6 12.6 -75.8 27 15 34 33 22.2 14,310 13,450 2,810 2,910 -79.7

Tidal 4.3 1.8 1.9 0.7 -83.1 11 4 10 7 -36.4 1,940 2,280 940 520 -73.2

Kilchis Fluvial 34.6 13.5 10.0 9.2 -73.4 28 15 31 28 0.0 6,170 4,500 1,650 1,680 -72.8

Tidal 13.0 7.4 8.2 9.9 -24.2 11 6 8 7 -36.4 3,130 3,260 2,730 3,780 20.8

Miami Upper 

Fluvial

54.6 9.0 18.9 27.9 -48.9 15 14 23 16 6.7 8,720 1,540 1,970 4,200 -51.8

Lower 

Fluvial

24.7 7.9 7.0 8.1 -67.3 69 34 45 50 -27.5 2,750 1,780 1,220 1,270 -53.8

Tidal 6.7 0.8 2.2 2.1 -69.5 10 2 6 4 -60.0 890 560 510 690 -22.5

Nehalem Fluvial 36.3 19.8 23.0 18.3 -49.8 29 14 38 39 34.5 8,690 9,470 4,240 3,220 -62.9

Tidal 228.3 195.8 203.9 262.0 14.7 53 34 43 44 -17.0 105,550 141,070 115,950 146,450 38.7
 

77

Table 18. Unit bar area data for predominantly fluvial reaches from this study and 

prior studies in select Oregon coastal rivers (Wallick and others, 2011; Jones and 

others, 2011, 2012a, 2012b).

[km2, square kilometer; m2/m, square meter of bar area per meter of channel length]

River/Creek

Basin area 

(km2)

Unit bar area for predominantly 

fluvial reaches

(m2/m) Source

Nehalem 2,207 18.3 This study

Miami 94 8.1 and 27.9 This study

Kilchis 169 9.2 This study

Wilson 500 12.6 and 18.6 This study

Trask 451 9.7 This study

Tillamook 156 7.1 This study

Umpqua112,103 5.0 to 17.6 Wallick and others (2011)

Coquille 2,745 0.4 to 12.6 Jones and others (2012b)

Rogue 13,390 10.6 to 63.1 Jones and others (2012a)

Applegate 1,994 4.3 and 71.5 Jones and others (2012a)

Illinois 2,564 91.8 Jones and others (2012a)

Hunter 44 19.1 and 19.7 Jones and others (2011)

Chetco1914 9.3 to 77.5 Wallick and others (2010)

1Bar area and channel length mapped from 2005 orthophotographs; all others mapped 

from 2009 orthophotographs

Fitzhugh Bar on the Chetco River, Upper Reach. 

Orchard Bar on the Rogue River, Lobster Creek 

Reach. 

Jones Bar on the Umpqua River, Coast Range Reach. 

Elliot Bar on the Coquille River, Broadbent Reach. 
 

78

Figure 24. Graphs showing bar area by river kilometer as delineated from orthophotographs taken in 2009 for 

study areas on the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. [RKM, 

river kilometer]
 

79

Figure 25. Graphs showing unit bar area, number of bars, channel centerline length, and average wetted channel width as delineated from photographs taken in 1939, 1967, 2005, and 2009 for study areas on the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern 

Oregon.
 

80

Table 19. Repeat channel feature data as delineated from photographs taken in 1939, 1967, 2005, and 2009 for 

the Tillamook, Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon.

Centerline length (meters) Average wetted channel width (meters)

River Reach 1939 1967 2005 2009

Net 

change

(percent) 1939 1967 2005 2009

Net 

change

(percent)

Tillamook Fluvial 3,870 3,790 3,940 3,960 2.3 15 18 13 14 -7.0

Tidal 9,980 9,990 10,130 10,120 1.4 62 54 46 46 -25.8

Trask Fluvial 9,700 9,100 9,300 9,310 -4.0 35 43 28 29 -17.1

Tidal 6,980 6,970 7,000 7,000 0.3 35 35 36 37 5.7

Wilson Upper 

Fluvial

2,580 2,540 2,650 2,610 1.2 34 46 30 32 -5.9

Lower 

Fluvial

7,740 7,400 7,600 7,590 -1.9 42 52 33 34 -19.0

Tidal 5,000 4,980 5,000 5,000 0 34 39 33 33 -2.9

Kilchis Fluvial 5,100 5,000 5,120 5,120 0.4 26 34 24 26 0

Tidal 2,650 2,640 2,670 2,680 1.1 21 24 20 20 -4.8

Miami Upper 

Fluvial

2,290 2,390 2,400 2,400 4.8 9 14 13 11 22.2

Lower 

Fluvial

7,970 7,660 7,830 7,860 -1.4 14 22 14 14 0

Tidal 1,360 1,330 1,350 1,350 -0.7 18 18 16 17 -5.6

Nehalem Fluvial 6,930 6,710 7,010 6,870 -0.9 50 68 44 51 2.0

Tidal 24,500 24,500 24,450 24,600 0.4 227 256 246 186 -18.1

From 1939 to 2009, changes in the average 

wetted width of the channels were less than 7 

percent in fluvial reaches on the Tillamook, Wilson (Upper Fluvial), Kilchis, Miami (Lower Fluvial), and Nehalem Rivers and tidal reaches on 

the Trask, Wilson, Kilchis, and Miami Rivers 

(table 19; fig. 25). In contrast, average wetted 

channel width decreased more than 17 percent in 

the Fluvial Trask (17.1 percent; 6 m), Lower 

Fluvial Wilson (19.0 percent; 8 m), Tidal Nehalem (18.1 percent; 41 m), and Tidal Tillamook 

(25.8 percent; 16 m) Reaches and increased by 

22.2 percent (2 m) in the Upper Fluvial Miami 

Reach. Although mapped wetted channel width 

is sensitive to the streamflow and tide conditions 

at the time photographs were taken, streamflow 

was comparable in 1939 and 2009 (table 16).

Consequently, some of the larger changes in average wetted channel width likely signify actual 

channel narrowing or widening in the fluvial 

reaches. A more detailed delineation of active 

channel width (instead of wetted channel width, 

which can be affected by small streamflow and 

stage differences) and accounting for streamflow 

and stage differences may help better quantify 

possible changes in channel width in relation to 

the area and number of bars for theses study areas. Accounting for possible tide differences may 

help in assessing channel width changes in tidal 

reaches. 

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

As outlined above and shown in the figures 

below, the Tillamook Bay rivers and the Nehalem River generally had extensive bed-material 

deposits flanking the channels in 1939, but diminished bed-material deposits in 2009 (with the 

exception of the Tidal Tillamook and Nehalem 

Reaches). Although any mapped bar and channel 

datasets inherently have some level of uncertainty and error, the magnitude of the reductions in 

bar area reported here and visual comparison of 

the aerial photographs suggest considerable declines in bar area from 1939 to 2009. Compari-
 

81

son of the mapping results and the four sets of 

photographs indicates that the reduction in bar 

area may be attributable to several factors, including vegetation establishment on bars that 

previously lacked apparent vegetation, lateral 

channel changes and resulting alterations in sediment deposition and erosion patterns, and 

streamflow and/or tide differences between photographs. Other factors that may be associated 

with the observed reduction in bar area but not 

assessed in this reconnaissance level study include changes in the sediment and hydrology 

regimes of these rivers over the analysis period. 

The following sections describe the mapped bar 

and channel changes from 1939 to 2009 by river 

and reach. 

Tillamook River

In the fluvial reach of the Tillamook River, 

unit bar area declined a net 66.4 percent from 

1939 to 2009 with the decline greatest from 1939 

to 1967 (table 17; fig. 25). Most of the net reduction in bar area, especially in the large lateral and 

point bars from RKM 14.1–11.8, owes to vegetation growth and subsequent stabilization of previously apparently unvegetated bars (such as 

near RKM 13.6 and 12.2; fig. 26A–C) and 

changes in the channel’s position and deposition 

patterns (such as from RKM 13.4–12.0). Upstream of RKM 11.4, the channel shifted laterally in several locations. For instance, the Tillamook River cut a new channel through a lateral 

bar, moving 65 m southward between RKM 13.0 

and 12.8. At RKM 11.6, the channel straightened 

and shifted 65 m southwestward. In addition, 

sinuosity increased from RKM 13.4 to12.0, resulting in a modest increase in channel centerline 

length (table 19). Downstream of RKM 11.6, the 

lateral stability of the channel over the analysis 

period probably results in part from confinement 

by the valley wall along the left channel bank 

near RKM 11.0 (fig. 26D–F). Overall, channel 

length increased modestly (2.3 percent), as did 

average wetted width (7 percent) over the analysis period (table 19).

In the Tidal Tillamook Reach, unit bar area 

increased by approximately 4 m2/m from 1939 to 

1967 and 3 m2/m from 1967 to 2005, and then 

remained relatively stable from 2005 to 2009 

(table 17; fig. 25). The overall net increase of 

98.0 percent in unit bar area from 1939 to 2009 

is associated with an increase in mapped bar area 

in the reach’s lowermost 1.8 km (fig. 27A–C). 

Differences in bar area here may owe to possible 

tidal differences between photographs and the 

formation and growth of bars behind log booms 

and piles between 1939 and 1967 (such as from 

RKM 7.2 to 6.8; fig. 27D–F). During the analysis period, the channel’s average wetted width 

narrowed 25.8 percent or 16 m (table 19). Some 

of the reduction in average wetted channel width 

is attributable to a medial bar near the Tillamook 

River mouth, which had grown in size by 2009. 

