Coastal Hazards and Shoreline Development

Visit the Commission's website to obtain further guidance on addressing coastal hazards, including the Commission’s Sea Level Rise Policy Guidance, "Interpretive Guidelines for Addressing Sea Level Rise in Local Coastal Programs and Coastal Development Permits," adopted on August 12, 2015.

Coastal Hazards and Shoreline Development Basics

The Coastal Act requires new development to be sited away from coastal hazards to minimize risks to life and property in areas of high geologic, flood, and fire hazard (Coastal Act Section 30253). The Coastal Act also recognizes that existing development might not have been sited away from coastal hazards, and in those situations, it allows for construction of shoreline protective devices that are otherwise inconsistent with the Coastal Act only when both of the following criteria are met:

  • the device is required to serve coastal-dependent uses or to protect existing structures or public beaches provided that these areas/structures are in danger from erosion; and
  • the device is designed to eliminate or mitigate adverse impacts on local shoreline sand supply (Coastal Act Section 30235).


The Coastal Act provides these limitations because shoreline protective devices (or structures) designed to forestall erosion can have a variety of adverse impacts on coastal resources, such as:

  • Interruption of natural shoreline processes that may contribute to erosion of the shoreline and the loss of public sandy beach area.
  • Direct loss of sandy and rocky intertidal areas that are a critical component of the marine ecosystem.
  • Physical encroachment of the structure onto the public beach, which could impede public access to the coastline.
  • Degradation of scenic and visual resources by changing the character of a natural beach.


Coastal Act Policies Related to Coastal Hazards and Shoreline Development

The Coastal Act policies that address coastal hazards and shoreline development include Sections 30235, 30236, and 30253 through 30214, 30500(a), and 30604(c). Important sections of the Coastal Act to consider for Caltrans projects include:

  • Coastal Act Section 30235 states: Revetments, breakwaters, groins, harbor channels, seawalls, cliff retaining walls, and other such construction that alters natural shoreline processes shall be permitted when required to serve coastal-dependent uses or to protect existing structures or public beaches in danger from erosion, and when designed to eliminate or mitigate adverse impacts on local shoreline sand supply. Existing marine structures causing water stagnation contributing to pollution problems and fish kills should be phased out or upgraded where feasible.

  • Coastal Act Section 30236 states: Channelizations, dams, or other substantial alterations of rivers and streams shall incorporate the best mitigation measures feasible, and be limited to (1) necessary water supply projects, (2) flood control projects where no other method for protecting existing structures in the floodplain is feasible and where such protection is necessary for public safety or to protect existing development, or (3) developments where the primary function is the improvement of fish and wildlife habitat.

  • Coastal Act Section 30253 states (in part): New development shall: (a) Minimize risks to life and property in areas of high geologic, flood, and fire hazard. (b) Assure stability and structural integrity, and neither create nor contribute significantly to erosion, geologic instability, or destruction of the site or surrounding area or in any way require the construction of protective devices that would substantially alter natural landforms along bluffs and cliffs.


Coastal Hazards and Shoreline Development considerations when developing your project and preparing to submit a coastal development permit

When an existing facility is at risk from coastal hazards and a shoreline protective device is being considered, it is important to determine the appropriate permitting agency. The proposed shoreline protective device could fall within the Coastal Commission’s (Commission’s) retained permit jurisdiction (i.e., tidelands, submerged lands, and public trust lands), rather than the permit jurisdiction of a local government, requiring a permit directly from the Commission. If part of the project is within the Commission’s retained jurisdiction and part of the project is within the local government’s permit jurisdiction pursuant to a certified Local Coastal Program (LCP), the local government and Caltrans could ask that the Commission take jurisdiction over the entire project and process a consolidated CDP. When applying for a CDP directly from the Commission or from a local government for a project that includes a shoreline protective device, the appropriateness, design and duration of the structure(s) will be considered during the permit review for both the existing facility needing the protection and for the shoreline protective device itself.

To help determine your shoreline protection project’s consistency with applicable policies and its potential for approval, consider the following information as part of your CDP process:

  • Baseline: The Commission will first evaluate whether the existing development that will be protected by the revetment, seawall, etc., could be relocated to avoid the need for the shoreline protective device. The Commission will consider the existing setback of the development in need of protection and review the recommendations in the submitted technical reports to ultimately determine the appropriate placement and dimensions of the shoreline protective device, based on the site-specific geologic and engineering constraints. The Commission will likely request detailed technical data informed by the best available sea level rise projections, such as a wave uprush study, geotechnical report, etc., to substantiate the baseline information you submit. Furthermore, if a new seawall or revetment is proposed near or adjacent to an already existing seawall or revetment, the Commission may evaluate the permit history of the existing structures and may request information on the original construction to determine whether the original structure is still necessary if it is proposed to be retained in any shape or form. (For new development projects, such as bridge replacement, road expansion or facility development, where no shoreline protective device currently exists the Commission will consider what the appropriate design and development setback should be, based on the site-specific geologic and engineering constraints, as well as detailed technical data informed by the best available sea level rise projections, to avoid the need for shoreline protective devices over the lifetime of the proposed development.)

  • Alternatives Analysis: Because of the potential impacts from shoreline protective device projects, it is critical to provide an alternatives analysis as part of the application process that is based upon the technical and resource data specific to the site. The alternatives analysis must demonstrate that the project is the least environmentally damaging feasible alternative that can serve to achieve the goal of protecting the threatened structure, coastal-dependent use, or public beach. For example, the Commission will look to ensure that new protective devices incorporate “soft solutions” where feasible, are located as landward as feasible, and occupy the least amount of sandy beach or have the smallest footprint feasible. The Commission will also evaluate whether the mass and scale of the protective device is the minimum necessary to ensure long-term protection. Alternatives to evaluate could include a vertical tie-back wall, a sloping rock revetment, or other less intensive design option. In past approvals, the Commission has requested an analysis of the potential for beach nourishment or vegetated sand dunes, alone or in combination with engineered structures. They have also requested reports on the feasibility of the phased retreat of existing structures.

  • Avoidance and Minimization: The Coastal Act requires shoreline protective devices to be designed to eliminate or mitigate adverse impacts on local shoreline sand supply. For the chosen alternative, a written analysis describing how the proposed shoreline protective device has been sited and designed to avoid or minimize adverse impacts on sand supply, as well as an analysis of the impacts that are anticipated to occur, based on the technical studies prepared for the project, should be provided. The necessary mitigation will depend on the specific circumstances of the project. In the past, the Commission has approved mitigation measures such as:
    • Sand mitigation fee (to compensate for the loss of beach area and public access and recreation on public lands)
    • Design modifications to ensure the structure will be visually compatible with the environment
    • Requirements to implement beach nourishment
    • Maintenance and monitoring to ensure that the shoreline protection continues to perform effectively
    • Requirements to address repair, maintenance, and removal of protective devices, and other policies related to siting and design of development to avoid the need for armoring
    • Requirements to limit the time period for which a shore protection device permit is valid and to tie the approval of the shore protection device to the continued existence of the existing structure only.