Preliminary Assessment of Channel Stability and Bed-Material 

Transport along Hunter Creek, Southwestern Oregon

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

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

of State Lands 

Open-File Report 2011–1160

U.S. Department of the Interior 

U.S. Geological Survey 
Cover: Gravel bar on Hunter Creek (Photograph by Joseph Mangano, U.S. Geological Survey) 
Prepared in cooperation with the U.S. Army Corps of Engineers and 

the Oregon Department of State Lands 

Preliminary Assessment of Channel Stability and Bed-Material 

Transport along Hunter Creek, Southwestern Oregon

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

Open-File Report 2011–1160

U.S. Department of the Interior 

U.S. Geological Survey 
ii

U.S. Department of the Interior 

KEN SALAZAR, Secretary 

U.S. Geological Survey 

Marcia K. McNutt, Director 

U.S. Geological Survey, Reston, Virginia 2011 

For product and ordering information: 

World Wide Web: http://www.usgs.gov/pubprod

Telephone: 1-888-ASK-USGS 

For more information on the USGS—the Federal source for science about the Earth, 

its natural and living resources, natural hazards, and the environment: 

World Wide Web: http://www.usgs.gov

Telephone: 1-888-ASK-USGS Suggested citation: 

Jones, K.L, Wallick, J.R., O’Connor, J.E., Keith, M.K., Mangano, J.F., and Risley, J.C., 2011, Preliminary assessment of channel stability and bed-material transport along Hunter Creek, southwestern Oregon: U.S. Geological 

Survey Open-File Report 2011–1160, 41 p. 

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

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

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

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

Location References ...................................................................................................................................................... 3

Physical Characteristics of the Hunter Creek Basin ....................................................................................................... 3

Geographic, Geologic, and Geomorphic Setting ........................................................................................................ 3

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

Land Uses in the Basin .................................................................................................................................................. 9

Study Area................................................................................................................................................................... 11

Approach and Key Findings ......................................................................................................................................... 13

Review of Previous Hydrologic and Geomorphic Studies ........................................................................................ 13

Assessment of Existing Spatial Datasets ................................................................................................................. 13

Review of Gravel-Operator Information and Surveys ............................................................................................... 16

Compilation and Review of Bridge-Inspection Reports ............................................................................................ 20

Repeat Delineation of Gravel Bars, Channel Centerlines, and Channel Width, 1940–2009 .................................... 22

Results for Repeat Bar Delineation, 1940–2009 ................................................................................................... 23

Results for Channel Planform and Width, 1940–2009 .......................................................................................... 30

Bed-Material Particle-Size Analyses ........................................................................................................................ 31

Summary of Findings ................................................................................................................................................... 35

Outstanding Issues and Possible Approaches ............................................................................................................. 36

Hunter Creek Streamflow ......................................................................................................................................... 37

Bed-Material Transport Rates and Sediment Budget ............................................................................................... 37

Detailed Channel-Morphology Assessment ............................................................................................................. 38

Legacy and Ongoing Effects of Land-Use Activities ................................................................................................. 39

Acknowledgments ........................................................................................................................................................ 40

References Cited ......................................................................................................................................................... 40

Figures

Figure 1. Map of the Hunter Creek basin, southwestern Oregon. ...............................................................................4

Figure 2. Diagram showing longitudinal profiles for the Hunter Creek basin, southwestern Oregon, and the study 

area, with locations of sediment-sampling sites and bridges denoted. ........................................................................5

Figure 3. Diagram showing gravel bars and wetted channel as delineated for the study reaches on Hunter Creek, 

southwestern Oregon, in 1940, 1965, 2005, and 2009. ...............................................................................................7

Figure 4. Graph showing partial-volume estimates of gravel extracted 1966–2010 from Hunter Creek, southwestern 

Oregon .......................................................................................................................................................................17

Figure 5. Diagram showing repeat channel cross-sections collected by Oregon Department of Transportation at 

Hunter Creek Road crossings at river kilometer (RKM) 9.1, RKM 3.5, and RKM 0.6, as well as the Highway 101 

bridge crossing at RKM 0. ..........................................................................................................................................21
iv

Figure 6. Graphs showing the distribution and size of gravel-bar accumulations and wetted-channel width by river 

kilometer transect as mapped from 1940, 1965, 2005, and 2009 aerial photographs for the Hunter Creek study area, 

southwestern Oregon. ................................................................................................................................................25

Figure 7. Photographs showing examples of gravel bars and wetted channel edge as delineated from 1940, 1965, 

2005, and 2009 aerial photographs for river-kilometer transects 6–8, where the active channel is confined in the 

Hunter Creek study area, southwestern Oregon. .......................................................................................................26

Figure 8. Photographs showing examples of gravel bars and wetted channel edge as delineated from 1940, 1965, 

2005, and 2009 aerial photographs for river kilometers 1–3, where the active channel is unconfined in the Hunter 

Creek study area, southwestern Oregon. ..................................................................................................................27

Figure 9. Graph showing bar area for the two study reaches and study area as delineated from aerial photographs 

dated 1940, 1965, 2005, and 2009 for Hunter Creek, southwestern Oregon,. ...........................................................28

Figure 10. Photographs showing gravel bars and wetted channel edge as delineated from 1940, 1965, 2005, and 

2009 aerial photographs for the mouth of Hunter Creek, southwestern Oregon. The lower 2.2 kilometers of Hunter 

Creek are tidally influenced. .......................................................................................................................................29

Figure 11. Photographs showing examples of gravel bars and wetted channel edge as delineated from 1940, 1965, 

2005, and 2009 aerial photographs for sections where the Hunter Creek Road has impinged on the historical active 

channel in the Hunter Creek study area, southwestern Oregon. ................................................................................31

Figure 12. Photographs showing gravel bars as delineated from 1940, 1965, 2005, and 2009 aerial photographs for 

Menasha Bar (river kilometer [RKM] 4.1), Ringer Bar (RKM 4.7), and Conn Creek Bar (RKM 9.7) along Hunter 

Creek, southwestern Oregon. ....................................................................................................................................32

Figure 13. Photographs of the bed-material-sampling sites at Conn Creek (A–B) and Menasha (C–D) Bars along 

Hunter Creek, southwestern Oregon. ........................................................................................................................33

Figure 14. Graph showing size distributions of surface and subsurface particles collected in July 2010 at two sites 

along Hunter Creek, southwestern Oregon. ...............................................................................................................34

Tables

Table 1. Estimated peak flows at sites in the Hunter Creek basin, southwestern Oregon. ..........................................8

Table 2. Peak-flow characteristics at U.S. Geological Survey streamflow sites within or near the Hunter Creek basin, 

southwestern Oregon. ................................................................................................................................................10

Table 3. Summary of characteristics for the study reaches in the Hunter Creek basin, southwestern Oregon. ........12

Table 4. List of spatial datasets reviewed during this study for the Hunter Creek study area, southwestern 

Oregon .......................................................................................................................................................................15

Table 5. Partial compilation of instream gravel extracted from Hunter Creek, southwestern Oregon, 1966–2010. ...17

Table 6. Summary of changes in bar features and channel length, 1940–2009, for the Hunter Creek study area, 

southwestern Oregon. ................................................................................................................................................24

Table 7. Summary of findings for the Hunter Creek study area, southwestern Oregon ............................................35
v

Conversion Factors and Datums

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Area

square meter (m2) 10.76 square foot (ft2) 

square kilometer (km2) 0.3861 square mile (mi2)

Volume

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

cubic meter (m3) 35.31 cubic foot (ft3)

cubic meter (m3) 1.308 cubic yard (yd3) 

Mass

kilogram (kg) 2.2046 pound avoirdupois (lb)

metric ton (megagram) 1.1023 ton [U.S.]

Flow rate

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

Abbreviations, Acronyms, and Symbols

+ positive

< less than

> greater than

BLM Bureau of Land Management

commun. communication

D50 median diameter

DEM Digital Elevation Model

DOGAMI Oregon Department of Geology and Mineral Industries

EA Engineering, Science and Technology Ecological Analysts Engineering, Science, and Technology

ESRI Environmental Systems Research Institute, Inc.

GIS Geographic Information Systems

GLO General Land Office

LiDAR Light Detecting and Ranging

NA not available/applicable

NAD 83 North American Datum of 1983

NAIP National Agriculture Imagery Program

NAVD 88 North American Vertical Datum of 1988

ODOT Oregon Department of Transportation

Oregon DOR Oregon Department of Revenue

PLSS Public Land Survey System

RI recurrence interval

RKM river kilometer

RM river mile

RMSE root mean square error

SCS Soil Conservation Service

UO University of Oregon

USACE U.S. Army Corps of Engineers

USFS U.S. Forest Service

USGS U.S. Geological Survey

UTM, Zone 10N Universal Transverse Mercator, Zone 10 North

WAC Western Aerial Contractor
1

Preliminary Assessment of Channel Stability and BedMaterial Transport along Hunter Creek, Southwestern 

Oregon

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

and John C. Risley

Significant Findings

This preliminary assessment of (1) bedmaterial transport in the Hunter Creek basin, (2) 

historical changes in channel condition, and (3) 

supplementary data needed to inform permitting 

decisions regarding instream gravel extraction 

revealed the following: 

Along the lower 12.4 km (kilometers) of 

Hunter Creek from its confluence with the 

Little South Fork Hunter Creek to its mouth, 

the river has confined and unconfined segments and is predominately alluvial in its 

lowermost 11 km. This 12.4-km stretch of 

river can be divided into two geomorphically 

distinct study reaches based primarily on valley physiography. In the Upper Study Reach 

(river kilometer [RKM] 12.4–6), the active 

channel comprises a mixed bed of bedrock, 

boulders, and smaller grains. The stream is 

confined in the upper 1.4 km of the reach by 

a bedrock canyon and in the lower 2.4 km by 

its valley. In the Lower Study Reach (RKM 

6–0), where the area of gravel bars historically was largest, the stream flows over bed 

material that is predominately alluvial sediments. The channel alternates between 

confined and unconfined segments. 

The primary human activities that likely have 

affected bed-material transport and the extent 

and area of gravel bars are (1) historical and 

ongoing aggregate extraction from gravel 

bars in the study area and (2) timber harvest 

and associated road construction throughout 

the basin. These anthropogenic activities 

likely have varying effects on sediment 

transport and deposition throughout the study 

area and over time. Although assessing the 

relative effects of these anthropogenic activities on sediment dynamics would be 

challenging, the Hunter Creek basin may 

serve as a case study for such an assessment 

because it is mostly free of other alterations 

to hydrologic and geomorphic processes such 

as flow regulation, dredging, and other navigation improvements that are common in 

many Oregon coastal basins. 

Several datasets are available that may support a more detailed physical assessment of 

Hunter Creek. The entire study area has been 

captured in aerial photographs at least once 

per decade since the 1940s. This temporally 

rich photograph dataset would support quantitative analyses of changes in channel 

planform as well as vegetation cover. Light 

Detection And Ranging (LiDAR) data collected in 2008 would facilitate hydraulic and 

sediment-transport modeling and characterization of bar elevations throughout most of 

the study area.

Few studies describing channel morphology 

and sediment transport exist for the Hunter 

Creek basin. The most detailed study reported channel incision and bank instability as 

well as the loss of point bars and pools in the 

lower 3.9 km of Hunter Creek from slightly 

downstream of its confluence with Yorke 

Creek to its mouth (EA Engineering, Science, and Technology, 1998). 
2

Repeat channel cross-sections collected from 

1994 to 2010 at four bridges indicate that 

Hunter Creek is dynamic and subject to 

channel shifting, aggradation, and incision. 

