Credit 1.5: Soft Shore Protection or Enhancement
This credit applies to the construction of soft shore protection rather than hard shore protection structures anywhere shoreline erosion control is needed.
Soft shore protection refers to installing natural, flexible shoreline material where erosion control is needed. Soft shore protection approaches may use beach “nourishment,” logs and large natural woody debris, vegetation, and re-sloping a bank or bluff. Often these soft shore protection approaches are used in combination to augment site stability or to address different issues in different parts of a site.
Using soft shore protection to address shoreline erosion is an environmentally friendly alternative to armoring; however, it is important to note that for a project to receive points for this credit, the site must:
- truly require shoreline erosion control to protect existing major buildings OR
- have degraded shore habitat that can be demonstrably enhanced by soft-shore measures.
Beach enhancement refers to actions, other than bulkhead removal (Credit 1.3) that augment natural features of shoreline systems that may be degraded. Typical beach enhancement projects include adding beach sediment to enlarge a beach, pocket beach, or marsh area where these habitats are moderately impacted. Ideally, beach enhancement designs would replicate historic conditions or those from a nearby unaltered beach with similar dominant drivers (waves, geology, etc.).
Where this credit applies
This credit applies to marine and freshwater shores with sediment-based shorelines. Adding sediment to a naturally rocky shore does not qualify for this credit.
As noted above, this credit applies to sites at risk to shoreline erosion and/or where there is potential to restore damaged shoreline habitat. If neither of these two criteria is met, sediment cannot be added just to qualify for this credit.
Finally, points cannot be earned for both this credit and Credit 1.3 “Bulkhead Removal” for the same length of shoreline, EXCEPT if a bulkhead is removed from a portion of the shoreline (Credit 1.3) and a portion of the previously unprotected shoreline is treated with soft shore methods (Credit 1.5).
Soft shore protection projects are most successful on more protected shorelines, and typically not feasible where there are high wave energy and high erosion rates. In areas that are unsuitable for soft shore protection, moving buildings further landward should be considered over installing hard shoreline protection structures.
This credit offers up to 12 base points and up to 5 bonus points.
Use soft shore measures instead of armoring for protection from erosion over*:
|95-100% of the shoreline||
|75-94% of the shoreline||
|50-74% of the shoreline||
|25-49% of the shoreline||
|10-24% of the shoreline||
Bonus (available once 1 of the base conditions has been met)
|In areas where the beach and nearshore habitat have been degraded, provide documentation that the soft shore measures recreate, restore or enhance spawning habitat for forage fish (surf smelt, sand lance, herring, etc.) by at least 50% by area.||
|Set up and implement a system for monitoring the effectiveness of your soft shore protection project.||
* Note that the remaining % of the shoreline NOT subject to soft shore measures may be bulkheaded OR may have had a bulkhead removed and received points under credit 2.3.
How to proceed
Note that in the US, beach nourishment projects that extend below the OHWM must be reviewed by federal, state and local regulatory agencies. Similarly in Canada, any beach nourishment below the OHWM must be reviewed by Fisheries and Oceans Canada (due to the potential impact on fish habitat) and provincial land authorities (the foreshore is owned and managed by the Provincial Crown), as well as be subject to local government regulation.
Soft shore projects should be designed and supervised by a qualified coastal engineer or geologist. The project must employ a design that allows for the continuation of natural processes such as littoral drift and riparian vegetation growth, and not completely alter beach or backshore areas.
If you have to work in the foreshore (below the OHWM), approval from state, provincial or federal fisheries or environment agencies is required. Also, any work in shoreline and riparian areas will likely be regulated at the local level (e.g., as “development permit areas”). Always consult with your local government to find out what approvals are needed.
Beach “nourishment” or “replenishment” is a common means of soft shore protection in which sediment lost to erosion is replaced or augmented with imported sediment, typically from an upland source. Beach nourishment material should resemble native beach substrate in both size and composition, but may be slightly larger/coarser. No “fines” – grain size less than 0.5 mm – can be present in nourishment material. Gravel is used most commonly as it is less mobile than sand.
Beach nourishment can protect beach resources by creating a larger sand or gravel reservoir, moving the shoreline seaward. In areas where sediment supply has been substantially reduced due to armored bluffs, beach nourishment can mitigate the lost sediment supply and enable local beaches to more closely resemble their historic sediment composition.
If forage fish spawning has been documented on the subject beach, soft shore protection projects must not bury these habitats without designing in their replacement. Use an appropriate sediment composition (rich in 1-7 mm sized sediment) to assure that spawning habitat is enhanced rather than degraded. Up to five years is needed for this to come to fruition at more impacted sites. Monitor the project to assure that spawning habitat is preserved or enhanced.
Beach nourishment differs from fill because it is mobile and permeable, and as such, will likely need to be replenished from time to time.
Logs or other woody debris may be placed to add complexity and elevation to a beach nourishment project, and to help to hold added beach material. In some cases, logs may be anchored to buried boulders or concrete blocks. Do NOT use creosoted or chemically treated woody debris in soft shore protection projects.
On marine sites, woody debris are typically only used above the higher high tideline to protect the area landward of the beach during storms at low to moderate wave energy sites. Logs have only been used successfully at lower elevations on the beach in low wave energy sites (less than 2 miles, or 3.2 km fetch, or open water distance).
