8-2-3 Guidelines for Fire Fuel Management in Riparian Corridors

Version: 07/07/2020

To provide guidance on fire fuel vegetation management in riparian corridors that is in compliance with County fire safe standards for existing structures and roads, provides for minimum vegetation removal necessary for fire safety purposes, and ensures the continued protection and preservation of the beneficial uses of riparian corridors, as defined in the Riparian Corridor Ordinance. These guidelines do not apply to new development.

"Abate" and/or "abatement"

means an act used to remove, destroy, eliminate, seize, impound, or any action taken to mitigate a public nuisance.

"Combustible material"

means rubbish, litter, or material of any kind other than hazardous vegetation that is flammable and endangers the public safety by creating a fire hazard.

“County fire safe standards”

means Chapters 13 and 13A of the Sonoma County Code.

“Fire Professional”

means an employee of a local, county, state fire department or a Registered Professional Forester (RPF).

"Hazardous vegetation"

means vegetation that is flammable and endangers the public safety by creating a fire hazard including but not limited to seasonal and recurrent weeds, stubble, brush, dry leaves, etc.

“Qualified Professional”

means any professional that provides expertise and professional recommendations in a particular subject matter. For the purposes of this document, this could include, but is not limited to natural resource professionals such as: arborists, biologists, botanists, foresters, hydrologists, landscape architects.

“Redwood”

refers to coast redwood (Sequoia sempervirens).

1. Sonoma County Code – Chapters 13, 13A, and 26-65
2. Sonoma County General Plan, Public Safety Element Goal PS-3, Objectives PS-3.1

Sonoma County has established Riparian Corridors along designated mapped streams in its Riparian Corridor Combining District Ordinance (Sonoma County Ordinance No 6089).  This ordinance generally prohibits development or other activities including vegetation removal, agricultural cultivation, structures, roads, utility lines, and parking lots or other activity which could disturb or remove soils and vegetation unless:

1. The activity is one of the limited “exceptions” listed in Section 26-65-030 or is an allowable activity listed in Section 26-65-040; and
2. Is authorized by a zoning or use permit, if required; and
3. Has an approved Streamside Conservation Plan, if required for a use permit

Fire fuel management is an allowed activity within the Riparian Corridor is an allowed use in accordance with Sonoma County Code Chapter 26-65-040(K), which states:

Fire fuel management in compliance with county fire safe standards, provided that no redwood trees are removed and vegetation removal is limited to the minimum required for fire safety purposes. New development located within one hundred feet (100’) of any riparian corridor shall be allowed with a zoning permit only where there are no feasible alternative development locations that do not require vegetation removal for fire protection and fire resistive construction materials are used to avoid or minimize the need for vegetation removal in the riparian corridor.

For existing structures and roads, Subparagraph 26-65-040(K) allows fire fuel management, without a zoning or use permit provided it is

1. In compliance with County fire safe standards,
2. Does not remove redwood trees, and
3. is limited to the minimum required for fire safety purposes.

The purpose of this document is to provide guidance as to what “in compliance with County fire safe standards” and “limited to the minimum required for fire safety purposes” means in order to undertake fire fuel management associated with existing structures and roads within the designated setback (streamside conservation area) of a mapped stream.  As stated in Section 26-65-040(K), “new development should be located such that fire fuel management for defensible space does not need to occur within the Riparian Corridor, unless there is no feasible alternative and fire resistive construction materials are used.  New development that may affect the Riparian Corridor requires authorization from Permit Sonoma and is not addressed further here. Please contact Permit Sonoma to obtain permitting approval for new development within the Riparian Corridor.

The guidance provided in this document is designed to also provide for the protection and preservation of the beneficial uses of the Riparian Corridor, such as improving water quality; increasing groundwater recharge; providing flood protection; enhancing wildlife and aquatic habitat; and supporting the recovery of salmon, steelhead, and other endangered species.

To determine whether a fire fuel management activity complies with Chapter 26, Article 65 (Riparian Corridor Combining Zone) and Chapters 13 (Fire Safety Ordinance ) and 13A (Abatement of Hazardous Vegetation and Combustible Material ), follow the procedure below. It is recommended that work in the riparian corridor should be done with the input from environmental professionals to protect riparian resources while improving fire safety. The property owner is responsible for being in compliance with all environmental laws and regulations. 