Despite this dynamism, the channel at three 

bridge crossings showed little net change in 

thalweg elevation during this period. However, the channel thalweg aggraded 0.55 m 

from 2004 to 2008 near the bridge at RKM 

3.5. 

Systematic delineation of gravel bars from 

aerial photographs collected in 1940, 1965, 

2005, and 2009 indicates a 52-percent reduction in the area of bed-material sediment 

throughout the study area from 1940 to 2009. 

Net bar loss was greatest in the Lower Study 

Reach from RKM 1–4 and mainly is associated with the encroachment of vegetation 

onto upper-bar surfaces lacking apparent 

vegetation in 1940. 

Bar-surface material was approximately 

equal in size to bar-subsurface material at 

Conn Creek Bar, whereas it was distinctly 

coarser than the subsurface material at 

Menasha Bar. Armoring ratios, which indicate the coarseness of the bar surface relative 

to the bar subsurface, were calculated as 0.97 

for Conn Creek Bar and 1.5 for Menasha 

Bar. These ratios tentatively show that 

transport capacity and sediment supply are 

relatively balanced at these sites. 

On the basis of datasets reviewed in this reconnaissance-level study, study results 

indicate that (1) the size and overall position 

of gravel bars in the lower 12.4 km of Hunter 

Creek are determined largely by valley physiography such that unconfined alluvial 

sections have large channel-flanking bars, 

whereas confined reaches accommodate only 

relatively smaller bars, (2) the alluvial segments are prone to vertical and lateral 

channel adjustments, (3) substantial aggradation or incision did not occur except near 

RKM 3.5, where the channel aggraded 

0.55 m (meters) from 2004 to 2008, 

and (4) bed-material transport in Hunter 

Creek is tentatively considered unlimited relative to sediment supply. 

Study findings indicate that more detailed 

investigations are needed to assess channel 

condition in the Lower Study Reach as well 

as longitudinal trends in particle size, the relative balance between sediment supply and 

transport capacity, and potential drivers of 

bar area loss (such as vegetation encroachment and peak-flow patterns) throughout the 

study area. 
3

Introduction

This report summarizes a reconnaissancelevel assessment of channel condition and bedmaterial transport relevant to the permitting of 

instream gravel extraction in Hunter Creek, a 

coastal stream draining to the Pacific Ocean 

south of Gold Beach, Oregon (fig. 1, next page). 

The assessment is based on a review of existing 

datasets (such as bridge-inspection surveys, watershed analyses, and gravel-extraction records), 

repeat delineation of bar and channel features 

from aerial photographs, and field observations 

and particle-size measurements made during July 

2010. Findings from these multiple datasets and 

observations were used to (1) assess the vertical 

stability of the Hunter Creek channel and identify locations where the channel may be incising, 

aggrading, or stable and (2) identify key datasets 

and issues that are relevant to understanding 

channel condition, bed-material transport, and 

potential effects of instream gravel extraction on 

Hunter Creek. Overall, this preliminary study 

constitutes a ―Phase I‖ investigation, similar to 

the Umpqua Phase I assessment by O’Connor 

and others (2009), as outlined by the U.S. Army 

Corps of Engineers, Portland District, and the 

Oregon Department of State Lands to inform the 

permitting of instream gravel extraction in Oregon. 

Location References

Locations along Hunter Creek are referenced to river kilometers (RKM) that begin at 

the Highway 101 bridge, which is less than 200 

m upstream from the mouth of Hunter Creek at 

the Pacific Ocean. To develop this linearreference system, (fig. 1) a centerline was digitized through the wetted channel of Hunter Creek 

for the entire study area from orthoimagery collected in 2009 by the National Agriculture 

Imagery Program (NAIP). Points were then distributed at 0.2-km intervals along this centerline 

and used to determine locations in terms of river 

kilometer for this project. Even after accounting 

for the conversion between river miles (RM) 

shown on current (1986) U.S. Geological Survey 

(USGS) quadrangle maps and river kilometers 

produced by this study for Hunter Creek, the two 

reference systems differ owing to factors such as 

some channel shifting. Additionally, USGS 

quadrangles of the Hunter Creek basin include 

only RM 4–7 (as indicated in fig. 1). 

Physical Characteristics of the Hunter 

Creek Basin

Geographic, Geologic, and Geomorphic 

Setting 

Hunter Creek is an unregulated system that 

drains 115 km2

of southwestern Oregon before 

flowing into the Pacific Ocean south of the town 

of Gold Beach, Oregon (fig. 1). The basin is located wholly within Curry County. The drainage 

basin is flanked to the north by the Rogue River 

basin, to the east by the Illinois River basin, and 

to the south by the Pistol River basin. The main 

stem and its four principal tributaries (North 

Fork Hunter Creek, Big South Fork Hunter 

Creek, Little South Fork Hunter Creek, and 

Conn Creek) drain the rugged Klamath Mountains, which are underlain by a Cretaceous and 

Jurassic accretionary complex composed of 

weakly to intensely metamorphosed sedimentary, volcanic, and intrusive igneous rocks 

(Ramp and others, 1977). 

The headwaters of Hunter Creek begin near 

Sugarloaf Mountain (peak elevation 1,017 m) in 

the Rogue River–Siskiyou National Forest. 

Hunter Creek then flows generally westward for 

14 km before its confluence with the higher gradient North Fork Hunter Creek (drainage area of 

15.4 km2) (figs. 1 and 2A). The channel within 

this uppermost portion of the drainage basin is 

steep (gradient of 0.049 m/m; as measured from 

a 10-m USGS Digital Elevation Model [DEM], 

fig. 2A) and carves a narrow canyon through 

Cretaceous-age Colebrook Schist and partially 

metamorphosed sedimentary rocks of the Jurassic-age Dothan and Otter Point Formations 

(fig. 1).
4

Figure 1. Map of the Hunter Creek basin, southwestern Oregon. River kilometer (RKM) locations were derived by this project (see Location References section for details); river mile (RM) locations were derived from U.S. Geological Survey quadrangle maps. 
5

In the 2009 NAIP orthoimagery of the basin, the 

main channel in the upper 14 km of the basin is 

narrow and completely obscured by adjacent tree 

canopies except for in landslide-prone areas that 

are dominated by Jurassic and Cretaceous ultramafic rocks. Within these unstable segments, the 

channel widens to approximately 12 m (as measured from 2009 NAIP orthoimagery for this and 

all widths provided in this section), accommodating numerous channel-flanking gravel bars. 

About 3.5 km above its confluence with 

North Fork Hunter Creek, Hunter Creek exits the 

ultramafic rock formations and enters the Dothan 

and Otter Point Formations that underlay the 

middle and lower portions of the drainage basin 

(fig. 1). Downstream of this confluence, Hunter 

Creek flows southward for 5 km until it is joined 

by Big South Fork Hunter Creek (15.7 km2) and 

shortly thereafter by Little South Fork Hunter 

Creek (6.8 km2) (fig. 1). Within this middle portion of the drainage basin, the channel widens to 

nearly 25 m, decreases in gradient to 0.021 m/m 

(fig. 2A), and flows on a mixed bed of boulders 

and bedrock with intermittent gravel bars positioned at high-amplitude bends. At its confluence 

with Little South Fork Hunter Creek, the drainage area of Hunter Creek is 82.6 km2

. 

 

Figure 2. Longitudinal profiles for (A) the Hunter Creek basin, southwestern Oregon (as measured from 

U.S. Geological Survey 10-meter Digital Elevation Model) and (B) study area (as measured from 1-meter 

LiDAR survey), with locations of sediment-sampling sites and bridges denoted.
6

From its confluence with Little South Fork 

Hunter Creek to 1.4 km downstream, the Hunter 

Creek channel is confined by a bedrockdominated canyon and flows over a mixed bed of 

bedrock, boulders, and gravel. The lower 11 km 

of Hunter Creek flows northwest towards its 

mouth at the Pacific Ocean as a ―wandering 

gravel bed river‖ (Church, 1983) dominated by a 

single channel with some multichanneled reaches. The active channel in this lowermost 11 km 

primarily is alluvial and flanked by nearly continuous swaths of large, active gravel bars that 

are separated by several 1–2 km confined reaches (figs. 1 and 3A–D). Within the unconfined 

segments, the channel generally contains large 

gravel bars and alternates its position between 

valley walls, forming shallow riffles where it 

crosses the valley floor and deep pools where it 

flows against valley walls. The main tributary in 

this section is Conn Creek (6.0 km2), which enters Hunter Creek approximately 2.5 km 

downstream from its confluence with Little 

South Fork Hunter Creek (fig. 1). The channel in 

the lower 10.7 km of Hunter Creek has an average gradient of 0.002 m/m (as measured from a 

1-m LiDAR survey; fig. 2B) and a wetted width 

ranging from 15 m in the confined, upper portion 

of the study area to nearly 165 m near the mouth. 

Hunter Creek is tidally influenced in approximately its lowest 2.2 km. 

The longitudinal profile (fig. 2A–B) shows a 

smooth gradation in slope along Hunter Creek to 

its confluence with the Pacific Ocean. This profile, together with abundant gravel bars observed 

to the mouth and the absence of an estuary, indicates that Hunter Creek has transported gravel to 

the Pacific Ocean at a rate that has exceeded the 

depositional accommodation space created by 

Holocene sea-level rise and hence differs from 

many Coast Range drainages where extensive 

tidal reaches and fluvial estuaries occur (Komar, 

1997). The wide valley bottom in the lowest portion of the study area, in part, reflects Holocene 

filling of the Hunter Creek valley. 

Hydrology 

The hydrology of Hunter Creek is not systematically monitored by any existing local or 

Federal program. The only discharge data for the 

Hunter Creek basin are provided by a USGS 

crest-stage station (14378550), which was operated from water years 1965–1977 on Hunter 

Creek upstream of its confluence with Elko 

Creek (fig. 1). This crest-stage station provides 

the date and magnitude of annual peak flows 

during its period of operation. 

Since bed-material transport is determined 

largely by the magnitude and frequency of highflow events, this project compiled existing information for the Hunter Creek basin and nearby 

basins and estimated peak flow for a range of 

discharge events on Hunter Creek (tables 1 and 

2). Unlike nearby higher elevation basins, where 

peak flows derive from rain-on-snow events 

(such as the Illinois River; mean basin elevation 

814 m), peak flows in Hunter Creek (mean basin 

elevation 466 m) derive mainly from large 

frontal rainstorms because only 15 percent of the 

basin is within the transient snow zone (EA Engineering, Science, and Technology, 1998). 

Streamflow typically peaks during the rainy winter season and recedes to base flow (or periods of 

no flow) during the late summer, when precipitation is scarce. Peak-flow discharge was estimated 

for 2-, 5-, 10-, 25-, 50-, 100-, and 500-year recurrence-interval events at three locations by using 

regional-regression relationships developed by 

Cooper (2005): the former site of the USGS 

crest-stage station in the upper watershed, Hunter 

Creek at its confluence with Little South Fork 

Hunter Creek (near the upstream boundary of the 

study area), and Hunter Creek at its mouth 

(table 1).
7

Figure 3. Gravel bars and wetted channel as delineated for the study reaches on Hunter Creek, southwestern 

Oregon, in (A) 1940, (B) 1965, (C) 2005, and (D) 2009. Locations of sediment-sampling sites, bridges, and historical and ongoing instream gravel extraction sites are indicated on (D).
8

Table 1. Estimated peak flows at sites in the Hunter Creek basin, southwestern Oregon.

