NOAA Technical Memorandum NMFS-NWFSC-120

Working with Beaver to Restore 

Salmon Habitat in the Bridge Creek 

Intensively Monitored Watershed

Design Rationale and Hypotheses

October 2012

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Northwest Fisheries Science Center
NOAA Technical Memorandum

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Marine Fisheries Service, NOAA, uses the NOAA Technical 

Memorandum NMFS-NWFSC series to issue scientific and 

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and edited. Documents published in this series may be cited 

in the scientific and technical literature.

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Memorandum series is now used by the Alaska Fisheries 

Science Center.

Reference throughout this document to trade names does not 

imply endorsement by the National Marine Fisheries Service, 

NOAA.

This document should be referenced as follows:

Pollock, M.M., J.M. Wheaton, N. Bouwes, C. Volk, 

N. Weber, and C.E. Jordan. 2012. Working with beaver 

to restore salmon habitat in the Bridge Creek intensively 

monitored watershed: Design rationale and hypotheses. U.S. 

Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-120, 

47 p.
NOAA Technical Memorandum NMFS-NWFSC-120

Working with Beaver to Restore 

Salmon Habitat in the Bridge Creek 

Intensively Monitored Watershed

Design Rationale and Hypotheses

Michael M. Pollock, Joseph M. Wheaton,1 Nick Bouwes,2

Carol Volk,3 Nicholas Weber,2 and Chris E. Jordan

Northwest Fisheries Science Center

2725 Montlake Boulevard East

Seattle, Washington 98112

1

Utah State University

Watershed Sciences Department

5210 Old Main Hill

Logan, Utah 84322

2

Eco Logical Research, Inc.

456 South 100 West

Logan, Utah 84321

3

South Fork Research, Inc.

44842 Southeast 145 Street

North Bend, Washington 98045

October 2012

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service
Most NOAA Technical Memorandums

NMFS-NWFSC are available at the 

Northwest Fisheries Science Center

Web site, http://www.nwfsc.noaa.gov

Copies are also available from the

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

Phone orders: 1-800-553-6847

E-mail orders: orders@ntis.fedworld.gov

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Table of Contents

List of Figures...............................................................................................................................................v

List of Tables..............................................................................................................................................vii

Executive Summary.....................................................................................................................................ix

Acknowledgments........................................................................................................................................xi

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

Background...................................................................................................................................................5

Observations of Natural Beaver Dams in Bridge Creek...........................................................................5

Mechanisms of Beaver Dam Breaching in Incision Trenches..................................................................6

Synthesis of Observations ........................................................................................................................7

Site Description.............................................................................................................................................9

Methods ......................................................................................................................................................10

Site Selection..........................................................................................................................................10

Pretreatment Monitoring.........................................................................................................................10

Defining Hypotheses at Multiple Scales.................................................................................................13

Hypotheses at the Watershed Scale ........................................................................................................13

Hypotheses at the Reach Scale ...............................................................................................................14

Hypotheses at the Scale of Individual Structures...................................................................................15

Structure Design and Installation Details...............................................................................................17

Conclusions.................................................................................................................................................32

References...................................................................................................................................................33

Appendix A: BDS Structure Maps..............................................................................................................35
iv
v

List of Figures

Figure 1. Location and vicinity maps of Bridge Creek................................................................................2

Figure 2. Sequence of channel incision and aggradation typical of streams in semiarid landscapes 

with cohesive fine-grained banks..................................................................................................................3

Figure 3. Sediment aggradation rates behind beaver dams in Bridge Creek ...............................................7

Figure 4. Conceptual diagram of the hypothesized positive physical feedback loops for beaver and 

steelhead from the presence of beaver dams...............................................................................................15

Figure 5. A BDS structure can follow multiple pathways, depending on the type of structure and 

the natural processes acting on it ................................................................................................................16

Figure 6. Location of BDS structures installed in 2009 in the Lower Owens reach..................................21

Figure 7. Location of BDS structures installed in 2009 in the Meyer’s Camp reach ................................22

Figure 8. Location of BDS structures installed in 2009 in the Pat’s Cabin reach......................................23

Figure 9. Location of BDS structures installed in 2009 in the Sunflower reach........................................24

Figure 10. A typical SD with willow branches woven between vertical posts and the back side 

sealed with rock and clay............................................................................................................................25

Figure 11. A PLWW is similar to a SD, but acts more like a weir in that water is allowed to flow 

through the willow branches such that low flows are not overtopping the structure and the woven 

branches may not extend to the top of the posts.........................................................................................26

Figure 12. The purpose of a PL is to provide a site where beaver can build a stable dam ........................27

Figure 13. Any active dams within the treatment areas were strengthened with posts to lengthen 

their functional life, since most dams along the incised Bridge Creek have been shown to last less 

than a year...................................................................................................................................................28

Figure 14. Any abandoned dams with significant structure remaining were reinforced with posts, 

since these were sites where beaver had previously built dams and with additional structure available 

might do so again........................................................................................................................................29

Figure A-1. Screen shot of Web portal for downloading individual pdf maps and browsing 

interactively in Google Maps for this appendix..........................................................................................36

Figure A-2. Midview map of upper reach at Lower Owens with April 2010 drone aerial imagery 

as base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey.............................................................................................................................................37

Figure A-3. Midview map of lower reach at Lower Owens with April 2010 drone aerial imagery 

as base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey.............................................................................................................................................38

Figure A-4. Midview map of upper reach at Meyer’s Camp with April 2010 drone aerial imagery

as base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey.............................................................................................................................................39
vi

Figure A-5. Midview map of middle reach at Meyer’s Camp with April 2010 drone aerial imagery 

as base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey.............................................................................................................................................40

Figure A-6. Midview map of bottom reach at Meyer’s Camp with April 2010 drone aerial imagery 

as base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey.............................................................................................................................................41

Figure A-7. Midview map of top reach at Pat’s Cabin with April 2010 drone aerial imagery as 

base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey.............................................................................................................................................42

Figure A-8. Midview map of middle reach at Pat’s Cabin with April 2010 drone aerial imagery 

as base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey.............................................................................................................................................43

Figure A-9. Midview map of bottom reach at Pat’s Cabin with April 2010 drone aerial imagery 

as base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey.............................................................................................................................................44

Figure A-10. Midview map of top reach at Sunflower with April 2010 drone aerial imagery as 

base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey.............................................................................................................................................45

Figure A-11. Midview map of bottom reach at Sunflower with April 2010 drone aerial imagery 

as base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey.............................................................................................................................................46

Figure A-12. Screen shot from Google Earth illustrating an example at Sunflower of the pushpins 

denoting each structure type and the balloons at each structure, which provide links to the BDSView 

pdfs and links to geotagged Picassa albums of every structure ..................................................................47
vii

List of Tables

Table 1. The restoration project seeks to create change at three spatial scales: watershed, 

reach, and individual structures ..................................................................................................................11

Table 2. Description of BDS structure types installed in four reaches in Bridge Creek in 

September 2009 ..........................................................................................................................................19

Table A-1. List of hyperlinks to all the static PDF maps by reach ............................................................35
viii
ix

Executive Summary

The incised and degraded habitat of Bridge Creek is thought to be limiting a population 

of steelhead (Oncorhynchus mykiss) listed as threatened under the U.S. Endangered Species Act. 

A logical restoration approach is to improve their habitat through reconnecting the channel with 

portions of its former floodplain (now terraces) to increase both stream and riparian habitat 

complexity. Using conventional restoration techniques to achieve such objectives can be quite 

costly, because it involves moving and grading large volumes of fill with heavy equipment that 

exposes bare ground and is usually followed by extensive revegetation efforts. Here we seek a 

cost-effective, process-based approach to restore geomorphic, hydrologic, and ecological 

functions of this degraded system, helping a small, extant beaver (Castor canadensis) population 

build longer-lived dams.

Currently, the beaver population is limited because their dams are short-lived. Most 

beaver dams are constructed within the incision trench and during high discharge events the full 

force of flood waters is concentrated on these dams rather than dissipating across floodplains.

Consequently most dams breach and fail within their first season. The primary hypothesis we 

are testing is that by assisting beaver to create stable colonies and aggrade incised reaches of 

Bridge Creek, there will be measurable improvements in riparian and stream habitat conditions 

and abundance of native steelhead. The main restoration design challenge is to help beaver build 

dams that will last long enough to lead to the establishment of stable colonies. If this can be 

accomplished, the beaver dams should promote enough aggradation to reverse channel incision 

and reap a number of well documented positive ecosystem benefits associated with dynamic 

beaver dam complexes that will benefit steelhead and other species.

We are assisting the beaver using an extremely simple and cost-effective restoration 

treatment. The treatment involves installing round wooden fence posts approximately 0.5 to 1 m 

apart across potential floodplain surfaces (now terraces) and the channel at a height intended to 

act as the crest elevation of an active beaver dam. This report provides details of the design 

rationale and design hypotheses employed and summarizes placement of the 85 beaver dam 

support (BDS) structures installed in four reaches in 2009. Additionally, the ongoing monitoring 

campaign devised to test these design hypotheses is discussed and some preliminary observations 

from the first year of the campaign are presented.

Five variants of the restoration treatment were used; post lines only, post lines with 

wicker weaves, construction of starter dams, reinforcement of existing active beaver dams, and 

reinforcement of abandoned beaver dams. The biodegradable posts are intended to buy enough 

time for 1) beaver to occupy the structures and build on or maintain the structures as their own 

dams and 2) aggradation to take place in the slack waters of the pond from the dam and promote 

reconnection with a floodplain (terrace). Just as with natural beaver dams, individual dams are 

expected to be transient features on the landscape, expanding and contracting, coming and going 

as they lose functionality for beaver (e.g., when a pond fills with sediment). The treatment 

design is geared to saturate four distinct reaches of Bridge Creek with BDS structures so that 
x

enough potential dams are available to the current beaver population that they can pick and 

choose the best sites to establish stable, multidam complexes to support healthy and persistent 

colonies.
xi

Acknowledgments

Many people have contributed and continue to contribute to the success of the Bridge 

Creek Restoration and Monitoring Project and our thanks go out to all of them. The project and 

this report are possible because of a collective desire among numerous individuals in various 

federal and state agencies and nongovernmental organizations to help restore stream habitat and 

rebuild the population of steelhead that once thrived in the John Day River basin.

