Chapter 30 - Categorical Exclusions

What Does This Topic Include?

This chapter discusses the criteria that a proposed action must meet to be categorically excluded from the National Environmental Policy Act (NEPA) and the preparation and processing of the Categorical Exclusion (CE) documentation for Caltrans and Local Assistance projects.

NEPA Categorical Exclusion Decision Tree

View the NEPA Categorical Exclusion Decision Tree (PDF)

Laws, Regulations, and Guidance

See also Chapter 1- Federal Requirements

Definition of a Categorical Exclusion

Categorical exclusions (CEs) are categories of actions that have been determined not to have a significant effect on the human environment either individually or cumulatively. In its regulations for the implementation of NEPA, the Council on Environmental Quality (CEQ) directed all federal agencies to adopt procedures which include identifying actions that are categorically excluded, i.e., normally do not require the preparation of either an environmental impact statement or an environmental assessment. Pursuant to CEQ's regulations, the Federal Highway Administration (FHWA) has defined categories of actions that do not involve significant environmental impacts. These actions are defined in 23 CFR 771.117.

Classes of Actions Qualifying for Categorical Exclusion

Under 23 CFR 771.117, CEs are divided into two groups based on the action's potential for impacts. The first group consists of categories of actions that experience has shown almost never cause significant environmental impacts. These categories involve minor construction activities and activities that do not lead to construction. They are listed in subsection (c) of 23 CFR 771.117 (shown below). These actions are automatically classified as CEs, except where unusual circumstances occur. The determination that the action is excluded must be documented by the completion of the CE/CE form.