Reductions in wetted width may also owe to 

deposition behind piles and log booms from 

1939 to 1967 and the occurrence of features likely composed of fine sediment flanking the tidal 

channel apparent in the 1967, 2005, and 2009 

photographs (fig. 27A–F). The stability of the 

channel’s position from 1939 to 2009 is attributable to levees and bank protection, which border 

approximately 77 percent of the banks in this 

reach (table 6).

Trask River 

In 1939, the Fluvial Trask Reach had the 

highest unit bar area value of the fluvial reaches 

(58.9 m2/m; table 17). From 1939 to 2009, however, the net reach unit bar area decreased by 

83.6 percent (fig. 25), with substantial reductions 

in unit bar area from 1939 to 1967 and 1967 to 

2005 followed by relatively little change from 

2005 to 2009. Most of the apparent changes from 

1939 to 1967 were the result of greater streamflows in 1967 (table 16) and glare along the 

channel, both of which obscure bars in the 1967 

photographs (table 16). The reduced unit bar area 

after 1967 owes to changes in channel position 

(and thus erosional and depositional spaces) and 
 

82

Figure 26. Images showing repeat bar and channel delineations in two sections (river kilometers 13.6–11.4 and 11.6–10.0) of the Fluvial Tillamook 

Reach, northwestern Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally formed levees reinforced with nonerodible materials (source: Oregon Coastal Management Program, 2011). 
 

83

Figure 27. Images showing repeat bar and channel delineations near the Tillamook River mouth (river kilometer 

1.2–0) and pile structures and log booms (river kilometer 7.6–6.6) in the Tidal Tillamook Reach, northwestern Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally formed levees reinforced 

with nonerodible materials (source: Oregon Coastal Management Program, 2011). 

vegetation growth, and stabilization of bar surfaces, such as near RKM 15.2–14.0 (fig. 28A–D) 

and 13.0–11.8 (fig. 28A–H). Over the analysis 

period, the lateral position of channel shifted 

throughout the reach. For instance, the channel 

moved approximately 100 m southward (measured as the distance between 1939 and 2009 centerlines; fig. 28A–D) from RKM 15.4 to 14.1 

and approximately 160 m from RKM 12.8 to 

11.8 to cut a straight path through two large bars 

(fig. 28E–H). The losses of sinuosity at these locations as well as at RKM 10.4–9.2 are partly 

responsible for the 4.0 percent (390 m) reduction 

in channel centerline length (table 19). Over the 

analysis period, the average wetted width of the 

channel declined 17.1 percent (6 m; table 19) and 

is noticeably narrower in locations, such as near 

RKM 15.6–15.0, in 2009 (fig. 28A–D).

Downstream in the Tidal Trask Reach, unit 

bar area declined a net 70.4 percent with most of 

those reductions occurring from 1939 to 1967 

(table 17; fig. 25). Overall, the reductions in bar 

area owe to several factors, including possible 

tide and streamflow differences between photo
 

84

Figure 28. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar surfaces, and lateral channel migrations in two sections (river kilometers 15.6–14.0 and 13.0–11.8) of the Fluvial 

Trask Reach, northwestern Oregon. 

graphs, vegetation growth on previously unvegetated bars (such as near RKM 6.6 in figure 29A–

C, and RKM 5.2), and vegetation growth combined with floodplain modifications (such as 

near RKM 2.8–2.6 in figure 29D–F). The channel changed little in position (less than 18 m) and 

its length and average wetted width experienced 

relatively minor changes from 1939 to 2009 (table 19), likely because approximately 71 percent 

of banks have some modifications (table 6). 

Wilson River 

Of all the fluvial reaches, the Upper Fluvial 

Wilson Reach had the smallest net reduction (5.3 
 

85

Figure 29. Images showing repeat bar and channel delineations and vegetation growth and stabilization of bar 

surfaces in two sections (river kilometers 7.0–6.6 and 3.0–2.6) of the Tidal Trask Reach, northwestern Oregon. 

Floodplain modifications identified in the map include dikes, levees, and naturally formed levees reinforced with 

nonerodible materials (source: Oregon Coastal Management Program, 2011). 

percent) in unit bar area with bar distributions 

remaining fairly stable from 1939 to 2009 (table 

17; fig. 25). Over this period, bar area increased 

slightly from RKM 14.0–13.8, but declined near 

RKM 13.4 owing to less apparent bar scour at 

1:2,000 (fig. 30A–C). The narrow and confined 

geometry of the upper reach likely influences 

sediment deposition at the upstream extent of the 

Mills Bridge Bar as well as the location and area 

of bars over time (fig. 30A–C). The photographs 

indicate that most of the bar loss from 1939 to 

1967 resulted from vegetation growth, glare in 

the 1967 photographs obscuring some of the 

channel, and higher streamflows in 1967 (table 

16). As expected in this confined reach, the 

channel in the Upper Fluvial Wilson Reach 

maintained a stable position (with shifts less than 

32 m), although it slightly lengthened and narrowed (table 19; fig. 25).
 

86

Figure 30. Images showing repeat bar and channel delineations from river kilometer 14.0 to 13.4 in the Upper 

Fluvial Wilson Reach, northwestern Oregon. 

In the Lower Fluvial Wilson Reach, unit bar 

area declined a net 75.8 percent over 1939–2009, 

mostly from 1939 to 2005 (table 17; fig. 25). 

Channel migration (RKM 11.0–8.6 and 8.0–7.0), 

sediment deposition and erosion changes, and 

vegetation establishment likely explain most of 

the net reduction in unit bar area. For example, 

the channel shifted approximately 225 m northwestward, eroding a lateral bar, to occupy a high 

flow channel near Upper and Lower Donaldson 

Bars (RKM 10.6–10.0; fig. 31A–C). The channel 

also shifted approximately 210 m into a high 

flow channel on the north side of a lateral bar 

near RKM 9.4–8.6 (fig. 31A–C). Since 1939, 

large lateral and point bars in this section have 

diminished owing to factors like vegetation 

growth (RKM 10.6–10.0 and 9–8.6) and floodplain modifications (RKM 10.0–9.2). Additionally, the channel migrated near RKM 8.2 between the GLO surveys of the 1850s and 1939 

aerial photographs (Coulton and others, 1996). 

At RKM 7.8–7.0, the channel contained large 

lateral and medial bars in 1939 (fig. 32A–C). In 

2009, this same section of the Wilson River has 

several floodplain modifications, reduced sinuosity, smaller lateral and point bars, and vegetation 

establishment on formerly active bars. Vegetation establishment explains most of the reduction 

in bar area where the channel was stable over the 

analysis period. The channel experienced a 1.9 

percent (150 m) reduction in channel length and 

a 19.0 percent (8 m) reduction in average wetted 

width (table 19).
 

87

Figure 31. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar 

surfaces, and channel migrations from river kilometer 10.6 to 8.2 in the Lower Fluvial Wilson Reach, 

northwestern Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally 

formed levees reinforced with nonerodible materials (source: Oregon Coastal Management Program, 

2011).
 

88

Figure 32. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar surfaces, and channel simplification from river kilometer 8.0–6.4 in the Lower Fluvial Wilson Reach, northwestern 

Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally formed levees reinforced with nonerodible materials (source: Oregon Coastal Management Program, 2011). 

The Tidal Wilson Reach had the lowest unit 

bar area in 1939 (4.3 m2/m), which further declined a net 83.1 percent from 1939 to 2009 (table 17; fig. 25). Like the other Wilson River 

reaches, net reductions in unit bar area are associated with vegetation establishment and subsequent stabilization of bar surfaces (such as near 

RKM 4.8 and 4.2; fig. 33A–C). Also, some of 

the bar surfaces delineated from the 1939 photographs were mapped as part of the wetted channel in 2009 (such as near RKM 4.6–3.8; fig. 

33A–C), indicating potential erosion of these 

surfaces as streamflows were similar during photograph acquisition (table 16). Owing to floodplain modifications that line 77 percent of the 

tidal channel (table 6), the channel was primarily 

stable from 1939 to 2009, with lateral changes in 

position generally less than 40 m, no detectable 

changes in centerline length, and minor narrowing (table 19). 

Kilchis River 

The fluvial reach of the Kilchis River experienced a net 73.4 percent loss in unit bar area 

(table 17; fig. 25). This reduction is attributable 

to vegetation stabilizing bar surfaces (such as 
 

89

Figure 33. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar surfaces, and other changes from river kilometer 5.0 to 3.6 in the Tidal Wilson Reach, northwestern Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally formed levees reinforced with nonerodible materials (source: Oregon Coastal Management Program, 2011). 

near RKM 7.4–6.8, 6.2–5.0, and 4.0–2.7; figs. 

