| LARGE WOODY
DEBRIS STRUCTURES
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1. CATEGORY
1.0 – River Training
2. DESIGN STATUS
Level II
3. ALSO KNOWN AS
Engineered log jams, debris groins, rootwad composites, rootwad deflectors.
4. DESCRIPTION
Structures made from felled trees may be used to redirect, deflect, or dissipate erosive flows. The structural complexity and hydraulic complexity created by Large Woody Debris (LWD) will provide important components of good aquatic habitat. The use of LWD structures for bank stabilization is often intended to mimic natural systems. LWD can be used to enhance the effectiveness and mitigate for the impacts of other bank protection treatments, such as riprap.
5. PURPOSE
There is considerable documentation that the presence of LWD has a positive influence on stream structure and habitat, primarily providing instream cover and supporting pool formation. The creation of stable pool habitats is a key component of stream restoration and pool habitats are frequently associated with LWD (Shields et al. 1994, 2004; House et al. 1990). However, the amount of LWD and the subsequent stream diversity and habit has been in decline for decades. Historically streams have been cleared of LWD by such ecologically damaging practices as wood removal (snagging), splash damming, placer mining, channelization, logging, riparian clearing for cattle grazing, as well as loss of meander bends for transportation corridors.
More than a century ago, Van Cleef (1885) concluded from an investigation of the Catskill streams in New York that "...the destruction of the trees bordering on streams and the changed conditions of the banks produced thereby, has resulted in the destruction of the natural harbours or hiding places of the trout, that this is the main cause of depletion, and that unless these harbours are restored, it will be useless to hope for any practical benefit of restocking them."
Natural instream decay/loss rates of LWD (about 3% per year), without riparian re-supply, can leave a legacy of featureless streams with few pools and limited cover (Slaney et al., 2001). Many of these impacts are so long-standing that degraded rivers and streams, lacking in large woody structures and deep pools, appear normal to untrained eyes.
With increasing frequency, highway engineers are being asked to incorporate LWD into their bank protection designs. Current stream restoration and rehabilitation work involves reintroducing LWD and protecting or reestablishing the natural riparian sources. Without inputs of LWD to the system the recovery time for many of these streams could be quite lengthy, especially in many of forested streams of the Pacific Northwest which were historically logged up to the edge of the bank. In the Midwest, fisheries values provided much of the incentive for rehabilitative work while in the Pacific Northwest the decline of anadromous fish has provided the impetus.
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The use of rock and other resistive measures can result in loss of fish habitat, yet studies have shown that fish use increased when LWD is included in rock revetments. The debris itself will provide extremely valuable macroinvertebrate substrate (Shields et al., 2001). The incorporation of LWD into riprap and Spur Dikes is, therefore, considered a form of mitigation (Washington, 2003) especially when the LWD is un-trimmed and forms a complex cover.
LWD is specified in streambank stabilization for three primary reasons: 1) to assist in providing bank protection, 2) to alter channel morphology, to form pools, provide cover and enhance aquatic habitat in general, and 3) as a means to rehabilitate riverine and floodplain environments (Washington, 2003, Harmon and Smith, 2000).
In EMRRP Technical Note SR-13, Fischenich and Morrow (2000) list some specific benefits:
Create pool habitat.
Generate scour and substrate complexity.
Increase depths through shallow reaches.
Redirect flows away from the banks thereby reducing erosion.
Armor stream banks to reduce erosion.
Promote bar formation and induce sedimentation.
Increase in-stream cover and refugia.
6. PLANNING
Useful for Erosion Processes:
Toe erosion with upper bank failure Scour of middle and upper banks by currents Local scour Erosion of local lenses or layers of noncohesive sediment Erosion by overbank runoff General bed degradation Headcutting Piping Erosion by navigation waves Erosion by wind waves Erosion by ice and debris gouging General bank instability or susceptibility to mass slope failure
Spatial Application:
Instream Toe Midbank Top of Bank
Hydrologic / Geomorphic Setting
Resistive Redirective Continuous Discontinuous Outer Bend Inner Bend Incision Lateral Migration Aggradation Conditions Where Practice Applies:
Intermittent Large Woody Debris (LWD) structures function similar to permeable spurs. HEC-23 lists the following river environments as suitable for permeable spurs.