771.117(c) list

  1. Activities that do not involve or lead directly to construction, such as planning and research activities; grants for training; engineering to define the elements of a proposed action or alternatives so that social, economic, and environmental effects can be assessed; and Federal-aid system revisions that establish classes of highways on the Federal-aid highway system.
  2. Approval of utility installations along or across a transportation facility.
  3. Construction of bicycle and pedestrian lanes, paths, and facilities.
  4. Activities included in the State's highway safety plan under 23 U.S.C. 402.
  5. Transfer of Federal lands pursuant to 23 U.S.C. 107(d) and/or 23 U.S.C. 317 when the land transfer is in support of an action that is not otherwise subject to FHWA review under NEPA.
  6. The installation of noise barriers or alterations to existing publicly owned buildings to provide for noise reduction.
  7. Landscaping.
  8. Installation of fencing, signs, pavement markings, small passenger shelters, traffic signals, and railroad warning devices where no substantial land acquisition or traffic disruption will occur.
  9. The following actions for transportation facilities damaged by an incident resulting in an emergency declared by the Governor of the State and concurred in by the Secretary, or a disaster or emergency declared by the President pursuant to the Robert T. Stafford Act (42 U.S.C. 5121):
    1. Emergency repairs under 23 U.S.C. 125; and
    2. The repair, reconstruction, restoration, retrofitting, or replacement of any road, highway, bridge, tunnel, or transit facility (such as a ferry dock or bus transfer station), including ancillary transportation facilities (such as pedestrian/bicycle paths and bike lanes), that is in operation or under construction when damaged and the action:
      1. Occurs within the existing right-of-way and in a manner that substantially conforms to the preexisting design, function, and location as the original (which may include upgrades to meet existing codes and standards as well as upgrades warranted to address conditions that have changed since the original construction); and
      2. Is commenced within a 2-year period beginning on the date of the declaration.
  10. Note: If using (c)9, distinguish between (c)9(i) or (c)9(ii) on the CE/CE form and include copy of the emergency declaration in the file.
  11. Acquisition of scenic easements.
  12. Determination of payback under 23 U.S.C. 156 for property previously acquired with Federal-aid participation.
  13. Improvements to existing rest areas and truck weigh stations.
  14. Ridesharing activities.
  15. Bus and rail car rehabilitation.
  16. Alterations to facilities or vehicles in order to make them accessible for elderly and handicapped persons.
  17. Program administration, technical assistance activities, and operating assistance to transit authorities to continue existing service or increase service to meet routine changes in demand.
  18. The purchase of vehicles by the applicant where the use of these vehicles can be accommodated by existing facilities or by new facilities that themselves are within a CE.
  19. Track and railbed maintenance and improvements when carried out within the existing right-of-way.
  20. Purchase and installation of operating or maintenance equipment to be located within the transit facility and with no significant impacts off the site.
  21. Promulgation of rules, regulations, and directives.
  22. Deployment of electronics, photonics, communications, or information processing used singly or in combination, or as components of a fully integrated system, to improve the efficiency or safety of a surface transportation system or to enhance security or passenger convenience. Examples include, but are not limited to, traffic control and detector devices, lane management systems, electronic payment equipment, automatic vehicle locaters, automated passenger counters, computer-aided dispatching systems, radio communications systems, dynamic message signs, and security equipment including surveillance and detection cameras on roadways and in transit facilities and on buses.
  23. Projects, as defined in 23 U.S.C. 101, that would take place entirely within the existing operational right-of-way. Existing operational right-of-way means all real property interests acquired for the construction, operation, or mitigation of a project. This area includes the features associated with the physical footprint of the project including but not limited to the roadway, bridges, interchanges, culverts, drainage, clear zone, traffic control signage, landscaping, and any rest areas with direct access to a controlled access highway. This also includes fixed guideways, mitigation areas, areas maintained or used for safety and security of a transportation facility, parking facilities with direct access to an existing transportation facility, transportation power substations, transportation venting structures, and transportation maintenance facilities.
    Note: If using (c)22, identify in the project description that all work is within operational right-of-way.
  24. Federally funded projects:
    • (i) and (ii) Please check FHWA’s website for current dollar amounts. Qualifying projects must receive less than the dollar amount specified on FHWA’s website, or have a total estimated cost less than the specified dollar amount (with federal funding less than 15% of total estimated project cost). These amounts are adjusted annually for inflation based on the Consumer Price Index prepared by the Department of Labor.
      Note: If using (c)23, distinguish between (c)23(i) and (c)23(ii) on the CE/CE form
  25. Localized geotechnical and other investigation to provide information for preliminary design and for environmental analyses and permitting purposes, such as drilling test bores for soil sampling; archeological investigations for archeology resources assessment or similar survey; and wetland surveys.
  26. Environmental restoration and pollution abatement actions to minimize or mitigate the impacts of any existing transportation facility (including retrofitting and construction of stormwater treatment systems to meet Federal and State requirements under sections 401 and 402 of the Federal Water Pollution Control Act (33 U.S.C. 1341; 1342)) carried out to address water pollution or environmental degradation.
  27. Modernization of a highway by resurfacing, restoration, rehabilitation, reconstruction, adding shoulders, or adding auxiliary lanes (including parking, weaving, turning, and climbing lanes).
    Note: If using (c)26, the project must meet the constraints listed in 771.117(e).  If it does not, the project may qualify for a CE under 771.117(d)13.
  28. Highway safety or traffic operations improvement projects, including the installation of ramp metering control devices and lighting.
    Note: If using (c)27, the project must meet the constraints listed in 771.117(e) (shown below).  If it does not, the project may qualify for a CE under 771.117(d)13.
  29. Bridge rehabilitation, reconstruction, or replacement or the construction of grade separation to replace existing at-grade railroad crossings.
    Note: If using (c)28, the project must meet the constraints listed in 771.117(e) (shown below).  If it does not, the project may qualify for a CE under 771.117(d)13.
  30. Purchase, construction, replacement, or rehabilitation of ferry vessels (including improvements to ferry vessel safety, navigation, and security systems) that would not require a change in the function of the ferry terminals and can be accommodated by existing facilities or by new facilities that themselves are within a CE.
  31. Rehabilitation or reconstruction of existing ferry facilities that occupy substantially the same geographic footprint, do not result in a change in their functional use, and do not result in a substantial increase in the existing facility's capacity. Example actions include work on pedestrian and vehicle transfer structures and associated utilities, buildings, and terminals.