34A–C and 35A–C) and channel planform 

changes and associated effects on depositional 

and erosional patterns (such as near RKM 6.4–

6.0; RKM 3.4–2.7). A few of the 1939 bars coincide with the wetted channel mapped in 2009 

near RKM 7.0, 6.8, and 5.0 (fig. 34A–C), indicating possible erosion of these bars. Over the 

analysis period, the Kilchis River channel migrated more than 50 m at three places (RKM 

6.4–6.0, 5.8–5.2; RKM 3.4–2.7). In particular, 

the channel moved approximately 120 m south 
 

90

and straightened from RKM 6.4–6.0, resulting in 

the loss of a large point bar near RKM 6.2. The 

Kilchis River near RKM 6.2 is slightly downstream of where GLO surveyors noted a change 

in channel planform from 1857 to 1884 (near 

RKM 6.5, as described above), indicating that 

this location has been persistently dynamic. As 

shown in figures 34A–C and 35A–C, the channel 

contains smaller and narrower lateral and point 

bars in 2009 compared to 1939. The Kilchis River channel otherwise maintained a stable position 

with no detectable change in average wetted 

width and a minor increase in channel length (table 19).

Figure 34. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar surfaces, and channel migrations from river kilometer 6.4 to 4.8 in the Fluvial Kilchis Reach, northwestern Oregon.
 

91

Figure 35. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar surfaces, and channel migrations from river kilometer 4.0 to 2.8 in the Fluvial Kilchis Reach, northwestern Oregon. 

Floodplain modifications identified in the map include dikes, levees, and naturally formed levees reinforced with 

nonerodible materials (source: Oregon Coastal Management Program, 2011). 

Of the tidal reaches, the Tidal Kilchis Reach 

had the second highest unit bar area in 1939 and 

third highest in 2009 (13.0 and 9.9 m2/m, respectively; table 17). This tidal reach also had the 

lowest net reduction in unit bar area of the tidal 

reaches (24.2 percent loss compared to losses of 

69.5 to 83.1 percent in other tidal reaches; table 

17). In 1939 and 2009, bar area was greatest 

from RKM 2.9–1.8 near of the head of tide (fig. 

36A–C). As shown in figure 36A–C, riparian 

vegetation was less prominent in 1939 compared 

to 2009. By 2009, vegetation had established 

successfully on the large lateral bar on the south 

bank. Channel sinuosity increased slightly from 

RKM 2.4–2.0, likely because of sediment deposition on the north bank upstream of RKM 2.2. 

Otherwise, the Tidal Kilchis Reach had a relatively stable planform, a small increase in channel length, and some narrowing in the average 

wetted channel width (table 19).

Miami River 

In the Upper Fluvial Miami Reach, unit bar 

area declined a net 48.9 percent over the analysis 

period, with the declines primarily occurring 

from 1939 to 1967 followed by increases from 

1967 to 2009 (table 17). The initial reduction in 

bar area apparently resulted from increased vegetation growth on the bar surfaces that were exposed in 1939 and some channel planform 

changes (fig. 37A–F). In later years, the area of 

bars increased throughout the reach, particularly 

from RKM 11.6–10.2, owing to the erosion of 

vegetation surfaces and an apparent increase in 

the area of the active channel area. Over the 

analysis period, the channel shifted its lateral 
 

92

Figure 36. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar surfaces, and channel migrations from river kilometer 2.6 to 1.8 in the Tidal Kilchis Reach, northwestern Oregon. 

Floodplain modifications identified in the map include dikes, levees, and naturally formed levees reinforced with 

nonerodible materials (source: Oregon Coastal Management Program, 2011). 

position throughout the reach and increased by 

110 m in length (table 19). Average wetted 

channel width increased 22.2 percent or 2 m 

from 1939 to 2009, which is probably within the 

range of uncertainty associated with rectifying 

and digitizing from historical aerial photographs 

(table 19).

In the Lower Miami Fluvial Reach, unit bar 

area declined a net 67.3 percent from 1939 to 

2009 with the greatest loss occurring from 1939 

to 1967 and minor fluctuations in mapped unit 

bar area from 1967 to 2009 (table 17). Throughout the reach, bars that were apparently unvegetated in 1939 had established vegetation by 1967, 

and remained largely vegetated in 2009, resulting 

in a substantial loss in mapped bar area (figs. 

38A–C and 39A–C). Additionally, some of the 

reductions in bar area owe to channel migration 

and resulting changes in depositional and erosional patterns, such as at RKM 7.4. Over the 

analysis period, the channel shifted laterally in 

the relatively unconfined sections throughout the 

reach; most shifts were generally less than 170 m 

between aerial photographs used in this study. 

Although some planform changes increased sinuosity, some changes straightened segments, 

such as near RKM 8.0–7.2 and 2.4–2.2, and may 

explain the modest reduction (1.4 percent or 110 

m) in channel centerline length (table 19). No net 

changes were detected in average wetted width 

(table 19).

Like the other reaches on the Miami River, 

the Tidal Miami Reach exhibited a net reduction 

(69.5 percent) in unit bar area from 1939 to 

2009, primarily from 1939 to 1967 (table 17). 

Unit bar area increased from 0.8 to 2.2 m2

/m 

from 1967 to 2005, and then remained relatively 

stable from 2005 to 2009. The overall reduction 

in unit bar area from 1939 to 2009 is attributed to 

vegetation establishment on formerly unvegetated bars like near RKM 1.2, 0.8, and 0.1 and 

some lateral channel shifts like near RKM 1.1 

and 0.7 (fig. 40A–C). Upstream of RKM 0.5 

where the Miami River is unconfined by floodplain modifications, the channel shifted (generally less than 40 m) in several locations, but 
 

93

Figure 37. Images showing repeat bar and channel delineations, channel migrations, and vegetation changes 

from river kilometer 11.6 to 10.2 in the Upper Fluvial Miami Reach, northwestern Oregon. 
 

94

Figure 38. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar surfaces, and channel migrations from river kilometer 8.4 to 6.4 in the Lower Fluvial Miami Reach, northwestern Oregon. 
 

95

Figure 39. Images showing repeat bar and channel delineations and vegetation growth and stabilization of bar 

surfaces from river kilometer 5.4 to 3.8 in the Lower Fluvial Miami Reach, northwestern Oregon. 

Measurement transect at Lower Waldron Bar Surface of Lower Waldron Bar within measurement transect 
 

96

Figure 40. Images showing repeat bar and channel delineations and vegetation growth and stabilization of bar 

surfaces from RKM 1.4 to 0 in the Tidal Miami Reach, northwestern Oregon. Floodplain modifications identified in 

the map include dikes, levees, and naturally formed levees reinforced with nonerodible materials based on Oregon Coastal Management Program (2011). [RKM, river kilometer] 

changed little in terms of centerline length (net 

0.7 percent or 10 m reduction) and average wetted width over the analysis period (net 5.6 percent or 1 m reduction; table 19).

Nehalem River 

The mapping results for the Fluvial Nehalem 

Reach indicated that unit bar area declined 45.6 

percent from 1939 to 1967 and then fluctuated 

from 1967 to 2009, resulting in a net unit bar area reduction of 49.8 percent from 1939 to 2009 

(table 17). Nearly two–thirds of the net loss in 

bar area occurred from RKM 26.6–24.6, which is 

a broad unconfined segment of the floodplain 

where the channel transitions from fluvially to 

tidally influenced (figs. 14, and 41A–C). This 
 

97

Figure 41. Images showing repeat bar and channel delineations, vegetation growth and stabilization of bar surfaces, and channel migrations from RKM 26.4 to 24.8 in the Fluvial Nehalem Reach, northwestern Oregon. [RKM, 

river kilometer] 

reduction is attributable to the lateral channel 

migration between 1939 and 1967 and subsequent vegetation establishment. The channel 

moved over 150 m south from RKM 26.2 to 

25.6, eroding into a large lateral bar on the south 

bank, and about 90 m north from RKM 25.6 to 

25.0, eroding into a large point bar on the north 

bank. Upstream of RKM 26.6, bar area also diminished from 1939 to 2009 as vegetation established on bars that were apparently unvegetated 

in 1939 (such as near RKM 30.2, 28.0, and 27.2–

26.6) or bars mapped in 1939 were eroded or underwater in 2009 (such as near RKM 29.8 and 

27.6; fig. 42A–C). The position of the channel 

was relatively stable with lateral changes of less 

than 35 m in this upper section. Overall, the 

channel changed little in length or width from 

1939 to 2009 in this reach (table 19).
 

98

Figure 42. Images showing repeat bar and channel delineations and stable channel planform from RKM 31.4 

to 28.6 in the Fluvial Nehalem Reach, northwestern Oregon. [RKM, river kilometer] 

Downstream in the Tidal Nehalem Reach, 

unit bar area increased a net 14.7 percent from 

1939 to 2009 despite a small decrease from 1939 

to 1967 (table 17). This increase in unit bar area 

occurred within the Nehalem Bay (RKM 9.6–0) 

as more tidal mud flats and bars were mapped in 

2009 relative to 1939 (fig. 43A–C). Most of 

these mapping differences likely owe to tide differences between photographs because the general outlines of the large mud flats mapped in 

2009 are visible but submerged in the 1939. Despite the overall increase in bar area over the 

analysis period, bar area declined a net 17 percent from RKM 24.6–19.2 (fig. 44A–C). Vegetation establishment on formerly unvegetated bar 

surfaces (such as near RKM 24.2 and 22.8) and, 

to a lesser extent, other factors like bar erosion or 

differences in streamflow and/or tide (such as 

near RKM 24.8, 22.8, and 22) explain most of 

this reduction in bar area. Over the analysis period, the position of the channel was relatively 

stable except for lateral movements as much as 

140 m from RKM 21.6–20.4 and 195 m from 

RKM 6.6–2.2 (fig. 43A–C). Channel width narrowed 18.1 percent (41 m) between 1967 and 

2009 (table 19).