[m3/s, cubic meter per second; km2, square kilometer; peak flows estimated using regional regression 

equations from Cooper (2005); basin area from StreamStats (http://streamstatsags.cr.usgs.gov)]

U.S. Geological Survey crest-stage site (14378550) on Hunter Creek near Gold Beach, Oregon

Basin drainage area: 2.51 km2

Recurrence

interval

(years)

Flow

(m3/s)

Prediction error

(percent)1

Equivalent years 

of record2

90-percent prediction interval

Lower

(m3/s)

Upper

(m3/s)

2 3.68 27 2.4 2.37 5.72

5 5.61 25 3.7 3.68 8.49

10 6.94 26 5.0 4.56 10.6

25 8.78 27 6.4 5.66 13.6

50 10.2 28 7.2 6.46 16.1

100 11.7 29 7.9 7.22 18.8

500 15.2 33 8.9 8.92 26.0

Hunter Creek at its confluence with the Little South Fork Hunter Creek

Basin drainage area: 82.6 km2

Recurrence

interval

(years)

Flow

(m3/s)

Prediction error

(percent)1

Equivalent years 

of record2

90-percent prediction interval

Lower

(m3/s)

Upper

(m3/s)

2 110 27 2.4 71.1 170

5 161 25 3.7 107 243

10 195 26 5.0 129 294

25 240 27 6.4 156 368

50 274 28 7.2 175 428

100 309 29 7.9 193 496

500 391 33 8.9 231 660

Hunter Creek at its mouth

Basin drainage area: 115 km2

Recurrence

interval

(years)

Flow

(m3/s)

Prediction error

(percent)1

Equivalent years 

of record2

90-Percent prediction interval

Lower

(m3/s)

Upper

(m3/s)

2 142 27 2.4 91.5 219

5 206 25 3.7 136 311

10 248 26 5.0 164 377

25 303 27 6.4 197 467

50 345 28 7.2 221 544

100 388 29 7.9 242 626

500 490 33 8.9 289 830

1

 Square root of the sum of the squared standard error of the model and the average squared standard 

error of the sampling, in log units (Cooper, 2005).

2 Number of years of data needed to give the same average prediction error as the regression model 

(Cooper, 2005).
9

The estimated peak-flow discharges reflect 

the small size of the Hunter Creek watershed 

(table 1). For example, the 2-year flood discharge at the mouth of Hunter Creek is 

approximately 142 m3/s, with a 90-percent prediction interval ranging from 91.5 to 219 m3

/s 

(table 1). The 90-percent prediction intervals for 

the 10- and 100-year recurrence-interval floods 

at the mouth of Hunter Creek are 164–377 m3/s 

and 242–626 m3/s, respectively (table 1). Comparison of estimated peak flows for Hunter Creek 

and five nearby USGS streamflow stations in 

basins of varying size show that regional flooding is localized (table 2). For example, during the 

large magnitude rain-on-snow flood of December 1964 (water year 1965), discharge on the 

Illinois and Chetco Rivers exceeded the 500- and 

100-year recurrence intervals, respectively 

(table 2). Similarly, peak flow for water year 

1965 at the USGS crest-stage in the upper 

Hunter Creek basin was greater than the 

weighted peak flow for a 500-year recurrenceinterval flood (table 2). 

Despite large uncertainties in the weighted 

peak-flow estimates (Cooper, 2005), flooding 

during the December 1964 flood in the upper 

Hunter Creek basin may not be representative of 

overall watershed conditions. Harris Creek (a 

coastal basin north of the Chetco River) and 

Ransom Creek (a tributary to the lower Chetco 

River) are both relatively small, low-elevation 

basins that experienced a less than 2-year recurrence-interval event during the December 1964 

storm (table 2). The lower Hunter Creek channel 

may have responded similarly with relatively 

low flow during this storm. Further hydrologic 

analyses that estimate the historical peak flows in 

lower Hunter Creek may help better quantify the 

hydrologic response of the basin to peak-flow 

events. 

Land Uses in the Basin

The Hunter Creek Watershed Assessment 

(Maguire, 2001) and Hunter Creek Watershed 

Analysis (EA Engineering, Science, and Technology, 1998) summarize land-use activities in 

the basin. Like other basins along the southwestern Oregon coast, Euro-American settlement of 

the Hunter Creek basin was fueled by the discovery of gold in the nearby Rogue River basin 

and elsewhere along the Oregon coast during the 

1850s. The population of the Hunter Creek basin 

grew slowly during the 19th and early 20th centuries and remains sparse today, owing in part to 

the limited amount of arable land along Hunter 

Creek and its remote location. When the lower 

portion of the Hunter Creek basin was annexed 

into the City of Gold Beach in 1995, the area had 

an estimated population of only 414 (Maguire, 

2001). Another impediment to basinwide development was the lack of roads. Until the end of 

World War II, the primary transportation routes 

connecting the coast and upper watershed were 

trails carved along steep hill slopes and the river 

bed during low flows (Maguire, 2001). 

The watershed-scale activities that likely 

have had the greatest effect on channel morphology in Hunter Creek are timber harvesting and 

associated road building. In 2001, private and 

Federal forest lands accounted for 97 percent of 

the basin area; urban, agricultural, and ruralresidential areas along the lower main stem accounted for the remaining 3 percent (Maguire, 

2001). EA Engineering, Science, and Technology (1998) reported that commercial timber 

harvest began in the late 1940s, peaked from 

1955 to 1964, with logging mainly on privately 

owned lands, and then went through a second 

period of substantial harvest from 1980 to 1989, 

when the Rogue River–Siskiyou National Forest 

lands were timbered. Prior to timber harvest, the 

main watershed disturbances were fire and large 

wind-throw events (EA Engineering, Science, 

and Technology, 1998); no fires have occurred 

during the modern period of record (Peck and 

Park, 2006). 
10

Table 2. Peak-flow characteristics at U.S. Geological Survey streamflow sites within or near the Hunter Creek basin, southwestern Oregon.

[m, meter; mm, millimeter; km2, square kilometer; RI, recurrence interval in years; >, greater than; NA, not available; <, less than; flows in cubic meters per 

second; estimated peak flows are weighted using regional regressions and station data from Appendix D, Cooper, 2005; mean basin elevation, mean annual 

precipitation, and basin area from StreamStats (http://streamstatsags.cr.usgs.gov)]

Station

number

Station

name

Unregulated 

period used 

in peak-flow 

analysis

Mean 

basin 

elevation1

(m)

Mean annual 

precipitation1

(mm)

Basin 

area 1

(km2)

Weighted2 peak flows for indicated recurrence intervals

(m3/s)

Measured annual peak flows

Water year 

1965

Water year 

1997

2 5 10 25 50 100 500 Flow RI Flow RI

14372300

Rogue 

River near 

Agness

1961–1976 930 1,052 10,205 2,888 4,870 6,286 8,155 9,599 11,100 14,866 8,212 > 25 NA3 NA

14377100

Illinois 

River near 

Kerby

1962–19994881 1,918 987 677 937 1,116 1,345 1,521 1,702 2,135 2,611 > 500 1,059 < 10

14378550

Hunter 

Creek near 

Gold 

Beach

1965–1977 850 3,785 3 6 8 9 11 12 14 18 25 > 500 NA NA

14378800

Harris 

Creek near 

Brookings 

1953–1968 184 2,281 3 5 7 9 11 12 14 18 3 < 2 NA NA

14378900

Ransom 

Creek near 

Brookings

1953–1977 123 2,078 2 3 5 6 8 9 11 14 2 < 2 NA NA

14400000

Chetco 

River near

Brookings

1965; 1970–

20004 671 3,099 702 1,022 1,413 1,656 1,954 2,166 2,373 2,832 2,418 > 100 2,155 < 50

1 Reported values for basin elevation, precipitation, and area refer to contributing watershed for each gaging station, not basin outlet.

2 Weighted peak flows incorporate both historical station data and calculated peak flows from regional regressions. Weighted peak flows differ from values in 

table 1, which are based solely on regional regression formulas.

3

Flow in water year 1997 affected by regulation.

4 Although Illinois and Chetco Rivers currently (2011) are unregulated, the peak-flow values provided in this table are based on estimates from Cooper (2005), 

which incorporate data only up to 1999 and 2000, respectively.
11

The Hunter Creek basin also has a history of 

mining that likely has affected channel morphology and bed-material transport. In the 1850s, 

placer deposits near the mouth of Hunter Creek 

and nearby terraces were mined briefly for gold 

(EA Engineering, Science, and Technology, 

1998). On the basis of historical mining practices 

in other coastal basins, like the Umpqua River 

basin (Beckham, 1986), placer deposits in 

Hunter Creek may have been extracted hydraulically, potentially liberating large volumes of 

sediment from streamside terraces. Since at least 

the 1960s, commercial aggregate has been extracted from gravel bars along the lower 10 km 

of Hunter Creek (on the basis of data provided 

by Dan Crumley, Curry County Road Department, written commun., 2010). Because instream 

gravel extraction can result in channel incision 

and bar armoring (Kondolf, 1994), extraction 

volumes and gravel replenishment at mining 

sites are described in more detail in a subsequent 

section of this report. Other mining activities 

include commercial exploration and mining in 

the 1930s–1950s for nickel, gold, and chromite 

deposits in the upper watershed near Signal 

Buttes and Red Flat (fig. 1). These activities 

probably had a minimal impact on Hunter Creek 

channel morphology because they were located 

more than 5 km from the main channel and 

mainly involved trenching and prospecting rather 

than large-scale extraction (EA Engineering, 

Science, and Technology, 1998; Maguire, 2001). 

Aggregate continues to be extracted in the uplands of the basin. 

The morphology of the lower 3.9 km of 

Hunter Creek (from below its confluence with 

Yorke Creek to its mouth) has been directly affected by channel straightening and bank 

armoring undertaken by local entities to protect 

properties and road infrastructure as well as 

floodplain reclamation (EA Engineering, Science, and Technology, 1998). Completed in the 

mid-1940s, Hunter Creek Road generally follows 

the lower 13 km of Hunter Creek and impinges 

upon the historical active channel in several locations, such as near RKM 4.5, 7.6, and 9.6. 

Study Area

For the purposes of this reconnaissance 

study, the study area includes the lower 12.4 km 

of Hunter Creek from its confluence with the 

Little South Fork Hunter Creek at RKM 12.4 to 

near its mouth at the Highway 101 bridge (figs. 1 

and 3A–D). This predominately alluvial stretch 

of river contains most of the gravel bars in the 

basin and all instream gravel-extraction operations active in 2010. This study area was further 

subdivided into two study reaches (Upper Study 

Reach and Lower Study Reach) based primarily 

on valley morphology (table 3 and fig. 3A–D).