The second group of CEs consists of actions that normally do not involve significant impacts, but may, depending upon circumstances, have the potential to cause significant environmental impacts. Subsection (d) of 23 CFR 771.117 (shown below) lists examples of actions generally found appropriate for CE classification. Because of the potential for significant impacts, these actions require some documentation in order to determine if the CE classification is proper. This second group of actions is not limited to the specific activities listed in subsection (d) and can include additional actions of a similar type or scope of work.

771.117(d) list

  1. [Reserved]
  2. [Reserved]
  3. [Reserved]
  4. Transportation corridor fringe parking facilities.
  5. Construction of new truck weigh stations or rest areas.
  6. Approvals for disposal of excess right-of-way or for joint or limited use of right-of-way, where the proposed use does not have significant adverse impacts.
  7. Approvals for changes in access control.
  8. Construction of new bus storage and maintenance facilities in areas used predominantly for industrial or transportation purposes where such construction is not inconsistent with existing zoning and located on or near a street with adequate capacity to handle anticipated bus and support vehicle traffic.
  9. Rehabilitation or reconstruction of existing rail and bus buildings and ancillary facilities where only minor amounts of additional land are required, and there is not a substantial increase in the number of users.
  10. Construction of bus transfer facilities (an open area consisting of passenger shelters, boarding areas, kiosks and related street improvements) when located in a commercial area or other high activity center in which there is adequate street capacity for projected bus traffic.
  11. Construction of rail storage and maintenance facilities in areas used predominantly for industrial or transportation purposes where such construction is not inconsistent with existing zoning, and where there is no significant noise impact on the surrounding community.
  12. Acquisition of land for hardship or protective purposes. Hardship and protective buying will be permitted only for a particular parcel or a limited number of parcels. These types of land acquisition qualify for a CE only where the acquisition will not limit the evaluation of alternatives, including shifts in alignment for planned construction projects, which may be required in the NEPA process. No project development on such land may proceed until the NEPA process has been completed.
    1. Hardship acquisition is early acquisition of property by the applicant at the property owner's request to alleviate particular hardship to the owner, in contrast to others, because of an inability to sell his property. This is justified when the property owner can document on the basis of health, safety or financial reasons that remaining in the property poses an undue hardship compared to others.
    2. Protective acquisition is done to prevent imminent development of a parcel that may be needed for a proposed transportation corridor or site. Documentation must clearly demonstrate that development of the land would preclude future transportation use and that such development is imminent. Advance acquisition is not permitted for the sole purpose of reducing the cost of property for a proposed project.
  13. Actions described in paragraphs (c)26, (c)27, and (c)28 of this section that do not meet the constraints in paragraph (e) of this section.


Actions described in 771.117(c)26, (c)27, and (c)28 may not be processed as CEs under 771.117(c) if they involve:

  1. An acquisition of more than a minor amount of right-of-way or that would result in any residential or non-residential displacements;
  2. An action that needs a bridge permit from the U.S. Coast Guard, or an action that does not meet the terms and conditions of a U.S. Army Corps of Engineers nationwide or general permit under section 404 of the Clean Water Act and/or section 10 of the Rivers and Harbors Act of 1899;
  3. A finding of “adverse effect” to historic properties under the National Historic Preservation Act, the use of a resource protected under 23 U.S.C. 138 or 49 U.S.C. 303 (section 4(f)) except for actions resulting in de minimis impacts, or a finding of “may affect, likely to adversely affect” threatened or endangered species or critical habitat under the Endangered Species Act;
  4. Construction of temporary access or the closure of existing road, bridge, or ramps that would result in major traffic disruptions;
  5. Changes in access control;
  6. A floodplain encroachment other than functionally dependent uses (e.g., bridges, wetlands) or actions that facilitate open space use (e.g., recreational trails, bicycle and pedestrian paths); or construction activities in, across or adjacent to a river component designated or proposed for inclusion in the National System of Wild and Scenic Rivers.

