Credit 2.1: Riparian Vegetation
This credit applies to the maintenance or replanting of native riparian vegetation to help conserve or enhance its value and preserve the ecological functions that it provides along the shoreline.
Riparian areas where land and water converge are among the most biodiverse of any habitats. Riparian vegetation is native vegetation that exists or is planted on the landward side of the OHWM extending up to 200 feet (60 m) landward, and includes trees, shrubs, and ground cover.
Native vegetation is preferred for shorelines because native species:
- are better adapted to local physical conditions such as soil, geology, and climate and therefore require less maintenance;
- are resistant to most pests and diseases;
- require little or no irrigation or fertilizers, once established;
- are non-invasive (do not dominate to the extent of excluding all other species); and
- usually provide better food sources for native wildlife.
However, mature non-invasive or “native adapted” plant species may be maintained if they provide some ecological functions.
Overhanging vegetation in both marine and lakeside shores provides important organic input to the aquatic environment. Research in Puget Sound has shown that up to 40% of juvenile chinook food items are terrestrial in origin, much of it falling or blowing into the water from nearshore vegetation. In addition, surf smelt tend to spawn in beach areas with overhanging vegetation. In lakes, nearshore emergent vegetation such as cattails, sedges and rushes as well as clusters of fine woody debris provide important nearshore cover for juvenile fish, including salmon.
How to proceed
Choose native species that are suitable to your site. As much as possible, planting should be comprised of multi-storied vegetation that includes trees, shrubs and ground cover; however, in some environments, such as south facing rocky bluffs with thin dry soils, only shrubs, grasses and other ground cover may be suitable.
Mature non-invasive non-native or “native adapted” plant species can be maintained as they provide some ecological functions; however, avoid planting new non-native species. Example plant species lists, one for lakes and one for marine shorelines, are provided in Appendix C.
Space plants to achieve full vegetation coverage within 10 years. For example, space trees at 8–14 feet on center and shrubs at 2–6 feet on center depending on the plant species. You may need some assistance from a landscape architect, restoration biologist or landscaper with riparian planting experience to determine the best species and spacing to achieve the desired effect.
Retain and/or plant overhanging vegetation that extends out over the water. Trees such as alder, native maples, and willows and tall shrubs such as oceanspray and red-osier dogwood are excellent overhanging species.
Similarly, along lake shores, retain existing or plant emergent vegetation as much as possible. Emergent vegetation are plants that thrive in partially submerged conditions; examples of emergent species are cattails, bulrushes and sedges. They create excellent rearing and feeding habitat for juvenile forage fish and salmon. In lake shore properties, consider dedicating a section of your shore as juvenile fish rearing habitat by planting emergent vegetation and adding clusters of branches along the high water mark (see Credit 2.4).
Where this credit applies
This credit applies to all types of projects on a waterfront property, but particularly development occurring within the riparian area. It applies to any type of shore in both marine and lake environments. The characteristics of riparian vegetation are somewhat different in marine versus freshwater shorelines, but it serves the same functions and generates the same benefits in either situation.
This credit offers up to 10 base points plus up to 5 bonus points
For the purpose of this guide, “riparian buffer” (RB) is the shoreline area that lies within the minimum riparian buffer or setback required by the local jurisdiction OR within 35 ft/10 m of the OHWM (measured as the horizontal distance landward of the OHWM), whichever is greater.
|Riparian vegetation||*For lots <¼ acre||*For lots >¼ acre||
|Maintain and/or plant native vegetation in –||75-100% of the RB||90-100% of the RB||
|Maintain and/or plant native vegetation in –||50-74% of the RB||70-89% of the RB||
|Maintain and/or plant native vegetation in –||30-49% of the RB||50-69% of the RB||
|Retain or plant overhanging and/or emergent vegetation along >50% of the shoreline length||3|
|Retain or plant overhanging and/or emergent vegetation along >25-49% of the shoreline length||2|
|Retain or plant overhanging and/or emergent vegetation along >10-24% of the shoreline length||1|
|Bonus (available once 1 or more base conditions have been met)||
|Maintain and/or plant native vegetation in additional 10 ft (3 m) width inland from the riparian buffer for the length of the shoreline, or equivalent. Equivalency may be measured as greater than 10 ft (3 m) additional width over less than the entire shoreline.||
1 bonus point per 10 ft (3 m) of additional width of riparian vegetation, up to a maximum of 3 bonus points (i.e., 30 ft/9 m of additional riparian vegetation width)
|Provide and implement a plan for monitoring and maintaining your riparian plantings||
Example 3.1.1 Marine: An example of overhanging vegetation and maintenance of native vegetation along the shoreline. (MSDG LW-13 and RE-8).
Example 3.1.2 Freshwater: An example of riparian vegetation plantings along the lakeshore.
For more information
Brennan, J.S. 2007. Marine Riparian Vegetation Communities of Puget Sound. Puget Sound Nearshore Partnership Report No. 2007-02. Published by Seattle District, U.S. Army Corps of Engineers, Seattle, Washington.Go to www.pugetsoundnearshore.org click on Technical Reports and scroll down to 2007-02.
Brennan, J.S., and H. Culverwell. 2004. Marine Riparian: An Assessment of Riparian Functions in Marine Ecosystems. Published by Washington Sea Grant Program Copyright 2005, UW Board of Regents, Seattle, WA. 34 p.
EnviroVision, Herrera Environmental, and Aquatic Habitat Guidelines Program. 2010. Protecting Nearshore Habitat and Functions in Puget Sound. http://wdfw.wa.gov/publications/00047/
Knutson, K. Lea and Naef, Virginia L. 1997. Management Recommendations for Washington’s Priority Habitats: Riparian. Washington Department of Fish and Wildlife. http://wdfw.wa.gov/publications/00029/
Naturescape British Columbia. www.naturescapebc.ca
US Environmental Protection Agency. 2012. The Economic Benefits of Protecting Healthy Watersheds. Healthy Watersheds Initiative Fact Sheet. U.S. Environmental Protection Agency (EPA), publication #EPA 841-N-12-004; available at this website: http://water.epa.gov/polwaste/nps/watershed/ecoben_factsheet.cfm
Washington State Department of Ecology. Slope Stabilization and Erosion Control – role of vegetation. http://www.ecy.wa.gov/programs/sea/pubs/93-30/using01.html
Washington State Department of Ecology. Vegetation Management: a guide for Puget Sound bluff property owners, Publication 93-31, May 1993. Go to https://fortress.wa.gov/ecy/publications/ and enter “vegetation management” in the search box.
Washington State University Beach Watchers EZ-ID Guides – Shoreline Plants http://www.beachwatchers.wsu.edu/ezidweb/