The Upper Study Reach spans the upper 

6.5 km of Hunter Creek from RKM 12.4 near its 

confluence with Little South Fork Hunter Creek 

to RKM 6.0 near its confluences with Crossen 

and Smith Creeks (figs. 1 and 3A–D). In the uppermost 1.4 km of the Upper Study Reach, the 

channel is confined by a narrow, bedrockdominated canyon. Here, active channel width, 

or the area typically inundated during annual 

high flows as determined by the presence of water and flow-modified surfaces (Church, 1988), 

ranges from 12 to 20 m (as measured from 2009 

NAIP orthoimagery for this and all widths reported in this section). The bedrock canyon at the 

upstream boundary of the study area would prevent any channel changes in the study area from 

propagating upstream. Downstream from RKM 

11, the valley in the Upper Study Reach opens, 

allowing the active channel to widen 40 to 75 m 

and transition into a fully alluvial segment with a 

pool-drop morphology and large channelflanking gravel bars. Near RKM 8.4, the channel 

enters a second confined segment that extends to 

RKM 6, where the active channel width is less 

than 30 m but fully alluvial. The average watersurface gradient of the Upper Study Reach is

0.009 m/m (as measured from LiDAR data collected from RKM 6 to 10.7; fig. 2B and table 3).
12

The Lower Study Reach begins at RKM 6 at 

the outlet of a confined segment and extends to 

RKM 0 at the Highway 101 bridge (figs. 1 and 

3A–D). Although alternating bars are present 

throughout this reach, the Lower Study Reach 

has broad, unconfined segments with activechannel widths up to 80 m (such as near RKM 

4.1 and 4.6) as well as a narrower, confined 

active-channel segment where the maximum 

width generally is less than 35 m (such as near 

RKM 2.6–3.9). Near RKM 0.6, Hunter Creek 

abruptly turns westward across its coastal plain 

and widens to 165 m as it flows towards its 

mouth at the Pacific Ocean. The average watersurface gradient for the Lower Study Reach is

0.005 m/m (fig. 2B and table 3).

Table 3. Summary of characteristics for the study reaches in the Hunter Creek basin, southwestern Oregon.

[RKM, river kilometer; km2, square kilometer; m, meter; km, kilometer; LiDAR, Light Detection And Ranging]

Attribute Lower Study Reach Upper Study Reach

Position RKM 0–6 RKM 6–12.4

Reach and channel descriptionAlternating confined and unconfined segments. Unconfined segments have large, 

channel-flanking bars whereas confined, 

narrow segments have smaller bars. Tidally 

affected to about RKM 2.2. Dynamic 

mouth frequently changes position. Gravel 

and some sand bars are present in reach.

Uppermost 1.4 km confined and bedrock 

dominated with little gravel. Channel from 

RKM 8.4 to 11 is unconfined with large 

gravel bars and has pool-riffle morphology. 

Channel from RKM 6 to 8.4 is confined to 

narrow canyon and has smaller bars. 

Area of downstream end of 

segment (km2)

1 115.0 102.0

Area at upstream end of 

segment (km2)

1 102.0 82.6

Average water-surface gradient (m/m)2 0.005 0.009

Major flow factors Tidally affected to ~ RKM 2.2; minimal 

irrigation diversions

No regulation

Major sedimentation factors Low gradient in unconfined segments promotes sediment deposition. Placer mining 

in 1850s near mouth of channel; historical 

and ongoing in-stream gravel extraction; 

forestry practices in upper basin.

Low gradient in unconfined segments promotes sediment deposition; historical and 

ongoing instream gravel extraction; forestry 

practices in upper basin; sediment inputs 

from the Little and Big South Forks of 

Hunter Creek and Conn Creek.

Direct impacts to active 

channel

Gravel mining; recreational vehicle use; 

channel straightening and bank armoring in 

lower 3.9 km; placer mining in 1850s.

Gravel mining; recreational vehicle use

General channel trends Channel flows on alluvium and historically 

has been dynamic, particularly near river's 

mouth. 

Upper 1.4 km historically stable due to 

bedrock influence. Channel from RKM 6 to 

11 mainly flows on alluvium and has been 

more historically dynamic and subject to 

shifting. 

1 Basin area for the total contributing area from StreamStats (http://streamstatsags.cr.usgs.gov).

2 Water-surface gradient extracted from 2008 LiDAR survey encompassing RKM 0–10.7; therefore, gradient for Upper 

Study Reach was determined only for RKM 6–10.7.
 

13

Approach and Key Findings

For this study, we reviewed existing datasets 

and studies regarding channel condition and bedmaterial transport in the Hunter Creek basin, 

applied reconnaissance-level GIS analyses, and 

collected field observations and particle-size 

measurements during July 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 instream gravel-extraction activities, (3) characterize broad-scale patterns in 

gravel-bar area and channel features using four 

sets of aerial photographs spanning 1940–2009, 

(4) determine particle-size distributions and armoring ratios on two gravel bars, and (5) identify 

locations where the channel may be aggrading or 

incising. Additionally, this assessment provides a 

preliminary review of channel condition and 

bed-material transport in Hunter Creek and identifies outstanding issues relevant to the 

permitting of instream gravel extraction that may 

be addressed by future studies. The following 

sections summarize each of the major activities 

and key findings. 

Review of Previous Hydrologic and 

Geomorphic Studies 

Two watershed-scale assessments provide 

information on the hydrology and geomorphology of Hunter Creek. The Hunter Creek 

Watershed Assessment (Maguire, 2001) provides 

general information on basin hydrology and 

land-use while the Hunter Creek Watershed 

Analysis (EA Engineering, Science, and Technology, 1998), which also is summarized by 

Peck and Park (2006), provides a more detailed 

description of erosion processes throughout the 

basin. 

Based on EA Engineering, Science, and 

Technology (1998), sources of sediment to 

Hunter Creek and its tributaries primarily are 

mass movements with smaller inputs contributed 

by surface erosion associated with road networks 

and skids trails at logging sites. Throughout 

much of the upper and middle portions of the 

Hunter Creek basin, the channel flows directly 

on bedrock and is relatively stable (EA Engineering, Science, and Technology, 1998). The main 

areas of Hunter Creek prone to channel instability are in (1) portions of the upper basin and Elko 

Creek where the channel flows adjacent to unstable, landslide-prone slopes derived from 

ultramafic rocks and (2) lower, alluvial reaches 

where stream banks are composed of alluvium 

and subject to erosion (EA Engineering, Science, 

and Technology, 1998). Additionally, they reported incision along the lower 3.9 km of Hunter 

Creek as well as channel straightening, bank 

failures, and loss of point bars and pools; these 

changes were attributed to bank stabilization and 

floodplain reclamation (EA Engineering, Science, and Technology, 1998). 

The finding of incision by EA Engineering, 

Science, and Technology (1998) is particularly 

relevant to this study since documentation of 

incision or aggradation is a major focus of Phase 

I analyses (Janine Castro, U.S. Fish and Wildlife 

Service, written commun., 2006). Field visits and 

interviews are cited as evidence for channel incision (p. 4–25; EA, Engineering, Science, and 

Technology, 1998). As described in subsequent 

sections, our limited review of quantitative data 

describing channel elevation does not indicate 

systematic channel incision since 1994. 

Assessment of Existing Spatial Datasets 

We assessed the availability of spatial datasets in the Hunter Creek basin that could be 

used to evaluate channel condition and bedmaterial transport. This search focused primarily 

on aerial photographs and included other datasets 

such as Light Detection And Ranging (LiDAR), 

geologic maps, General Land Office (GLO) surveys, and navigation surveys. 

This project included the review of aerial 

photographs of the Hunter Creek basin available 

from the U.S. Army Corps of Engineers’ Aerial 

Photograph Library (Portland, Oregon) and the 

University of Oregon Map Library (Eugene, Or-
 

14

egon) as well as digital orthophotographs available from online sources (table 4). Other potential 

sources of aerial photographs not considered in 

this review include (but are not limited to) the 

Bureau of Land Management, National Archives, 

Curry County departments, and South Coast 

Lumber Company. 

On the basis of the aerial photography review, at least 12 sets of aerial photographs are 

available that cover all or most of the 12.4-km 

long Hunter Creek study area (table 4). Complete 

photographic coverage for the study area is 

available at least once per decade since the 

1940s. Six additional sets of photographs partially cover the study area, four of which completely 

capture the Lower Study Reach. A majority of 

the identified sets of photographs were taken at a 

sufficient resolution (1:24,000 or greater) for 

assessing long-term changes in channel condition, gravel-bar area, and vegetation cover. 

The earliest available surveys of the Hunter 

Creek study area were conducted by the GLO in 

1857 and produced as maps in 1881 and 1891 

(table 4). As summarized by Atwood (2008), the 

main purpose of GLO surveys was to establish 

the Township, Range, and Section lines of the 

Public Land Survey System (PLSS). Since these 

maps were based on non-meandered surveys, the 

approximate location of Hunter Creek is depicted 

in the GLO maps, but specific features such as 

gravel bars were not systematically mapped and 

channel banks were not continuously surveyed. 

Further review of the GLO data would help determine if surveyors recorded any relevant 

descriptions of channel and vegetation conditions in their notes. 

Other spatial datasets include a LiDAR survey that provides high resolution (1-m scale) 

topographic data for the river corridor from 

RKM 0 to 10.7 (table 4). This dataset, collected 

in 2008 would support detailed analyses of 

channel hydraulics and sediment transport. Topography data at a coarser scale (10-m) are 

available for the entire watershed (table 4). Also 

available is the geologic map of Curry County 

developed by Ramp and others (1977), which 

depicts major geologic units and geomorphic 

divisions of the river basin (table 4 and fig. 1). 

Our preliminary search for navigation reports 

and surveys did not yield any results, which is 

reasonable given the minimal size of the estuary, 

lack of navigation improvements such as jetties, 

and the dynamic river mouth that shifts position 

frequently (fig. 3A–D).Furthermore, Farnell 

(1981) states that in Curry County, ―only on the 

Chetco River was there sufficient commercial 

use to warrant a claim by the State to the bed of 

the river‖ for navigation purposes.
 

15

Table 4. List of spatial datasets reviewed during this study for the Hunter Creek study area, southwestern Oregon—continued. 

[USFS, U.S. Forest Service; UO, University of Oregon; USGS, U.S. Geological Survey; SCS; Soil Conservation Service; Oregon DOR, Oregon Department of 

Revenue; WAC, Western Aerial Contractor; USACE, U.S. Army Corps of Engineers; BLM, Bureau of Land Management; m, meter; NAIP, National Agriculture Imagery Program; NA, not available; LiDAR, Light Detection And Ranging; DOGAMI, Oregon Department of Geology and Mineral Industries; DEM, 

digital elevation model; NED, National Elevation Dataset; aerial photographs noted in bold were used to delineate gravel-bar features for this project]

Data type Year1 Area covered2 Scale Source Flight date(s) Current location

Aerial photographs and 

orthophotos

1940 Full coverage 1:20,000 USFS 8/3/1940; 

10/14/1941 UO Library

1952 Full coverage 1:47,200 USGS UO Library

1965 Full coverage 1:20,000 SCS 6/22/1965; 

8/13/1965 UO Library

1970 Full coverage 1:12,000 Oregon 

DOR UO Library

1983 Full coverage 1:48,000 WAC USACE, Portland District

1986 Full coverage 1:12,000 BLM USGS; UO Library

1995 Full coverage 1 pixel = 1 m USGS UO Library; 

USGS, http://edcsns17.cr.usgs.gov/NewEarthExplorer/

2000 Full coverage 1 pixel = 1 m USGS USGS, http://edcsns17.cr.usgs.gov/NewEarthExplorer/

2002 Full coverage 1:12,000 BLM UO Library

2005 Full coverage 1 pixel = 0.5 m NAIP 7/17/2005 USGS; http://datagateway.nrcs.usda.gov/

2009 Full coverage 1 pixel = 1 m NAIP 6/17/2009 USGS; http://datagateway.nrcs.usda.gov/

1962 RKM 0–2.6 1:12,000 NA USACE, Portland District

1964 RKM 0–10.8 1:24,000 NA USACE, Portland District

1977 RKM 0–5.4 1:24,000 WAC USACE, Portland District

1980 RKM 0–8.2 1:24,000 WAC USACE, Portland District

1982 RKM 0–12.2 1:48,000 WAC USACE, Portland District

1989 RKM 0–8.2 1:24,000 USACE USACE, Portland District

1998 RKM 0–3.2 1:16,200 USACE USACE, Portland District

LiDAR 

survey

2008 RKM 0–10.7 1 pixel = ~1 m DOGAMI DOGAMI

DEM

Source 

dates vary Full coverage 1 pixel = 10 m USGS 

NED USGS website: http://seamless.usgs.gov/
 

16

Table 4. List of spatial datasets reviewed during this study for the Hunter Creek study area, southwestern Oregon—continued. 