Characteristic
Permeable spurs
Planform
Braided or meandering
Stream size
Wide to moderate
Bend radius
Long to moderate
Velocity
Slow to moderate
Bed material
Sand or fine
Ice Debris load
Low
Bank angle
All
Floodplain width
All
Resource requirement for maintenance
High to moderate
The beneficial use of LWD structures is well-documented especially when placed in locations and configurations where it could be expected to occur naturally. The designer should also consider the availability by identifying woody debris sources and specification of haul routes and methods in a way to minimize stream corridor disturbance. In environments where wood decays rapidly the ultimate success of a project depends on creation of conditions within and adjacent to the structures that lead to successful revegetation or colonization by permanent terrestrial vegetation. Without such colonization, effects of structures may be short-lived. Another question to keep in mind is whether there is existing vegetation that can be salvaged and used during construction e.g., clumps of willows that can be transplanted or used for sources of live branches or poles.
LWD can be designed, engineered, and anchored in a manner that will pass design flows and provide bank stabilization by redirecting, or deflecting, or resisting erosive flows while providing beneficial habitat characteristics. Since LWD are used at the toe or mid-bank the designs are independent of design high water elevation or freeboard.
LWD can be keyed into the streambank (rootwads), partially embedded into the channel, constructed to form lateral, mid-channel or channel-spanning log jams, or placed in the floodplains of channels that are laterally migrating following incision. The LWD can provide energy dissipation which creates scour pools and in turn creates substrate complexity and cover.
The foremost fishery benefits are scour pool formation and increased cover which are both rearing type habitats. The use of LWD structures for stabilization and habitat enhancements in coarse-bedded streams of the Pacific Northwest has been described by others (Abbe et al. 1997, Hildebrand et al. 1998, Drury et al. 1999). For incised sand bed streams the use of LWD structures should be limited to reaches in advanced stages of channel evolution e.g., Level IV or Level V (Shields, 2004).
Shields et al. (2000) suggest that installations along streams experiencing incision should be limited to reaches that have evolved through bed degradation into Simon stage V (Simon, 1989), which features bank erosion and bed aggradation while berms form within the cross-section enlarged by erosion.
Ice can severely damage or destroy woody debris structures (USACE, 1981, Ryan & Short, 1995), and intermittent structures anchored to pilings may be damaged by floating debris (Biedenharn et al., 1998). Damage by beavers has also been reported (USACE, 1981). Stabilization of eroding banks using structures composed entirely or partially from LWD has been described for streams in Vermont (Edminster et al., 1949), Arkansas (Mott, 1994), Washington (Abbe et al., 1997), and Illinois (Derrick, 1997). Stream aquatic habitat rehabilitation or enhancement using LWD addition has been described for a small gravel-bed stream in Virginia (Hilderbrand et al., 1998), for small rivers in British Columbia (D’Aoust and Millar, 2000) and for a large, regulated river in British Columbia (Goldberg et al., 1995).Complexity:
Moderate. Design should include revegetation and anchoring considerations.Design Guidelines / Typical Drawings:
In general, LWD structures, including rootwad deflectors and engineered log structures should be designed for the channel-forming (Q cf) or bankfull discharge (Q bf). See Special Topic: Bankfull Discharge.Rootwad deflectors are designed with the rootwad oriented facing upstream. Design considerations that must be taken into account when installing rootwads include: 1) material dimensions, configurations, and spacing, 2) habitat requirements, 3) revegetation, and 4) potential failure mechanisms. The size of the rootwad material to be used relies primarily on the dimensions of the stream. The rootwad fan should be relatively large, typically in the range of 2 to 5 m (6.6 to 16.4 ft), depending on the channel type. The rootwad fan should span from the maximum scour depth to bank-full elevation (generally rootwads are placed at an elevation such that one-third of the fan remains below base flow water surface elevation, and one-third above AHW (bankfull) water surface elevation). As a general rule, three quarters of the length of the rootwad should be imbedded into the bank once anticipated scour has occurred. The face of the rootwad fan must be configured to intersect flow at a 90° angle, however it may be rotated as much as 15° into the channel. When footer logs are required, the rootwad bole should rest on the stream side of the footer log. To adequately deflect current away from the bank, rootwads should be spaced 3 to 4 times the projected rootwad length apart. To effectively provide complex flows and important habitat, the rootwad fans should be angled within a few feet of the bank. Vegetation should be established on the downstream and upstream banks adjacent to the rootwad to minimize potential scour from new secondary eddies and provide additional habitat. Potential failures are mainly a result of flanking and undercutting. Flanking can be minimized by installing the rootwad into secure substrates such as bed rock. Undercutting can be reduced by paying close attention to the design elevation and embedment length. If placed too high in the channel, undercutting will occur. Footer logs, boulders, pole planting and/or transplants should be placed to arrest undesirable scour immediately downstream. For further detail and design criteria, please see Sytle and Fischenich (2000).
