To: Board of Supervisors
From: Planning and Building Department
Agenda Section: Departmental
Vote Requirement: Majority
SUBJECT:
title
Adoption of a Vehicle Miles Traveled Policy by Resolution for CEQA Threshold and Screening Criteria Assessor Parcel Numbers (APN) 000-000-000 Record No.: LRP-2023-18792 Unincorporated Humboldt County
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RECOMMENDATION(S):
Recommendation
That the Board of Supervisors:
1. Adopt the resolution [Attachment 1] taking the following action:
a. Find that the proposed policy for VMT threshold is not a project pursuant to Sections 15060(c)(3) and 15378 (b)(5) of the State CEQA Guidelines; and
b. Adopt the proposed VMT Threshold Policy Guidelines [Attachment 2] establishing thresholds of significance and screening criteria for the purpose of analyzing VMT transportation impacts under CEQA, utilizing either:
i. The Unincorporated Humboldt County data to establish baseline VMT and CEQA thresholds; or
ii. The Countywide data including the Incorporated Cities data to establish the baseline VMT and CEQA thresholds.
Body
STRATEGIC PLAN:
This action supports the following areas of your Board’s Strategic Plan.
Area of Focus: Safe & Healthy Communities
Strategic Plan Category: 1007 - Improve the transportation network to be multi-model, safe, sustainable and equitable
Area of Focus: Housing for All
Strategic Plan Category: 4002 - Increase and prioritize housing development
Area of Focus: Sustainable Natural Resources & Infrastructure Stewardship
Strategic Plan Category: 5001 - Enhance climate adaptation landscapes and communities
DISCUSSION:
Executive Summary:
The Board of Supervisors (BOS) is being asked to adopt a policy document establishing CEQA thresholds of significance for Vehicle Miles Traveled (VMT). In 2020, SB 743 took effect and changed traffic impact analysis from the traditional Level of Service analysis (LOS) to VMT. Under this legislation, the county has the discretion to devise VMT thresholds of significance to assess projects under CEQA, or continue to evaluate a project’s transportation impacts on a case-by-case basis. Adopting standardized thresholds and screening criteria provides a consistent and repeatable format for transportation impact analysis and increases VMT reduction for the county.
The proposed thresholds and screening criteria outlined in the VMT Policy Threshold Guidelines, or “VMT Policy” (Attachment 2), are based upon information from the Humboldt County VMT Study prepared by Fehr & Peers Traffic Consultants (Attachment 3), and the California Governor’s Office of Land Use and Climate Innovation (LCI) Technical Advisory on Evaluating Transportation Impacts in CEQA, or “Technical Advisory” (Attachment 4). The proposed CEQA VMT threshold of significance is 15% or more below existing VMT. Projects that screen out would not require a detailed VMT analysis or mitigation measures, whereas other projects not screened out would require a detailed VMT analysis, and some form of mitigation if found to be above the threshold.
A Planning Commission (PC) hearing was held on May 1, 2025, to consider the proposed VMT Policy. A unanimous decision was made to recommend that the BOS adopt the proposed VMT Policy, and thresholds of significance as recommended by staff with a few requested modifications (PC Resolution Attachment 5), all of which have been updated in this Staff Report and Attachments. However, the PC was deadlocked on whether to use the unincorporated county boundary as recommended by staff (Option 1), or the countywide boundary (Option 2, including data for the incorporated cities) to establish the baseline VMT for CEQA thresholds. The BOS is being asked to decide on Option 1 or Option 2 for establishing the baseline VMT and CEQA VMT Thresholds of Significance.
Background:
SB 743 required agencies to use VMT for analyzing projects’ transportation impacts over Level of Service (LOS) starting July 1, 2020, and CEQA Guidelines Section 15064.3 specifies that automobile delay under LOS, or similar measure of traffic congestion, is no longer considered a significant impact. The intent of SB 743 is to ensure that the environmental impacts of traffic (such as noise, air pollution, and safety concerns) continue to be properly addressed and mitigated through CEQA with the use of VMT, and to balance the needs of congestion management more appropriately with statewide goals related to the reduction of greenhouse gas (GHG) emissions and traffic-related air pollution. This is being accomplished through the promotion of infill development, increasing multi-modal transportation and public health through active transportation. While projects are no longer reviewed for LOS under CEQA, LOS is still a standard in the Circulation Element of the General Plan and projects will need to continue to be reviewed for consistency with these standards.