In particular, the project would not have been successful without the efforts of Ian 

Tattam, our field manager and steelhead expert. He spent countless hours surveying streams, 

counting and tagging fish, tracking beaver, and generously opening his home to students and 

scientists passing through the Bridge Creek watershed. Nicholas Weber also worked tirelessly to 

make this project successful and as of 2011 played an even more central role in the project as the 

new field manager. Others who have contributed substantially to the collection of field data 

include Matt Allen and Bryn Fleming, Eco Logical Research, Inc. Rick Demmer, U.S. Bureau 

of Land Management, deserves thanks for the many years he spent surveying Bridge Creek for 

beaver activity and for helping develop many of the concepts that were incorporated into this 

project.

We also appreciate the contributors to this project who are listed by organization below.

• Field Crew: Matt Allen, Sean Anderson, Emma Anspach, John Decker, Bryn Fleming, 

Taira Flute, Andrae Genus, Bryan Mathias, Andrew McClary, Dan Myers, Rob Ottoway, 

Levi Raber, Brian Rhode, Sam Rizza, Bill Tattam, and Ian Tattam.

• National Park Service, John Day Fossil Beds: Jenny DeLucca, Jim Hammett, Shirley 

Hoh, and Scott Ritner.

• Northwest Fisheries Science Center: Sarah Baker, Tim Beechie, Jason Hall, Steve 

Rentmeester, Phil Roni, Louis Tullos, and Danielle Werner.

• Oregon Department of Fish and Wildlife: Jeff Neal, Jim Ruzycki, and Tim Unterwegner.

• Oregon Natural Desert Association: Alexa Bontager, Brent Fenty, and Kate Martin.

• Oregon State University: Joseph Feldhaus, Hiram Li, Luis Francisco Madrinan, Julie 

Maenhout, and Seth White.

• Private landowners and ranchers in Bridge Creek: David and Linda Gorton, Jake Polvi, 

and Jim Woodward.

• U.S. Bureau of Land Management: Rick Demmer, Michelle McSwain, Jeff Moss, Anna 

Smith, and Christina Welch.

• U.S. Fish and Wildlife Service: Jimmy Taylor.

• Utah State University: Boyd Bouwes, Kenny Demeurichy, Katrina Langenderfer, and 

Sonya Welsh.
xii

• Wheeler County Conservation District: Debbie Bunch and Gabe Williams.

Ongoing funding for this project is provided by the National Marine Fisheries Service

and the Bonneville Power Administration.
Introduction

The Bridge Creek Intensively Monitored Watershed Project is a long-term study to 

restore stream and riparian habitat along the incised and degraded lower 32 km of Bridge Creek, 

a tributary to the John Day River in eastern Oregon (Figure 1), and to measure the physical and 

biological changes that occur as a result of the restoration. The overarching restoration goal is to 

measurably increase the number of wild steelhead (Oncorhynchus mykiss) that use this system, 

which are part of a larger population listed as threatened under the U.S. Endangered Species Act 

(NMFS and NWFSC 2008). This project is part of NWFSC’s Integrated Status and 

Effectiveness Monitoring Program, which is developing methods to accurately assess changes in 

salmonid habitat and salmonid populations within the Columbia River basin. Thus the results of 

this project are integral to designing future restoration and monitoring projects throughout the 

Pacific Northwest.

The main stem of Bridge Creek is typical of many incised streams throughout the western 

United States in that it is confined within a narrow incision trench and high flows rarely access 

its former floodplain (Figure 2b) (Shields et al. 1995, Beechie et al. 2007). Typically, incision

also results in a loss of channel planform and bedform complexity (Schumm et al. 1984, Rosgen 

1996, Shields et al. 1999). Channel incision also affects groundwater-surface water interactions 

and often results in lowered water tables and reduced hyporheic exchange (Darby and Simon 

1999). Manifestations of these changes include decreased stream flows, less riparian vegetation,

and increased stream temperatures. The overall effect is a simplification of habitat and 

subsequent reduction in its quality for both instream and riparian biota. This describes much of 

Bridge Creek, where there are many simplified, linear, plane-bed reaches with a narrow band of 

willows growing on either side of the stream within a confined incision trench.

By contrast, in other reaches within Bridge Creek the incision trench has widened to 

create inset floodplains or terraces (Figure 2d), and in some of these reaches, beaver (Castor 

canadensis) have built numerous dams and established colonies. Where such dam complexes are 

present, water tables are elevated and the channel bed is rapidly aggrading such that the stream 

can now flood some of the inset terraces (Pollock et al. 2007). In such cases, system complexity 

has greatly increased, the stream and riparian condition appears to be improving markedly, and 

the system is restoring itself. These sites, though few in number, provide an example of how 

incised streams can naturally restore themselves.

These phenomena are not unique to Bridge Creek. It is well-known that beaver dam 

complexes provide numerous ecosystem benefits, primarily through reconnecting streams to 

their former floodplains by raising water level elevations and causing widespread aggradation of 

the incised streambed (reviewed in Pollock et al. 2003, Westbrook et al. 2006, Westbrook et al. 

2010). We have also observed beaver dam building within narrow incision trenches, but these 

dams rarely last more than a year and are typically destroyed during spring floods (Demmer and 

Beschta 2008). This is because within an incision trench there is limited floodplain access or 
2

Figure 1. Location and vicinity maps of Bridge Creek. The inset maps show the location of Bridge Creek 

and Murderers Creek in the John Day River basin of eastern Oregon. The main map shows the 

mainstem Bridge Creek drainage network and the primary treatment reaches described in this 

report.

planform complexity to help disperse flow energy. Beaver dams are often the only large 

structural element within incision trenches and they are unable to retain their structural integrity 

when the full force of spring floods acts upon them.

Such observations of beaver dams lead to a basic question: Can beaver be encouraged to 

build dams in narrow reaches of incised streams where a wide inset floodplain has not yet 

developed, and would such dam building lead to the formation of stable colonies with 

subsequent improvements in riparian and stream habitat conditions? That is, can we actively 

work with beaver and provide them with structure to help them build relatively stable dams in 
3

Figure 2. Sequence of channel incision and aggradation typical of streams in semiarid landscapes with 

cohesive fine-grained banks. Light brown fill is old alluvium, medium brown fill is bedrock, and 

dark brown fill is new alluvium. Water table is demarcated with a blue line. The stages are: a) 

the channel prior to incision; b) rapid downcutting (to a hard surface such as bedrock) occurs 

within a period of a few years, usually as a result of a land use change such as channel 

straightening or increased discharge; c) over decades, the incised channel slowly erodes its banks 

and forms an inset floodplain, with little aggradation occurring and the water table remaining near 

the bedrock; d) as the channel increases in planform complexity and structural roughness,

elements such as large wood and beaver dams enter the system, aggradation begins and the water 

table slowly rises, increasing groundwater recharge and hyporheic exchange, and riparian 

vegetation covers the inset floodplain; e) aggradation continues until riparian species can 

reoccupy the former floodplain; and f) aggradation may continue to preincision conditions, but 

often remains at stage d or e such that there are one or more inset terraces. (Reprinted with 

permission from Pollock et al. 2007, copyright Wiley & Sons, Ltd.)

incision trenches that would last long enough to trap sediment and cause aggradation of the bed 

such that the stream could reconnect to former floodplains?

The dramatic changes in physical habitat and channel reconfiguration that beaver can 

produce are precisely the sorts of changes many attempt to mimic in much more costly 

restoration interventions with the use of heavy equipment, engineered restoration designs, 

imported building materials, and an extensive permitting process. Since beaver are a free source 

of labor and the structures they build are exempt from costly permit requirements, if they can 

achieve the same as or better than outcomes of human-based stream restoration efforts, the 

economic implications are significant (McKinstry et al. 2001). The primary means by which we 
4

are “working” with beaver is to help them build stable dams with the use of inexpensive, 

biodegradable structural support (i.e., wood fence posts) that can be installed cheaply with 

logistically simple procedures (i.e., using portable hydraulic post drivers). This study seeks to 

address the general hypothesis that, by working with beaver to create stable colonies and aggrade 

incised reaches of Bridge Creek, there will be measurable improvements in riparian and stream 

habitat conditions and the abundance of native steelhead.

This report presents the restoration design rationale and hypotheses of a long-term 

restoration and monitoring program designed to test those hypotheses. We start by providing 

some background related to observations of natural beaver dams in Bridge Creek. We then cover 

the methods employed in developing the restoration design and implementing the restoration 

treatment.
5

Background

Observations of Natural Beaver Dams in Bridge Creek

From 1988 to 2004, the U.S. Bureau of Land Management surveyed the lower 32 km of 

Bridge Creek 1–2 times per year for the presence of beaver dams (Demmer and Beschta 2008). 

These data provide information on the longevity of beaver dams and the locations where beaver 

colonies persist. Our analysis of the Bureau of Land Management survey data used by Demmer 

and Beschta (2008) indicated that most of the dams were extremely short-lived, with many 

lasting less than a year. Field observations suggest the majority were breached during annual 

spring floods or by flash floods that sometimes occur in the summer.

Using Demmer and Beschta (2008) data and a digital elevation model from the 2005

aerial Light Detection and Ranging (LIDAR) survey by Washington State University’s 

Watershed Sciences Department (http://www.opentopography.org), we qualitatively examined 

the spatial patterns of beaver dams to determine whether there was a relationship between beaver 

dam persistence and near stream geomorphology. We found that beaver dams failed and were 

subsequently abandoned under a wide range of geomorphic conditions, but most of the dams that 

failed and were not repaired were built in reaches with relatively narrow incision trenches. 