Vegetation is often used for soft shore protection in conjunction with other approaches. Do not bury backshore vegetation without replanting. Planting with salt-tolerant species like native dune grass and native trees and shrubs is focused on the area immediately above the normally inundated beach. On low energy shores with fine-grained sediment, salt marsh vegetation can be installed or enhanced to reduce intermittent erosion, although this would typically not be a site that would require soft shore protection and would instead be considered beach enhancement.
Bank re-sloping reduces the slope of an unstable bank and smoothes out landslide scarps or other features that are particularly steep and unstable. This may require installation of erosion control fabric on the slope in very unstable slope sites. To be successful over time, re-sloping is immediately followed by intensive planting of native vegetation selected for high root strength. Re-sloping may not be feasible on small waterfront lots where there is little room between the bank and major buildings, or room to move the buildings back.
Limited hard elements where necessary: Soft shore protection projects may need to employ limited amounts of rock in sites with moderate to high wave energy, severely impacted shoreline processes and/or a minimal available setback (refer to Johannessen 2000 for more detail). However, do not include significant amounts of rock armor except in limited areas, and never use vertical elements such as cement walls, lock block, etc.
Note that soft-shore protection measures are not zero-maintenance solutions to shore erosion. Any soft shore protection may require maintenance or replenishment every few years, depending on the level of activity of shoreline processes.
Monitoring bonus point: Observing the effect and/or effectiveness of an action indicates whether that action has a positive, negative or neutral effect on ecological or physical processes on the site. Monitoring can also indicate whether a project is having the desired effect, and whether any changes are required. Small, incremental corrections early in the life of a project usually cost a lot less than correcting a major failure further down the road.
A monitoring program requires a record of “before” and “after” an activity is completed. This can take the form of before and after photos and measurements, ensuring that they are taken from the same locations and vantage point(s) and, if possible, similar season and weather conditions. It can also include a list of project features or indicators than can be measured consistently before and after construction.
Set up a schedule for inspecting the protection measures on a seasonal basis as well as after major storm events, to determine how key features stand up to erosion, deposition, wind, waves, etc. Typical features or effects to monitor are toe erosion at the bottom of a berm, log or rock movement, losses/gains in plant material, beach profiles, etc.
To achieve this bonus point, commit to monitor and record your observations for a minimum of six years (six summer and winter seasons). It is always a good idea to monitor your protective structure on an ongoing basis to ensure it continues to serve its original purpose.
The Marine Shoreline Design Guidelines (Johannessen et al., 2014 – see full reference under “For more information”) devotes a chapter to beach nourishment (Chapter 7 – Technique 1), which provides insights on effects, cost, monitoring and maintenance. While written for marine shorelines, there are still useful ideas for lake shoreline situations.
Freshwater: This example shows a soft shore enhancement project consisting of reslope/revegetation, large woody debris and beach nourishment.
Beach nourishment example from the marine environment. (MSDG BN-7 and BN-8).
Marine: Large Woody Debris example from the marine environment. (MSDG LW -16 to LW-18)
Marine: An example of a forage fish/surf smelt habitat map from San Juan County (From Friends of the San Juans). This would be of use to qualify for bonus points confirming the project area is in forage fish spawning habitat.
Marine: An example of photo monitoring points (MSDG 8-5) and common monitoring elements and their data collection methods (MSDG 8-3).
For more information
American Society of Landscape Architects. The Sustainable Sites Initiative. www.sustainablesites.org
Brennan, J.S. (2007). Marine Riparian Vegetation Communities of Puget Sound. Puget Sound Nearshore Partnership Report No. 2007-02. Go to www.pugetsoundnearshore.org click on Technical Reports and scroll down to 2007-02.
Clancy, M., I. Logan, J. Lowe, J. Johannessen, A. MacLennan, F. B. Van Cleve, J. Dillon, B. Lyons, R. Carman, P. Cereghino, B. Barnard, C. Tanner, D. Myers, R. Clark, J. White, C. Simenstad, M. Gilmer, and N. Chin, 2009. Management Measures for Protecting the Puget Sound Nearshore. Puget Sound Nearshore Ecosystem Restoration Project Report No. 2009-01. Published by Washington State Department of Fish and Wildlife, Olympia, Washington. See: chapters 2, Beach nourishment; 11, Large wood placement; and 17, Revegetation . Go to www.pugetsoundnearshore.org click on Technical Reports and scroll down to 2009-01
Gerstel, W.J., J.F. Brown, 2006. Alternative Shoreline Stabilization Evaluation Project. Report for the Puget Sound Action Team. Go to https://salishsearestoration.org/wiki/ and enter “Gerstel Brown 2006” in the search box.
Johannessen, J., A. MacLennan, A. Blue, J. Waggoner, S. Williams, W. Gerstel, R. Barnard, R. Carman, and H. Shipman, 2014. Marine Shoreline Design Guidelines. Washington Department of Fish and Wildlife, Olympia, Washington. 419 p. http://wdfw.wa.gov/publications/01583/
Seattle, City of. 2011. Green Shorelines: Bulkhead alternatives for a healthier Lake Washington. 34 pg. Go to http://www.seattle.gov/dpd/ and enter “Green Shorelines” in the search box.
Zelo, I., H. Shipman, and J. Brennan, 2000. Alternative Bank Protection Methods for Puget Sound Shorelines, prepared for the Shorelands and Environmental Assistance Program, Washington Department of Ecology, Olympia, Washington, Publication # 00-06-012.