River Sections Near Instream Gravel Mining Sites 

Bar and channel trends near segments with 

instream gravel mining are similar to the overall 

trends for most of the fluvial reaches. Near most 

sites, lateral migration and vegetation establishment appear to have resulted in decreased bar 

area and slightly less sinuous channels. 

On the Trask River, lateral channel migration resulted in a straighter channel near Bush 

Bar at RKM 12.2 (fig. 28E–H). This section had 

three large channel-flanking bars and three 

smaller lateral bars in 1939, encompassing an 

area of 48,900 m2. By 2009, this section contained five much smaller bars with a total 1,900 

m

2

flanking a much straighter channel.
 

99

Figure 43. Images showing repeat bar and channel delineations from RKM 10.0 to 3.0 in the Tidal Nehalem 

Reach, northwestern Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally 

formed levees reinforced with nonerodible materials based on Oregon Coastal Management Program (2011). 

[RKM, river kilometer] 

On the Wilson River, lateral channel migration has significantly affected the geometry and 

area of Upper and Lower Donaldson Bars (RKM 

10.4 and 10.0, respectively; fig. 31A–C). By 

1967, the channel cut a new path through the 

mapped 1939 bar, splitting this large bar into 

multiple ones. These multiple bars became increasingly vegetated over the analysis period; the 

main vegetated surface is now south and west of 

the current location of Lower Donaldson Bar 

(fig. 31A–C). The area of bars mapped from 

RKM 10.5–9.8 declined from approximately 

45,670 m2in 1939 to 23,970 m2in 2009. 

Downstream, near Barker and Tannler Bars 

(RKM 8.0–6.4; fig. 32A–C), the Wilson River 

had eight bars mapped in 1939 totaling 100,390 

m

2

in area, but only six bars mapped in 2009 totaling 12,860 m2 in area. This reach of the Wilson River is constrained by levees, which have 

probably inhibited bar growth. Slightly downstream at Tannler Bar (RKM 6.6; fig. 32A–C), 

which was sampled by Stinson and Stinson 

(1998), the bar remained in the same location, 

but diminished from approximately 9,000 to 

5,000 m2, owing to apparent vegetation growth. 

On the Kilchis River (fig. 34A–C), repeat 

mapping shows channel planform changes, side 

channel loss, and vegetation establishment near 

Crusher (RKM 5.8), Upper Landolt (RKM 5.3) 

and Averill Bars (RKM 2.9). All of these historical mining were sampled by Stinson and Stinson 

(1998). From RKM 6.4–5.0, the extensive gravel 

deposits mapped in 1939 were reduced to much 

narrower surfaces in 2009, with total mapped bar 

area declining from 76,700 to 14,600 m2

over the 

analysis period. Similarly, near Averill Bar at 

RKM 2.9, bar area and side channel losses are 

evident over 1939–2009 (fig. 35A–C). Near 

Gomes Bar (historically known as Lower Landolt Bar; RKM 4.8), however, the channel has
 

100

Figure 44. Images showing repeat bar and channel delineations and planform changes from RKM 24.2 to 19.2 in 

the Tidal Nehalem Reach, northwestern Oregon. Floodplain modifications identified in the map include dikes, levees, and naturally formed levees reinforced with non-erodible materials based on Oregon Coastal Management 

Program (2011). [RKM, river kilometer] 

been stable and bar area has slightly increased 

from about 5,000 to 6,000 m2(fig. 34A–C). 

On the Miami River, sections near active 

and historical mining sites generally show channel planform changes, vegetation establishment 

on formerly unvegetated surfaces, and a reduction in bar area. Gravel has been mined from at 

least two historical sites (Upper and Middle 

Lower Waldron Bars at RKM 4.8 and 4.6) and 

one historical and active site (Lower Waldron 

Bar at RKM 4.8; fig. 39A–C). Bars became 

smaller in extent and vegetated in some locations 

while channel planform changed in several locations over the analysis period. In this section, the 

total area of mapped bars was approximately 

26,800 m2in 1939 and 14,200 m2in 2009. 
 

101

On the Nehalem River, gravel has been 

mined from Plant and Winslow Bars (RKM 25.8 

and 24.8, respectively; fig. 41A–C). Owing to 

channel migrations, the location of Plant Bar has 

moved from the south to the north bank of the 

Nehalem River. Over the analysis period, the area of Plant Bar has declined from approximately 

51,600 to 18,600 m2. Although Winslow Bar has 

not changed in location, this bar also diminished 

from approximately 84,200 to 18,900 m2between 1939 and 2009. Losses in bar area at both 

sites appear to be related to a combination of bar 

erosion and vegetation establishment. 

Because trends in the number and area of 

bars and channel planform mirror overall trends, 

particularly in the overall reduction in bar area, it 

is unclear how these changes may specifically 

relate to gravel mining activities. Even in the absence of gravel mining, unconfined fluvial sections of the Trask, Wilson, Kilchis, Miami, and 

Nehalem Rivers are likely dynamic with active 

building and erosion of bars in conjunction with 

lateral channel migration over time. Changes in 

gravel volumes as a result of mining activities, 

however, likely have some local effects on channel behavior and bar geometry, although documenting such effects would require more detailed site-specific studies and a comprehensive 

understanding of the flow and sediment regimes 

of these rivers and their interactions with human 

modifications of the floodplain and gravel mining. 

Analyses of Bed-Material Particle Sizes 

In October 2010, we measured the distributions of surface particle sizes at nine bars, and 

collected subsurface bulk samples for five of 

these bars along the Trask, Wilson, Kilchis, Miami, and Nehalem Rivers (table 20). These bars 

were selected based on bar size, accessibility, 

and condition (such as little to no vehicle disturbance). To maintain consistency with previous 

bed-material studies along the Oregon coast 

(Wallick and others, 2010; 2011; Jones and others, 2011, 2012a, and 2012b), we collected bedmaterial data at point or lateral bars likely 

formed by recent deposition events as indicated 

by the absence or minimal coverage of vegetation. 

At these bars, we measured 200 surface particles using a modified grid technique (Kondolf 

and others, 2003) and gravelometer measurement 

template (Federal Interagency Sediment Project 

US SAH–97 Gravelometer), which allows for 

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 to 2 m apart and parallel to the 

long axis of the bar. To support consistent intersite comparisons, measurement transects were 

located at the bar apex (defined as the topographic high point along the upstream end of the bar) 

when possible. Measurements at the Bush Bar 

were collected at the upstream end of the bar in 

an area relatively undisturbed by recent gravel 

mining. Measurements at all other active instream mining sites were made before gravel 

mining activities began for the season. 

Subsurface bed material was also sampled at 

five bars to evaluate differences in particle sizes 

between surface and subsurface bed material (a 

measure of bar “armoring”). We removed approximately 1 m2

of bar-surface material, and 

then collected 59 to 67 kg of subsurface material. 

Bulk samples then were dried and analyzed for 

1⁄2-phi particle sizes by the U.S. Geological Survey Sediment Laboratory in Vancouver, Washington. 

The median diameter (D50) of surface particles was generally coarsest (surface D50 greater 

than 64.0 mm) at Bruck, Bush, and Batterson 

Bars in the upper fluvial reaches of the Kilchis, 

Trask, and Nehalem Rivers, respectively (table 

20; fig. 45A–H). The Lower Waldron Bar on the 

Miami River and Mills Bridge and Lower Donaldson Bars on the Wilson River had median surface particles ranging from 37.8 to 48.5 mm in 

diameter. Median bar surface material was 32.0 

mm or less in diameter at Clear Creek and 
 

102

102

Table 20. Bed-material data collected at sampling sites along the Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon.

[RKM, river kilometer; D16, 16th percentile diameter in millimeters (mm); D50, median diameter in mm; D84, 84th percentile diameter in mm]

Site information Easting 

(meters)

Northing

(meters)

Surface particles Subsurface particles Armoring 

River Reach Bar1 Site Type Location D16 D50 D84 D16 D50 D84 ratio

Trask Fluvial Bush Active or 

recent mining

RKM 12.2 439,721 5,031,982 35.9 68.4 108.7 1.0 12.5 40.2 5.5

Wilson Upper 

Fluvial

Mills Bridge Control RKM 13.8 442,264 5,035,716 20.7 45.0 85.0 -- -- -- --

Lower 

Fluvial

Lower Donaldson Historical 

mining

RKM 10 439,103 5,035,845 14.8 48.5 81.5 0.7 16.8 56.0 2.9

Kilchis -- Clear Creek Historical 

mining

2.8 km upstream 

of study area

438,682 5,042,560 11.0 32.0 71.7 -- -- -- --

-- Bruck Historical 

mining

0.6 km upstream 

of study area

437,329 5,041,495 36.5 84.6 146.7 -- -- -- --

Fluvial Gomes Active or 

recent mining

RKM 4.8 435,078 5,040,118 14.9 29.4 55.5 1.1 10.5 33.6 2.8

Miami Lower 

Fluvial

Lower WaldronActive or 

recent mining

RKM 4.3 432,045 5,048,425 18.7 37.8 78.2 4.4 23.8 53.6 1.6

Nehalem Fluvial Batterson Control RKM 31.2 440,329 5,060,849 53.0 104.1 167.5 -- -- -- --

Fluvial Winslow Active or 

recent mining

RKM 24.8 435,481 5,060,392 14.7 23.6 35.5 0.6 9.6 23.9 2.4

1 Bar names were assigned based on features on USGS quadrangle maps (such as nearby tributaries), mining permits, or nearby locations
 

103

Figure 45. Graphs showing distributions of surface and subsurface particle sizes for bed-material sampling sites 

along the Trask, Wilson, Kilchis, Miami, and Nehalem Rivers, northwestern Oregon. Surface size distributions 

were determined by measuring 200 clasts; subsurface size distributions were determined from a bulk sample taken below the armor layer. Locations for Bruck and Clear Creek Bars on the Kilchis River are approximated. 