These reaches were characterized by a lack of active floodplain or inset floodplain and hydraulic 

geometry in which channel width hardly expanded with increasing discharge and stage. In 

contrast, the small number of dams that persisted for more than a year were usually located in 

reaches where there was an adjacent stream terrace 50 m or wider and low enough in elevation 

(usually within a meter of the streambed) that it could be flooded by a typical beaver dam as well 

as by spring floods.

The highest rates of dam persistence were found within a 1.5 km reach of Bridge Creek 

bordering the Painted Hills National Monument and about 12 km upstream from the mouth 

(Demmer and Beschta 2008). Within this area is a small population of 1–4 beaver colonies that 

has persisted more or less continuously since about 1990 (Demmer and Beschta 2008). Much of 

this reach contains a 50–80 m wide floodplain inset within a broader incision trench. Many of 

these dams are backfilled with sediment and have been colonized by riparian and wetland 

vegetation, such that they look more like large, stream-adjacent wetlands rather than an open 

pool. Within these wetlands, beaver maintain multiple channels such that they can access the 

vegetation, which they then utilize as food and building material for their dams and lodges. 

These multiple channels also disperse flow, which likely helps to reduce the frequency or 

severity of dam breaching. In many reaches, the entire width of the inset terraces are flooded or 

have saturated soils. Where these dam complexes exist, the riparian and wetland vegetation has 

greatly expanded relative to the rest of Bridge Creek. Although in any given year individual 

beaver dams within a complex may be abandoned and new dams constructed, it appears that 

throughout this area, beaver have built a series of stable, self-sustaining ecosystems that provide 

them with the necessary food and shelter for stable colonies to persist.
6

Outside of the Painted Hills National Monument, few colonies persist for more than 2 

years and most dams are maintained for less than 1 year (Demmer and Beschta 2008). The 

contrast in longevity between the stable colonies within the Painted Hills National Monument 

and the short-lived colonies elsewhere along Bridge Creek is striking, particularly since many of 

the ephemeral colonies were built on the main stem above two major tributaries, where flows are 

much lower. Since young beaver (kits) are born in the spring and typically disperse 2 years later, 

a breeding pair that establishes a colony in the fall must persist for at least 2.5 years to 

successfully produce offspring that may expand the zone of influence of beaver. This suggests 

that for the existing beaver population to expand, dam and colony longevity must be increased.

Mechanisms of Beaver Dam Breaching in Incision Trenches

Demmer and Beschta (2008) categorized the mechanisms of beaver dam breaching in 

Bridge Creek for a period of 17 years, which is particularly helpful in understanding why beaver 

colonies fail to persist. They reported that of 161 beaver dams observed from 1988–1993 along 

25.4 km of lower Bridge Creek, 30% washed away completely, 32% breached in the center, and 

on 38%, flows eroded the bank on one end of the dam. Another 9% remained for a few years, 

with the dam backfilling with sediment, then a new channel forming by cutting through the dam,

washing it out, or cutting around the edge of the dam. The remaining 3% either partially 

breached (1%) or the dam was inundated by another dam further downstream (2%).

The Demmer and Beschta (2008) analysis of dam breaching mechanisms and our own 

observations of beaver dams in Bridge Creek during high flows suggest that breached dams were 

often built in an incision trench where high flows had limited access to a potential floodplain or 

terrace. Further, in some instances, it appears that the concentrated flows over dams in the 

incision trench also caused scouring below dams and undermined them, causing collapse. Some 

breached dams had a section missing, almost always near the deepest point of the dam, 

suggesting that dam breaching is often related to excessive hydrostatic pressure on the upstream 

dam face. In reaches where the incision trench has substantially widened, observations indicate 

that high flows spread out onto an adjacent floodplain or terrace surface and pressure against the 

dam face is alleviated. Unfortunately in much of Bridge Creek, high flows are confined within a 

narrow incision trench. Thus the flow depth increases above the height of the dam and pressure 

increases against the dam face. During such overtopping events, breaching can also result from 

erosion of the dam top simply because the shear stress is sufficient to entrain some of the woody 

and nonorganic material that compose the dams. We have observed some dams where a top 

portion of a section of dam was missing, but there wasn’t complete dam breaching, a situation 

that is explained by erosive processes rather than excessive pressure against the face of the dam. 

We also observed that when dams breached by endcutting a new channel around a dam and 

through a bank, the thalweg was often partially or completely filled with sediment just upstream

of the dam.

Collectively, these observations and data suggest two sequential events occurred that 

often resulted in (relatively) stable dams and the persistence of colonies:

1. Beaver constructed dams with a tall, narrow section built within the bankfull channel or 

incision trench, and a shorter, long section built across a terrace such that high flows 

dispersed across the entire length of the dam and over a low terrace and were not 
7

concentrated in the incision trench. The total length of such dams were generally much 

wider (50–80 m) than dams built only within the incision trench (4–7 m). 

2. There was subsequent rapid aggradation behind dams. Because Bridge Creek has a high 

sediment load (35,000–53,000 m3 • yr-1), aggradation can be fairly rapid behind beaver

dams, depending on local sediment supplies, with beds rising 40 cm within the bankfull 

channel during the first year (Figure 3) (Pollock et al. 2007). Frequently, dams 

completely backfill with sediment such that a new aggraded bed formed, the stream slope 

lowered, bed substrate composition shifted from cobble to silt (when the pond was 

aggrading) and then to gravel, and a plunge pool formed below the dam.

Synthesis of Observations

Based on observations of intact and failed dams along Bridge Creek and consideration of 

the likely mechanisms for dam failures, we can explain the overall lack of persistent beaver 

colonies throughout much of Bridge Creek. However, the persistent beaver dam colonies and 

subsequently richer function of the Painted Hills Monument reach gives us an insight into what 

is possible within Bridge Creek. Collectively, these observations helped to guide us toward a 

restoration strategy of working with beaver in Bridge Creek to achieve floodplain connectivity 

and reverse the detrimental effects of stream incision.

We hypothesized that the addition of strategically placed beaver dam support (BDS) 

structures within incised reaches would facilitate longer lasting dams, which in turn would 

promote bed aggradation and reconnection of floodplain surfaces and an overall increase in both 

instream and riparian habitat heterogeneity and habitat quality. “Longer-lasting dams” is taken 

here to mean long enough to retain structural integrity and functionality for more than a year. 

Such longer-lived, less transient dams are hypothesized to become building blocks for resilient

Figure 3. Sediment aggradation rates behind beaver dams in Bridge Creek. (Reprinted with permission 

from Pollock et al. 2007, copyright Wiley & Sons, Ltd.)

0

0.1

0.2

0.3

0.4

0.5

0 1 2 3 4 5 6

Age (yr)

Aggradation rate (m•yr-1)
8

and dynamic beaver dam complexes that support thriving colonies of beaver (e.g., the stream 

reaches in Painted Hills National Monument).

Although resilience and dynamics may seem at odds with each other, it is worth noting 

that activity in natural beaver dam complexes ebbs and flows and these are far from static 

features in the landscape (Naiman et al. 1988, Pastor et al. 1993, Burchsted et al. 2010). 

Individual dams within a dam complex may be washed out or abandoned, but the importance of 

individual dams is not as critical as the combination of different dams within a broader dam 

complex. Individual dams may serve different functional purposes or be at different stages in 

their trajectories. While overall an active dam complex should have dams that boast longer dam 

life than those typically found in Bridge Creek, the significance of the failure of an individual 

dam in a dam complex is much less than that of an isolated beaver dam. The resilience of a dam 

complex is its ability to maintain a healthy and stable system state (i.e., population) despite 

disturbances or external forcings. If other suitable locations are available, a colony may also be 

able to retain resiliency by shifting to a new location and abandoning a dam complex when its 

functionality decreases (Naiman et al. 1988, Burchsted et al. 2010). This leads to a dynamic,

shifting habitat mosaic in time and space (Tockner and Stanford 2002), which we hypothesize in 

turn promotes habitat complexity and resilience for beaver and species such as steelhead that 

benefit from the beaver dam complexes.

Although reintroduction or relocation of beaver has been proposed to achieve ecosystem 

restoration goals (e.g., see Albert and Trimble 2000, McKinstry et al. 2001, McKinstry and 

Anderson 2002), we are not aware of any other studies that have actively assisted beaver in the 

construction of dams. Similarly, we know of no proven techniques for employing this 

restoration strategy. Thus in 2008 we conducted a pilot study to assess the viability of 

strengthening existing beaver dams or creating structures that would later be utilized by beaver to 

build stable dams. The pilot study also allowed us to experiment with some techniques to better 

understand what kind of structural support would lead to the construction of stable beaver dams 

and to help refine our techniques. The results of that study were used as the basis for 

development of the methodology for the placement and installation of BDS structures as 

described in the Methods section below. Although there is potential to promote a more rapid 

response by augmenting the beaver population with beaver relocated to Bridge Creek from other 

watersheds, this is not currently part of the restoration design or experiment.

By providing some short term (<10 yr) structural complexity in a stream system generally 

lacking structure, we hypothesize that we will set in motion natural processes by which the 

stream restores its natural dynamics. This is the expected outcome of the project. Beaver dams 

will facilitate fluvial geomorphic changes that include sediment retention, streambed 

aggradation, increased stream sinuosity, pool formation, increased stream length, reduced stream 

slope, reduced bed shear stress, and a shift in the bed composition from cobble toward gravel 

(Pollock et al. 2007, Demmer and Beschta 2008). Beaver dams should also raise water tables in 

the alluvial aquifer and thus help to greatly expand the amount of riparian forest and reduce 

stream temperatures (Lowry 1993, Westbrook et al. 2006, Pollock et al. 2007). Previous 

research has shown that these are reasonable outcomes to expect from the presence of stable 

beaver dams, particularly in streams with high sediment loads (Scheffer 1938, Pollock et al. 