Design guidelines for LWD structures are in an early stage of development relative to other bank stabilization techniques. Some intermittent structures are comprised of criss-crossed members (Abbe et al, 1997, Shields et al., in review and 2001). D'Aoust and Millar (2000) describe that boulder-ballasted, triangulated log and boulder structures performed hydraulically as designed.
Design requires analysis of forces acting on the debris: The forces tending to destabilize the structure include fluid drag and buoyancy while those resisting motion include gravity and the weight of ballast or forces exerted by anchoring systems. A structure is stable when the sum of the resisting forces exceeds the sum of the driving forces (e.g., fluid drag and buoyancy). Hydraulic conditions immediately downstream can result in deposition which will bury the wood and increase the effective weight and, hence, the stability of the structure (Washington, 2003). Therefore proper entrenchment, ballast, and anchors is extremely important initially. Example design computations are presented by Abbe et al. (1997), D'Aoust and Millar (2000), and Shields et al. (2004).
Stability of earth anchors is dependent on the strength of soils, which vary widely in floodplain environments. In addition, anchoring cables tend to become slack as structures settle; contract specifications should include provisions for periodically tightening cables during the first few weeks following construction.
7. ENVIRONMENTAL CONSIDERATIONS / BENEFITS
The creation of stable pool habitats is a key benefit from LWD structures. In addition to supporting pool formation, LWD has a positive influence on stream structure, fish and wildlife habitat, and instream cover. Woody debris provides important substrate for benthic macroinvertebrates, cover and holding areas for fish, provides velocity refugia, and promotes formation of stable pool habitats (Gough, 1991). In addition, as the structures accrete sediments, they are often colonized by terrestrial vegetation, leading to riparian zone recovery. Studies of degraded streams in the Southeast have shown that habitat diversity (Shields & Smith, 1992), invertebrate species richness and abundance (Cooper & Testa, 1999), invertebrate biomass (Wallace & Benke, 1984) and fish species richness (Shields et al., 1998a) are associated in a positive fashion with LWD density.
Peters et al. (1998, USFWS) studied salmonid densities at five different types of bank stabilization projects (riprap, riprap with LWD, rock deflectors, rock deflectors with LWD and LWD exclusively) and reported that sites using LWD had consistently greater salmonid densities.
8. HYDRAULIC LOADING
LWD structures are suitable for velocities up to 3 m/s (10 ft/s).
Allen and Leech (1997) reported various local velocities measured with a flowmeter. Roaring Fork River, CO, log revetments cabled to bank measured 3 m/s (10 ft/s), Snowmass Creek, CO rootwads measured 2.6 m/s (8.7 ft/s), Upper Truckee River, rootwads, 1.2 m/s (4.0 ft/s).
9. COMBINATION OPPORTUNITIES
The use of these structures may be accompanied by plantings on upper bank and through the structures. The proper application of these structures will often result in the deposition of sediment on top of or behind the woody debris. This accretion provides an opportunity for revegetation or colonization with permanent bank-stabilizing vegetation.
LWD is often used in concert with or incorporated into other techniques to enhance the environmental effectiveness or mitigate for the treatment’s negative effects on aquatic habitat.
Willow Posts and Poles, Live Siltation, Live Brushlayering, ECBs, TRMs, VMSE, Vegetated Riprap, and Meander Restoration are all techniques that can be combined with Large Woody Debris structures.
10. ADVANTAGES
Incorporating LWD can be very cost-effective for habitat rehabilitation and adding stream habitat complexity to a project. LWD structures often cost much less than stone or metal structures and provide valuable aquatic and terrestrial habitat.
As scour pools develop adjacent to the structures, the interlocking nature of engineered log structures allow them to deform and settle, thereby retaining the structural integrity of the structure (Washington, 2003).
11. LIMITATIONS
The natural effectiveness of LWD is largely dependent on channel type and geomorphology. If LWD is not a natural component of the stream system then the addition of LWD, while it may still have some habitat or mitigation value, may not be prudent. LWD should be used with caution in streams that are large, unstable, or unsuitable for vegetation establishment.