Gomes Bars on the Kilchis River and Winslow 

Bar on the Nehalem River. For the Kilchis, Wilson, and Nehalem Rivers where surface particle 

measurements were made at two or more bars, 

bar surface particles diminished in size along the 

Nehalem River, increased in size between Mills 

Bridge and Lower Donaldson Bars on the Wilson River, and fluctuated in size between the 

three Kilchis River bars. Stinson and Stinson 

(1998) reported that sites in the Wilson, Kilchis, 

and Miami River basins were dominated by particles ranging from 19 to 76 mm in diameter (or 

pebbles and cobbles), which is comparable to 

these results (fig. 45C–D). 

Differences in surface and subsurface particle sizes can be related to the balance between 

sediment supply and transport capacity, or the 
 

104

ability of the river to move sediment, which is 

largely determined by discharge and slope. When 

a river’s transport capacity exceeds its supply of 

sediment, the surface layer of bars is generally 

coarser than subsurface layers because finer 

clasts on the bar surface are selectively transported downstream (Dietrich and others, 1989; 

Lisle, 1995; Buffington and Montgomery, 1999). 

The degree of coarsening, or armoring, of the bar 

surface can be assessed with the armoring ratio, 

or the ratio of the median grain sizes (D50) for 

the surface and subsurface layers. This ratio is 

typically close to 1 (meaning surface and subsurface particles are of similar sizes) for rivers with 

a high sediment supply, and approaches or exceeds 2 for supply-limited rivers with large 

transport capacity (Bunte and Abt, 2001). Armoring ratios were lowest at Lower Waldron Bar 

on the Miami River (1.6) and greatest at Bush 

Bar on the Trask River (5.5; table 20; fig. 45). 

The large armoring ratio at Bush Bar may owe to 

measurement collection at a relatively undisturbed location toward the head of the bar, which 

may be coarser than the bar apex where measurements were typically taken at other sites. The 

armoring ratio of 1.6 at Lower Waldron Bar tentatively indicates a relative balance between 

transport capacity and sediment supply. Armoring ratios ranged from 2.4 to 2.9 at Gomes, Lower Donaldson, and Winslow Bars on the Kilchis, 

Wilson, and Nehalem Rivers, respectively, and 

indicate possible sediment supply limitation at 

these sites. 

Armoring ratios reported by this and previous USGS bed-material studies along the Oregon 

coast vary considerably (table 21). As evident 

from these previous studies and as summarized 

by Wilcock and others (2009), bar texture can 

vary tremendously between sites on gravel-bed 

rivers. Additional bed-material measurements, 

especially at unmined bars, would help refine 

assessments of transport and sediment-supply 

conditions and longitudinal bed-material trends 

for these rivers.

Table 21. Armoring ratios reported from this and prior bed-material studies 

by the U.S. Geological Survey in select Oregon coastal rivers from north 

to south.

[--, no data collected]

River/Creek

Armoring 

ratio(s)

number

of sites Source

Nehalem 2.4 1 This study

Miami 1.6 1 This study

Kilchis 2.8 1 This study

Wilson 2.9 1 This study

Trask 5.5 1 This study

Umpqua 0.99–4.73 30 Wallick and others (2011)

South Fork Coquille 3.5 1 Jones and others (2012b)

Rogue 1.2–3.4 7 Jones and others (2012a)

Applegate 1.2 1 Jones and others (2012a)

Hunter 0.97–1.5 2 Jones and others (2011)

Chetco 1.38–2.09 3 Wallick and others (2010)
 

105

Discussion and Synthesis

On the basis of a literature review, field observations, topographic analysis and delineation 

of bars and channels from available photograph 

coverages, we defined six study areas on the 

Tillamook, Trask, Wilson, Kilchis, Miami, and 

Nehalem Rivers that in total make up over 96 km 

of channel. Within the study areas, the channels 

flow predominately over alluvial deposits (as 

well as intermittent bedrock outcrops in the Upper Wilson and Nehalem Fluvial Reaches), and 

through confined and unconfined segments. Tide 

affects varying lengths of these rivers, ranging 

from approximately 1.3 km on the Miami River 

to 24.6 km on the Nehalem River (table 1). 

Within these six study areas, our analysis in conjunction with previous studies allow for a broad 

synthesis of channel and floodplain characteristics as well as overall transport conditions. 

Spatial Variation in Bar Conditions 

Like other Oregon coastal basins, such as 

the Umpqua River (Wallick and others, 2011), 

Rogue River (Jones and others, 2012a), Coquille 

River (Jones and others, 2012b), and Hunter 

Creek (Jones and others, 2011), valley and channel confinement and gradient influence channel 

morphology and bed-material transport in the 

Tillamook Bay subbasins and Nehalem River 

basin. In their upper sections, the rivers are confined by their valleys and have relatively steep 

gradients. As rivers enter the focal areas of this 

study, channels and valleys widen and their gradients decline, promoting deposition of coarse 

sediment within the active channels. Subsequent 

gradient reductions in the tidal reaches further 

promote the deposition of primarily fine sediment. Valley confinement often exerts some lateral control on channel planform within the fluvial study areas, such as on the Tillamook (RKM 

11.6–10.0; fig. 26D–F), Wilson (Upper Fluvial, 

RKM 14.0–13.4; fig. 30A–C), Miami (Lower 

Fluvial, RKM 5.4–3.8; fig. 39A–C), and Nehalem (RKM 31.4–28.6; fig. 42A–C) Rivers. Additionally, floodplain modifications restrict the 

width and position of most of the tidal channels 

(table 1) that would otherwise probably be considerably wider, have numerous side channels 

and sloughs, and prone to lateral migration. 

Basin geology also exerts considerable control on channel morphology and bed-material 

transport in these six basins, particularly the varying proportions of Coast Range sedimentary 

and volcanic rocks (table 2; figs. 1 and 2). The 

soft rocks of the Coast Range sedimentary subdivision dominates most of the Tillamook River 

basin, leading to few bars along this river except 

for between RKM 12.0–13.0 (fig. 24A), which is 

downstream of several tributaries draining the 

much harder volcanic rocks. Bar area in the fluvial reaches on the Trask, Wilson, Miami, and 

Kilchis Rivers is greatest downstream of areas 

with Coast Range volcanic rocks, and then diminishes as the proportion of tributaries draining 

Coast Range sedimentary rocks increases, such 

as downstream of approximately RKM 13.0, 8.0, 

2.6, and 8.0 on the Trask, Wilson, Kilchis, and 

Miami Rivers, respectively (figs. 1 and 24B–E). 

The abundance of gravel bars within the Fluvial 

Nehalem Reach (fig. 24F) owes in part to the 

increased proportion of the Coast Range volcanic 

rocks within the fluvial reach and in larger tributaries, such as Cronin and Cook Creeks and the 

Salmonberry River that join the mainstem slightly upstream of the study area (fig. 2). In contrast, 

channels in the tidal reaches cut through Quaternary deposits and have tributaries that primarily 

drain Coast Range sedimentary rocks (figs. 1 and 

2).

Based on the 2009 mapping for the fluvial 

reaches, unit bar area was greatest in the upper 

fluvial reaches of the Wilson and Miami Rivers 

and the Nehalem Fluvial Reach (table 17; fig. 

24C, E, F). For all of these reaches, local valley 

widening and declines in channel gradient are 

probably important factors promoting bed material deposition and bar formation. The Fluvial 

Nehalem Reach has the greatest reported mining 

volumes (table 12; fig. 16G–H). Other reaches 

with considerable reported mining include the 

Lower Fluvial Wilson and Fluvial Kilchis 
 

106

Reaches (table 12; fig. 16B–C). Unit bar area 

was lowest in the Fluvial Tillamook and Lower 

Fluvial Miami Reaches (figs. 17 and 25), owing 

likely to the large percentage of Coast Range 

sedimentary rocks in the drainages contributing 

to these areas (table 8). 

In the tidal reaches, however, gradients are 

generally much lower (0.0001 to 0.0013 m/m; 

table 8; fig. 9), preventing substantial transport 

of gravel-sized bed material. Generally, tidal 

reaches have fewer mapped bars than the fluvial 

reaches except near the mouths of the Tillamook, 

Trask, and Nehalem Rivers (fig. 24A, B, F). 

Bedload, and consequently most bed material, in 

these reaches is predominately sand and finersized particles, much of which was transported 

as suspended load from upstream, steeper sections. Some large bars like those in the Tidal 

Tillamook and Nehalem Reaches (fig. 24A,F) 

are largely composed of this finer material. 

Temporal Trends in Bar and Channel 

Conditions 

Channel and valley physiography, hydrology, and geology largely explain the observed 

spatial patterns in the accumulation and texture 

of bed material. Interpretations of bar temporal 

trends, however, are more ambiguous and vary 

by reach. These interpretations are also influenced by varying climate and hydrologic conditions, natural disturbances like fire and mass 

wasting that are affected by humans, and complex and locally intense land use practices like 

floodplain modifications and sand and gravel 

mining. 