2003, McCullough et al. 2005, Westbrook et al. 2010).
9

Site Description

This restoration and monitoring project is being conducted in Bridge Creek, Oregon, (lat 

44.6492°N, long 120.2455°W). Bridge Creek is a 710 km2 watershed draining northwesterly 

into the lower John Day River. Elevation ranges from 500 m at the mouth to 780 m at the upper 

end of our study site to 2,078 m at Mt. Pisgah, the highest point in the watershed. The basin is 

dominated by sagebrush (Artemisia spp.) steppe and juniper (Juniperus occidentalis) steppe in 

the lower elevations, with the vegetation changing progressively with increasing elevation to 

forests dominated by ponderosa pine (Pinus ponderosa), Douglas fir (Pseudotsuga menziesii), 

and Engelmann spruce (Picea englemannii). The main stem of Bridge Creek is in a semiarid 

landscape with 7.4 cm average cumulative summer rainfall (June-September) and average daily 

maximum and minimum summer temperatures of 26.9°C and 8.7°C, respectively. Average 

annual cumulative precipitation in Bridge Creek at 800 m elevation is 28.7 cm with an additional 

46.2 cm of snow occurring in the fall, winter, and spring months. Average daily maximum and 

minimum winter (November-April) temperatures are 9.6°C and –1.9°C, respectively. 

Temperature and precipitation data were obtained from National Climate Data Center station 

355638 (online at http://www.ncdc.noaa.gov/oa/ncdc.html).

Most of the main stem and lower tributary reaches of Bridge Creek are incised, thus the 

riparian vegetation is generally limited to a very narrow band along the stream. Riparian 

vegetation in this portion of the river is dominated by willows (Salix spp.), primarily coyote 

willow (S. exigua) and to a lesser extent onecolor willow (S. monochroma), Pacific willow (S. 

lasiandra), MacKenzie’s willow (S. prolixa), and peach-leaf willow (S. amygdaloides). Black 

cottonwood (Populus trichocarpa) is present in small quantities in some areas, as are a variety of 

shrubs and emergent vegetation. The geology of Bridge Creek is dominated by thick layers of 

basalt and andesite that originated from numerous lava flows during the Eocene and Oligocene 

epochs. There are also substantial areas of highly erosive volcanic ash known as the John Day 

Formation that originated from a series of volcanic eruptions in the Miocene epoch. The surface 

geology along our study site is generally cohesive, fine-grained quaternary alluvium, much of 

which is derived from the ashes of the John Day Formation. Lenses of alluvial gravels and 

cobble are also present in some exposed banks. Active lateral erosion into these coarser deposits

is an important source of coarse sediment for the construction of active bars, which provide 

critical spawning habitat for steelhead. Some reaches contain occasional bedrock outcrops that 

help limit the depth of incision.

Soils on the site are diverse and range in field texture from silty clay loam near the 

present stream to coarse loamy sand on the lower terraces. Soil bulk density values range 1.4–

1.5 g • cm-3 while porosities range 52–57% (Lowry 1993). Edaphic variability appears to be 

related to several factors, including relative height and distance of the soils profile from the 

stream, hillslope erosion rates, and sediment transport processes (Lowry 1993). Sediment loads 

within Bridge Creek are high, due to the erosive nature of the John Day Formation, the sparse 

vegetation, and the high intensity, short duration rainfall events that are common to the region in 

the summer months.
10

Methods

This report summarizes the implementation of the first phase of the restoration treatment,

and as such, the restoration design and implementation are the focus of our methodological 

description here. We also review the site selection elements of that design and review what 

pretreatment monitoring took place to document baseline conditions. The focus of the broader 

intensively monitored watershed effort and restoration experiment in Bridge Creek is to help 

beaver build stable dams for the purposes of creating habitat that will benefit the steelhead 

population. Specific design hypotheses help articulate the details of those designs. These 

hypotheses were formulated across a range of nested spatiotemporal scales and their testing 

provides the basis for the ongoing monitoring campaign.

Site Selection

We used an aerial LIDAR (light detection and ranging) and color photography survey 

from Utah State University’s Watershed Sciences Department (2005, online at http://www

.OpenTopography.org) combined with field surveys to identify 4 pairs of geomorphically similar 

reaches within the lower 32 km of the main stem of Bridge Creek. For each pair we assigned 

one reach as a control, where the stream would be left unrestored (and may recover naturally or 

remain in a degraded state), and the other as a treatment, where active restoration would occur 

(Figure 1). We also identified two reaches within the Painted Hills National Monument where 

beaver are abundant and have been active there at least since 1988 (Demmer and Beschta 2008), 

and used them as positive control sites. We also selected two sites on two tributaries to Bridge 

Creek (Bear and Gable creeks) to use as additional control sites within the watershed that were 

outside the main stem, primarily for the purpose of monitoring steelhead populations. Site 

selection within the Bridge Creek drainage was generally limited to public lands and where other 

constraints, such as current land use activities or archaeological sites, did not preclude a 

restoration treatment. Because the overall goal is to cause a detectable population level increase 

in the steelhead that utilize this system, we also selected another tributary to the John Day 

(Murderers Creek) as a control watershed outside the Bridge Creek main stem where we could 

monitor steelhead populations to compare population trends of steelhead to changes in the 

population of Bridge Creek as a whole (Figure 1) (NMFS and NWFSC 2008).

Pretreatment Monitoring

For several years before and now continuing during the restoration treatment, numerous 

biological and physical parameters have been measured within the treatment and control sites for 

the purpose of detecting physical and biological changes resulting from our restoration treatment. 

These are listed in Table 1 and described in more detail in NMFS and NWFSC (2008).
11 

Table 1. The restoration project seeks to create change at three spatial scales: watershed, reach, and individual structures, with expected 

differences in the response time needed to detect change.

Treatment 

site

Control 

site

Temporal 

scale of 

detection Hypothesis for treatment areas Data collection

Watershed level

Bridge 

Creek, 

lower 32 

km 

Murderers 

Creek

5–10 yr Cumulative restoration actions will result in a 

measurable population level change in the 

steelhead that use this system.

Juvenile outmigration, spawner counts, redd 

counts on Bridge and Murderers creeks 

Base flow discharge will increase. Gage stations at Bridge and Murderers creeks

Beaver population will increase. Dam, pond, and lodge census

Site level

Sunflower, 

Pat’s Cabin, 

Meyer’s, 

Lower

Owens

Corral, 

Boundary, 

Woodward, 

Upper 

Owens

1–10 yr Floodplain connectivity will increase through the 

process of aggradation.

Topographic and aerial surveys of channel and 

stream adjacent terrace morphology 

Riparian vegetation will increase. Aerial surveys (remote drone and fixed wing)

Sinuosity will increase. Aerial surveys

Stream gradient will decrease. Topographic and aerial surveys of channel and 

stream adjacent terrace morphology

Pool frequency will increase. Habitat surveys

Pool depth will increase. Habitat surveys

Substrate will shift from cobble towards gravel. Habitat surveys

Stream temperatures will decrease. Stream temperature loggers

Number of multichannel reaches will increase. Topographic and aerial surveys of channel and 

stream adjacent terrace morphology

Conversion from plane-bed to pool-riffle 

morphology.

Habitat surveys

Juvenile fish density will increase. Juvenile mark-recapture surveys 3 times/yr

Juvenile fish growth rate will increase. Juvenile mark-recapture surveys 3 times/yr

Juvenile fish size/fitness will increase. Juvenile mark-recapture surveys 3 times/yr

Groundwater levels will increase (only being 

monitored and tested in Lower and Upper 

Owens).

Water level logger well fields

Beaver colony density will increase. BDS structure survey/beaver dam census
12 

Table 1 continued. The restoration project seeks to create change at three spatial scales: watershed, reach, and individual structures, with expected 

differences in the response time needed to detect change.

Treatment 

site

Control 

site

Temporal 

scale of 

detection Hypothesis for treatment areas Data collection

Structure level

Sunflower, 

Pat’s Cabin, 

Meyer’s, 

Lower

Owens

Corral, 

Boundary, 

Woodward, 

Upper 

Owens

1–3 yr Beaver will build dams on bare post lines. BDS structure survey/beaver dam census

Reinforced existing dams will last longer than 

those that are unreinforced.

BDS structure survey

Reinforced abandoned dams will last longer than 

those that are unreinforced.

BDS structure survey

Post lines with willow weaves and starter dams 

will behave similarly to beaver dams as 

described below.

BDS structure survey

Reinforced beaver dams will have certain 

hydrogeomorphic effects:

BDS structure survey

1. A backwater pool will form upstream. BDS structure survey

2. A scour pool will form downstream. BDS structure survey

3. A transverse bar will form downstream of 

the scour pool.

BDS structure survey

4. Stream-adjacent terraces will flood more 

frequently.

BDS structure survey

5. A multichannel planform will develop. BDS structure survey

6. Aggradation will occur upstream of the 

structure, eventually filling in the upstream 

pool.

BDS structure survey

7. Beaver will utilize starter dams to establish 

new colonies.

BDS structure survey/beaver dam census

8. Fish densities in backwater pools will be 

higher than reaches without such pools.

Juvenile mark-recapture surveys in winter

9. Transverse bars will become sites of 

steelhead spawning.

Redd surveys
13

Defining Hypotheses at Multiple Scales

This study seeks to test hypotheses regarding the effects of restoration at three nested 

spatial scales:

1. The scale of the individual structure within a reach that receives a restoration treatment, 

2. The scale of the entire reach that is treated, and

3. The scale of the Bridge Creek watershed, that is, the cumulative effects of treating 

multiple reaches.

The hypothesis for each of these scales and the data being collected to test these hypotheses is 

provided in detail in Table 1 and described below.

We are making comparisons between treatment and controls before and after the 

implementation of the restoration actions as a means to increase the power to detect changes in 

the physical habitat and steelhead responses. These before-after-control-impact (BACI) designs 

have been employed in areas where spatial replication is low or not possible to best detect 

environmental impacts (Steward-Oaten and Bence 2001). How long after the treatment 

monitoring will occur depends on the process being tested. For example, biological responses 

like utilization and occupation can be tested within the first year, whereas a population-level 

response will take multiple generations to test. We implemented BACI-like designs in a nested 

hierarchy to compare restored and unrestored areas at the watershed, subwatershed, and reach 

scales. At the watershed scale, Bridge Creek is being compared to nearby Murderers Creek, 

where ongoing intensive monitoring of steelhead populations and physical habitat conditions is 

already occurring. Within the main stem of Bridge Creek, comparisons are being made between 

control and manipulated reaches, separated by enough distance to minimize movement between 

reaches by steelhead parr. The hierarchical design helps identify the scale of influence of the 

restoration actions (which may differ between physical habitat and steelhead responses) and the 

appropriate scale at which restoration efforts of this type should be monitored (Underwood 

1994). Preproject data have been collected in Bridge Creek since 2005. Postproject monitoring 

is expected to last approximately 10–20 years; however, large changes in responses should occur 

earlier than this and may highlight reasons to adapt the intensive monitoring.