LOS has been historically used to measure traffic congestion levels on intersections and roadways, and to assess the impacts of new development projects on automobile delay. In the context of Humboldt County, which is rural in nature and widespread with primarily low-density development, achieving a less than significant impact on transportation using LOS has been unchallenging. VMT, however, measures how much auto travel a proposed project would produce on roadways and assesses project impacts based on how much additional driving they are likely to generate. Mitigating VMT has shown to be more challenging in a rural setting due to factors like limited transportation alternatives, having a dispersed population, and common measures to reduce VMT are generally less effective or infeasible. Unincorporated Humboldt County contains just over half of the total population for the county, and with limited available public transit in rural areas, many residents drive longer distances for services, work, or other retail or recreational purposes than residents within incorporated cities. These facts pose some challenges with reducing VMT in the county.
While agencies have the discretion to apply the VMT metric on a case-by-case basis, this allows for subjectivity. Adoption of the VMT Policy would provide a clear, quantitative measure to assess transportation impacts under CEQA, and identify specific VMT screening criteria that are essential for department staff, decision makers, local professionals and the public when evaluating projects. This allows for better planning to mitigate VMT, promote sustainable land use practices, and would facilitate the future buildout of the General Plan and other adopted plans.
There are several ways a local jurisdiction can establish VMT thresholds, through the General Plan, a Climate Action Plan, a Regional Transportation Plan (RTP), or through a standalone policy document. To be done through a General Plan amendment, adoption of a Climate Action Plan or a Regional Transportation Plan, an assessment of what population increase is anticipated with the plan and the level of associated increase in VMT that is considered acceptable would need to be provided for substantial evidence to support the threshold. This information was not included in the amendment to the General Plan update in 2017 and establishing a threshold was deferred to future action. This information was also not included in the RTP Variety in Rural Options of Mobility “RTP-VROOM 2022-2042,” prepared by HCAOG in 2022 (Attachment 6). While the original plan was to include this assessment in the Climate Action Plan for the county, there were complications with funding requirements and deadlines for this to happen. Therefore, the county has developed a VMT Policy to establish thresholds, which is based on the LCI Technical Advisory for substantial evidence supporting the recommended threshold of 15% below existing VMT.
Policy Proposal
The VMT Policy will establish a baseline for existing VMT which is used to set the threshold for VMT reduction. The Technical Advisory recommends a standard reduction of 15% from existing (baseline) VMT for new development projects considered to have a less than significant transportation impact. The following recommendations related to the policy guidelines are being considered:
1. Methodology for Establishing a Baseline VMT: Staff are proposing using 2022 StreetLight data to establish the baseline VMT. However, it is at the discretion of the BOS whether the baseline for existing VMT utilizes data for unincorporated Humboldt County (Option 1) or countywide which includes data for the incorporated cities (Option 2).
2. Thresholds - Land Use Projects: The county is establishing a threshold of 15% or more below existing VMT for residential and employment land use projects.
3. Screening Criteria: Staff has selected the following screening criteria to identify projects that would result in less than significant VMT impacts without requiring a detailed VMT analysis. These criteria are in line with the recommendations in the Technical Advisory.
a. Small projects consistent with the General Plan and Zoning Code that generate 110 trips or less.
b. Residential and employment projects consistent with the General Plan and Zoning Code that are located within Low-VMT mapped areas.
c. Projects consistent with the General Plan and zoning code that are within a half-mile of an existing major transit stop identified in the RTP VROOM 2022-2042 and contain no more than the minimum required parking spaces.
d. Projects containing 100% affordable housing located in infill areas defined as Urban Areas under the US Census Bureau.
e. Local-serving retail projects or other local-serving employment projects less than 50,000 square feet that improve retail destination proximity and thus shorten trips and reduce VMT.
f. Mixed-use projects consistent with the General Plan and Zoning Code that are located within applicable Low-VMT mapped areas.
g. Redevelopment projects that lead to no increase in VMT.