In the 1939 photographs, extensive sediment 

deposits are apparent in the fluvial reaches of all 

rivers except the Tillamook River (figs. 26A–F, 

28A–H, 30A–C, 31A–C, 32A–C, 34A–C, 35A–

C, 37A–F, 38A–C, 39A–C, 41A–C, 42A–C).

Previous reports, such as those by Coulton and 

others (1996), Tillamook Bay National Estuary 

Project (1998), Pearson (2002), Komar and others (2004), and Ferdun (2010), suggested the 

Tillamook Burn is the likely source of this sediment. Some sediment in the 1939 photographs 

was probably associated with the first of the 

Tillamook Burn fires, which in August 1933 

burned the largest area, including portions of the 

Trask, Wilson, Kilchis, Miami and Nehalem 

River basins (Oregon State Department of 

Forestry, 1983; Johnson and Maser, 1999; 

Tillamook County, 2010). This fire was followed 

by a flood on December 21, 1933 that exceeded 

a 10-year event on the Wilson River (14301500; 

fig. 5B) and likely delivered considerable sediment to downstream channels. 

Although these fires almost certainly contributed to the large areas of bars mapped from 

the 1939 photographs, other factors may also be 

important. For instance, other Oregon coastal 

rivers unaffected by the Tillamook Burn or similar fires, such as the Chetco and Umpqua Rivers 

have reduced bar areas since 1939, owing to 

long-term decreases in flood magnitude (Wallick 

and others 2010; 2011). Similarly, reconnaissance level studies have documented reductions 

in mapped bar area from 1939 to 2009 in the 

Hunter Creek and Coquille River basins (Jones 

and others, 2011; Jones and others 2012b). Because of the apparent consistent reduction in bar 

area for studied Oregon coastal rivers, other factors in addition to the Tillamook Burn may explain the large bar areas mapped by this study 

from the 1939 photographs. 

Bar areas mapped from the 1967, 2005, and 

2009 photographs along the fluvial reaches were 

generally less than those mapped from 1939 photographs, corresponding to net declines in unit 

bar area for all fluvial reaches (table 17; fig. 25). 

Similarly, Pearson (2002) reported net reductions 

in bar area for the Kilchis (51 percent reduction; 

approximately RKM 7.7 to 0.6 km downstream 

of RKM 0), Wilson (57 percent reduction; approximately RKM 13.1 to 0.1 km downstream of 

RKM 0), and Trask (35 percent reduction; approximately RKM 13.4–0) Rivers from 1939 to 

1990. In our study, however, two exceptions to 

this general reduction trend were the Upper Fluvial Wilson and Miami Reaches. In these steeper, 

more confined reaches, unit bar area substantial-
 

107

ly declined between 1939 and 1967, but then increased considerably, although not to 1939 values, by 2009. 

Although the basin and channel response to 

the Tillamook Burn may be a key factor affecting temporal trends in sediment supply, other 

factors are probably also important, including 

channel planform changes and related alterations 

in sediment deposition and erosion patterns, vegetation establishment on bars that previously 

lacked apparent vegetation, and streamflow 

and/or tide differences between photographs. 

Other important factors not addressed in this preliminary study may include potential changes in 

the rivers’ hydrologic regimes from 1939 to 

2009, which directly affects sediment transport 

capacity and vegetation establishment on bar surfaces, changes in the occurrence and volume of 

large wood, debris flows, and mass movements. 

Multiple lines of evidence indicate that all 

fluvial reaches have the potential for some local 

vertical and lateral channel adjustments in response to changes in streamflow, sediment, and 

possibly riparian vegetation. Our review of repeat channel cross sections near bridges in the 

study areas indicates few systematic trends, but 

evidence of local incision and aggradation up to 

2.0 m (table 14; figs. 17–22). For example, the 

thalweg of the Tillamook and Miami Rivers incised locally 0.5 m or more from 1999 to 2004 

and 1996 to 2004, respectively, whereas the 

thalweg of the Wilson River aggraded locally 

more than 2.0 m from 1996 to 2004 (table 14).

Similarly, the specific gage analyses show channel-elevation fluctuations of as much as 0.3 m on 

the Wilson and Nehalem Rivers, mainly in conjunction with high flows, but with no apparent 

systematic long-term trend (fig. 23). Similarly, 

Pearson (2002) reported general aggradation 

with localized bed lowering from 1978 to 2000 

in the lower fluvial and tidal reaches on the 

Trask, Wilson, Kilchis, and Miami Rivers. 

Likewise, all fluvial reaches have sections 

with potential for lateral movement and width 

changes as indicated by the repeat bar and channel mapping (fig. 24; Tillamook, fig. 26A–C; 

Trask, fig. 28A–H; Wilson, figs. 31A–C and 

32A–C; Kilchis, figs. 34A–C and 35A–C; Miami, figs. 37A–F and 38A–C; Nehalem, fig. 

41A–C). Historical accounts noted channel migration on the Wilson and Kilchis Rivers (Coulton and others, 1996). Previous studies have 

documented localized channel width changes on 

the Trask, Wilson, and Kilchis Rivers 

(Follansbee and Stark, 1998a; Snyder and others, 

2003; Reckendorf, 2006; Duck Creek 

Associates, 2008; Reckendorf, 2008a, b). To 

date, however, determining systematic changes 

in channel width from previous studies is challenging owing to varying aerial photographs 

used in analyses, mapped channel attributes 

(such as active channel width or channel area), 

and focal areas for analysis (longer or shorter 

reaches or a mixture of tidal and fluvial sections). Detailed analyses incorporating additional 

aerial photographs would enable identifying systematic morphologic changes along these rivers. 

In the tidal reaches, mapped bar areas also 

generally declined over 1939–2009 with the exception of net increases on the Tillamook and 

Nehalem Rivers (fig. 17). The subsequent decline in bar area resulted in part from stabilization by vegetation establishment. Other factors 

controlling mapped bar area in the tidal reaches 

include lateral channel changes and resulting alterations in sediment deposition and erosion patterns, and streamflow and/or tide differences between photographs. Net increases in the Tidal 

Tillamook and Nehalem Reaches are probably 

attributable to tide differences on both rivers and 

sediment deposition behind pilings on the Tillamook River. 

Over the analysis period, all tidal reaches 

had relatively stable planforms with lateral channel movements generally less than 40 m from 

1939 to 2009 (Tillamook, fig. 27A–F; Trask, fig. 

29A–F; Wilson, fig. 33A–C; Kilchis, fig. 36A–

C; Miami, fig. 40A–C). The exception is the 

Tidal Nehalem Reach where the channel migrated laterally approximately 140 m between RKM 

21.6–20.4 (fig. 44A–C) and 195 m between 
 

108

RKM 6.6–2.2 (partially shown in fig. 43A–C). 

The lateral stability of most of the tidal reaches 

owes largely to floodplain levees and dikes that 

stabilize the channel margins in the Tillamook 

Bay area (table 6; figs. 8 and 10–13) and floodplain modifications and valley confinement in 

the Tidal Nehalem Reach (fig. 15). As suggested 

by Pearson (2002), floodplain modifications may 

prevent the Tillamook Bay rivers from mobilizing sediment stored in streamside areas and the 

floodplain during high flow events. 

Although the tidal reaches are largely stable 

laterally, repeat channel cross-sections indicate 

that these reaches have some potential for vertical adjustments (table 14). In some tidal reaches, 

channels locally aggraded and incised 0.5 m or 

more on the Tillamook and Trask Rivers (figs. 

17B–D and 18A–B), incised 0.5 m or more on 

the Kilchis and Miami Rivers (figs. 20D and 

21C), and aggraded 0.5 m or more on the Nehalem River (fig. 22A–B). 

General Bed-Material Transport Conditions 

Our observations of the spatial and temporal 

characteristics of the reaches support preliminary 

interpretations of current overall bed-material 

transport conditions. On the basis of mapping 

results (table 18; fig. 24A–F) and armoring ratios 

(table 20), fluvial reaches within this study’s focal areas on the Tillamook, Trask, Kilchis, and 

Nehalem Rivers are likely sediment supplylimited in terms of bed material—that is the 

transport capacity of the channel generally exceeds the supply of bed material. Further studies 

would be needed to assess the relation between 

transport capacity and sediment supply outside 

of the study areas, such as at Bruck Bar, upstream of the study area on the Kilchis River. On 

the Tillamook and Trask Rivers, sediment is deposited and stored as gravel bars primarily within short sections where the channels transition 

from relatively confined to unconfined. Elsewhere, however, bar area is comparatively sparse 

in these reaches (fig. 24A, B). For the Tillamook 

River, low gravel supply likely owes chiefly to 

the preponderance of sedimentary rocks in the 

basin. For the Trask River, high transport capacity through the fluvial reach owes to the relatively 

steep channel gradient and narrow valley (table 

8). These preliminary observations of sediment 

supply limitation are consistent with the repeat 

cross sections measurements indicating bed lowering at two locations in the Fluvial Tillamook 

Reach (RKM 11.5 and 8.8; table 14) and the 

high armoring ratio at the Bush Bar in the Fluvial Trask Reach (RKM 5.5; table 20). 