Hypotheses at the Watershed Scale

At the scale of the entire Bridge Creek watershed, we are primarily interested in testing 

the overarching hypothesis that we can concentrate enough restoration activity within a single 

watershed such that there is a measurable population-level change in the steelhead that utilize the 

system (Table 1). To test this hypothesis, we have been monitoring returning steelhead 

populations at Bridge Creek and Murderers Creek, a similarly sized stream in the John Day River 

basin where no restoration is occurring (Figure 1). Over the long-term (10+ years), if the 

restoration treatments in Bridge Creek have a cumulative effect on the steelhead population, we 

hypothesize that a change in population characteristics should be observable, relative to the 

population characteristics of the Murderers Creek population (Table 1). Since the main 

restoration treatment we are employing is assisting beaver to improve instream and riparian 

habitat for steelhead, a corollary prediction at the scale of the Bridge Creek watershed is that we 

should see a general increase in the beaver population in Bridge Creek. Finally, at the watershed 
14

scale we hypothesize that beaver dams will elevate water tables and increase groundwatersurface water exchange. Thus if there is sufficient long-term storage of water in alluvial 

aquifers, summer baseflows may also increase (Table 1).

Hypotheses at the Reach Scale

At the reach scale, the general restoration objective is to aggrade entire incised sections 

(0.5–1 km long) of Bridge Creek such that the channel is reconnected to former floodplains and 

all the attendant benefits of increased channel complexity and floodplain reconnection are 

realized (Table 1). The BDS structures in a reach are designed to work in concert with each 

other (much like multiple dams in a natural beaver dam complex) to cause net aggradation of bed 

elevations and increase habitat complexity by promoting the establishment of more stable beaver 

colonies and associated dam complexes. Although the net predicted response is aggradation, 

both local erosion and deposition are necessary processes to build dynamic functioning fluvial 

habitats with the sort of habitat complexity we seek for steelhead. For example, erosion of banks 

may be critical for providing a coarse-grained sediment supply locally to build bars that provide 

good spawning habitat. Similarly, building bars in areas of divergent flow can be helpful in 

forcing zones of convergent flow nearby that promote scour and the subsequent construction or 

maintenance of pool habitat (MacWilliams et al. 2006).

At the reach scale, we predict numerous changes in physical and biological parameters in 

the restored reaches relative to the control reaches, as enumerated in Table 1. Generally 

speaking, we expect to see improvements in steelhead population parameters in the restored 

reaches, such as growth, abundance, and fitness. Physical parameters where we expect to see 

detectable change are listed in Table 1. Examples of physical changes we expect to see include 

increased aggradation resulting in increased planform and bedform complexity (i.e., higher 

sinuosity, more pools, increased sediment sorting, multiple channels), more floodplain access, 

raised water tables, decreases in stream temperatures, an expansion of the riparian forest, and an 

increase in the number of beaver dams.

We hypothesize that ultimately these physical changes will result in several positive 

feedback loops that will yield improved habitat conditions for beaver that in turn will lead to the 

construction of more beaver dams, which will continue to improve habitat conditions and make it 

more suitable for the establishment of stable beaver colonies, as illustrated in Figure 4. This 

figure also illustrates the habitat improvements resulting from beaver dam construction that will 

benefit steelhead and other salmonids (e.g., Chinook salmon [Oncorhynchus tshawytscha]). 

Such benefits include lower water temperatures, increased baseflows, greater diversity of 

substrate sizes, and more pool habitat.

The four treatment reaches range in length from 0.5 to 1.0 km. Baseline monitoring of 

Bridge Creek suggests potential colony densities of 2 to 4 km-1

, with colonies generally 

occupying dam complexes comprised of three to eight individual dams. As such, the individual 

structures placed in these reaches were typically placed in sequences of five to eight structures, 

designed to mimic the functionality of a dam complex that might be occupied and maintained by 

one colony and to provide additional sites in the event of dam breaching. Given the currently 

low densities of beaver populations in Bridge Creek and the fact that beaver kits remain with 

their parents for 2 years, any population response may take multiple generations to be detected as 
15

Figure 4. Conceptual diagram of the hypothesized positive physical feedback loops for beaver and 

steelhead from the presence of beaver dams. The key barrier to this feedback loop in Bridge 

Creek is that individual dams do not persist long enough to realize or maintain the hypothesized 

benefits.

a response (i.e., at least 4 years). Initially, we might expect a redistribution of the existing beaver 

population from more marginal dam sites into the zones where sequences of BDS structures were 

installed and they may be able to establish dam complexes that can eventually (i.e., 2–3 

generations of kits later) support a stable colony.

Hypotheses at the Scale of Individual Structures

At the scale of individual structures, predicted response depends on the type of structure 

installed. Five types of BDS structures were installed to test the response of beaver and the 

response of the stream to structures at the scale of the individual structure and the treatment area: 

starter dams (SD), post lines (PL), post lines with wicker weaves (PLWW), reinforced 

abandoned dams (RAD) and reinforced existing dams (RED). Each treatment reach has similar, 

broad-level objectives as described above, while each of the structures has specific 

hydrogeomorphic objectives, or more correctly, competing hypotheses as to how the structure is 

likely to respond depending on which type of structure was installed and what stochastic 

processes occur after installation (Figure 5). For example, a RAD or SD may backfill with 

sediment. The composition of that fill (i.e., fine or coarse sediment) depends on the availability 
16

Figure 5. A BDS structure can follow multiple pathways (A through I), depending on the type of 

structure and the natural processes acting on it. Thus the predicted hydrogeomorphic changes 

created by a structure largely depend on the timing, sequence, and magnitude of natural processes 

such as beaver dam construction, debris transport, bank failures, and floods.

of sediment sources (e.g., coarse gravels in Bridge Creek often sourced locally from bank failure 

of coarse-grained alluvial deposits). Likewise, for a PLWW, the hydrogeomorphic response of 

the stream to the structure will largely depend on whether or not it is colonized by beaver. The 

structures are designed to follow multiple pathways, with multiple possible outcomes, depending 

on the stochastic events acting upon them. Thus the structure-specific objectives can best be 

thought of as a series of if-then pathways in a flow chart (Figure 5). Defining objectives for the 
17

individual structures helps to identify what type of structure is most suitable or effective for a 

given location and whether we can accurately predict the local hydrogeomorphic response of the 

stream to a structure. However, the structure-specific objectives are of secondary importance to 

the objectives of the reach-scale treatment and the entire project (Table 1).

It is important to emphasize that although every structure had a specific design for how it 

was supposed to function in the event of beaver colonization, all of the structures were placed 

with consideration for what might happen in the event that beaver did not utilize the structure. 

Given the limited beaver population currently in Bridge Creek, part of the restoration design was 

to provide an oversupply of potential stable dam complex sites for beaver to expand into. We 

fully expected that many of the individual structures would not be utilized and the overall 

distribution of beaver habitat to be underseeded. SDs, PLWWs and REDs were all designed to 

promote aggradation whether or not beaver actively colonized or maintained them. We 

hypothesize that the longevity of those deposits will be positively correlated with active beaver 

maintenance.

By contrast, PLs that are not colonized by beaver may promote collection of mobile 

woody debris and other material, which could lead to localized deposition and scour and even the 

potential washing out of part or all of the PL structure. Although such a response was not our 

primary design objective, it is a perfectly acceptable backup plan, as this may increase the 

channel complexity locally, which should be an improvement in terms of steelhead habitat. The 

worst case scenario is that such structures will simply wash away, providing no real benefit, but 

no harm either.

Structure Design and Installation Details

Structure Siting

At the reach scale, structures were placed at a frequency to capitalize on all opportunities 

to promote aggradation and floodplain reconnection throughout the treatment area. In many 

instances, secondary structures placed a short distance downstream from a primary structure 

were used to avoid steep gradient drops within the treatment area that could potentially result in 

excessive scour and limit the likelihood of headcutting and undermining of structures upstream. 

Additionally, the presence of multiple structures in series provides capacity for a colony to build 

a multiple dam complex. This is a typical strategy that beaver employ, which seems to provide 

additional resiliency in that the significance of any single dam failure is less important when an 

intact dam is in close proximity. This is important because beaver need a stable colony to 

consistently produce offspring. However, the dynamics of individual dam failure and evolution 

should not be confused with necessarily promoting an “unstable colony” or “unstable dam 

complex.” It takes 2 years to produce offspring, and if colonies fail in less than 2 years, it limits 

the likelihood of colony persistence and population expansion. In Bridge Creek, individual dam 

failure is so common (Demmer and Beschta 2008) that establishment of larger dam complexes 

and stable colonies is currently rare.

Further, beaver colonies cycle through individual dams within a complex and the 

boundaries of the colony are not static. Beaver may move their primary dam and lodge in 

response to environmental conditions, such as dam breaching or pool filling, exhaustion of 
18

building or food supplies, etc. (Morgan 1986, Naiman et al. 1988). Beaver colonies frequently 

move the focus of their activity within an area or a complex, thus the frequency of maintenance 

of any particular dam changes over time and dam sites may be temporarily abandoned, only to be

repaired later when conditions such as the regrowth of willow make the site desirable again.