[USFS, U.S. Forest Service; UO, University of Oregon; USGS, U.S. Geological Survey; SCS; Soil Conservation Service; Oregon DOR, Oregon Department of 

Revenue; WAC, Western Aerial Contractor; USACE, U.S. Army Corps of Engineers; BLM, Bureau of Land Management; m, meter; NAIP, National Agriculture Imagery Program; NA, not available; LiDAR, Light Detection And Ranging; DOGAMI, Oregon Department of Geology and Mineral Industries; DEM, 

digital elevation model; NED, National Elevation Dataset; aerial photographs noted in bold were used to delineate gravel-bar features for this project]

Data type Year1 Area covered2 Scale Source Flight date(s) Current location

Geologic 

map of Curry 

County 1977 Full coverage 1:125,000

DOGAMI; 

Ramp and 

others

(1977)

DOGAMI

General 

Land Office 

surveys

Surveyed 

in 1857; 

maps completed in 

1881 and 

1891

Full coverage 1:31,680 BLM BLM website:

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

1 Actual acquisition dates vary and may include multiple years.

2 The provided spatial extent is approximate for datasets with partial coverage.

Review of Gravel-Operator Information and Surveys 

In 2004, Curry County Department of Public Services inventoried instream gravel-removal permits issued in the county 

since 1972 (Pratt, 2004) and documented permits issued within 

the Hunter Creek basin during this period. In 1972, eight permits with a total annual-removal limit of approximately 

52,750 m3 were issued along Hunter Creek for primarily highway and county-road maintenance, flood prevention, and 

commercial uses (Pratt, 2004). The number of active instream 

gravel-removal permits decreased to five by 2004 with a total 

annual-removal volume limit of approximately 30,580 m3. The 

declining number of instream gravel-extraction permits on 

Hunter Creek mirrors the general downward trend in these 

permits throughout Curry County, where the number of countywide permits declined from 61 in 1972 to 19 in 2004 (Pratt, 

2004). 

Partial-volume estimates of gravel extracted from Hunter 

Creek from 1966 to 2010 were provided by the Curry County 

Road Department (table 5; Dan Crumley, Curry County Road 

Department, written commun., 2010). Although gaps within 

the record preclude a full accounting of the total volume mined 

from all sites, annual instream gravel-extraction volumes noted 

for five sites on Hunter Creek ranged from 235 to 11,808 m3

but typically were less than 6,000 m3(fig. 4 and table 5). On 

the basis of available data, the cumulative volume of gravel 

removed from Hunter Creek by the Curry County Road Department from 1966 to 2010 was at least 112,612 m3

. Although 

unknown, the total volume of instream gravel extraction during 

these 44 years likely was much higher given the multiple sites 

operating along the river. 
 

17

Figure 4. Partial-volume estimates of gravel extracted 1966–2010 from Hunter Creek, southwestern Oregon (data 

provided by Dan Crumley, Curry County Road Department, written commun., 2010). The data do not include all 

removal sites and years, thus they provide a minimum estimate of gravel extracted from Hunter Creek during the 

period. Years denoted with an asterisk had removal volumes reported by fiscal year (July 1–June 30) rather than 

calendar year. Approximate site location denoted by river kilometer (RKM). 

Table 5. Partial compilation of instream gravel extracted from Hunter Creek, southwestern Oregon,

1966–2010—continued. 

[m3, cubic meter; RKM, river kilometer, --, data gaps; *, removal volumes provided for fiscal year, extending 

October 1–September 30, rather than calendar year; data provided by Dan Crumley, Curry County Road Department, 

written commun., 2010)]

Gravel removed (m3) from instream extraction sites

Oceanview Bar Bartlett Bar Menasha Bar Ringer Bar Conn Creek Bar

Year RKM 2.1 RKM 2.3

RKM 4.1 and 4.7 

pre-1990; RKM 4.1 

post-1990 RKM 4.7 RKM 9.7

1966 -- -- 2,575 -- --

1967 -- -- -- -- --

1968 -- -- -- -- --

1969 -- -- -- -- --

1970 -- -- -- -- --

1971 -- -- -- -- --
 

18

Table 5. Partial compilation of instream gravel extracted from Hunter Creek, southwestern Oregon,

1966–2010—continued. 

[m3, cubic meter; RKM, river kilometer, --, data gaps; *, removal volumes provided for fiscal year, extending 

October 1–September 30, rather than calendar year; data provided by Dan Crumley, Curry County Road Department, 

written commun., 2010)]

Gravel removed (m3) from instream extraction sites

Oceanview Bar Bartlett Bar Menasha Bar Ringer Bar Conn Creek Bar

Year RKM 2.1 RKM 2.3

RKM 4.1 and 4.7 

pre-1990; RKM 4.1 

post-1990 RKM 4.7 RKM 9.7

1972 -- -- -- -- --

1973 -- -- -- -- --

1974 -- -- 318 -- --

1975 -- -- 1,936 -- --

1976 -- -- 235 -- --

1977* -- -- 4,704 -- --

1978* -- -- 1,492 -- --

1979* -- -- 1,825 -- --

1980 -- -- -- -- --

1981* -- -- 2,074 -- --

1982 -- -- -- -- --

1983 -- -- -- -- --

1984 -- -- -- -- --

1985 -- -- -- -- --

1986 -- -- -- -- --

1987 -- -- -- -- --

1988 -- -- -- -- --

1989 1,002 184 -- -- --

1990 -- -- -- 1,348 3,846

1991 -- 579 3,813 -- --

1992 1,634 267 2,663 -- --

1993 196 1,030 4,285 -- --

1994 894 1,353 4,641 -- --

1995 -- -- 3,819 -- --

1996 -- -- 5,455 -- --

1997 -- -- 4,349 3,383 --

1998 -- -- 1,305 1,485 --

1999 914 2,008 3,981 4,903 --

2000 Not mined Not mined 4,270 4,086 --

2001 Not mined Not mined -- -- --

2002 Not mined Not mined Not mined 1,752 --

2003 Not mined Not mined Not mined Not mined --

2004 Not mined Not mined Not mined Not mined --
 

19

Table 5. Partial compilation of instream gravel extracted from Hunter Creek, southwestern Oregon,

1966–2010—continued. 

[m3, cubic meter; RKM, river kilometer, --, data gaps; *, removal volumes provided for fiscal year, extending 

October 1–September 30, rather than calendar year; data provided by Dan Crumley, Curry County Road Department, 

written commun., 2010)]

Gravel removed (m3) from instream extraction sites

Oceanview Bar Bartlett Bar Menasha Bar Ringer Bar Conn Creek Bar

Year RKM 2.1 RKM 2.3

RKM 4.1 and 4.7 

pre-1990; RKM 4.1 

post-1990 RKM 4.7 RKM 9.7

2005 Not mined Not mined Not mined Not mined --

2006 Not mined Not mined 6,186 Not mined --

2007 Not mined Not mined 2,875 2,942 --

2008 Not mined Not mined 3,171 1,897 --

2009 Not mined Not mined 4,065 1,942 --

2010 Not mined Not mined 2,745 2,169 --

As of 2010, the three instream gravelextraction sites active on Hunter Creek (fig. 3D) 

were: 

Conn Creek Bar, RKM 9.7, privately operated

Ringer Bar, RKM 4.7, operated by Curry 

County Road Department 

Menasha Bar, RKM 4.1, operated by Curry 

County Road Department 

Menasha Bar and Ringer Bar originally were 

privately owned, but later were acquired by Curry County Road Department in 1991 and 1989, 

respectively (Dan Crumley, Curry County Road 

Department, oral commun., 2010). These three 

sites have a total annual-removal limit of approximately 17,200 m3

.

In Oregon, topographic surveys of sites before and after instream gravel extraction are 

required by regulatory agencies to document bar 

conditions and total removal volumes. For 

Hunter Creek, recent survey data were only 

available for Menasha and Ringer Bars (Dan 

Crumley, Curry County Road Department, written commun., 2010). Although no mining 

occurred at Menasha Bar from 2002 to 2005, 

annual removal volumes ranged from 2,746 to 

6,187 m3

at this site from 2006 to 2010 (fig. 4 

and table 5). Likewise, Ringer Bar was not 

mined from 2003 to 2006, but was mined for 

1,898 to 2,943 m3

of gravel from 2007 to 2010 

(fig. 4 and table 5). While pre- and postextraction surveys for the Menasha and Ringer 

Bars do not report annual-replenishment volumes, repeat cross-sections of the mined areas 

indicate that deposition during winter months 

rebuilds mined surfaces to approximately their 

pre-mining elevations. These surveys, however, 

also show that these sites are dynamic and subject to local scour and deposition. Therefore, a 

more detailed analysis of the survey data for these sites as well as the Conn Creek Bar would 

assist in accurately assessing bar-replenishment 

rates and changes in bar morphology at active 

instream gravel-extraction sites. 
 

20

Compilation and Review of Bridge-Inspection 

Reports 

The Oregon Department of Transportation 

(ODOT) conducts periodic bridge inspections to 

assess overall bridge condition, footing stability, 

and scour. Information from these assessments 

can be useful for evaluating channel condition. 

Since 1994, ODOT completed bridge-inspection 

reports for the following four bridges (fig. 3D) 

spanning the main channel in the Hunter Creek 

study area (Oregon Department of Transportation, 2010): 

Hunter Creek Road bridge, RKM 9.1 

Hunter Creek Road bridge, RKM 3.5 

Hunter Creek Road bridge, RKM 0.6 

Highway 101 bridge, RKM 0 

Our review of the bridge-inspection reports 

for these four sites focused primarily on comparing repeat channel cross-sections and secondarily 

on reviewing supplemental data such as underwater reports, photographs, and scour 

assessments, which also are helpful for assessing 

channel condition adjacent to these bridges. 

Channel cross-section surveys were collected at three bridges in 1994, 2004, and 2008 

(fig. 5A–C) and at the Highway 101 bridge near 

the mouth in 1998 and 2010 (fig. 5D). Repeat 

channel cross-sections taken near the Hunter 

Creek Road bridge at RKM 9.1 show that the 

elevation of the thalweg has remained similar 

over time even though the channel has shifted 

from bank to bank between surveys (fig. 5A). 

The thalweg near the Hunter Creek Road bridge 

at RKM 3.5 maintained a similar elevation while 

shifting its position and depositing nearly a meter of material along the left bank from 1994 to 

2004, which was followed by 0.55 m of aggradation from 2004 to 2008 (fig. 5B). 

Farther downstream, near the Hunter Creek 

Road bridge at RKM 0.6 (fig. 5C), the channel 

aggraded from 1994 to 2004, resulting in nearly 

2 m of deposition along the left side of the channel and 0.84 m of deposition in the thalweg. 

From 2004 to 2008, however, the channel incised through this fill, resulting in a 2008 cross 

section that resembles the 1994 cross-section and 

little net change in elevation from 1994 to 2008 

(fig. 5C). At Hunter Creek near the Highway 101 

bridge, repeat surveys from 1998 and 2010 show 

that this cross-section has remained relatively 

stable with little net change (< 0.3 m) in bed elevation for much of the cross section (fig. 5D). 
 