4. Mitigation Strategies: Transportation mitigation strategies identified by the California Air Pollution Control Officers Association’s (CAPCOA) Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity (Attachment 7).
Establishing a policy that reduces VMT in Humboldt County will assist the region in achieving GHG emissions reduction targets identified in the Draft Regional Climate Action Plan, and is consistent with the following objectives of the General Plan which facilitate the reduction of VMT and GHG emissions in line with SB 743:
• Reduce the county’s off-street parking requirements to encourage business development and reflect multi-modal access options, which are identified within the Land Use Element.
• Reduce vehicle miles traveled, increase walking and biking capacity and use of multi-modal transportation, which are identified within the Circulation Element.
• Reduce GHG emissions and yield significant public health benefits, which are identified within the Energy Element and Air Quality Element.
• Promote infill development identified within policies of the Housing Element.
Methodology and Metrics for Baseline VMT
VMT metrics require a geographical boundary to define the extent of data to select and analyze, and the daily average can change depending on the geographical boundary. According to the Technical Advisory, the county has the option of using the unincorporated county average or the regional average (countywide average) which includes data for the incorporated cities. On May 1, 2025, the PC was deadlocked 3-to-3 on whether to use the unincorporated county average (Option 1), or the countywide average (Option 2) for establishing the baseline VMT and CEQA thresholds of significance.
Option 1 would reflect vehicle trips that start or end in the unincorporated areas of Humboldt County and aligns with the area over which the county has land use jurisdiction. Unincorporated county metrics reflect the differences in the built environment and land use context of unincorporated Humboldt compared to the incorporated cities.
Option 2 would reflect all vehicle trips that start or end in Humboldt countywide including within the incorporated cities.
Data to Establish Baseline VMT
In 2023 county staff began working with Fehr & Peers to conduct an analysis of the average existing VMT and produced a VMT Study for Humboldt County. While conducting the analysis it was considered whether the county should utilize the Humboldt County Travel Demand Model (HCTDM) to forecast existing VMT, or use location-based StreetLight data to estimate existing VMT. Staff decided that StreetLight data would be the best available current data, as the HCTDM was last updated in 2015 and is based on 2010 California household travel surveys.
While travel demand models are traditionally considered the best available traffic data, they often have limitations. Location-based data such as StreetLight provides a powerful alternative for calculating VMT because estimations are based on robust datasets with less demographic bias than household travel surveys, trips are calculated from start to finish with no boundaries and can be identified as resident, employee or visitor, and trips in different geographic areas can be compared apples-to-apples without concern of whether the underlying survey methods are dissimilar. StreetLight data is captured from smart phones and cars with Global Positioning Systems (GPS), which is highly anonymized and has a robust set of samples for estimating average VMT. However, there are some concerns about the use of StreetLight data such as the future availability of data with privacy settings changing on iPhones, as well as the accuracy of trips calculated in rural areas without available cell or Wi-Fi services.
Since some StreetLight data comes from GPS in cars, it is anticipated that this type of data will become more available and accurate over time with people transitioning to newer vehicles. StreetLight has also changed their methodology to address the change in iPhone default privacy settings. In addition, trips that occur in rural areas without cell or Wi-Fi services are still counted if the trip starts and ends with service. While there may be some potential issues with StreetLight data, it has been found to be more reliable and accurate for vehicle travel patterns than travel demand models, which are highly conservative. The use of StreetLight data for developing VMT metrics was found to be compliant with SB 743 in the white paper from StreetLight (Attachment 8).
The VMT Study used StreetLight data from the year 2022 to get the average VMT per resident (HBX) and average VMT per employee (HBW) for unincorporated Humboldt County and countywide including data for the incorporated cities. Having these different metrics is useful in reviewing different types of development projects for an apples-to-apples comparison. (i.e. A proposed residential project would be measured against the established HBX, and a proposed employment project would be measured against the established HBW.) The identified HBX and HBW for unincorporated Humboldt County and countywide are shown in Table 1 below.
