Review the Coastal Commission Memorandum: Mitigation for Natural Resource Impacts - Background for Caltrans Projects (April 2022)

To further understand the Commission’s guidance and interpretation of wetlands, view the webcast of a workshop held at the April 2016 Commission hearing:

Wetlands Basics

The Coastal Act restricts development within wetland resources, and requires protection against significant disruption of habitat values. It also requires that areas adjacent to wetland resources be sited and designed to prevent degradation of those resources and to be compatible with the continuance of that habitat. A typical wetland setback standard is 100 feet, but setbacks may be larger based on the resource of concern, such as presence of special-status species habitats or other considerations. At a minimum, the CDP application should include the following:

  • A map depicting wetland resources and a 100-foot buffer in relation to the project footprint;
  • The results of a wetland delineation conducted pursuant to the standards of the Coastal Act and implementing regulations;
  • An alternatives analysis; and
  • Plans for mitigation and monitoring, as appropriate.

Coastal Act Policies Related to Coastal Wetlands

  • Coastal Act Section 30230 requires that uses of the marine environment be carried out in a manner that will sustain the biological productivity of coastal waters for long-term commercial, recreational, scientific, and educational purposes. Additionally, Coastal Act Section 30231 requires that the biological productivity and quality of coastal waters be maintained and, where feasible, restored through minimizing adverse effects of waste water discharges and entrainment, controlling runoff, preventing depletion of ground water supplies and substantial interference with surface water flow, encouraging waste water reclamation, maintaining natural vegetation buffer areas that protect riparian habitats, and minimizing alteration of natural streams.
  • Coastal Act Section 30233 states (in relevant part): (a) The diking, filling, or dredging of open coastal waters, wetlands, estuaries, and lakes shall be permitted in accordance with other applicable provisions of this division, where there is no feasible less environmentally damaging alternative, and where feasible mitigation measures have been provided to minimize adverse environmental effects, and shall be limited to the following:
    • New or expanded port, energy, and coastal-dependent industrial facilities, including commercial fishing facilities.
    • Maintaining existing, or restoring previously dredged, depths in existing navigational channels, turning basins, vessel berthing and mooring areas, and boat launching ramps.
    • In open coastal waters, other than wetlands, including streams, estuaries, and lakes, new or expanded boating facilities and the placement of structural pilings for public recreational piers that provide public access and recreational opportunities.
    • Incidental public service purposes, including but not limited to, burying cables and pipes or inspection of piers and maintenance of existing intake and outfall lines.
    • Mineral extraction, including sand for restoring beaches, except in environmentally sensitive areas.
    • Restoration purposes.
    • Nature study, aquaculture, or similar resource dependent activities.

  • Coastal Act Section 30121 identifies wetlands, a type of ESHA, as "lands within the coastal zone which may be covered periodically or permanently with shallow water and include saltwater marshes, freshwater marshes, open or closed brackish water marshes, swamps, mudflats, and fens”.
Unique to the Coastal Act’s definition of wetlands—see California Code of Regulations Section 13577(b)—a wetland need only display one of the parameters typically used to define wetland areas, in contrast to the U.S. Army Corps of Engineers, which uses a three-parameter definition under its federal authorities. It is also important to note that the Coastal Act definition of wetlands (Section 30121) does not distinguish wetlands according to their quality. Thus, under the Coastal Act, poorly functioning or degraded areas that meet the definition of wetlands are nonetheless subject to wetland protection policies.

Wetlands considerations when developing your project and preparing to submit a coastal development permit

When applying for a CDP from the Commission or a local agency, it is critical to accurately delineate, identify, and map wetland resources potentially affected by a project. This is because the Coastal Act, and the majority of Local Coastal Programs (LCPs), restrict or deny certain types of development within wetlands to ensure the long-term protection of the habitat, similar to an ESHA. Transportation facilities are generally not considered a use allowed within a wetland or its associated buffer area; however, public trails associated with the project may be considered an allowable use. To help determine a project’s consistency with applicable coastal wetlands policies and its potential for approval, consider the following:

  • Baseline: The Commission will often require wetland delineations and biological surveys that are based on actual site-specific conditions when assessing impacts to wetlands. Regardless of the prior presence or absence of the wetland resource, any area that actually meets the definition of wetlands must be given all the protections afforded by the Coastal Act and/or the applicable LCP policies.
  • Allowable Uses: The Coastal Act and most LCPs identify the seven limited allowable uses that may result in diking, filling, or dredging within a wetland, lake, or open coastal waters, as specifically outlined in Coastal Act Section 30233. The Commission has found that activities including dredging to maintain an existing navigational channel depth, restoration efforts, or an incidental public service such as maintenance of an existing outfall, can be allowed where there is no feasible less environmentally damaging alternative, and where feasible mitigation measures have been provided to minimize adverse environmental effects.
  • Alternatives Analysis: Most Caltrans development does not qualify as an “allowable use” in wetland resources; therefore, a thorough alternatives analysis is required to determine if a more appropriate alignment, design, or buffer alternative would be feasible to reduce the potential for impact. The Commission is required to identify the least environmentally damaging alternative when making its findings.
  • Avoidance and Minimization: The analysis of project impacts on the identified wetland resource should discuss avoidance and minimization efforts taken to reduce effects and mitigate to the greatest extent feasible. If the project is not an allowable use, mitigation alone will not ensure that the Commission can approve a project. The Commission has used a 4:1 mitigation ratio for offsetting impacts through wetland restoration and creation because of the potential for less than 100 percent success in restoring a given area. The necessary mitigation ratio will depend on the site-specific circumstances of the project.
  • Conflict Resolution: In exceptional circumstances, the Commission may use the Coastal Act’s “conflict resolution” provisions (Sections 30007.5 and 30200(b)) to approve non-resource-dependent uses in wetlands. In cases where either approval or disapproval denial of a project would result in conflicts between Chapter 3 conflict with Coastal Act resource protection policies, these provisions allow the Commission to select the course of action that, on balance, is the most protective of significant coastal resources, even if it will cause impacts that are generally prohibited by the Act. In these cases, there must also be no feasible less environmentally damaging alternative, and mitigation measures must be provided to minimize adverse environmental effects.  *Note: When a project is not located in original (retained) Commission jurisdiction, or if the local agency and the Commission do not agree to process a consolidated CDP and conflict resolution is not available to address unavoidable, unallowable impacts or development encroachment into required setback areas per certified LCPs, an LCP amendment may be required for the project to proceed.