Remember a categorical exclusion from NEPA does not exclude a project from the other federal or state environmental requirements for permits or consultation, except as provided in the other agreements such as the Section 106 Programmatic Agreement. Formal consultation with federal resource or regulatory agencies is carried out by FHWA or Caltrans as assigned. All environmental consultation requirements, including consultation pursuant to Section 7 of Federal Endangered Species Act and Section 106 of the National Historic Preservation Act, must be met before FHWA or Caltrans as assigned will make an exclusion determination.

23 USC 326 Categorical Exclusion vs. 23 USC 327 Categorical Exclusion (CE)

There are two general means of categorically excluding a project under NEPA: 1) 23 USC 326 categorical exclusions, and 2) 23 USC 327 categorical exclusions. To aid in determining which type of categorical exclusion to use, to help document the CE determination, and to document compliance with other federal requirements, the Categorical Exclusion checklist may be used. The Categorical Exemption/Categorical Exclusion (CE/CE) form must be used to document the CE determination and address the provisions of the CE Assignment and the NEPA Assignment MOUs.

23 USC 326 CE

Caltrans and FHWA renewed the Memorandum of Understanding (CE Assignment MOU) pursuant to 23 USC 326.

The 23 USC 326 CE Assignment MOU assigns to Caltrans authority and responsibility for CE determination under the 23 CFR 771.117 (c) list and 23 CFR 771.117(d) list, plus those activities specifically listed in Appendix A – Assigned Categories of Activities of the CE Assignment MOU.  Appendix A – Assigned Categories are:
  1. Construction, modification, or repair of stormwater treatment devices (e.g. detention basins, bioswales, media filters, infiltration basins), protection measures such as slope stabilization, and other erosion control measures.
  2. Replacement, modification, or repair of culverts or other drainage facilities.
  3. Projects undertaken to assure the creation, maintenance, restoration, enhancement, or protection of habitat for fish, plants, or wildlife (e.g., revegetation of disturbed areas with native plants species; stream or river bank revegetation; construction of new, or maintenance of existing fish passage conveyances or structures; restoration or creation of wetlands).
  4. Routine repair of facilities due to storm damage, including permanent repair to return the facility to operational condition that meets currents standards of design and public health and safety without expanding capacity (e.g. slide repairs, construction or repair of retaining walls).
  5. Routine seismic retrofit of facilities to meet current seismic standards and public health and safety standards without expansion of capacity.
  6. Actions including, but not limited to, right-of-way use agreements, encroachment permits and consent letters that are subject to Subpart D of 23, Part 710.
  7. Drilling of test bores/soil sampling to provide information for preliminary design and for environmental analyses and permitting purposes.

The project must fall within a category specifically listed in order to qualify for a 23 USC 326 CE under the 23 CFR 771.117(c) list, 23 CFR 771.117(d) list, plus those activities listed in Appendix A - Assigned Categories of Activities of the CE Assignment MOU. If the project qualifies for a CE determination under 23 USC 326, Caltrans will assume not only responsibility for preparing and approving the CE but will also be responsible under applicable federal laws for environmental review, consultation and other related actions. The one exception to this is for government-to-government consultation with Indian tribes as defined in 36 CFR 800.16(m). For a complete list of FHWA’s responsibilities assigned to Caltrans, please see Appendix B of the CE Assignment MOU. If the proposed project does not qualify for a 23 USC 326 CE, then determine whether it meets the requirements to be categorically excluded under the NEPA Assignment MOU.

