Develop Mitigation Requirements
Case Study:
Overview:
Under some circumstances, where shorelines are well-developed, shoreline armoring may be necessary. While adverse impacts should first be avoided and then minimized, sometimes some loss of ecological function and/or public access to the shoreline is unavoidable. Mitigation can be required to compensate for these lost uses and functional values. Depending on the type of loss, mitigation can take the form of restoring another impaired shoreline, preserving a shoreline of significant ecological value, or enhancing or creating another public access site. Similar to established wetland mitigation banks, shoreline mitigation banks could also be created to facilitate selection and prioritization of mitigation projects. Property owners could pay into a mitigation bank which is then used to fund regional shoreline restoration and beach renourishment efforts.
Benefits: In highly developed areas where a hardened structure is the only feasible alternative, mitigation allows for positive environmental/societal benefits to be gained to off-set any adverse environmental or public access impacts that occur at the site.
Drawbacks: Mitigated systems are rarely as good as the unaltered natural systems they are meant to replace. Good scientific data and project monitoring is needed to ensure that the mitigation will be comparable to the functions and uses lost. Mitigation may not be environmentally or socially relevant if the mitigation project is geographically removed from the project area.
Case Study:
California's Mitigation Approach to Shoreline Armoring
The California Coastal Act contains provisions to allow hard stabilization structures along the shore if an existing development is in jeopardy of being lost to erosion and no other alternative solution is possible. However, the Act also emphasizes the need to protect public recreational opportunities and to provide public access along the coast. Similarly, the Act also calls for the protection of scenic and aesthetic qualities of coastal resources.
Shoreline structures can lead to loss of public access along the beach by: (1) reducing the public beach area when constructed on state-owned beach (in California this represents any area below the mean high tide line); (2) preventing the back beach/bluff from eroding naturally to feed the front beach area; and (3) increasing scouring leading to additional beach erosion. Seawalls, rip rap and other hardened structures can also change the visual character of the beach.
Therefore, the California Coastal Commission, which administers the California Coastal Act, requires these impacts be mitigated when shoreline armoring is allowed. While the exact mitigation requirements are evaluated on a site-by-site basis, the Commission commonly requires the property owner to Offer To Dedicate (OTD) a public access easement seaward of the approved structure to compensate for any loss in public beach. If a suitable agency or non-governmental organization does not agree to hold title to the easement by the time the OTD expires (typically after 21 years) the easement doesn't come into effect. The Commission, which does not have authority to directly accept offers, works with local and county governments and local land trusts to accept the offers. The California Coastal Conservancy, a sister state agency, has also committed to accepting OTDs slated to expire.
Once the easement goes into effect, if the land owner requests permission to enlarge their seawall and use even more of the sandy beach in the future, the Commission rejects the proposal. The previously recorded public access easement has already "fixed" the line between what the property owner can use and what the public is guaranteed in perpetuity. The property owner can not encroach on what the public now legally has the right to access.
For larger seawall projects (~100 feet long or more), the Commission sometimes also requires the property owner to pay a fee in addition to placing a public access easement on their property. Fees assessed typically range from $10,000 to $12,000. The fee is derived from a formula used to place a value on the sand that is prevented from feeding the beach as the bluff erodes naturally and the subsequent loss of public beach access. Factors such as the length, height and expected life of the sea wall, annual erosion rate, and value of a beach day are all incorporated into the equation. The fee is used to support other recreation projects in the county, which may include public beach enhancements, but could also include improvements to inland parks.