Step 1. Does the fuel management activity occur in the defensible space (0-100 feet) of a legally established structure or existing building?  If yes, proceed to Step 2, if no, contact Permit Sonoma to obtain a zoning or use permit, as applicable.

Step 2. Is the proposed fire vegetation management “in compliance with County fire safe standards”?

“Compliance” with County fire safe standards is interpreted to mean the following:

1. The “standards” referred to are those listed in Chapter 13A-4 and are summarized in Appendix A of this Guidance.  These standards are applicable to structures and roads associated with improved and unimproved parcels. 
2. In compliance with the “standards” means one of the following:
   1. Not exceeding the distances, clearances, or heights specified in the ordinance or the activity required (removal of dead/dying vegetation or combustible materials) (see Appendix A), or
   2. The requirements prescribed in a notice of violation or abatement order issued by an appropriate fire inspection official, or
   3. The proposed fuel reduction is recommended in writing by an appropriate fire inspection official or Registered Professional Forester.

Step 3. Is the proposed vegetation management the “minimum required for fire safety purposes”?

The “minimum” vegetation management for “fire safety purposes” in the Riparian Corridor is interpreted to mean that it is:

1. Vegetation management that is no more than 100 feet from the perimeter of the structure or ten feet from the edge of the drivable road surface and
2. The amount and type of vegetation management are able to accomplish both of the following:
   1. Achieve the fire safety purpose for needing to manage the vegetation; and
   2. Achieve the goal of the Riparian Corridor ordinance to protect the ecological integrity and functions of riparian corridors from the negative effects of vegetation removal and development, using the guidelines and recommendations in Appendix B – Best Management Practices for Implementation of Fuel Reduction within the Riparian Corridor.

It is recommended that property owners and land managers review the following recommendations with a qualified professional and develop a vegetation management plan that both reduces fire hazards and improves fire safety while protecting the riparian corridor and its associated stream. The property owner is responsible for conducting vegetation management activities in compliance with any prohibitions, permits, approvals, and/or authorizations required by applicable resource agencies, including, but not limited to, California Department of Fish and Wildlife, Regional Water Quality Control Board, California Coastal Commission, U.S. Fish, and Wildlife Service, U.S. National Marine Fisheries Service, and U.S. Army Corps of Engineers.

Fuel reduction within the riparian corridor should be practiced to the extent feasible and practicable to achieve the goals of 13A and meet the standards of the Riparian Corridor Ordinance. Landowners with questions or concerns about implementing the above-described process should contact Permit Sonoma Natural Resources staff.

1. Appendix A
   Minimum requirements for compliance with county fire safe standards (Chapter 13A of County Code) in the riparian corridor
2. Appendix B
   Best Management Practices for Implementation of Fuel Reduction within the Riparian Corridor

The minimum requirements for compliance with county fire safe standards (Chapter 13A of County Code) in the riparian corridor are as follows:

1. For Improved Parcels in the Local Responsibility Area
   1. Maintain a thirty-foot defensible space around all structures:
      1. The grass needs to be cut to six inches or less. Do not cut to bare mineral soil
      2.  The tree branches need to be limbed up to six feet from the ground.
      3. Shrubs need to be maintained.
      4. Climbing vines must be maintained to be clear of dead and dying materials or removed from trees and structures.
   2. Additional defensible space outward to one hundred feet from all structures may be required depending on the property slope, fuel load and/or fuel type.
   3. Maintain a ten-foot minimum clearance next to the roadside; more may be required by Fire Warden/Fire Marshal.
   4. Remove all portions of trees within ten feet of chimney and/or stovepipe outlets
      1. Property owners are responsible for maintaining trees year round.
      2. Trees need to be cut ten feet away from the chimney in any direction.
   5. Maintain trees adjacent to or overhanging a structure free of dead/dying wood. Cut the trees back and remove any dead or dying wood.
   6. Maintain the roof of any structure free of leaves, needles, or other dead/dying wood. Remove any leaves, needles, branches, or debris from the roof and/or gutters.
   7. Install a spark arrester on chimney and/or stovepipe outlets. The spark arrester must be constructed of heavy wire mesh with openings not to exceed one-half inch.
      1. Provide street address numbers that are clearly visible from the roadside, minimum height: Four inches  The address numbers should be posted on the house.
      2. If the house sits back from the street, post the address at the beginning of the driveway and on the house.
      3. The address numbers should be reflective in a contrasting color for visibility pursuant to Sonoma County Code Chapter 13.
   8. Remove all tree limbs and branches within six feet of the ground.
   9. Remove dead/dying vegetation from property.
2. For unimproved parcels in the State Responsibility Area and Local Responsibility Area:
   1. Flammable vegetation and other combustible growth within ten feet of neighboring structures and roadway frontage shall be removed;
   2. Grass and combustible surface vegetation within ten feet  of structures and roadway frontage must be trimmed to less than four inches in height unless necessary for erosion control;
   3. All trees within ten feet of neighboring structures and roadway frontage must be pruned to at least six feet  above grade; and
   4. Combustible material shall be removed from the property.