Where the stream is incised, structural support that lengthens the life of dams can expand 

food supplies for beaver insofar as it may continue to flood terraces and floodplain surfaces or 

raise groundwater levels such that willow can become established and grow. In older beaver 

dams, trees often grow out of the dams themselves. In incised settings without the structural 

support (artificial or natural), such dams are breached and eroded away quickly during regular 

high flow. The breaching of the dam brings a corresponding drop in water levels, an isolation of 

the terrace from the stream, and a drop in the abundance of riparian vegetation such as willows 

(i.e., a negative feedback loop).

Within a reach, the location of a given type of BDS structure was determined by sitespecific conditions. The consideration for the siting of individual structures is elaborated below. 

The type and intended functions of each structure are provided in Table 2 (Lower Owens, 

Meyer’s Camp, Pat’s Cabin, and Sunflower). The locations of each structure are shown for 

Lower Owens in Figure 6, Meyer’s Camp in Figure 7, Pat’s Cabin in Figure 8, and Sunflower in 

Figure 9. For additional maps, see Appendix A. Below we elaborate on the different BDS 

structure types and their design rationale.

Starter dams

SDs (Figure 10) had the most criteria for siting. Generally, they were placed in locations 

where:

1. The water elevation upstream of the dam could be raised to the level of a terrace, so that 

flow would be dispersed across the terrace and it would be less likely that the structural 

integrity of the dam would be compromised.

2. The incision in the surrounding area was generally less than 1–1.5 m so that additional 

dams built were more likely to be stable.

3. The backwater from the pond would provide access to soft banks upstream of the dam, 

which would act as suitable locations for bank lodges.

4. There was adequate access to existing food and building supplies (e.g., existing wood and 

riparian vegetation).

5. There was no existing beaver colony nearby (i.e., within 300 m).
19

Table 2. Description of BDS structure types installed in four reaches of Bridge Creek in September 2009:

Lower Owens, Meyer’s Camp, Pat’s Cabin, and Sunflower. Locations of each structure are 

provided in Figure 6 through Figure 9. PL = post line, PLWW = post line with wicker weave, 

SD = starter dam, RED = reinforced existing dam, and RAD = reinforced abandoned dam.

BDS no. by reach BDS no. total Year installed Structure type Totals

Lower Owens

LO-01 1 2009 PL PL 6

LO-02 2 2009 RAD RAD 3

LO-03 3 2009 RAD PLWW 17

LO-04 4 2009 PLWW SD 5

LO-05 5 2009 PLWW RED 3

LO-06 6 2009 PLWW Subtotal 34

LO-07 7 2009 SD

LO-08 8 2009 PL

LO-09 9 2009 PL

LO-10 10 2009 PLWW

LO-11 11 2009 PLWW

LO-12 12 2009 PLWW

LO-13 13 2009 SD

LO-14 14 2009 PLWW

LO-15 15 2009 SD

LO-16 16 2009 PLWW

LO-17 17 2009 PLWW

LO-18 18 2009 PL

LO-19 19 2009 PL

LO-20 20 2009 RED

LO-21 21 2009 PL

LO-22 22 2009 RED

LO-23 23 2009 RED

LO-24 24 2009 PLWW

LO-25 25 2009 SD

LO-26 26 2009 RAD

LO-27 27 2009 PLWW

LO-28 28 2009 PLWW

LO-29 29 2009 PLWW

LO-30 30 2009 PLWW

LO-31 31 2009 PLWW

LO-32A 32 2009 SD

LO-32B 33 2009 PLWW

LO-32C 34 2009 PLWW

Meyer’s Camp

MC-01 35 2009 PL PL 5

MC-02 36 2009 RED RAD 0

MC-03 37 2009 RED PLWW 9

MC-04 38 2009 PL SD 0

MC-05 39 2009 PLWW RED 2

MC-06 40 2009 PLWW Subtotal 16
20

Table 2 continued. Description of BDS structure types installed in four reaches of Bridge Creek in 

September 2009: Lower Owens, Meyer’s Camp, Pat’s Cabin, and Sunflower. Locations of each 

structure are provided in Figure 6 through Figure 9. PL = post line, PLWW = post line with 

wicker weave, SD = starter dam, RED = reinforced existing dam, and RAD = reinforced 

abandoned dam.

BDS no. by reach BDS no. total Year installed Structure type Totals

Meyer’s Camp (continued)

MC-07 41 2009 PL

MC-08 42 2009 PLWW

MC-09 43 2009 PLWW

MC-10 44 2009 PLWW

MC-11 45 2009 PLWW

MC-12 46 2009 PL

MC-13 47 2009 PL

MC-14 48 2009 PLWW

MC-15 49 2009 PLWW

MC-16 50 2009 PLWW

Pat’s Cabin

PC-01 51 2009 SD PL 5

PC-02 52 2009 PLWW RAD 1

PC-03 53 2009 PLWW PLWW 7

PC-04 54 2009 SD SD 2

PC-05 55 2009 PLWW RED 0

PC-06 56 2009 PLWW Subtotal 15

PC-07 57 2009 PLWW

PC-08 58 2009 PL

PC-09 59 2008 PL

PC-10 60 2009 PLWW

PC-11 61 2009 PL

PC-12 62 2009 PL

PC-13 63 2009 PLWW

PC-14 64 2009 PL

PC-15 65 2009 RAD

Sunflower

SF-01 66 2009 SD PL 5

SF-02 67 2009 PLWW RAD 0

SF-03 68 2009 PLWW PLWW 11

SF-04 69 2009 PLWW SD 4

SF-05 70 2009 PLWW RED 0

SF-06 71 2009 PL Subtotal 20

SF-07 72 2009 SD

SF-08 73 2009 PLWW

SF-09 74 2009 PLWW

SF-10 75 2009 PLWW

SF-11 76 2009 PL

SF-12 77 2009 SD

SF-13 78 2009 PLWW

SF-14 79 2009 PL
21

Table 2 continued. Description of BDS structure types installed in four reaches of Bridge Creek in 

September 2009: Lower Owens, Meyer’s Camp, Pat’s Cabin, and Sunflower. Locations of each 

structure are provided in Figure 6 through Figure 9. PL = post line, PLWW = post line with 

wicker weave, SD = starter dam, RED = reinforced existing dam, and RAD = reinforced 

abandoned dam.

BDS no. by reach BDS no. total Year installed Structure type Totals

Sunflower (continued)

SF-15 80 2009 PL PL 21

SF-16 81 2009 PL RAD 4

SF-17 82 2009 SD PLWW 44

SF-18 83 2009 PLWW SD 11

SF-19 84 2009 PLWW RED 5

SF-20 85 2009 PLWW Grand total 85

Figure 6. Location of BDS structures installed in 2009 in the Lower Owens reach. Coordinates are UTM 

system (i.e., each grid cell is 100 m × 100 m).
22

Figure 7. Location of BDS structures installed in 2009 in the Meyer’s Camp reach. Coordinates are 

UTM system (i.e., each grid cell is 100 m × 100 m).
23

Figure 8. Location of BDS structures installed in 2009 in the Pat’s Cabin reach. Coordinates are UTM 

system (i.e., each grid cell is 100 m × 100 m).
24

Figure 9. Location of BDS structures installed in 2009 in the Sunflower reach. Coordinates are UTM 

system (i.e., each grid cell is 100 m × 100 m).
25

Figure 10. A typical SD (SF-17 at Sunflower) with willow branches woven between vertical posts and 

the back side sealed with rock and clay. Note that the dam height is sufficient to divert flow onto 

the river left terrace, mimicking a stable beaver dam.

Post lines with wicker weaves

PLWWs (Figure 11) were the most common type of structure installed and served a 

variety of purposes. They were always placed where aggradation was not only desirable but also

deemed geomorphically plausible to increase channel access to stream adjacent terraces. 

PLWWs mimic the functional impact of beaver dams in the short term, and were used to invoke 

a geomorphic response whether or not they were actively colonized and utilized by beaver in the 

short term. They were also used to promote one or more of the following:

• Increase stream sinuosity,

• Increase the number of pools (from mix of beaver pond upstream of structure, scour pool 

downstream of structure, and bar forced pools),

• Direct flow away1 from an eroding cut bank, and

• Provide potential sites for future beaver dam construction (i.e., conversion from single 

dam to dam complex).

The specific intended purposes of a given PLWW were determined by site-specific geomorphic 

conditions.

 1 Note that flows could be usefully directed at banks with good local sediment supplies of coarse alluvium to build 

bars and fish habitat. However, due to concerns from the Bureau of Land Management, this opportunity was avoided 

and in some cases actively discouraged as part of the design.
26

Figure 11. A PLWW is similar to an SD, but acts more like a weir in that water is allowed to flow 

through the willow branches such that low flows are not overtopping the structure and the woven 

branches may not extend to the top of the posts. These may naturally seal up by trapping 

sediment and organic material moving downstream or they may be utilized by beaver. Note that 

beaver have started to colonize this PLWW, as evidenced by the chewed stems aligned parallel to 

the flow in the middle of the photograph.

To achieve the broader goal of reversing the impacts of homogenized habitat from 

channel incision, extensive use of PLWWs was employed to kick-start the recovery. We 

recognized that the existing population of beaver in Bridge Creek is low and the likelihood of 

colonization of any one structure is correspondingly low without additional beaver population 

supplementation. As mentioned earlier, population supplementation is not part of the current 

restoration treatment. Population supplementation of beaver was originally intended to be part of 

the restoration plan, but concerns about disease, lack of an adequate food supply, regulations 

pertaining to the live trapping and release of beaver, and logistical considerations precluded the 

timely introduction of additional beaver to the treatment areas. Thus the PLWWs roughly 

simulate some of the functions of beaver dams, and in particular help to cause aggradation of the 

streambed such that floodplain reconnection should begin to occur throughout the treatment 

areas. This is particularly useful in areas that are highly entrenched with limited riparian 

vegetation and where beaver would be unlikely to build a dam even if PLs were installed. 

Eventually, as the PLWWs allow for floodplain reconnection within much of the treatment area 

and the existing beaver population expands (either naturally or through supplementation), the 

need for PLWWs should diminish as they begin to be replaced by actual beaver dams.
27

Post lines

PLs (Figure 12) were placed in sites where a future beaver dam was desired and where 

geomorphic conditions were suitable for a dam. In contrast to PLWWs, PLs by themselves were 

limited to sites where there was minimal risk if no aggradation occurred because beaver did not 

use them to build a dam. These structures were not intended to be functional unless beaver 

utilized them to build a dam.