In the fluvial reaches of the Kilchis and Nehalem Rivers, bars are most abundant where gradient declines near the head of tide (fig. 24D, F), 

indicating excess transport capacity in the upstream fluvial reaches. Results suggest the 

Kilchis River study area is sediment supplylimited, owing to its relatively steep gradient. 

Similarly, Pearson (2002) reported that the 

Kilchis River is likely supply-limited in its lower 

7.7 km. Above the study area, the relation between transport capacity and sediment supply 

may vary. For instance, Stinson and Stinson 

(1998) suggested that the Kilchis River probably 

has a large sediment supply that may exceed 

transport capacity, as evidenced by a gravel plug 

forming at Bruck Bar in 1996. In-channel bedrock outcrops within and along the Nehalem 

River indicates excess transport capacity. Consistent with these preliminary conclusions of sediment supply limitation for the Fluvial Kilchis 

and Nehalem Reaches are the armoring ratios 

that exceed 2.0 at Gomes Bar on the Kilchis River and Winslow Bar on the Nehalem River (table 

20).

Preliminary relations between transport capacity and sediment supply are more ambiguous 

for the fluvial reaches on the Wilson and Miami 

Rivers. In this study, the Upper Fluvial Wilson 

Reach had the lowest decline in unit bar area (5.3 

percent; table 17) and a modest 0.4 m of net aggradation at RKM 14.1 from 1939 to 2009 (table 

14; fig. 19A). Although these changes may indicate that sediment supply balances or slightly 

exceeds transport capacity in this reach, the presence of bedrock exposures, such as between 

Mills Bridge and slightly upstream of Mills 
 

109

Bridge Bar, indicates there are still areas where 

transport capacity exceeds sediment supply. Additional bed-material data collection and evaluation of armoring ratios would help assess the relation between transport capacity and sediment 

supply in the Upper Fluvial Wilson Reach. Similarly, the Lower Fluvial Wilson Reach had a 

relatively high armoring ratio (2.9; table 20), indicating sediment supply limitation at this site. 

However, the repeat cross sections at RKM 6.3 

indicate local deposition of 2.1 m in the thalweg 

from 1996 to 2004 (table 14; fig. 19B), indicating that sediment supply may locally exceed 

transport capacity in this reach, such as near 

RKM 6.3. Although Pearson (2002) suggested 

that sediment loads on the lower 13.1 km of the 

Wilson River might be declining to pre-fire levels, extending the streamflow record back to 

1900 would be useful to assess the relative effects of the Tillamook Burn and antecedent peak 

flows on bed-material accumulations on the Wilson River. 

On the Miami River, unit bar area increased 

in 2005 and 2009 despite initial reductions from 

1939 to 1967 (table 17). This increase may indicate some level of active sediment supply to the 

reach in more recent years. Our tentative conclusion regarding bed-material supply is that the 

reach has a sediment supply that may balance or 

slightly exceed the transport capacity. Downstream, the Lower Fluvial Miami Reach has an 

armoring ratio of 1.6 (table 20), which tentatively indicates a relative balance between transport 

capacity and sediment supply at Lower Waldron 

Bar. The thalweg, however, incised 0.6 m from 

1996 to 2004 at RKM 8.5 and 2.7 (table 14; fig. 

21A–B), indicating transport capacity exceeds 

sediment supply at these locations. Pearson 

(2002) noted that the lower 3.2 km of the Miami 

River is transport limited. Future studies that collect additional bed-material measurements at undisturbed sites and collect bedload samples or 

estimate bed-material fluxes would be useful for 

understanding the relation between transport capacity and sediment supply in the fluvial reaches 

of the Miami River. 

The tidal reaches on the Tillamook, Trask, 

Wilson, Kilchis, and Nehalem Rivers are all 

transport limited because of their exceedingly 

low gradients (0.0001 to 0.0007 m/m; table 8) 

and tidal influence. Transport conditions in the 

Tidal Reach Miami may be less limited owing to 

its gradient (0.0013 m/m; table 8), which is the 

greatest of all the tidal reaches. Bed material is 

primarily sand and finer-grain materials in the 

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

and transport of fine sediment. 

The six rivers have likely had substantially 

varying rates of gravel transport over time. The 

long tidal reaches on the Tillamook, Trask, and 

Nehalem Rivers (7.0–24.6 km) reflect Holocene 

sea-level rise and consequent drowning of the 

river valleys at rates faster than they are filling 

with coarse (sand and gravel) bed material. This 

difference between sea-level rise and coarse sediment flux suggests that these rivers have 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. By contrast, the shorter tidal 

reaches of the Wilson, Kilchis, and Miami Rivers (1.3 to 5.0 km; table 1) and the presence of 

gravel bars to approximately the mouths of 

Kilchis and Miami Rivers (fig. 24D,E) indicate 

that coarse bed-material deposition has probably 

matched rates of Holocene sea-level rise. 

Judging from the more abundant, extensive, 

and largely unvegetated bars evident in the 1939 

photographs, most or all of the fluvial reaches 

were likely transport limited at that time. As described above, this probably resulted from multiple, overlapping factors, such as enhanced sediment supply from fires prior to timber cruises in 

1908 (as described in Coulton and others, 1996) 

and the Tillamook Burn (Coulton and others, 

1996; Tillamook Bay National Estuary Project, 

1998; Pearson, 2002; Komar and others, 2004; 

Ferdun, 2010) as well as possibly from more frequent large floods that maintained active bar sur-
 

110

faces and limited vegetation establishment. As 

these areas have revegetated and sediment supply has diminished with reforestation, transport 

and supply conditions have possibly balanced 

about a state of fewer and smaller bars. Some 

reaches have likely evolved to having transport 

capacity conditions that at least locally exceed 

bed-material supply. Such temporal variations in 

bed-material transport conditions are probably 

not uncommon in these coastal watersheds where 

major disturbances like fire and mass wasting 

events are probably important natural processes

introducing sediment into the rivers. 

Outstanding Issues and Possible 

Approaches

This reconnaissance level analysis provides 

a framework and baseline information for understanding bed-material transport in the Tillamook 

Bay subbasins and Nehalem River basin. Future 

analyses 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 of interest. Such information would provide a solid basis 

for evaluating future hydrologic and geomorphic 

changes in these basins. 

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 a thorough 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. Assess bed-material composition 

throughout the study areas, focusing on 

unmined sites. Additional measurements 

of particle size would be required for 

calculating bed-material transport and 

may support assessments of temporal 

changes in bed-material composition in 

conjunction with other study components. 

2. Assess mass-wasting contributions to 

bed-material flux. In several of these 

drainage basins, landslides may be a significant factor in delivering bed material 

to the channels (Reckendorf, 2008), and 

their distribution may be strongly related 

to land use, geology, and natural disturbance processes. 

3. Supplement the existing streamflowgaging network. Modeling and predicting bed-material transport require high 

quality streamflow information, particularly for peak flows. As of 2011, no 

streamflow-gaging station is operated on 

the Kilchis or Tillamook Rivers. Such 

hydrologic data would be required by 

most approaches to quantify sediment 

supplied to the Fluvial Kilchis and 

Tillamook Reaches. The most accurate 

approach for obtaining such data would 

be to expand the gaging station network 

to include sites on these rivers as well as 

tributaries probably delivering considerable amounts of gravel like the Little 

North Fork Wilson River in the Wilson 

basin and Cook Creek and Salmonberry 

River in the Nehalem basin. Mean daily 

flow data measured at 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 applied in Wallick and 

O’Connor (2011). An operational gage 

would be the optimal location for sampling bedload and later estimating sediment flux in the Kilchis and Tillamook 

River basins and other tributary basins of 

interest. An alternative approach, with 
 

111

lower costs but greater uncertainties, 

would be to apply regional regression 

equations to estimate discharge for a 

range of flow events for specific locations. 

4. Estimate sediment flux based upon equations of bedload transport, as conducted 

by Wallick and others (2010, 2011) on 

the Chetco and Umpqua Rivers. This 

approach could be used with most confidence in reaches where bed-material 

transport is likely transport-limited, such 

as for the fluvial reaches on the Wilson 

and Miami Rivers. 

5. Estimate sediment flux for a reach of interest by developing a hydraulic model 

in conjunction with systematic measurements of bed-material size, as conducted in the Chetco River analysis 

(Wallick and others, 2010). Existing LiDAR coverages available for all study 

areas and streamflow measurements at

the USGS streamflow-gaging stations on 

the Trask, Wilson, and Nehalem Rivers 

and OWRD streamflow-gaging station 

on the Miami River would support the 

development of such models. 

6. Collect direct measurements of bedload 

transport in order to verify equations for 

bedload transport and estimate actual 

bedload fluxes. Possible locations for 

bedload measurements are Bewley 

Creek Bridge on the Tillamook River 

(RKM 11.5), Long Prairie Road Bridge 

on the Trask River (RKM 11.6), Sollie 

Smith and Kansas Creek Road Bridges 

on the Wilson River (RKM 6.3 and approximately 7.8 km above the study area, respectively), Curl Road Bridge on 

the Kilchis River (RKM 4.2), Moss 

Creek Road Bridge on the Miami River 

(RKM 2.7), and Miami Foley Road 

Bridge on the Nehalem River (RKM 

22.4). Ideally, such measurements would 

be collected at a site of continuous 

streamflow measurement, such as the 

USGS gaging stations on the Trask 

(Long Prairie Road Bridge, RKM 11.6) 

and Wilson (Sollie Smith Bridge provided a streamflow recorder was added to 

the station, RKM 6.3) Rivers and the 

OWRD streamflow gaging station on the 

Miami River (Moss Creek Road Bridge, 

RKM 2.7). Bedload measurements on 

the Wilson and Nehalem Rivers would 

be more difficult, where cableways are 

employed for most streamflow measurements at the existing gages. The 

nearest bridge to the Wilson River gage 

is the tall and high traffic load Mills 

Bridge (RKM 14.1), whereas the nearest 

bridge to the Nehalem gage is Cook 

Creek Bridge (about 2.6 km upstream of 

gage) where the channel flows predominately on bedrock. 