21

Figure 5. Repeat channel cross-sections collected by Oregon Department of Transportation at Hunter Creek 

Road crossings at (A) river kilometer (RKM) 9.1, (B) RKM 3.5, and (C) RKM 0.6, as well as (D) Highway 101 

bridge crossing at RKM 0. Water elevation, where available, is indicated on the cross-sections over the thalweg. 

Cross-sections are shown looking downstream. 
 

22

The bridge-inspection reports also state that 

the channel near all of the Hunter Creek Road 

bridges is prone to some level of bank slumping, 

and scour and erosion varies considerably from 

site to site. For example, the channel near the 

Highway 101 bridge is considered a low scour 

risk because of the influence of tide even though 

scour at the RKM 0.6 bridge led to undermining 

of the piers, resulting in an ―unstable‖ rating. 

Combined, the bridge-inspection reports show 

that the channel at these bridge crossings is dynamic and subject to frequent channel shifting, 

aggradation, and incision. Despite this dynamism, the limited cross-section data reviewed in 

this study indicate that the channel near RKM 

3.5 was the only location to experience substantial net change (+0.55 m in thalweg elevation) 

from 1994 to 2004. The channel at RKM 9.6 and 

0 showed little net change in channel morphology or thalweg elevation between the first and last 

surveys, whereas the elevation of the thalweg at 

RKM 0.6 increased 0.84 m from 1994 to 2004, 

but did not exhibit substantial net change from 

1994 to 2008. 

Repeat Delineation of Gravel Bars, Channel 

Centerlines, and Channel Width, 1940–2009 

Using the Geographic Information System 

(GIS) program ESRI ArcMap 9.3.1, we digitized 

gravel bars, channel centerlines, and wettedchannel edges throughout the study area from 

aerial photographs collected in 1940, 1965, 

2005, and 2009 (table 4) to assess spatial and 

temporal trends in bar and channel features. 

Scanned black-and-white photographs from 1940 

and 1965 were acquired from the University of 

Oregon Map Library and georeferenced using 

techniques similar to those in Wallick and others 

(2011). For mapping purposes, gravel bars were 

defined as exposed bed-material sediments 

greater than 200 m2in area and included both 

lateral and medial bars. 

Although bars were not classified according 

to grain size, field observations made during July 

2010 indicated that most bars, including those in 

the tidally affected portion of the Lower Study 

Reach, mainly were composed of gravel. Most of 

the mapped bars had little to no vegetation, but 

some bars had small areas that were partly or 

wholly covered by grasses, shrubs, and (to a 

lesser extent) mature trees. 

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). Aerial 

photographs of the Hunter Creek study area were 

of sufficient resolution (table 4) and generally 

free of glare and shadow, enabling precise mapping. The 1940 and 1965 photographs were 

georeferenced with a minimum of 15 groundcontrol points concentrated near the main channel and rectified with a second-order polynomial 

transformation. The total root mean square error 

(RMSE) values of the rectified photographs from 

1940 and 1965 indicated that horizontal-position 

uncertainties associated with the georectification 

process ranged from 2.9 to 5.9 m, but averaged 

5.8 m for the 1940 photographs and 3.7 m for the 

1965 photographs. Since control points were 

concentrated near the channel, error associated 

with mapped features along channel corridor 

should be lower than the total RMSE values for 

the entire photograph. Delineation of bars, channel centerlines, and wetted-channel edges at a 

scale of 1:2,000 was verified by project team 

members to ensure consistent delineation of features among years and throughout the study area 

and consistency with the delineation protocol of 

Wallick and others (2011). Lastly, while streamflow on the dates of aerial-photograph 

acquisition is unknown, all aerial photographs 

used in this study were acquired during low-flow 

months (table 4), minimizing potential mapping 

error introduced by flow variations. 
 

23

Results for Repeat Bar Delineation, 1940–2009 

The total area of gravel bars delineated within the 12.4-km long study reach was 502,230 m2

in 1940, 363,150 m2in 1965, and 236,100 m2in 

2005 (table 6). From 2005 to 2009, total bar area 

remained relatively stable, increasing by 2 percent to 240,520 m2

. In 2009, unit bar area, or the 

total area of gravel bars per meter of channel 

(m2/m), equates to 19.4 m2/m. This value exceeds similar measurements for the bedrockdominated Umpqua River, which drains an area 

nearly 41 times larger than Hunter Creek (unit 

bar area was 5–18 m2/m for fluvial reaches on 

the Umpqua River; Wallick and others, 2011). 

For comparison, the gravel-rich Chetco River 

basin is about eight times the size of the Hunter 

Creek basin and had approximately 49.9 m2of 

gravel bars per meter of channel in 2005 within 

its 18.4-km long study area (Wallick and others, 

2010).

Examination of the repeat delineation of 

gravel bars shows that the location, abundance, 

and size of gravel bars in Hunter Creek mainly 

dictated by valley physiography and the associated increase in valley width as the river 

approaches its mouth. Historically, smaller bars 

were located in confined segments such as the 

narrow canyon extending from RKM 6 to 8.4 

(figs. 6A and 7). Conversely, the largest dynamic 

bars were located in wide areas of the floodplain 

including RKM 0–3 (figs. 6A and 8) in the Lower Study Reach and RKM 8.4–9 in the Upper 

Study Reach and are associated with channel 

shifting, bar growth, and erosion.
 

24

Table 6. Summary of changes in bar features and channel length, 1940–2009, for the Hunter Creek study area, southwestern Oregon.

[m2, square meter; km, kilometer; m

2

/m, square meter per meter (bar area per meter of channel)]

Entire study area Lower Study Reach Upper Study Reach

1940 1965 2005 2009 1940 1965 2005 2009 1940 1965 2005 2009

Total area of 

gravel bars 

(m2)

502,230 363,150 236,100 240,520 296,470 171,710 113,500 114,580 205,750 191,440 122,600 125,940

Unit bar area, 

normalized by 

2009 centerline 

length (m2/m)

40.5 29.3 19.0 19.4 49.4 28.6 18.9 19.1 32.1 29.9 19.1 19.7

Percent net 

change in bar 

area, 1940–

2009

-52 -61 -39

Number of 

bars 71 70 96 82 29 32 43 41 42 38 53 41

Average gravel 

bar area (m2)

7,070 5,190 2,460 2,930 10,220 5,370 2,640 2,790 4,900 5,040 2,310 3,070

Maximum 

gravel bar area 

(m2)

52,610 36,010 32,050 19,090 52,610 28,790 32,050 19,090 39,640 36,010 15,980 15,900

Channel centerline length 

(km)

12.6 12.6 12.5 12.4 6.1 5.9 6.0 6.0 6.5 6.7 6.5 6.4

Percent net 

change in 

channel centerline length, 

1940–2009

-1.3 -1.6 -1.1
 

25

Figure 6. (A) Distribution and size of gravel-bar accumulations and (B) wetted-channel width by river kilometer 

transect as mapped from 1940, 1965, 2005, and 2009 aerial photographs for the Hunter Creek study area, southwestern Oregon. Note: The study area ended at river kilometer 12.4 and, thus, this transect includes data for only 

0.4 kilometer. 
 

26

Figure 7. Examples of gravel bars and wetted channel edge as delineated from 1940, 1965, 2005, and 

2009 aerial photographs for river-kilometer transects 6–8, where the active channel is confined in the 

Hunter Creek study area, southwestern Oregon. 
 

27

Figure 8. Examples of gravel bars and wetted channel edge as delineated from 1940, 1965, 2005, and 

2009 aerial photographs for river kilometers 1–3, where the active channel is unconfined in the Hunter 

Creek study area, southwestern Oregon. 
 

28

Throughout the Hunter Creek system, areal 

coverage of gravel bars has declined 52-percent 

since 1940 (fig. 9 and table 6). Bars near the 

mouth of Hunter Creek deviated from the overall 

systemwide decline, increasing substantially 

from 1965 to 2005, likely following captures of 

two floodplain pits and deposition and reworking 

of bed-material on river right (figs. 6A and 10). 

This increase in bar area near the mouth also 

may be affected by differences in tide levels at 

the time of aerial-photograph acquisition. 

Figure 9. Gravel bar area for the two study reaches (denoted by bars) and study area (denoted by line) as delineated from aerial photographs dated 1940, 1965, 2005, and 2009 for Hunter Creek, southwestern Oregon,. 
 

29

Figure 10. Gravel bars and wetted channel edge as delineated from 1940, 1965, 2005, and 2009 aerial photographs for the mouth of Hunter Creek, southwestern Oregon. The lower 2.2 kilometers of Hunter Creek are tidally 

influenced. Approximate bridge locations are denoted by river kilometer (RKM) 

Although the total area of bars has decreased 

substantially since 1940, the number of bars has 

not changed systematically. Consequently, the 

loss of bar area mostly is the result of individual 

bars becoming smaller, with average bar size 

diminishing from 7,070 m2

in 1940 to 2,930 m2

in 2009 (table 6). 

The apparent overall reduction in bar area 

along Hunter Creek may be partly owing to some 

challenges in delineating bar surfaces. In particular, distinguishing the boundary between bar 

surfaces and the floodplain in the aerial photographs collected in 1940 was difficult, possibly 

leading to some overestimation of bar area for 

this year. Ambiguity in delineating the outer 

boundary of bars from the 1940 photographs, 

however, is not a factor in the large decline in 

bar area evident in the much clearer 1965 and 

2005 photographs. 

Changes in bar area primarily are associated 

with the conversion of bare-bar surfaces to vegetated or developed surfaces. Development on 

former bar surfaces resulted in local declines in 

bar area (fig. 10). However, the greatest source 

of bar loss occurred as bar surfaces that were 

bare in 1940 became increasingly vegetated, 

likely with grasses and shrubs, in 1965 and 2005. 
 

30

Because we defined and delineated gravel 

bars as exposed bed-material sediment, increases 

in vegetation at the expense of bare bars resulted 

in a reduction in mapped bar surfaces. Although 

these relict bar surfaces may be stabilized with 

vegetation and are therefore not mapped as bars, 

the underlying substrate remains available for 

future erosion and transport during high-flow 

events. Vegetation establishment on bar surfaces 

was especially pronounced along the historically 

dynamic, gravel-rich areas from RKM 1 to 2 

(fig. 8) and near RKM 4 and coincided with 

large local losses in bar area (fig. 6A). Vegetation encroachment was minimal in the confined, 

upper 1.4 km of the study area (fig. 7). Further 

analysis of the trends in active channel width and 

vegetation coverage by type may provide additional insight into the mechanisms driving bar 

loss along Hunter Creek. 

Similar patterns of bar loss owing to vegetation encroachment have been documented in the 

nearby Chetco River (Wallick and others, 2010) 

and Umpqua River (Wallick and others, 2011). 

In both basins, vegetation establishment on upper bar surfaces mainly followed the December 

1964 flood and was attributed primarily to declines in peak flows, which probably owe to 

long-term climate cycles. The Oregon Coast 

generally experienced cool, wet conditions from 

1946 to1976, but the period since 1976 has been 

overall warmer and drier with intermittent, shorter periods of cool, wet years (George Taylor,

Oregon Climate Service, written commun., 

1999).

Results for Channel Planform and Width, 

1940–2009 

Comparison of channel centerline length 

over time reveals that channel length has decreased by 1.3-percent throughout the study area 

from 1940 to 2009 with both reaches losing a net 

0.1 km of centerline length (table 6). Specific 

areas with substantial channel shifting include 

RKM 0–0.6, 1.6–2.6, and 3.8–4.8 (figs. 8 and 

10).