23 USC 327 CE

For projects that are not on the ‘c’ or ‘d’ list or the Appendix A list, but for which a CE classification is appropriate under 23 CFR 771.117 ‘a’ and ‘b’, Caltrans will assume CE responsibility under NEPA Assignment (23 USC 327). Caltrans has also assumed the USDOT Secretary’s responsibilities for environmental review, interagency consultation, and other regulatory compliance-related action pertaining to the review or approval of NEPA Assignment (23 USC 327) CEs. See Section 3.2 of the Pilot Program MOU for the full list of responsibilities assumed.

Exceptions to Categorical Exclusions - Unusual Circumstances

FHWA regulation 23 CFR 771.117(b) provides that any action which normally would be classified as a CE but could involve unusual circumstances require Caltrans to conduct appropriate environmental studies to determine whether a categorical exclusion is proper. Unusual circumstances include actions that involve:
  1. Significant environmental impacts;
  2. Substantial controversy on environmental grounds;
  3. Significant impact to properties protected under 4(f) of the USDOT Act or section 106 National Historic Preservation Act;
  4. Inconsistencies with any Federal, State or local law relating to environmental impacts.

The type and scope of the studies necessary to determine the appropriateness of a CE will vary with the facts and circumstances of each situation. If the studies conclude that a CE is not appropriate, either an environmental assessment or environmental impact statement will need to be prepared. See SER, Vol 1, Chapters 31 and 32 respectively.

Eligibility, Preparation and Processing of 23 USC 326 CEs and 23 USC 327 CEs

Eligibility and Compliance with Other Federal Laws, Regulations, and Executive Orders

An accurate and complete project description is important in establishing that the proposed action is consistent with the requirements of 23 CFR 771.117 and the CE Assignment (23 USC 326) MOU or NEPA Assignment (23 USC 327) MOU. The project description should fully describe the action to be undertaken, including the purpose and need, location, project limits (logical termini/independent utility), construction activities such as shoulder backing, culverts, staging areas and facilities, disposal and borrow sites required, any right-of-way requirements (such as acquisition), utility relocations, and construction activities that may require temporary facilities such as roads, detours, or ramp closures. Any state or federal permit or consultation requirements should be noted.

Consideration must be given to compliance with NEPA requirements related to connected actions and segmentation (i.e. the project must have independent utility, connect logical termini when applicable, and not restrict further consideration of alternatives for other reasonably foreseeable transportation improvements) (FHWA Final Rule, “Background,” Federal Register Vol. 79, No. 8, January 13, 2014).

Sometimes technical studies may be needed to determine whether the project meets the conditions for a 23 USC 326 or 23 USC 327 CE. Any environmental studies and state or federal permit or consultation requirements should be identified and initiated early in the process. Technical studies may be as simple as documentation of a field review or consist of a detailed report requiring weeks or months to complete. When technical studies are prepared for local assistance projects, Caltrans’ district environmental staff reviews the reports for completeness and sufficiency. Under both the 23 USC 326 and 23 USC 327 MOUs, technical studies prepared pursuant to other federal agency permit/consultation requirements, including, but not limited to endangered species consultation (U.S. Fish and Wildlife Service/NOAA Fisheries), waters of the U.S. permitting (U.S. Army Corps of Engineers), Section 4(f) consultation (Department of Interior), and/or historic properties consultation (State Historic Preservation Officer) are prepared and approved in the district/region. The Categorical Exclusion Checklist may be used as a tool to document compliance with laws and regulations when making a NEPA CE determination. If utilized, the checklist should be included in the project environmental file. The checklist includes:

  • All designated CE actions;
  • The CE "unusual circumstances" from 23 CFR 771.117(b);
  • Other federal environmental laws, regulations, and Executive Orders that were considered in reaching the CE determination.

Air Quality

Under the 23 USC 326 CE Assignment MOU, Caltrans has been assigned authority and responsibility for making the project's regional air quality conformity determination, as well as any needed project-level (Hot Spot) conformity determination. The air quality conformity findings checklist must also be completed to summarize and document the conformity analysis and determination for CEs. This checklist is to be completed for each project and included in the project environmental file.