Best Management Practices for Implementation of Fuel Reduction within the Riparian Corridor

1. Dominant and Codominant Trees. Dominant trees are characterized as trees with crown extending above the general level of the canopy and receiving full light from above and partly from the sides. Codominant trees are characterized as being generally level with the crown canopy and crowns receive full light from above and little sunlight on their sides. Dominant and codominant trees should be maintained to the maximum extent practicable with the goal of creating areas similar to “shaded fuel breaks.” Dominant and codominant crown spacing should be minimally reduced in shaded fuel breaks within the riparian corridor.
2. Intermediate and Suppressed Trees and Shrubs. Intermediate trees are trees that are shorter than dominants and codominants, but their crowns extend into the canopy of codominant and dominant trees. Suppressed trees are those that receive no direct sunlight and their crowns do not extend into the canopy of codominant and dominant trees. Elements of the subcanopy of riparian forests should be retained such that forest reproduction is maintained.  Vegetation management should only selectively remove subcanopy vegetation to reduce ladder fuels reaching the upper canopy of the riparian forest. Particular attention should be given to removing dying or suppressed trees and shrubs to increase vigor of dominant and codominant trees.
3. Herbaceous Layer.  Herbaceous layer management should focus on removing nonnative annual grasses and herbaceous invasive plant species that contribute to fine fuels.  Native perennial grass and forb species should generally not be the focus of vegetation management, except where a clear and obvious fire risk is present. Within the defensible space around structures and roads, grasses should be trimmed to the code standards of 13A.
4. Leaf Litter and Duff.  Removing “combustible materials” should focus on slash piles or other accumulations of combustible vegetative matter, e.g., flood debris.  Normal amounts of leaf litter and duff layers on the ground should be retained. Combustible material should also be removed when immediately adjacent or posing a threat to structures (i.e. piles of leaves or dead material next to house). CCR 1299 allows for 3” of duff to remain in the 30-100 foot zone on improved parcels in the SRA.
5. Rare, Special Status or Listed Species.  Individuals or stands of rare, special status or listed plants should not be managed or, if managed, the management does not remove or destroy or otherwise permanently harm the individual or stand. It is recommended to consult with a qualified professional to ensure that the proposed fuel reduction does not impact rare, special status, or listed species.
6. Standing dead or snags.  Dead and dying vegetation is a typical focus of fire vegetation management.  Large standing dead trees (snags) in riparian corridors can provide important habitat.  Retaining some of these large diameter habitat trees should be considered in terms of the overall fire vegetation management and whether the tree can be retained with a nominal or incremental increased fire risk. If dead and dying vegetation is a result of disease, such as sudden oak death or pine pitch canker, care should be taken in the disposal of removed material to reduce the potential for the disease to spread. It is recommended to consult with a qualified professional for best practices.
7. Soil Compaction and Stream Sedimentation. Soil compaction should be minimized to the maximum extent possible. Heavy equipment use should be limited within the riparian corridor for vegetation removal and mechanical removal should be limited to less disturbing methods (hand treatments, lop and scatter treatment of slash, etc.). No new road construction should be completed as a result of fuel reduction operations. Avoid work around unstable areas.
8. Maintenance. Future maintenance of fuel reduction areas within the riparian corridor should be limited to the extent possible to maintain the original fire safety design of the fuel break.