The ability of the site to become vegetated should be of concern if long-term stability is desired. Establishing riparian vegetation is a fundamental requirement for the long-term success of LWD structures since the logs themselves are temporary. A realistic life span for the wood itself, not the technique, is 5 to 15 years (Sytle and Fischenich, 2000). However there are several factors influencing the longevity of the wood that include:
Tree species; avoid using hardwood species such as cottonwood or alder which can decay rapidly, conifers like fir and pine are moderately long lasting, while oak, cypress, redwood and cedar last the longest.
Climate (cool and dry climates prolong life).
Position relative to water surface (frequent wetting and drying can increase decomposition while submerged wood can last indefinitely).
Soil contact (microbial digestion can reduce longevity while anaerobic conditions will increase longevity).
12. MATERIALS AND EQUIPMENT
Most LWD structures require:
LWD, logs, limbs for habitat and rootwads with sufficient tree trunk (bole) attached.
Tracked excavators, preferably equipped with hydraulic thumbs, are the most functional piece of heavy equipment.
A chain saw may be used to "sharpen" the end of the bole if the drive point-method is used.
Rocks, stone, boulders.
Anchor cables and anchors.
Vegetation and biotechnical materials (post and poles, live brushlayers, and live stakes).
The use of previously saturated LWD can mitigate buoyancy problems during installation. Sufficient stone or other anchors will be necessary.
When specified, the biotechnical materials (willow branches, cottonwood poles etc.) should be onsite, stored in shaded area and soaking in water. (see Special Topic: Harvesting and Handling of Woody Cuttings).
13. CONSTRUCTION / INSTALLATION
Engineered LWD structures will be constructed as specified. Rootwads are often installed using the trenching method but the drive-point method is sometimes applicable. With the drive-point method, the rootwad is inserted into the bank by sharpening the end of the trunk and driving it into the bank.
Buoyancy of the wood can be problematic especially if the LWD needs to be installed below the water surface. Since wood is normally buoyant in water, structures must be designed to resist floating by partially burying some of the logs in the bank or bed, stacking woody material so that stems and branches interlock, and securing woody debris to the channel boundary with cables attached to deadmen, earth anchors, or piles, or weighting the LWD with large stone.
Protection of the existing riparian zone is critical; therefore, access and staging areas need to be carefully planned. Turbidity may be a significant problem during construction, therefore construction techniques which reduce turbidity shall be employed, such as: minimize disturbance, use tracked excavators, winches or hand labor, work during low-flow periods, use dewatering or stream diversion techniques, or use stream isolation techniques (McCullah, 2004).
14. COST
Shields et al. (In review) reported unit costs for a project in northern Mississippi that were 19% to 49% of recorded costs for stone bank stabilization projects in the same region. Demonstration woody debris structures constructed along the Missouri River in the 1970’s cost one-fourth to one-third as much per unit length of bankline protected as stone structures placed in adjacent reaches (USACE, 1981).
The cost of large woody debris can vary considerably from free for locally salvaged wood to large diameter full length trees which may have to be sawn for transport and later re-assembled. The pieces of large woody debris can vary between a few hundred dollars (see San Vacinte Creek Case Study) to a thousand dollars per piece (Washington, 2003). Washington (2003) also reports a broad cost range for engineered log jams of $1,800 to $80,000 each.
15. MAINTENANCE / MONITORING
Maintenance of LWD structures might include re-alignment or removal of moved pieces following large storm events. If anchored, the anchoring hardware may need adjustment or replacement, especially following the first few storms.
Monitoring to evaluate performance and structural integrity should be conducted annually and following any flow event that meets or exceeds the design flow event. With LWD structures this is usually the channel-forming discharge (Qcf) annual high water (AWH) or the bankfull event (Qbf)
16. COMMON REASONS / CIRCUMSTANCES FOR FAILURE
Failures of LWD structures are attributed mainly to inadequate anchoring and orientation, and unsuccessful vegetation establishment. The improper installation and orientation of LWD when imbedded in structural armor can result in undercutting, structural damage, and subsequent loss of the armor and the woody debris. When anchoring to bedrock or boulders, improper quantity, placement, gluing, or drilling of anchor points can lead to excessive movement and instability of the structure (Washington, 2003). Projects with under-ballasted box groins and no bank armoring adjacent to the structure in particular streams have been known to fail (Slaney, et al., 2001). If vegetation does not establish properly, the habitat benefits of the structure may be somewhat limited and the integrity of the structure and adjacent banks could be compromised. Vegetation may fail to establish due to a variety of circumstances such as: improper orientation of the rootwad that accelerates local scour or negatively alters scour patterns; lack of access to water during periods of drought; lack of seed recruitment; or inappropriate installation timing (e.g., planting live willow stakes during the dry season).
