Credit 2.5: Overwater Structures
This credit discourages installation of new overwater structures and provides design standards if such structures are necessary. To qualify for this credit, do not install new overwater structures at a project site, and remove any existing overwater structures. If overwater structures are necessary, design them to be Green Shores friendly.
Overwater structures include piers, ramps, floats, covered moorage, boat work sheds, and mooring pilings. Boats stored in cradles below the OHWM/NB are also considered overwater structures. An overwater structure may include multiple elements such as a pier, ramp, and float.
Where this credit applies
This credit applies to all types of shores, and to the construction, renovation or removal of overwater structures; however, constructing a new overwater structure is eligible for this credit only if:
- It will be used for water dependent uses (e.g., boating needs and not living space); and
- There is no publicly accessible dock or pier within 500 ft (150 m).
This credit offers up to 10 base points.
|Overwater structures||Base points|
|No OS:Existing overwater structures (OS) are removed and no new replacement overwater structures are installed. OR||8|
|No pre-existing OS and no new OS installed||6|
|”Best Practices” OS:If there is an existing overwater structure (OS) on your property, demonstrate that it is eligible for this credit (see “Where this credit applies” above) and meets the Best Practices outlined below (see “How to proceed”), or is being retrofitted as part of your project to meet the Best Practices outlined below (see “How to proceed”).||Size:- pier/ramp <4 ft wide or <6 ft wide with full grating-floating dock <60 ft2 or <80 ft2 with full grating||1|
|Grating coverage:- 80-100% of OS surfaces||
|– 50%-79% of OS surfaces||1|
|No lighting on OS, or diffuse lighting that is not directed downward to water or upward to sky||1|
|Shared OS:Share the use of an OS on your property or a neighbouring property||OS shared with one neighbour (one OS per two properties)||1|
|OS shared with two or more neighbours (one OS per three or more properties)||2|
How to proceed
Not having an overwater structure is the simplest way to achieve points under this credit. Applicants are encouraged to use mooring buoys if boat moorage is needed, use a public dock if one is nearby, or share an existing dock with neighbours. Note that San Juan County in Washington State requires anyone seeking to build a dock to first attempt to create and sign a “Joint Use Agreement” with neighbours.
Where an overwater structure is required, adhere to the following Best Practices in the design, construction, maintenance and renovation of overwater structures:
- Assess the nearshore and benthic habitat before starting to plan, so that the structure is located where no critical/sensitive habitat exists.
- Provide light penetration by using grating on all over structure surfaces that results in a total open area of at least 30. For example, this can be achieved by installing grating with 60% open area on at least 50 of the OS or by grating a larger portion of the OS with openings of less than 60%; e., % Grating Open Area X % Pier Area > 30%.
- Minimize the size of overwater structures to only what is needed to serve the purpose and avoid impacting riparian or emergent vegetation.
- Floating components should not rest on the bottom substrate at any time.
- For piers and ramps, minimize disturbance of the bottom by using only the number and size of piles required to achieve safety and stability.
- Use nontoxic materials for piles and other support elements (see Credit 3.4 “Creosote Materials Removal” for points).
- Minimize shading by orienting a structure in a north-south direction and positioning it a minimum of 7 ft (2.3 m) above benthic vegetation.
- Minimize overwater lighting and ensure that any lighting is not directed into the water.
- Design structures to be retractable when not in use (for example, during the winter season).
For more information
Adams A.M. 2002. Shoreline structures environmental design: a guide for structures along estuaries and large rivers. Fisheries and Oceans Canada, Vancouver B.C. and Environment Canada, Delta B.C. Go to http://www.stewardshipcentrebc.ca/the-resource-centre/ and enter “shoreline structures” in the search box.
B.C. Ministry of Environment and Fisheries and Oceans Canada. Standards and Best Practices for Instream Works – Wharf, Pier, Dock, Boathouse & Mooring. Go to http://www.gov.bc.ca/ener/ and enter “instreamworks docks” in the search box.
B.C. Factsheet – Marine Guide to Small Boat Moorage. Go to http://www.dfo-mpo.gc.ca/index-eng.htm and enter “small boat moorage” in the search box.
EnviroVision, Herrera Environmental, and Aquatic Habitat Guidelines Program. 2010. Protecting Nearshore Habitat and Functions in Puget Sound. http://wdfw.wa.gov/publications/00047/
Lake Sunapee Protective Association. Lake Friendly Dock Choices. http://www.lakesunapee.org/record_images/pdf/219.pdf
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.
Washington Dept. of Ecology. 2011. Shoreline Master Program (SMP) Handbook, chapter 12: Piers, Docks, and other Structures. http://www.ecy.wa.gov/PROGRAMS/sea/shorelines/smp/handbook/index.html
WRIA 8: Lake Washington/Cedar/Sammamish Watershed – Docks and Shoreline Permits www.govlink.org/watersheds/8/action/greenshorelines