Comparison of wetted-channel width over 

time indicates some subtle changes in width 

from 1940 to 2009 (fig. 6B) such as near the 

mouth of Hunter Creek. However, these results 

do not indicate systemwide or systematic changes in width and do not correspond directly with 

changes in bar area. This preliminary analysis of 

wetted-channel width does not indicate channel 

incision or aggradation. More detailed delineation of the active-channel width (instead of 

wetted-channel width, which can be influenced 

by small differences in streamflow or tide) may 

help better quantify possible changes in channel 

width throughout the study area. 

Road encroachment and mining of gravel 

bars, two direct disturbances to the active channel of Hunter Creek, have had no clear effect on 

channel planform. Hunter Creek Road, constructed in the 1940s, impinges in several places 

upon the historical active channel (fig. 3). The 

road alignment, however, does not appear to 

have had a substantial effect on subsequent 

channel change (fig. 11). The three Hunter Creek 

Road bridge crossings were constructed at confined, stable segments that do not show major 

planform changes from 1940 to 2009 (for example, the Hunter Creek bridge crossing near RKM 

3.5 shows only minor changes in bar area, fig. 

11). 

Hunter Creek Road was constructed on three 

surfaces mapped as bars in 1940 (such as RKM 

4.5, 7.6, and 9.6). In all instances, however, 

reachwide vegetation encroachment and localized development appear to have had larger 

impacts on local bar loss than road building (as 

illustrated for RKM 4.5, fig. 11). This assessment, however, does not take into account 

possible fill activities associated with road construction and subsequent protection. 

Additionally, road crossings throughout the river 

basin may increase erosion and fine sediment 

inputs that can cause subtle changes in pool 

morphology. Such possible changes in the 

transport and deposition of fine sediment were 

not addressed by this study. 
 

31

Figure 11. Examples of gravel bars and wetted channel edge as delineated from 1940, 1965, 2005, and 2009 

aerial photographs for sections where the Hunter Creek Road has impinged on the historical active channel in the 

Hunter Creek study area, southwestern Oregon. 

At the three active in-channel gravelextraction sites, the position of the channel has 

been nearly stable since the 1965 photographs 

(fig. 12, next page). Although bar area has decreased from 1940 to 2009 at the three extraction 

sites, these declines are consistent with reductions throughout the study area and are not 

obviously attributable to local gravel extraction. 

Future analyses of temporal changes in channel 

width, sinuosity, and bar morphology based on 

aerial photographs and LiDAR would be useful 

in discerning whether mined sites have been specifically affected. 

Bed-Material Particle-Size Analyses 

During the July 2010 reconnaissance trip, 

we measured surface particle-size distributions 

and collected subsurface bulk samples at two 

actively mined gravel bars in the study area: 

Menasha Bar (RKM 4.1) in the Lower Study 

Reach and Conn Creek Bar (RKM 9.7) in the 

Upper Study Reach (fig. 12). Samples were collected prior to the annual mining of these sites. 

At each site, the diameter of 200 surface particles 

was measured using a modified grid technique 

(Kondolf and others, 2003) such that measurements were taken at 0.3-m increments along two 

parallel 30-m tapes (fig. 13A–D). The tapes were 

spaced 1–2 m apart and were aligned parallel to 

the long axis of the bar. Clast-diameter measurements were made using an aluminum 

template (Federal Interagency Sediment Project 

US–SAH-97 Gravelometer) that enables standardized measurement of sediment clasts greater 

than 2 mm in diameter. Bulk samples of subsurface material were collected at the same 

locations as the surface-measurement sites by 

removing approximately 0.5 to1 m2of barsurface material and then collecting 65–78 kg of 

bar-substrate material. The bulk samples then 

were dried and analyzed for 1⁄2-phi particle sizes 

by the U.S. Geological Survey Sediment Laboratory in Vancouver, Washington. 
 

32

Figure 12. Gravel bars and wetted channel edge as delineated from 1940, 1965, 2005, and 2009 aerial photographs for Menasha Bar (river kilometer [RKM] 4.1), Ringer Bar (RKM 4.7), and Conn Creek Bar (RKM 9.7) along 

Hunter Creek, southwestern Oregon. 
 

33

Figure 13. Bed-material-sampling sites at Conn Creek (A–B) and Menasha (C–D) Bars along Hunter Creek, 

southwestern Oregon. 
 

34

Bar-surface material was approximately 

equal in size to bar-subsurface material at Conn 

Creek Bar, whereas it was distinctly coarser than 

the bar-subsurface material at Menasha Bar 

(fig. 14A–B). A relatively coarse surface layer 

(or armoring) is typical for gravel-bed rivers and 

can be the result of selective scouring of fine 

sediments or selective deposition of larger particle clasts (Bunte and Abt, 2001). Calculating the 

armoring ratio, or the ratio of the median grain 

sizes (D50) of the surface to subsurface layers, 

provides an indication of the degree of armoring. 

This ratio typically is close to 1 for rivers with a 

high sediment supply and approaches or exceeds 

2 for supply-limited rivers (Bunte and Abt, 

2001). The calculated armoring ratios were 0.97 

and 1.5 at Conn Creek and Menasha Bars, respectively, which are consistent with high bedmaterial transport rates (fig. 14A–B). For comparison, most armoring ratios reported for the 

Chetco and Umpqua Rivers exceeded 1.5 (Wallick and others, 2010; 2011). Because bar texture 

can vary greatly between sites on gravel-bed 

rivers (Wilcock and others, 2009), analyses including additional sampling at sites without 

recent gravel mining or recreational disturbance 

would refine assessments of transport and sediment-supply conditions and longitudinal trends 

in bed-material (fig. 14C). 

 

Figure 14. Size distributions of surface and subsurface particles collected in July 2010 at two sites along 

Hunter Creek, southwestern Oregon. Surface-particlesize distributions were sampled by a count of 200 

clasts; subsurface distributions were sampled from 

bulk sample below the armor layer. (A) particle data 

for the Conn Creek Bar, (B) particle data for the 

Menasha Bar, and (C) comparison of bar-surface 

particle sizes at the two bars. D50 is the measured 

median particle size in millimeters.
 

35

Summary of Findings

On the basis of field observations, delineation of bar and channel features from aerial 

photographs, and review of existing datasets and 

studies, the lower 12.4 km of the Hunter Creek 

study area is logically divided into two study 

reaches: (1) the Upper Study Reach, where the 

relatively narrow channel is confined by a bedrock canyon in its upper 1.4 km and then fully 

alluvial in its lower 5 km with smaller bars, and 

(2) the Lower Study Reach, where the channel is 

completely alluvial, generally wider, and more 

dynamic and has larger bars. Both reaches contain locally confined and unconfined segments as 

well as gravel bars used for historical and ongoing aggregate extraction. 

Table 7 contains a summary of project findings by dataset and reach. Repeat delineation of 

gravel bars shows that bar area throughout the 

study area declined 52 percent from 1940 to 

2009 (table 6). Bar loss was greatest in the lower 

6 km of Hunter Creek (table 6, fig. 9, and 

table 7). 

Some of the apparent loss in bar area possibly 

owes to mapping uncertainties; however, our 

preliminary assessment is that encroachment of 

vegetation onto the upper bar surfaces and subsequent stabilization of these formerly active 

surfaces likely caused this bar loss (such as 

shown in fig. 8). Vegetation encroachment and 

associated declines in bar area possibly were 

associated with long-term reductions in peak 

flows as noted for the Chetco and Umpqua Rivers (Wallick and others, 2010; 2011). During the 

December 1964 flood, the Chetco and Umpqua 

Rivers experienced extensive vegetation removal 

and sediment deposition on upper bar surfaces, 

leading to substantial increases in bar area on 

both rivers (Wallick and others, 2010; 2011). 

Because Hunter Creek experienced a 28-percent 

loss in bar area from 1940 to 1965 (table 6), indicating a muted response to this flood event, 

further investigation of peak-flow patterns in the 

basin would be helpful for understanding channel and bed-material responses to peak-flows 

over time. 

Table 7. Summary of findings for the Hunter Creek study area, southwestern Oregon—continued.

[RKM, river kilometer; km, kilometer; NA, not applicable; D50, median grain diameter; mm, millimeter]

Dataset Lower Study Reach (RKM 0–6) Upper Study Reach (RKM 6–12.4)

Review of previous 

studies

Incision, bank instability, and loss of point bars 

and pools noted in lower 3.9 km (EA Engineering, Science, and Technology, 1998).NA

Qualitative review of 

pre and post extraction 

surveys, 2006–10

Surveys tentatively indicate that the Menasha 

and Ringer Bars sites are: (1) dynamic with 

annual deposition and erosion, and (2) re-built 

by deposition post-mining to approximately 

pre-mining elevations.

NA

Comparison of repeat 

cross-section surveys 

collected at bridge 

crossings, 1994–2010

The channel at RKM 3.5 shifted between 1994 

and 2004, then aggraded 0.55 m in thalweg 

elevation between 2004 and 2008. Otherwise, 

the channel at RKM 0 and 0.6 had little net 

change between surveys.

The channel at RKM 9.1 shifted position between 1994 and 2004, but was otherwise stable 

with no substantial changes in thalweg elevation.

Repeat mapping of 

bar area and centerline 

length, 1940–2009 

Bar area decreased 61 percent from 1940 to 

2009. This loss was greatest in RKM 0–4. 

Centerline length decreased 0.1 km from 1940 

to 2009.

Bar area decreased 39 percent from 1940 to 

2009. This loss was greatest in RKM 7–9. 

Centerline length decreased 0.1 km from 1940 

to 2009.

Particle size data collected in July 2010At Menasha Bar, surface D50 = 27.3 mm, subsurface D50 = 18.1 mm; Armoring ratio = 1.5.At Conn Creek Bar, surface D50 = 14.3 mm, 

subsurface D50 = 14.7 mm; Armoring ratio = 

0.97.
 

36

Table 7. Summary of findings for the Hunter Creek study area, southwestern Oregon—continued.

[RKM, river kilometer; km, kilometer; NA, not applicable; D50, median grain diameter; mm, millimeter]

Dataset Lower Study Reach (RKM 0–6) Upper Study Reach (RKM 6–12.4)

Summary Dynamic alluvial channel has capacity for both 

lateral and vertical adjustments in channel 

position. Large declines in bar area tentatively 

correspond with slight loss in centerline length. 

Repeat cross-section surveys and field observations do not indicate obvious recent incision. 

Additional analyses are needed to determine 

cause of bar loss and verify incision noted by 

previous study.

Uppermost 1.4 km of channel stable with little 

likelihood of long-term incision due to confinement by bedrock canyon. Between RKM 6 

and 11, the channel is predominantly alluvial 

and subject to channel shifting, bar growth, and 

erosion. Although bar area has declined substantially between 1940 and 2009, repeat 

surveys and armoring ratio indicate tentative 

balance between sediment supply and transport 

capacity.

Additionally, reductions in bar area also 

may have been affected by incision (EA Engineering, Science, and Technology, 1998). 

Reconnaissance-level field observations, an 

analysis of wetted-width changes, and repeat 

channel cross-sections reviewed in this study, 

however, do not indicate substantial bed lowering. Channel length throughout the study area 

remained relatively stable, declining 0.1 km in 

both reaches, over the 69-year analysis period. 

Areas with substantial channel shifting and decreased sinuosity do coincide with areas of 

substantial bar loss (for example RKM 1.4–2.8 

and 4.2–4.8). Although such findings may be 

indicative of local incision, they also may reflect 

that the Hunter Creek channel is dynamic and 

subject to lateral channel shifting, bar growth, 

and erosion. 