17. CASE STUDIES AND EXAMPLES
West Kettle River, BC.
Nineteen LWD structures were installed in the 2 km test section of West Kettle River, BC, from 1996-1998. Thirteen of the structures were designed as pool-forming, and of these only two ‘box groins’ shifted in response to a prolonged bankfull flood in 1999, and one subsequently failed. The triangulated structures performed as desired and over three years remained functional and were well utilized by rainbow trout (Slaney, et al., 2001).
Little Topashaw Creek is a fourth-order stream in the Yalobusha River watershed in Chickasaw County, north central Mississippi. A geomorphic evaluation performed immediately prior to construction indicated that the downstream end of the reach was in the aggradational stage V of the of incised channel evolution conceptual model, while the middle part of the reach was stage IV, and the upstream fourth of the reach was still degrading (stage III). In general, concave banks on the outside of meander bends were caving, and sand was accreting on large point bars opposite failing banks. On the outside of bends, eroding banks frequently invaded adjacent cultivated fields, while inside bends and abandoned sloughs were vegetated with a diverse mixture of hardwood trees and associated species. This project was designed to accelerate evolution of the existing system toward a sinuous two-stage channel with wooded berms that could be classified as Stage VI. Bank stabilization structures made from large woody debris instead of stone were placed along the toe of eroding banks.
Flood flows from large storms in the winter of 1996-1997 resulted in erosion of a streambank on San Vacinte Creek, threatened three residential structures located on the high right-descending bank, and undermined an existing section of rock-filled gabion baskets protecting a commercial establishment located at the lower project reach. In 1998-99, vegetated riprap protection was installed along the project reach. In 2001, Vane and Rootwad Revetment structures were designed and installed to redirect flows away from and armor the toe of the riprap revetment.
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| A pool was created by the LWD structure as a result of scour. San Vacinte Creek, Santa Cruz Co. |
Finished project at San Vacinte Creek, Santa Cruz Co. |
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| Prior to restoration, the left bank of the Carmel River was actively
eroding. Photo courtesy of the Monterey Peninsula Water Management District
(MPWMD). |
Installation of footer logs on the right bank of the Carmel River .
Photo courtesy of the MPWMD. |
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| Installation of boulder
anchors on the right bank of the Carmel River. Photo courtesy of
the MPWMD. |
Finished Carmel River restoration project following the winter of 2002.
Photo Courtesy of MPWMD. |
Please visit the Photo Gallery for more pictures.
18. RESEARCH OPPORTUNITIES
Allowable velocities or hydraulic loading for redirective structures.
19. REFERENCES
Abbe, T. B., Montgomery, D. R., & Petroff, C. (1997). Design of stable in-channel wood debris structures for bank protection and habitat restoration: An example from the Cowlitz River, WA. In Wang, S.Y., Langendoen, E. & Shields, F. D. Jr., (eds.) Management of Landscapes Disturbed by Channel Incision, Stabilization, Rehabilitation, and Restoration, Center for Computational Hydroscience and Engineering, University of Mississippi, University, Mississippi, 809-815.
Biedenharn, D. S., Elliott, C. M., & Watson, C. C. (1998). Streambank stabilization handbook. Veri-Tech, Inc., Vicksburg, MS, CD-ROM.
Cooper, C. M., & Testa, S. (1999). Examination of revised rapid bioassessment protocols in a watershed disturbed by channel incision. Bulletin of the North American Benthological Society, 16(1), 198.
D'Aoust, S. G. & Millar, R. G. (2000). Stability of ballasted woody debris habitat structures. Journal of Hydraulic Engineering, 126(11), 810-817. (pdf)
Derrick, D. L. (1997). Twelve low-cost, innovative, landowner financed streambank protection demonstration projects. In S. S. Y. Wang, E. Langendoen, & F. D. Shields, Jr. (eds.), Management of Landscapes Disturbed by Channel Incision: Stabilization, Rehabilitation, and Restoration, University of Mississippi, Oxford, MS, 446-457.
Drury, T. A., Petroff, C., Abbe, T. B., Montgomery, D. R., & Pess, G. R. (1999). Evaluation of Engineered Log Jams as a Soft Bank Stabilization Technique: North Fork Stillaguamish River. Washington. In Proceedings of the American Society of Civil Engineers Conference, Rocky Mountain Section, Denver, CO.
Edminster, F. C., Atkinson, W. S., & McIntyre, A. C. (1949). Streambank Erosion Control on the Winooski River, Vermont., USDA Circular No. 837, 54 pp.