Table 1. Average HBX and HBW for Unincorporated Humboldt County vs Countywide Data
|
|
Option 1 Unincorporated Average VMT |
Option 2 Countywide Average VMT |
|
HBX (VMT per Resident) |
22.1 VMT per Resident |
20.11 VMT per Resident |
|
HBW (VMT per Employee) |
14.7 VMT per Employee |
13.17 VMT per Employee |
Average VMT per Resident - HBX
HBX encapsulates trips that start or end at a home-base, and includes home-base to other trips, or other to home-base trips (“other” would include retail or commercial locations, but not work). The unincorporated HBX only utilizes data for residential trips that have a home-base located in unincorporated Humboldt County. Countywide HBX includes all residential trips within unincorporated Humboldt County and the incorporated cities. Further explanation on StreetLight’s methodology to analyze and categorize data to establish HBX estimates is included in the SB743 Overview from StreetLight (Attachment 9).
Average VMT per Employee - HBW
HBW encapsulates trips that are from home-base directly to work or work directly to home-base. The unincorporated HBW only utilizes data for employee trips that end at work locations in unincorporated Humboldt County. Countywide HBW includes employee trips that end at work locations within both unincorporated Humboldt County and the incorporated cities. Further explanation on StreetLight’s methodology to analyze and categorize data to estimate HBW is included in Attachment 9.
Thresholds of Significance
Transportation thresholds of significance under CEQA are based on the established baseline VMT for HBX and HBW. On May 1, 2025, the PC agreed with staff’s recommendation to adopt a threshold of 15% or more below baseline VMT, in line with the Technical Advisory, but was deadlocked 3-to-3 on whether to use the unincorporated county or countywide VMT data to apply the threshold against. For residential projects to be considered to have a less than significant VMT transportation impact, they would need to show that they would generate project-HBX 15% or more below the established baseline HBX. For employment projects to be considered to have a less than significant transportation impact, they would need to show that they would generate project-HBW 15% or more below the established baseline HBW. Table 2 below shows Option 1 vs Option 2 thresholds.
Table 2. CEQA Thresholds of Significance for Option 1 vs Option 2
|
|
Option 1 Thresholds Unincorporated County Baseline |
Option 2 Thresholds Countywide Baseline |
|
Residential Projects |
VMT per Resident  18.79 miles = Less than Significant |
VMT per Resident ≤ 17.09 miles = Less than Significant |
|
Employment Projects |
VMT per Employee ≤ 12.5 miles = Less than Significant |
VMT per Employee ≤ 11.2 miles = Less than Significant |
Using the unincorporated county VMT data (Option 1) would mean adopting higher thresholds with lower intensity and using countywide VMT data (Option 2) would mean adopting lower thresholds with higher intensity. Projects that cannot be screened out would require further VMT analysis to calculate their project-VMT. Project VMT analysis should be prepared in accordance with the guidance in the VMT Policy.
Low-VMT Areas
The VMT Study identified HBX and HBW in 2022 for US Census block groups throughout the county. This information is available to the public on the Humboldt County Web GIS and will be useful to other local jurisdictions analyzing projects against their own adopted thresholds. Block group VMT data was used to establish and map low-VMT areas for HBX and HBW that meet the proposed thresholds for Option 1 and Option 2. Projects within established low-VMT areas allows the screening out of new development projects considered to have a less than significant impact to transportation without requiring a full VMT analysis.
Using the countywide data (Option 2) over the unincorporated county data (Option 1) would reduce the amount of block groups designated as low-VMT areas to be identified in the policy guidelines. See Figures 1 - 8 in Attachment 2 for the difference in low-VMT mapped areas for residential VMT (HBX) and employment VMT (HBW) for Option 1 and Option 2.
Mitigation Strategies
Projects that are found to generate project-VMT above the applicable threshold(s) in a detailed VMT analysis require mitigation strategies to be applied to the extent feasible. Available Transportation Demand Management (TDM) strategies identified in the California Air Pollution Control Officers Association’s (CAPCOA) Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity (Attachment 7) can be used to calculate VMT reductions that would be achieved and determine the project’s level of impact on VMT with mitigation. Methodology and calculation of VMT reductions achieved with mitigation shall be in accordance with the CAPCOA Handbook and be provided in the detailed project-VMT analysis.