Under the 23 USC 327 NEPA Assignment MOU, Caltrans has not been assigned air quality conformity determinations; for 23 USC 327 CEs, coordination with FHWA is needed to obtain the air quality conformity determination. FHWA's air quality conformity determination must be made by FHWA before the 23 USC 327 CE can be signed and approved by Caltrans. See the Air Quality Section of Chapter 38, NEPA Assignment for additional details on coordinating with FHWA to obtain the conformity determination.

Preparing and Processing Categorical Exclusions

Under 23 USC 326, Caltrans will fulfill all of FHWA’s current roles and responsibilities for CEs assigned under the 23 USC 326 CE Assignment MOU. If the project qualifies for a CE determination under 23 USC 326, Caltrans will assume not only responsibility for preparing and approving the CE but will also be responsible under applicable federal laws for environmental review, consultation and other related actions. The one exception to this is for government-to-government consultation with Indian tribes as defined in 36 CFR 800.16(m). For a complete list of FHWA’s responsibilities assigned to Caltrans, please see Appendix B of the CE Assignment MOU. Caltrans is required to follow FHWA’s formal guidance and policies, relating to environmental review matters, which are posted on the USDOT and FHWA website and contained in the FHWA Environmental Guidebook. For interagency agreements solely between Caltrans and FHWA, the assumption of FHWA responsibilities has automatically been assigned. If the interagency agreement involves signatories other than the FHWA and Caltrans, then the FHWA and Caltrans will work to obtain any necessary consents or amendments. See the Interagency Agreements section of Chapter 38 for additional details. Caltrans is also assigned responsibility for preparing and approving any needed reevaluation of the 23 USC 326 CE.

In no case will Caltrans categorically exclude a project that is found to have significant impacts on the environment, either individually or cumulatively, but otherwise meets the definition of a CE. When significant impacts are known or suspected an Environmental Assessment (EA) or Environmental Impact Statement (EIS), as appropriate, will be prepared.

Steps 1-4 of the Integrated Quality Control/Quality Assurance Review Procedures are followed for projects that require a CE. The preparation, review, and approval of the CE fulfils the requirements of Step 4 of the quality control/quality assurance process.  The CE/CE form is used to document the NEPA CE determination and address the provisions of the CE Assignment and the NEPA Assignment MOUs.

Signature Authority

For State Highway System (SHS) projects, the CE decision for all of the assigned categories will be approved by Caltrans’ District Environmental Office Chief or Senior Environmental Planner supervising the staff that performed the work, and by Caltrans’ Project Manager. Caltrans’ Senior Environmental Planner and Caltrans’ Project Manager will sign the CE/CE form. Signature authority for the CE/CE form cannot be delegated below the Senior Environmental Planner classification.

This same process will also be undertaken for Local Assistance projects. Caltrans, rather than FHWA, will review and sign the Local Assistance PES form to concur in the class of action and necessary field studies. For Local Assistance projects, the local agency and/or its consultants will conduct the field studies and prepare the technical memoranda/studies for review and approval by Caltrans. The District Local Assistant Engineer (DLAE) and the District Senior Environmental Planner will sign the Local Assistance CE once necessary field studies and coordination with resource agencies are complete. Again, signature authority for the CE/CE form cannot be delegated below the Senior Environmental Planner classification.

Project Files and Retention

Caltrans must maintain electronic and paper project records and general administrative records pertaining to its CE Assignment and NEPA Assignment responsibilities. The records must be available for inspection by the FHWA at any time. Caltrans must provide the FHWA with copies of any documents the FHWA may request. Caltrans must retain those records, including all letters and comments received from governmental agencies, the public, and others about the performance of activities assigned under this MOU, for a period of no less than three (3) years after completion of project construction. This 3-year retention provision does not relieve Caltrans of its project or program record keeping responsibilities under 49 CFR 18.42  or any other applicable laws, regulations, or policies. The project record will include, at minimum, the CE, all supporting documentation and the CE checklist (if applicable).

(Last content update: 10/31/2023, JH)