7. Estimate sediment flux based on mapped 

changes in bar area over specific temporal intervals following the morphological approach applied on the Chetco River (Wallick and others, 2010). Ideally, 

this approach would use LiDAR or other 

high-resolution topographic data from 

two periods to calculate volumetric 

change in sediment storage. This method, however, can also be implemented 

using a single LiDAR survey and sequential aerial photographs. This approach is best applied in reaches where 

bed-material transport is likely transportlimited. 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 long-term changes in channel and floodplain conditions. 

This approach would be most feasible 

for the Wilson and Miami fluvial reaches 

as well as all tidal reaches. 

8. Apply empirical GIS-based sediment 

yield analyses, factoring in sediment 

production, delivery to channels, and in-
 

112

channel attrition. This approach would 

be similar to that applied for the 

Umpqua River basin (Wallick and others, 2011). Although this type of analysis 

could focus on specific reaches regardless of transport or sediment supply limited conditions, 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 of 

bed-material delivered to these rivers. 

9. Review pre- and post-gravel-mining surveys. The review conducted for this 

study indicates that these surveys can 

provide limited quantitative information 

on bed-material deposition (table 12). 

Nevertheless, this information, especially if supplemented by additional records, 

may be helpful for constraining estimated sediment budgets (Wallick and others, 2011). 

10. Coordinate bed-material analyses with 

ongoing suspended sediment and turbidity data collection on the Wilson and 

Trask Rivers by the USGS Oregon Water Science Center to determine rates of 

sediment inputs to the Tillamook Bay. 

Detailed Channel Morphology Assessment 

In this study, we delineated bar surfaces 

from aerial and orthophotographs spanning 1939 

to 2009 for the six study areas and found that 

unit bar area declined in all fluvial reaches (table 

17). These datasets and measurements could 

serve as the starting point for more detailed and 

comprehensive analyses of sediment transport 

processes and morphological trends in these six 

basins. An approach that would meet these objectives would include the following elements: 

1. Detailed mapping of land cover for multiple periods, including delineation of the 

active floodplain, active channel width, 

and floodplain features based on vegetation density. Examining changes in bare 

and vegetated surfaces for smaller time 

steps would support a quantitative assessment of channel geometry, migration 

rates, erosion and deposition processes, 

and vegetation establishment. With this 

information, we could better describe 

bed-material processes and associated 

interactions with factors like floods and 

vegetation, and identify key temporal 

changes in bar area patterns. Many aerial 

photographs are available for such as effort, including those taken in 1951, 

1954, 1965, 1970, 1989, 1994, 2000, and 

2011 for the Tillamook Bay study areas 

(table 9) and in 1951, 1954–55, 1960, 

1965, 1970, 1980, 1989, 1994, 2000, 

2001, and 2011 for the Nehalem study 

area (table 10). This effort would also 

support a reliable and consistent assessment of channel changes over time. 

2. Detailed mapping of channel features before and after major floods to assess the 

response of the channel to different 

magnitude floods and, ultimately, sediment flux and channel evolution in the 

six study areas. Possible floods for focusing this effort include at least one on 

the Trask River (1996; fig. 5A), several 

on the Wilson River (such as those in 

1964, 1972, 1975, 1977, 1989, 1996, 

1998, 2006, and 2007; fig. 5B), several 

on the Miami River (such as those in 

1977, 1983, 1986, 1990, 1994, and 2008; 

fig. 5C), and several on the Nehalem 

River (such as those in 1949, 1955, 

1964, 1966, 1972, 1974, 1990, 1996, 

2006, and 2007; fig. 5D). 

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 (Wallick and others 

2010, 2011). Based on the long-term 

streamflow records on the Wilson and 
 

113

Nehalem Rivers, however, decreases in 

bar area do not appear to be correlated 

with a reduction in peak flows (fig. 5B, 

D). Other possible factors, in addition to 

those likely related to local fire history, 

include changes in the type and volume 

of instream large wood as well as changes in riparian vegetation conditions. Further characterization of hydrology patterns in the Tillamook Bay subbasins 

and Nehalem River basin and possible 

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. 

4. Investigation of bed-elevation changes 

near gages and bridges. Modern channel 

surveys could be compared to historical 

surveys, such as cross sections at USGS 

gages and cableways, flood-study surveys, and more detailed analyses of repeat cross sections near bridges to more 

systematically document spatial and 

temporal changes in bed elevation. For 

instance, USGS collects cross sections at

gaging stations near Long Prairie Road 

and Sollie Smith Bridges on the Trask 

and Wilson River, respectively, which 

may be useful for assessing channel 

changes at the Long Prairie Road Bridge 

(currently lacks cross section data; table 

14) and Sollie Smith Bridge (table 14; 

fig. 19b). Following Turnipseed and 

Sauer (2010), more detailed specific 

gage analyses can also be completed using USGS stage and streamflow data 

collected from 1984 to 2012. These 

analyses would be useful for assessing 

changes in the stage-streamflow relation 

and channel morphology near USGS 

gages with a greater temporal frequency 

(such as a seasonal basis or intermediately following flood events). 

5. Investigations of bed-elevation changes 

using bathymetry. Bathymetric surveys 

of the tidal and fluvial reaches would be 

useful for assessing vertical channel stability and assessing possible changes in 

bed elevation related to sediment deposition and reductions in flood capacity. 

Such analyses would complement detailed mapping of channel and floodplain 

characteristics to provide insights on factors controlling observed changes. 

Properly conducted and archived, such 

modern surveys could also serve as a basis for long-term monitoring of vertical 

channel conditions. 

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 and 

natural disturbances influenced by human activities such as fires and mass wasting have likely 

affected sediment transport and deposition dynamics in the study areas. Quantitatively assessing the past and present effects of these factors on sediment dynamics would be challenging 

owing to likely interactions among these factors 

as well as their interactions with background, 

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. Extend streamflow record to 1900 for the 

long-term Wilson River gage and other 

gages of interest (table 3). This information in combination with bedload 

transport equations may be useful for assessing flow and bed-material transport 
 

114

prior to the Tillamook Burn fires and the 

relations between those fires and antecedent streamflows and the large area of 

bars mapped in 1939. 

2. Assess land use and hydrologic conditions and relate to transport capacity and 

sediment supply in key basins of interest. 

3. 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. 

4. Assess changes in bar area and channel 

position near historical instream gravel 

mining sites with a detailed geomorphic 

analysis. 

Priority Reaches for Future Analysis 

In this study, we mapped and assessed overall patterns in bar and channel conditions for a 

total of 65 km in the six study basins. Addressing 

all the data gaps and analyses outlined above is 

probably not practical in the near future for all 

six study areas. Specific rivers, however, might 

particularly warrant additional analysis because 

of overall geomorphic conditions and ongoing 

and possible future disturbance activities. 

Fluvial study areas on the Wilson, Kilchis, 

Miami, and Nehalem Rivers may be logical 

analysis areas thereby providing detailed data on 

coarse sediment fluxes and channel dynamics for 

these ecologically important river segments. Additionally, these fluvial study areas have the 

highest reported deposition and mining volumes 

for bed material. These study areas are likely responsive to upstream basin disturbances as a result of their relatively low gradients. Although 

the 1939 photographs do not extend above approximately RKM 7.8 on the Kilchis River, extending the study area further upstream by approximately 1 km would be useful for assessing 

changes near the historically mined Bruck and 

Bay City Bars (table 13). Likewise, future efforts 

may consider extending the Wilson River study 

area upstream to include the area near Sylvan 

Creek. 

The tidally affected portions of the study areas may also be logical reaches for in-depth 

analysis. In these reaches, the issues would pertain more to fine sediment deposition and 

transport (and associated channel and riparian 

conditions and processes) rather than coarse bed 

material. Since the legacy of landuse effects in 

these basins have probably significantly affected 

fine sediment transport and deposition, the 

transport-limited character of these reaches 

makes them responsive to perturbations in sediment loads and river flow. Additionally, local 

flood issues and the ecological importance of 

these tidal reaches may justify additional investigation. 

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. Dennis Johnson of Coastwide 

Ready-Mix and Brian Mohler of Mohler Sand 

and Gravel, LLC provided copies of site surveys. 

These gravel mining operators and other landowners graciously granted access to instream 

gravel mining sites. Christy Leas, Oregon Department of State Lands, coordinated access to 

the gravel mining permits files housed at the Oregon Department of State Lands. The University 

of Oregon Map Library provided a summary of 

aerial photographs available for the study areas. 

Paul Pedone, National Resources Conservation 

Service, assisted with data collection and provided a copy of Stinson and Stinson (1998). Richard 

Marvin from Oregon Water Resources Department provided data for the Miami gaging station. 

Frank Reckendorf, Reckendorf and Associates, 

provided copies of several reports on gravel mining in the Tillamook Bay subbasins. 
 

115

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