Particle-size measurements from two actively mined sites broadly support the findings from 

the repeat bar mapping and cross-section surveys. Armoring ratios at Conn Creek Bar (RKM 

9.7) and Menasha Bar (RKM 4.1) were 0.97 and 

1.5, respectively, indicating that sediment supply 

is approximately balanced by transport capacity. 

In summary, although Hunter Creek is tidally affected in its lowermost 2.2 km, gravel bars 

extend to the frequently shifting mouth of the 

river (fig. 10), indicating substantial gravel 

transport through the reach and to the Pacific 

Ocean. Gravel transport and deposition evidently 

have kept pace with Holocene sea-level rise, 

filling the incised valley and creating a gradedriver profile to the sea and the lack of a fluvial 

estuary. These aspects of river and valley character, in conjunction with the nearly continuous 

alluvial channel in the lower 11 km and presence 

of bars to the mouth of the river, are strong evidence that bed-material transport to and through 

the Hunter Creek study area is ―transportlimited‖ in the sense that bed-material transport 

depends on flow and bed-material characteristics 

rather than on bed-material supplied to the study 

area. In this respect, Hunter Creek is more similar to the Chetco River (Wallick and others, 

2010) than the supply-limited Umpqua River 

(Wallick and others, 2011). 

Outstanding Issues and Possible 

Approaches

This reconnaissance-level analysis provides 

a framework and baseline information for understanding bed-material transport in the Hunter 

Creek basin. Future efforts addressing several 

data gaps and issues as well as key analyses (as 

outlined below) could greatly refine the understanding of historical and ongoing bed-material 

transport processes and their effects on channel 

morphology. Additionally, addressing and understanding these data gaps would provide a 

solid basis for evaluating future hydrologic and 

geomorphic changes in the Hunter Creek system. 
 

37

Hunter Creek Streamflow 

Modeling and predicting bed-material 

transport require high-quality streamflow information, particularly for peak flows. As of 2011, 

no streamflow-gaging station is operated routinely in the lower Hunter Creek basin. Although 

this study used regional-regression equations to 

estimate discharge for a range of flood events, 

these estimates include considerable uncertainty 

(table 2). For predicting bed-material transport 

within the study reach, such a gaging station 

optimally would be located near the upstream 

boundary of the study area such as the Hunter 

Creek Road bridge crossing at RKM 9.1 downstream of the confluence of Conn and Hunter 

Creeks. Additionally, repeat measurements of 

stage and discharge (obtained by USGS technicians during routine maintenance of the gage) 

form the basis of a specific gage analysis and 

could be used to track local changes in bed elevation over time following the approach used on 

the Chetco and Umpqua Rivers by Wallick and 

others (2010; 2011). 

Bed-Material Transport Rates and Sediment 

Budget 

Understanding possible effects of instream 

gravel extraction 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 owing to particle attrition, 

transport, and storage. Such information would 

support a comparison of the volumes of gravel 

extracted from the system by ongoing mining 

activities relative to gravel delivered to the study 

area. An approach for expediently developing 

this sediment budget might include the following 

components: 

1. Estimate sediment flux based upon equations of bedload transport. This approach 

will require installation of a streamflowgaging station (as described above) and 

subsequent calculations of bedload 

transport using methods similar to those 

used on the Chetco River by Wallick and 

others (2010). A hydraulic model would 

enable more accurate estimations of energy slope (a critical component to the 

transport calculations), and facilitate 

transport capacity estimates for sites 

throughout the study area. Because 

Hunter Creek is mainly a single-thread 

channel, a one-dimensional model as developed for the Chetco River (Wallick 

and others, 2010) would probably be sufficient for estimating bed-material flux at 

the reach scale. 

2. Collect direct measurements of bed-load 

transport in order to verify equations for 

bed-load transport and estimate actual 

bed-load fluxes. If possible, such measurements would be collected at a site of 

continuous-discharge measurement. The 

Hunter Creek Road bridges at RKM 9.1 

and 3.5 are possible locations for highquality bed-load measurements. 

3. Estimate sediment flux based on mapped 

changes in bar area between two time periods, in a manner similar to the 

morphological approach used on the 

Chetco River by Wallick and others 

(2010). Ideally, this approach would use 

LiDAR data from two periods to directly 

calculate volumetric change in sediment 

storage. This method, however, also can 

be implemented using sequential aerial 

photographs along with a single LiDAR 

survey, such as the survey available for 

much of the Hunter Creek study area (table 4). Despite the inherent uncertainties 

associated with this type of analysis 

(Wallick and others, 2010), such data and 

analyses can support efficient monitoring 

of long-term changes in channel and 

floodplain conditions. 

4. Review of pre- and post-gravel-extraction 

surveys. In-depth and comprehensive review of all mining surveys on Hunter 

Creek may provide insight into estimates 
 

38

of coarse-gravel recruitment. While these 

surveys are subject to uncertainties and 

limitations and may be missing for some 

years and locations, all available data on 

gravel replenishment would help reduce 

uncertainty in sediment-flux estimates at 

extraction sites. 

5. Assess bed-material composition 

throughout the study area. Additional observations of particle sizes would be 

required for calculating bed-material 

transport and also may support assessments of temporal changes in bedmaterial composition in conjunction with 

other study components. 

Detailed Channel-Morphology Assessment 

In this study, we delineated bar surfaces 

from aerial photographs taken in four different 

years, spanning 1940–2009, and found that bar 

area throughout the study area declined by 52-

percent from 1940 to 2009 (table 6). This 

mapping could serve as the starting point for 

more detailed and comprehensive temporal analyses of morphological trends in Hunter Creek. In 

particular, possible drivers of the reduction in bar 

area include (1) vegetation encroachment onto 

previously active bar surfaces, (2) long-term 

decreases in peak flows, (3) lowering of the 

channel bed, and (4) other causes. To address 

each of these issues and better explain the large 

net decrease in bar area for Hunter Creek would 

require a comprehensive approach, drawing upon 

the following elements: 

1. Detailed mapping of land cover for the 

lower 12.4 km of the Hunter Creek 

floodplain and for multiple time periods. 

This effort would involve delineating the 

active floodplain or floodplain features 

based on vegetation density, which may 

eliminate problems associated with determining the bar–floodplain boundary. 

Examining temporal changes in bare and 

vegetated surfaces would allow a more 

quantitative assessment of erosion, deposition, and vegetation colonization during 

different periods and enable a more complete description of the processes driving 

bar evolution. Assessment of overall bar 

condition and evolution would benefit 

from supplemental bar delineations from 

aerial photographs collected in the early 

1960s, 1970s, and 1990s.

2. Detailed mapping of channel features 

immediately before and after major 

floods to assess channel response to different magnitude floods and, ultimately, 

sediment flux and channel evolution in 

Hunter Creek. Possible floods for focusing this effort include the events of 

December 1964, November 1996, and 

January 1997. This effort optimally 

would be conducted in tandem with the 

construction a flood history for the basin. 

3. Assessment of the potential relationship 

between vegetation encroachment 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). Determining 

whether a similar process of vegetation 

encroachment owing to decreasing peak 

flows is responsible for bar loss in the 

Hunter Creek basin would require estimation of historical-flood discharges, as 

described above. Additionally, determining the linkages between peak flows in 

Hunter Creek and climate factors related 

to flood peaks, such as the Pacific Decadal Oscillation, could support inferences 

of likely future changes in vegetation and 

overall channel conditions. 

4. Investigation of planform changes and 

possible bed-level lowering. Although 

the preliminary analyses and datasets reviewed in this study do not indicate 

substantial incision along Hunter Creek, 

further investigations of planform evolution and bed-level lowering are warranted 

to determine whether local incision, par-
 

39

ticularly in the lower 3.9 km of Hunter 

Creek, has contributed to reachwide decreases in bar area. Since historical 

longitudinal surveys of the channel are 

unavailable, additional assessments of incision would rely upon detailed mapping 

of the active-channel features from different time periods and analysis of 

changes in channel width and sinuosity. 

Additional sources of data that may help 

to assess bed-level lowering include interviews with local landowners and a 

detailed assessment of bank stratigraphy 

in the lower 3.9 km. 

5. More detailed review of the data available for bridges. A review of the as-built 

surveys and construction plans for publicly owned bridges on Hunter Creek may 

yield the data necessary to assess sediment thickness and changes in bed 

elevation. Construction plans, permits, 

and investigations of bridges owned by 

Curry County and private landowners also may yield useful information. 

6. More detailed mapping and assessment 

of vegetation along the Hunter Creek corridor to assess (a) possible changes in the 

types of vegetation (such as invasive or 

water-tolerant species) present on bar surfaces over time and (b) broader linkages 

between riparian ecology, bar evolution, 

and flood histories. 

7. Assess historical land-use activities, including timber-harvest practices, road 

building, and placer mining that may 

have contributed to changes in channel 

morphology and sediment-transport processes. Such information may be found 

through interviews with local landowners

and historical documents available from 

historical societies, museums, and government records.

Legacy and Ongoing Effects of Land-Use 

Activities 

Anthropogenic activities such as logging, instream gravel mining, and road placement likely 

affect sediment transport and deposition dynamics in Hunter Creek to varying degrees over time 

and throughout the river network. Quantitatively 

assessing the role of these factors on sediment 

dynamics would be challenging owing to likely 

interactions among these factors as well as their 

interactions with background and physical controls on sediment dynamics, such as basin 

topography, channel slope, geology, and hydrology. Yet, such an assessment would provide 

insight into sediment dynamics and may be more 

feasible in the Hunter Creek basin than other 

coastal basins. 

Geomorphic and hydrologic processes often 

are altered by dredging, fire, flow regulations 

and dams, and substantial placer and hydraulic 

mining in coastal Oregon rivers such as the 

Chetco, Umpqua, and Rogue, but to a lesser extent in Hunter Creek. The preliminary 

morphological assessment presented in this report shows that the gravel bars are present 

throughout the study area and to the mouth of the 

river. Further investigations of fine- and coarsesediment inputs associated with land-use activities may provide information on the relative 

fluxes of different clast sizes delivered to the 

study area and on an annual basis. An approach 

for investigating the relative importance of past 

activities on overall sediment dynamics would be 

to: 

1. Determine the distribution of areas of active gravel transport and deposition and 

analyze temporal trends in channel and 

floodplain morphology with respect to 

land-use disturbances. 

2. Assess changes in bar area and channel 

planform near historical gravel-extraction 

sites; Pratt (2004) reported a total of eight 

instream extraction sites along Hunter 

Creek in 1972. 
 

40

3. Determine the relative contributions of 

fine and coarse sediments to the study area and identify storage and transport 

reaches and associated areas where fine 

sediments may fill in pool features. 

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 project was administered by Judy 

Linton along with Bill Ryan and Pamela Konstant of the Oregon Department of State Lands. 

Tana Haluska, USGS Oregon Water Science 

Center, contributed to topographic analyses. 

Field assistance was provided by Xavier Rodriguez Lloveras, National Museum of Natural 

Science, Spanish National Research Council, 

Spain. Information on past gravel mining and 

detailed topographic surveys of mining sites was 

graciously provided by Dan Crumley of the Curry County Road Department. Access to Conn 

Creek Bar was courteously provided by Thomas 

Leith. Copies of Maguire (2001), EA Science, 

Technology, and Engineering (1998), and Pratt 

(2004) were graciously provided by Pam Blake, 

Oregon Department of Environmental Quality, 

Cindy Myers, South Coast and Lower Rogue 

Watershed Councils, and Jodi Fritts, Curry 

County Department of Public Services, respectively. Scanned copies of the 1940 and 1965 

aerial photographs and a summary of available 

photographs were provided by University of Oregon Map Library personnel. Two colleagues 

provided insightful comments that improved this 

report. 

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