State of the Beach/State Reports/BC/Shoreline Structures
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Although only a small percentage of British Columbia’s shores have been modified, those shores tend to be in some of the most valuable and productive coastal areas. As such, it is important to understand how altered shores can have negative impacts on coastal habitats. The Stewardship Centre of British Columbia has outlined some of the problems commonly associated with shoreline armouring and this information is presented in Coastal Shore Stewardship: A Guide for Planners, Builders and Developers.
The British Columbia government has provided answers to frequently asked questions about seawalls.
In April 2010 three resort owners on Cox Bay in Tofino who had constructed seawalls in front of their properties were served with trespass notices from the Integrated Land Management Bureau and told to remove the seawalls by May 10. A letter accompanying the trespass notices states that ILMB and the District of Tofino inspected the walls on April 15 and found they had been constructed on foreshore Crown land. "Constructing a structure or other works on Crown land without authorization is an offence under Section 60 of the Land Act," wrote Compliance and Enforcement Specialist Steven Stussi to owners Tim Hackett (LBL), William Pettinger (Pacific Sands) and Chris LeFevre (Cox Bay Resort). Despite this, the seawalls remain.
In British Columbia the authority with respect to altered shores or shoreline armouring is rather convoluted between the various levels of government (federal, provincial and regional/municipal). Each level works together to ensure shoreline structures comply with local laws and policies aimed at protecting wildlife habitat as well as social and economic sustainability. At the federal level, the Department of Fisheries and Oceans Canada (DFO) is responsible for the protection of fish habitat and provides approval for foreshore development projects that follow the "no net loss of fish habitat" policy under the National Policy for Management of Fish Habitat. Often DFO are considered to be the true approval agency for shoreline amouring, as local governments with limited resources and infrastructure will often agree with the recommendations put forth by the federal government. DFO has developed general guidance and a published set of guidelines for shoreline development projects. Approvals, however, are based on a narrow interpretation of impacts to fish habitats and they tend to stay off the intertidal zone. Thus, historically many seawalls have been built in the name of protecting fish habitat.
The province of British Columbia has jurisdiction over all foreshore lands. The provincial government refers all applications to a host of stakeholders including DFO, First Nations, conservation groups and the local community of stakeholders.
Finally, at the local level municipal and regional governments make many of the land use decisions with regards to waterfront property development including seawalls, dikes and erosion prevention structures. However, local governments vary widely in the degree to which they actively manage coastal development and their coastal resources, as both technical and administrative resources are often limited.
Coastal development practices often disrupt shore functions and natural process of the marine environment. For example, seawalls can increase beach erosion at the toe of the wall and may disrupt sediment movement along the coast. Hardened shores, such as jetties and seawalls, reduce habitat complexity and diversity. Furthermore, protective structures often encroach on the natural water boundary, thus impacting riparian and beach habitat, shore processes, and public access.
Examples of Shoreline Structures present in British Columbia:
Groynes are intended to reduce or eliminate site-specific erosion. They trap sediment moving along the shore. They are built perpendicular to the shore, creating a new beach on the updrift side (the side from which most of the sediment comes) and reducing deposition on the downdrift side. This creates a series of small beaches between groynes oriented roughly at right angles to the prevailing wave direction. Groynes are typically constructed of timber panels supported by piles, rock or concrete blocks. The City of Vancouver has used groynes successfully along English Bay and Jericho Beach to stabilize artificial beaches made of imported sand.
Breakwaters are designed to protect a shore area, harbour or anchorage from waves. Breakwaters can be floating or attached to the bottom. Floating breakwaters, used in mild wave conditions, provide only partial wave protection because wave energy can pass below the float. Attached breakwaters can be designed for any wave condition, but water depths over 15 to 20 metres and waves bigger than 10 metres make this type of structure rather expensive. Breakwaters are usually connected to shore, but may be constructed offshore as well. The key factors to consider in breakwater design are wave height, length, direction and the effects of the structure on wave refraction and erosion. Floating breakwaters exist throughout the Fraser River.
Revetments are hard, smooth surfaces that are built to protect a bank or bluff from erosion by wave action and currents. Seawalls are free-standing structures made typically of concrete or rock. These structures usually create new land as a result of infilling behind the wall itself. They are also commonly used to create public walkways along the shore. Seawalls and revetments are built to facilitate various water-related activities and to protect upland property and structures from flooding, erosion and damage. The largest and most prominent seawall in the greater Vancouver region is that of Stanley Park.
Piers, wharves and jetties are pile-based structures designed to provide safe moorage for ships, tugs and commercial fishing boats. A pier normally extends at a right angle to the shore into deep water, providing moorage on both sides. Wharves generally run parallel to shore (often called a marginal wharf) with storage for industrial commodities such as wood products. Jetties are not technically used for mooring boats but are linear structures, similar to breakwaters, built out from shore and used to control sedimentation at the mouth of a river. The Steveston Jetty on the Fraser River is an example of this type of jetty. Many piers and wharves also exist throughout British Columbia in coastal areas which act as popular tourist destinations, such as White Rock.
Dikes are designed and constructed to prevent flooding of low lying lands. Dikes are extensive throughout the Fraser River estuary (large map, takes a while to download). While the era of large scale dike construction is over, habitat conservation remains a critical issue in the extension, modification and maintenance of existing dikes. The Corporation of Delta, located on the lowlands of the Fraser River, has an extensive dike system totaling 61.5 kilometres in length. The City of Richmond also maintains an extensive 49 kilometre dike network. Maps and a complete list of dikes occurring in the Lower Mainland can be found on the Water Stewardship branch of the British Columbia Ministry of Environment website. All dikes in British Columbia are managed under the Dike Maintenance Act.
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