Something to consider for future implementation is a VMT Impact Fee Program. This is a system where developers of new construction projects are charged a fee based on the projected increase in VMT that their development will generate. The collected funds would be used to fund transportation projects which are specifically designed to reduce VMT, such as improved transit or bicycling and pedestrian infrastructure. Implementing this type of program is in line with policy C-P12 Countywide Traffic Impact Fee of the Circulation Element and would help to further achieve local VMT reduction targets identified in the Humboldt Regional Climate Action Plan to be brought to the BOS later this year for decision.
Conclusion
Adopting a policy for VMT thresholds of significance will encourage infill development, mixing of uses, active and alternative transportation infrastructure, and promote use of the public transit system. All these efforts will reduce the need for vehicle travel, promote healthier lifestyles and reduce GHG emissions. The policy will enable the County of Humboldt to comply with state law and provide an established and consistent criterion for analyzing transportation impacts of development projects and long-range plans under CEQA. The policy will facilitate the buildout of the General Plan, the Humboldt Regional Climate Action Plan and other adopted plans, and will support and expedite new development in areas found to be suitable.
Project Location: All Unincorporated areas of Humboldt County, including the Coastal Zone.
Present General Plan Land Use Designation: All land use designations.
Present Zoning: All zoning districts.
Environmental Review: The proposed policy adoption is exempt from environmental review under Section 15060(c)(3) and Section 15378(b)(5) of CEQA Guidelines, the activity is not a project as defined under Section 15378; Section 15378(b)(5) states that a project does not include organizational or administrative activities of governments that will not result in direct or indirect physical changes in the environment.
State Appeal: This policy would not amend the Zoning Code or require a Local Coastal Plan Amendment and is therefore not appealable to the California Coastal Commission.
SOURCE OF FUNDING:
Regional Early Action Planning (REAP) Grant (1100282-410)
General Fund (1100-282)
FINANCIAL IMPACT:
Work on the project has been funded by the REAP grant and the General Fund. The REAP grant provided $105,675 in funds towards the Humboldt County VMT Study that was prepared by Fehr & Peers. Approximately $56,500 in funds have been provided for staff work on the project with General Funds in the Advance Planning budget 1100-282.
STAFFING IMPACT:
Staff time related to research and drafting the proposed VMT Threshold Policy was accomplished with current staff resources. There is no anticipated increase in workload for Planning Staff related to the adoption of CEQA VMT Thresholds of Significance and the VMT Policy Guidelines.
OTHER AGENCY INVOLVEMENT:
The VMT Study Report and proposed VMT threshold of 15% or more below existing VMT was consulted on with the Humboldt County Association of Governments (HCAOG), Caltrans, and the Incorporated Cities. As well, the proposal and report were sent out for referral to the Humboldt Transit Authority and the Department of Public Works for review. Referral comments from HCAOG, and Caltrans have been received and are included in Attachment 12 with responses to comments.
ALTERNATIVES TO STAFF RECOMMENDATIONS:
1. The Board of Supervisors could decide not to adopt a policy by resolution to establish a VMT threshold of significance, and that county staff continue to review new development projects for VMT metric and transportation impacts on a case-by-case basis.
2. The Board of Supervisors could decide to adopt a baseline VMT that is based off of the Humboldt County Travel Demand Model forecast instead of using 2022 StreetLight data.
3. The Board of Supervisors could decide to utilize StreetLight 2019 data for the baseline VMT and thresholds of significance.
ATTACHMENTS:
Attachment 1 - Draft Resolution
Attachment 2 - VMT Threshold Policy Guidelines
Attachment 3 - Humboldt County VMT Study
Attachment 4 - OPR Technical Advisory
Attachment 5 - PC Resolution 25-025 VMT Threshold Policy
Attachment 6 - HCAOG Regional Transportation Plan VROOM 2022 - 2042
Attachment 7 - CAPCOA Handbook
Attachment 8 - StreetLight SB743 VMT Methodology and Validation White Paper
Attachment 9 - StreetLight SB743 Overview Readme
Attachment 10 - 5/1/2025 PC Hearing Public Comments
Attachment 11 - 5/1/2025 PC Hearing Referral Comments
Attachment 12 - 5/1/2025 PC Hearing Response to Comments
PREVIOUS ACTION/REFERRAL:
Meeting of: 5/1/2025 Planning Commission
File No.: 25-585