Reinforcement of existing and abandoned dams

All active or intact abandoned beaver dams within the treatment areas were stabilized 

with posts (Figure 13) to lengthen their functional life, since most dams along the incised Bridge 

Creek have been shown to last less than a year (Demmer and Beschta 2008). Any abandoned 

dams with significant structure remaining were reinforced (Figure 14). These were sites where 

beaver had previously built dams and with additional structure available might do so again.

Structure Installation Overview

The details of how an individual BDS structure was installed depended on the structure 

type and site-specific conditions. The details of the precise installation of specific structures 

Figure 12. The purpose of a PL is to provide a site where beaver can build a stable dam. They generally 

create little or no geomorphic changes unless utilized by beaver.
28

Figure 13. Any active dams within the treatment areas were strengthened with posts to lengthen their 

functional life, since most dams along the incised Bridge Creek have been shown to last less than 

a year (Demmer and Beschta 2008). This structure was one of four dams built in sequence in 

Lower Owens to form a new colony. Within 1 year, all four dams had backfilled with sediment, 

which improved floodplain connectivity and habitat complexity, but made the site unsuitable for 

beaver. However, because we had installed additional PLs just downstream, the beaver were able 

to use them to build new dams, which allowed the colony to persist.

were decided in the field based on a combination of the functional design criteria described 

above, logistical constraints, and common sense. Although the design and installation 

techniques described are certainly amenable to providing detailed design drawings and plans for 

every single structure ahead of construction, such activities would greatly increase the design 

costs and lengthen the construction process.

One of the secondary hypotheses associated with this restoration technique is that when 

working to harness the natural geomorphic processes of the stream and the labor of beaver to do 

the work of restoration for us, detailed designs and expensive construction methods are not 

necessary. If this hypothesis is supported, the transferability of this low-cost restoration 

technique to other streams may be one of the most valuable contributions of this experiment. 

Thus a robust and defendable but ultimately simple design and construction process was 

employed to keep implementation costs at a minimum. Much more investment has been made in 

carefully formulating hypotheses associated with these treatments and designing and 

implementing monitoring campaigns to test those hypotheses.
29

Figure 14. Any abandoned dams with significant structure remaining were reinforced with posts, since 

these were sites where beaver had previously built dams and with additional structure available 

might do so again. Beaver abandoned this dam (PC-15 in foreground) and one immediately 

downstream (not in photograph) after they were breached by high flows. Within a year following 

reinforcement by posts, beaver rebuilt this dam and built two more dams on PLs (one visible 

immediately upstream of PC-15, the other farther upstream), resulting in a flooded terrace and 

complex, multichannel habitat forming on river left and diverting flow away from a high exposed 

bank on river right.

The physical construction methods are described here. All structures were built with 2 m 

long, 7–10 cm diameter, untreated lodge pole pine (Pinus contorta) fence posts that were 

stripped of their bark. Using a chainsaw, a point was made at one end of the post. The posts 

were spaced approximately 0.5–1 m apart and driven into the active channel and inset floodplain 

with a handheld hydraulic post pounder. Inert mineral oil was used as hydraulic fluid, which 

allowed it to be safely used around water. Where the depth of the incision trench was a meter or 

less, the posts in the trench were installed so that the tops were at the same level or slightly 

elevated above a stream adjacent terrace. This height is well within the height range of natural 

beaver dams currently found on Bridge Creek.

Beaver dam heights on Bridge Creek typically range between 0.5 and 1.5 m, but may be 

as high as 2 m (Pollock unpubl. data). Where the depth of the incision trench was greater than 

1 m, the elevation of the post lines was either left at 1 m above the channel bed or cut down to 

about 0.5 m. The risk of having structures more than 1 m high within a confined incision trench 
30

is that flow cannot disperse onto a stream-adjacent terrace and the forces acting on the structure 

will be sufficient to reduce structural integrity, either through undermining, endcutting, or inchannel scour. By reducing the height, the forces acting on the structure are reduced, but so is 

the corresponding potential for aggradation. If aggradation is successful but beaver colonization 

is not, these structures can be built upon in subsequent years with subsequent BDS structure 

installation, until such time that colonization may take place or floodplain reconnection occurs.

PLWWs and SDs also utilized willow whips that were woven between the posts as tightly 

as possible. These two structure types also had a line of cobble placed at the base of the willows 

on the upstream side to help prevent headcutting beneath the structure. The placement of cobble 

at the base of a dam is a common practice by beaver and we simply mimicked that design. 

Coyote willow, the most abundant willow along Bridge Creek, was the preferred material for 

wicker weaves, as it reproduces vegetatively by producing basal shoots that form dense clonal 

colonies of long-stemmed shoots that are relatively unbranched. Long, flexible stems that extend 

across most of the incision trench were preferred, as these impart the most strength to the 

structure. The advantage of using coyote willow was that all materials could be locally sourced 

(generally within 100 m of structures). Since coyote willow primarily reproduce vegetatively, 

harvesting building materials for the wicker weaves actually promoted regrowth, similar to the 

response observed when they are thinned by beaver. Further, the food value for beaver of 1-

year-old coyote willow stems is much greater than older branches. Thus removal of older stems 

and the subsequent sprouting of numerous young shoots increases the food supply for beaver. 

Branches or shoots of other tree species, such as cottonwood, juniper, or Douglas fir were tried,

but their less flexible nature and more branching structure suggests they may not be as effective.

A notable distinction between the PLWWs and beaver dam construction techniques is the 

orientation of the woody material. Beaver place many of the branches on the dams parallel to the 

flow (e.g., see Figure 11). This creates a wider downstream dam face or mattress of material and 

may help to minimize downstream scour relative to the PLWWs. The PLWWs are placed 

perpendicular to the flow because that is a more efficient use of building materials. Moreover, in 

monitoring beaver activity and colonization of wicker weaves, it is much easier to spot beaver 

activity and colonization of BDS structures by the placement of cuttings parallel to the flow 

(Figure 11). By contrast, woody debris and branches that wash down and rack on the dam tend 

to orient themselves perpendicular to the flow.

While PLWWs were designed to be initially permeable to water, SDs were intended to 

form a pool upstream and behave like a beaver dam, so additional rock, mud, and organic 

material were applied to the dam face to create a relatively impermeable structure sufficient to 

raise the water levels and disperse flow over a stream-adjacent terrace. This again was 

mimicking the construction methods beavers tend to use (Morgan 1986, Muller-Schwarze and 

Lixing 2003).

For all structures, the following rules (where applicable) were applied.

1. Within the incision trench, the planform shape of the PL was either straight or convex 

downstream (i.e., the center of the PL within the bankfull channel is the most 

downstream post) with the ends of the PL extending upstream along the bank(s), typically 

5–10 m, when bank erosion was not desired. A straight PL perpendicular to the main 

flow promotes parallel streamlines. A straight PL angled toward one bank can promote 
31

the shunting of flow to one side of the channel or the other. A convex downstream shape 

promotes divergent flow and keeps flow from concentrating in the thalweg downstream 

of the BDS structure and creating excessive scour, which can undermine the posts.

2. Where possible, PLs extended roughly perpendicular to stream flow along any low 

terraces within 1 m elevation of the low flow channel, extending no more than 15 cm 

above the terrace elevation, sufficient to disperse flow across the terrace and help create a 

more tortuous path for the flow to follow prior to returning to the main channel (Figure 

10 and Figure 14). Where appropriate, a gap was left on the terrace PL for a new channel 

to flow through once the channel aggraded to the elevation of the terrace. Gaps were 

strategically placed to take advantage of any depressions or old channels on the terrace 

and existing riparian vegetation, and to increase stream sinuosity. In some cases, 

however, beaver dammed up gaps, but this typically resulted in dispersed flow in 

multiple channels across the terrace downstream from the beaver dam, as typically 

happens with natural beaver dams extending across a low terrace.

3. The distance between structures roughly approximated the natural distance between 

beaver dams, and was a function of channel slope. Generally, structures were placed 

close enough to each other that the pool formed by one structure backed up water to the 

base of the next structure upstream. This helped to ensure that beaver have safe 

upstream-downstream access while the pool exists and that most of the length of the bed 

will aggrade once the pools fill in. Having a pool form on the downstream end of a 

structure also lessened the vertical distance between the water level at the top and bottom 

of the structure, helping to reduce scour depth and the potential for the BDS structure to 

be undermined by excessive scour.

4. Where there was a structural gap within an abandoned beaver dam (e.g., a portion of the 

dam had breached), posts were installed in the gap.

5. Within the bankfull channel, posts were pounded 1 m deep into the bed where possible, 

but this target depth could not always be achieved, primarily due to the presence of large 

cobble.

Structure Location Details

In 2009, 21 PLs, 44 PLWWs, 11 SDs, 5 REDs, and 4 RADs were installed in the four 

reaches: Lower Owens, Meyer’s Camp, Pat’s Cabin, and Sunflower (Table 2). A total of 34 

structures were placed in Lower Owens, 16 in Meyer’s Camp, 15 in Pat’s Cabin, and 20 in 

Sunflower. The total stream length treated was 3.5 km. Distances between structures ranged 

from 5 m to 89 m and averaged 30 m. For each of the four reaches, the type and location of each 

structure is illustrated in Figure 6 through Figure 9.
32

Conclusions

The incised and degraded habitat of Bridge Creek is thought to be limiting the population 

of ESA-listed steelhead. We are assisting a small, extant beaver population to restore 

geomorphic, hydrologic, and ecological functions in this system. The primary hypothesis we are 

testing is that by working with beaver to create stable colonies and aggrade incised reaches of 

Bridge Creek, there will be measurable improvements in riparian and stream habitat conditions,

which will translate to increased abundance of steelhead.