Fischenich, C., & Morrow, J., Jr. (2000). Streambank Habitat Enhancement with Large Woody Material. EMRRP Technical Notes Collection (ERDC TN-EMRRP-SR-13), U.S. Army Engineer Research and Development Center, Vicksburg, MS. (pdf)
Goldberg, H., Rublee, B., & Mitchell, C. A. (1995). Development of fish habitat for mitigation below Hydro Diversions. Journal of Energy Engineering, 121(2), 52-73.
Gough, S. (1991). Stream fish habitat response to restoration using tree revetments. In R. Sauer, (ed.), Proceedings of the Symposium on Restoration of Midwestern Streams, 52nd Midwest Fish and Wildlife Conference: North-Central Division of the American Fisheries Society, 45-55.
Harman, W., & Smith, R. (2000). Using Root Wads and Rock Vanes for Streambank Stabilization. River Course, Fact Sheet Number 4, NC A&T State University, North Carolina Cooperative Extension Service, Raleigh, NC. (pdf)
Hilderbrand, R. H., Lemly, D. A., Dolloff, A. C., & Harpster, K. L. (1998). Design considerations for large woody debris placement in stream enhancement projects. North American Journal of Fisheries Management, 18, 161-167. (pdf)
House, R.& Crispin, V. (1990). Economic analyses of the value of large woody debris as salmonid habitat in coastal Oregon streams. US Dept. of the Interior, Bureau of Land Management, Oregon State Office, Portland.
McCullah, J. A. (2004). Erosion Draw 5.0 - Erosion and Sediment Control Manual with Typical Drawing Files for Computer-Aided Drafting, Salix Applied Earthcare, Redding, CA
Mott, D. N. (1994). Streambank stabilization/riparian restoration action plan: Buffalo National River, Arkansas. unpublished report, U. S. Dept. of the Interior National Park Service, Harrison, Arkansas, 83 pp.
Shields, F. D. Jr., & Smith, R. H. (1992). Effects of large woody debris removal on physical characteristics of a sand-bed river. Aquatic Conservation: Marine and Freshwater Ecosystems, 2, 145-63.
Shields, F. D., Jr., Knight, S. S., Cooper, C. M., & Testa, S. III. (2000). Large woody debris structures for incised channel rehabilitation. In R. H. Hotchkiss and M. Glade (eds.) Building Partnerships Proceedings of the Joint Conference on Water Resources Engineering and Water Resources Planning and Management, Environmental and Water Resources Institute of the American Society of Civil Engineers, Reston, VA. Published on CD-ROM. (pdf).
Shields, F. D., Jr., Morin, N., & Cooper, C. M. (2001). Design of Large Woody Debris Structures for Channel Rehabilitation. In U. S. Subcommittee on Sedimentation. Proceedings of the Federal Interagency Sedimentation Conferences, 1947 to 2001, Seventh Conference Proceedings, CD-ROM, Washington, D. C. II-42--II-49. (pdf).
Shields, F. D., Jr., Morin, N., & Cooper, C. M. (2004). Large Woody Debris Structures for Sand-Bed Channels. Journal of Hydraulic Engineering, 130(3), 208-217. (pdf)
Slaney, P.A., Koning, D’Aoust, S.G,. & R.G. Millar. (2001). Increased Abundance of Rainbow Trout in Response to Large Woody Debris Rehabilitation at the West Kettle River Province of B.C., Ministry of Environment, Watershed Restoration Technical Bulletin Streamline vol. 5, no. 4. pp.32.
Simon, A. (1989). The discharge of sediment in channelized alluvial streams. Water Resources Bulletin, 25(6), 1177-1188.
USACE. (1981). Final Report to Congress, The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Main Report. Washington, D. C.
Van Cleef, J.S. (1885). How to restore our trout streams. pp. 51-55, 14th Annual Meeting of the American Fisheries Society.
Wallace, J. B. & Benke, A. C. (1984). Quantification of wood habitat in subtropical Coastal Plain Streams, Canadian Journal Fisheries Aquatic Sciences, 41, 1643-1652.
Washington Dept of Fish & Wildlife (2003). Integrated Streambank Protection Guidelines, published in co-operation with Washington Dept. of Transportation and Washington Dept. of Ecology, June 2003. (Chapter 6 pdf) (Appendix L pdf) (Appendix H pdf) http://www.wa.gov/wdfw/hab/ahg/ispgdoc.htm (April 2003)
