Managing Sedimentation Impacts to Water Infrastructure in Wildfire Country: Part 2

January 14, 2021 – Katie Chamberlin

Climate change is driving more frequent and larger wildfires in California, resulting in increased erosion and sedimentation of waterways. As wildfires burn away vegetation and ground cover, soils are left exposed, void of the natural protective cover that normally exists, and thus more prone to erosion and soil movement resulting from precipitation. Dredging or sediment excavation can restore the depth and capacity of water conveyance channels, such as creeks and streams, that are affected by sedimentation. Learn more about key considerations for California dredging projects in Part 1 of Managing Sedimentation Impacts in Wildfire Country.

Without plans for sufficient sediment management and removal, water and irrigation districts may be less able to efficiently obtain the water that they need. While navigating the environmental compliance process for dredging projects in California can be multifaceted and complex, fortunately, dredging can be seamlessly integrated into operations and maintenance programs with planning and attention to detail.

For California water resources managers, dredging is becoming a more routine necessity for waterways as increased incidence of wildfires spur erosion and sedimentation.

Understanding the Regulatory Compliance Processes for Water Resources Dredging Projects in California

A number of federal and state approvals are required to complete water resources dredging projects, typically including the following:

  • California Environmental Quality Act (CEQA) Compliance: CEQA requires state and local government agencies to inform decision makers and the public about the potential environmental impacts of proposed projects, and to reduce those environmental impacts to the extent feasible. CEQA documentation for dredging projects could range from Categorical Exemptions for low-impact maintenance dredging projects, to more in-depth evaluations (such as Initial Studies/Mitigated Negative Declarations or Environmental Impact Reports) of potential environmental impacts of dredging and dredged material placement activities.
  • National Environmental Policy Act (NEPA) Compliance: NEPA requires federal agencies to evaluate the environmental effects of their proposed actions prior to making decisions. NEPA also requires opportunities for public review and comment. Like CEQA, NEPA documentation for dredging projects can vary, including Categorical Exclusions, Environmental Assessments, or Environmental Impact Statements. The appropriate NEPA document type will depend on the anticipated environmental impacts.
  • Clean Water Act (CWA) Section 404/Rivers and Harbors Act (RHA) Section 10 Permits: The purpose of the CWA is to restore and maintain the chemical, physical, and biological integrity of waters of the U.S., including wetlands, and the RHA prohibits the obstruction or alteration of navigable waters of the U.S. without approval from the S. Army Corps of Engineers (Corps). Section 404 permits, also issued by the Corps, are required to discharge dredged or fill material into waters of the U.S., and Section 10 permits are required for any work in navigable waters. As part of Section 404 and Section 10 permitting, the Corps will initiate Endangered Species Act consultations with either or both the National Marine Fisheries Service and U.S. Fish and Wildlife Service, depending on which special-status species are potentially present in your dredging area. The Corps will also initiate consultation with the California State Historic Preservation Officer under Section 106 of the National Historic Preservation Act as part of its permitting process.
  • CWA Section 401 Water Quality Certification/Porter-Cologne Water Quality Control Act (Porter-Cologne) Waste Discharge Requirements (WDR): The CWA gives states and authorized tribes the authority to grant, deny, or waive certification of proposed federal permits that may discharge into waters of the U.S. California’s Regional Water Quality Control Boards (RWQCBs) issue 401 Water Quality Certifications for federal permits for dredging projects. The RWQCBs also ensure compliance with Porter-Cologne, through which the RWQCB requires that sediment be tested prior to dredging to determine its suitability for upland placement or potential beneficial reuse.
  • California Fish and Game Code Section 1600 Lake and Streambed Alteration Agreements (SAAs) and California Endangered Species Act (CESA) Compliance: The California Department of Fish and Wildlife (CDFW) issues Section 1600 Lake and Streambed Alteration Agreements for dredging projects occurring in streams or reservoirs. CDFW also issues Incidental Take Permits for projects that will result in harm or injury to CESA-protected species.

Additional Regulatory Considerations for Water Resources Dredging Projects

Timing. Water resources managers should plan for at least 12 to 18 months to complete the design and regulatory compliance processes for dredging projects. Early agency coordination is advised to ensure that dredging project planning reflects up-to-date agency requirements. Most waterbodies have seasonal in-water construction windows (for example, June through November in the San Francisco Bay, or July/August through November in the Delta) to avoid impacts on special-status aquatic species during critical life stages, so take note of those periods and plan for construction around them.

Frequency. For water conveyance channels that are anticipated to require annual or frequent dredging over 5 to 10 years, water resources managers should consider obtaining long-term programmatic permits for dredging and dredged sediment placement activities. Sediment testing may be required on a more frequent basis, but programmatic permits allow for a range of pre-approved activities to occur within established windows, areas, or volumes without needing updated agency approvals for between 5 and 10 years (depending on the agency).

Dredging in creeks and streams can restore capacity to water conveyance features that are critical for the successful operation of water systems and the people they serve.

Placement Locations/Beneficial Reuse. Regulatory permitting efforts for dredging projects must consider impacts from both dredging and dredged material placement activities. Potential impacts on jurisdictional features, wildlife, and habitat that could exist within or adjacent to dredged material placement areas must be considered as part of project permitting efforts. Finding opportunities to minimize or avoid environmental impacts and maximize benefits from dredged material placement is key to successful dredging projects. Dredged sediment is commonly beneficially reused for levee maintenance, habitat restoration, or other construction purposes, which is an effective way to derive additional benefits from water resources dredging projects.

Ultimately, dredging restores capacity to water conveyance features that are critical for the successful operation of water systems and the people they serve. Understanding the regulatory compliance processes for water resources dredging projects can have a positive impact on the success of a project. As dredging becomes a more routine necessity for waterways as increased incidence of wildfires spur erosion and sedimentation, sediment management will become increasingly critical to ensure water conveyance infrastructure and reservoirs are adequately maintained.