Continued monitoring is assessing the geomorphic and biological changes that are 

occurring at individual structures (21 PLs, 44 PLWWs, 11 SDs, 5 REDs, and 4 RADs) and to the 

reaches as a whole (Lower Owens, Meyer’s Camp, Pat’s Cabin, and Sunflower). Such 

monitoring will be used to test the hypotheses outlined in Table 1 and to assess whether the 

structures follow one of the stochastic developmental pathways outlined in Figure 5, or whether

there are additional pathways followed that were unanticipated. Ongoing monitoring will also 

allow us to modify structural designs as needed for the purposes of achieving the overarching 

goal of improving stream and riparian habitat.
33

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Reservation. Ecol. Restor. N. Am. 18:87–92.

Beechie, T. J., M. M. Pollock, and S. Baker. 2007. Channel incision, evolution, and potential recovery in 

the Walla Walla and Tucannon river basins, northwestern USA. Earth Surf. Process. Landf.

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Darby, S. E., and A. Simon (eds.). 1999. Incised river channels. Wiley, Chichester, UK.

Demmer, R., and R. L. Beschta. 2008. Recent history (1988–2004) of beaver dams along Bridge Creek 

in central Oregon. West. N. Am. Nat. 32:309–318.

Lowry, M. M. 1993. Groundwater elevations and temperature adjacent to a beaver pond in central 

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beaver dams on a small agricultural stream in eastern Nebraska. In Proceedings of the 12–15 

September 2004 conference: Self-sustaining solutions for streams, wetlands, and watersheds, p. 

264–369. American Society of Agricultural Engineers, St. Joseph, MI.

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canadensis, in Wyoming. Can. Field Nat. 116:60–68.

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35

Appendix A: BDS Structure Maps

Appendix A contains selected maps showing the locations of the beaver dam support 

(BDS) structures in four reaches. The maps are overlaid on two base maps: 1) a blimp aerial 

photography survey performed in November 2009 by Utah State University’s ET-AL, and 2) a 

drone aerial photography survey performed in April 2010. The drone imagery provides complete 

coverage of all BDS structure sites, whereas the blimp has some gaps in coverage in the upper 

part of the Lower Owens reach and the upper half of the Pat’s Cabin reach.

The complete set of maps is provided at two scales, midview and overview, and a 

BDSview of each structure is available from the authors. For each of the 85 BDS structures, two 

maps (one on each base) are available (the BDSview). They are included separately because of 

the large file sizes (approximately 400 MB total). The overview maps show all structures within 

the reach and is similar to those figures shown in Figure 6 through Figure 9. The midview maps 

divide the reaches into two or three segments and show between several and a dozen structures 

each. To maintain the fidelity of the high resolution base imagery, the individual file sizes of the 

PDFs vary between 2 MB and 10 MB. Table A-1 lists hyperlinks to all the individual maps.

A Web portal for navigating to each map by browsing, through interactive maps or 

Google Earth *.kmz files, has been created. At the portal (Figure A-1) are the hyperlinks listed 

in Table A-1. Access to that Web site can be obtained by contacting Joseph Wheaton at Utah 

State University’s Watershed Sciences Department (telephone 435-797-2465 or e-mail 

Joe.Wheaton@usu.edu). Ten of the midview drone aerial images are shown in this appendix for 

reference (Figure A-2 through Figure A-11). The *.kmz files can be browsed and show the 

locations of all structures and have pop-up balloons with images of every structure, links to 

Picassa albums, and links to the BDSview maps for each structure (e.g., Figure A-12).

Table A-1. List of hyperlinks to all the static PDF maps by reach. BDSview maps show just individual 

BDS structures. Midview maps show several BDS structures within the reach. Overview maps 

show all structures in the reach.

Lower Owens Meyer’s Camp Pat’s Cabin Sunflower

BDS maps blimp

• BDSview (33 maps)

• Midview (2 maps)

• Overview (1 map)

BDS maps blimp

• BDSview (17 maps)

• Midview (3 maps)

• Overview (1 map)

BDS maps blimp

• BDSview (15 maps)

• Midview (3 maps)

• Overview (1 map)

BDS maps blimp

• BDSview (20 maps)

• Midview (2 maps)

• Overview (1 map)

BDS maps drone

• BDSview (33 maps)

• Midview (2 maps)

• Overview (1 map)

BDS maps drone

• BDSview (17 maps)

• Midview (3 maps)

• Overview (1 map)

BDS maps drone

• BDSview (15 maps)

• Midview (3 maps)

• Overview (1 map)

BDS maps drone

• BDSview (20 maps)

• Midview (2 maps)

• Overview (1 map)
36

Figure A-1. Screen shot of Web portal for downloading individual pdf maps and browsing interactively 

in Google Maps, including the ones in this appendix.
37

Figure A-2. Midview map of upper reach at Lower Owens with April 2010 drone aerial imagery as base

map and 1 m contour intervals derived from the Watershed Sciences Department 2005 LIDAR 

survey. Coordinates are UTM system in 50 m increments.
38

Figure A-3. Midview map of lower reach at Lower Owens with April 2010 drone aerial imagery as base

map and 1 m contour intervals derived from the Watershed Sciences Department 2005 LIDAR 

survey. Coordinates are UTM system in 50 m increments.
39

Figure A-4. Midview map of upper reach at Meyer’s Camp with April 2010 drone aerial imagery as base

map and 1 m contour intervals derived from the Watershed Sciences Department 2005 LIDAR 

survey. Coordinates are UTM system in 50 m increments.
40

Figure A-5. Midview map of middle reach at Meyer’s Camp with April 2010 drone aerial imagery as 

base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey. Coordinates are UTM system in 50 m increments.
41

Figure A-6. Midview map of bottom reach at Meyer’s Camp with April 2010 drone aerial imagery as 

base map and 1 m contour intervals derived from the Watershed Sciences Department 2005 

LIDAR survey. Coordinates are UTM system in 50 m increments.
42

Figure A-7. Midview map of top reach at Pat’s Cabin with April 2010 drone aerial imagery as base map 

and 1 m contour intervals derived from the Watershed Sciences Department 2005 LIDAR survey. 

Coordinates are UTM system in 50 m increments.
43

Figure A-8. Midview map of middle reach at Pat’s Cabin with April 2010 drone aerial imagery as base

map and 1 m contour intervals derived from the Watershed Sciences Department 2005 LIDAR 

survey. Coordinates are UTM system in 50 m increments.
44

Figure A-9. Midview map of bottom reach at Pat’s Cabin with April 2010 drone aerial imagery as base

map and 1 m contour intervals derived from the Watershed Sciences Department 2005 LIDAR 

survey. Coordinates are UTM system in 50 m increments.
45

Figure A-10. Midview map of top reach at Sunflower with April 2010 drone aerial imagery as base map 

and 1 m contour intervals derived from the Watershed Sciences Department 2005 LIDAR survey. 

Coordinates are UTM system in 50 m increments.
46

Figure A-11. Midview map of bottom reach at Sunflower with April 2010 drone aerial imagery as base

map and 1 m contour intervals derived from the Watershed Sciences Department 2005 LIDAR 

survey. Coordinates are UTM system in 50 m increments.
47

Figure A-12. Screen shot from Google Earth illustrating an example at Sunflower of the pushpins 

denoting each structure type and the balloons at each structure, which provide links to the 

BDSView pdfs and links to geotagged Picassa albums of every structure.

Recent NOAA Technical Memorandums

published by the

Northwest Fisheries Science Center

NOAA Technical Memorandum NMFS-NWFSC119 Waples, R.S., K. Hindar, and J.J. Hard. 2012. Genetic risks associated with marine aquaculture. 

U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-119, 149 p. NTIS number pending.

118 Stout, H.A., P.W. Lawson, D.L. Bottom, T.D. Cooney, M.J. Ford, C.E. Jordan, R.G. Kope, 

L.M. Kruzic, G.R. Pess, G.H. Reeves, M.D. Scheuerell, T.C. Wainwright, R.S. Waples, E. Ward, 

L.A. Weitkamp, J.G. Williams, and T.H. Williams. 2012. Scientific conclusions of the status review 

for Oregon coast coho salmon (Oncorhynchus kisutch). U.S. Dept. Commer., NOAA Tech. Memo. 

NMFS-NWFSC-118, 242 p. NTIS number PB2012-113458.

117 Maynard, D.J., T.A. Flagg, W.C. McAuley, D.A. Frost, B. Kluver, M.R. Wastel, J.E. Colt, and 

W.W. Dickhoff. 2012. Fish culture technology and practices for captive broodstock rearing of ESAlisted salmon stocks. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-117, 65 p. NTIS 

number PB2012-110667.

116 Lian, C.E. 2012. West Coast open access groundfish and salmon troller survey: Protocol and results 

for 2005 and 2006. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-116, 52 p. NTIS 

number PB2012-107486.

115 Plummer, M.L., W. Morrison, and E. Steiner. 2012. Allocation of fishery harvests under the 

Magnuson-Stevens Fishery Conservation and Management Act: Principles and practice. U.S. Dept. 

Commer., NOAA Tech. Memo. NMFS-NWFSC-115, 84 p. NTIS number PB2012-107485.

114 Bradburn, M.J., A.A. Keller, and B.H. Horness. 2011. The 2003 to 2008 U.S. West Coast bottom 

trawl surveys of groundfish resources off Washington, Oregon, and California: Estimates of distribution, 

abundance, length, and age composition. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC114, 323 p. NTIS number PB2012-105507.

113 Ford, M.J. (ed.). 2011. Status review update for Pacific salmon and steelhead listed under the 

Endangered Species Act: Pacific Northwest. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC113, 281 p. NTIS number PB2012-104687.

112 Skidmore, P.B., C.R. Thorne, B.L. Cluer, G.R. Pess, J.M. Castro, T.J. Beechie, and C.C. Shea. 

2011. Science base and tools for evaluating stream engineering, management, and restoration proposals. 

U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-112, 255 p. NTIS number PB2012-104660.

Most NOAA Technical Memorandums NMFS-NWFSC are available at the

Northwest Fisheries Science Center Web site, http://www.nwfsc.noaa.gov