CEQA VMT Impact Thresholds
The City of Murrieta has established Vehicle Miles Traveled (VMT) thresholds of significance based on guidance and substantial evidence provided in the City's General Plan Update and Environmental Impact Report (EIR), as well as the Western Riverside Council of Governments (WRCOG) Implementation Study. The determination of whether a project has a significant VMT impact is based on a comparison with the assumptions in the General Plan. Before analyzing VMT impact thresholds under the California Environmental Quality Act (CEQA), it is essential to consider two key sections of CEQA:
15183. Projects Consistent with a Community Plan or Zoning
(a) CEQA mandates that projects which conform to the development density established by existing zoning, community plans, or general plan policies—where an EIR has already been certified—do not require additional environmental review. However, additional examination may be necessary to evaluate whether there are project-specific significant effects that are peculiar to the project or its site. This provision streamlines environmental review for projects that align with the General Plan, minimizing redundant studies.
The use of Section 15183 also addresses cumulative impacts, as outlined in Section 15130(e).
15130. Discussion of Cumulative Impacts
(e) If a cumulative impact has been adequately addressed in a prior EIR for a community plan, zoning action, or general plan, and if the project is consistent with that plan or action, then an EIR for such a project does not need to further analyze that cumulative impact, as stipulated in Section 15183(j).
As such, projects that align with the General Plan Update EIR generally do not require further environmental review unless specific conditions warrant additional analysis. This means that potential impacts—whether in the local context or cumulative—should first be assessed based on the land use assumptions in the General Plan. Additionally, projects should determine whether their potential impact has already been addressed in the City's General Plan.
VMT Impacts
Under CEQA, an impact is considered significant if it results in a change to the existing or baseline environment. Several approaches can be used to initiate VMT impact analysis. One approach is to assess the total daily VMT generated under baseline conditions. However, setting this as a jurisdictional threshold could create a fixed budget, limiting development and causing even minor increases in VMT to be deemed significant.
A more practical method is to assess the baseline VMT per resident, per employee, or per service population. This efficiency-based approach ensures that future land use projects perform at least as well as existing land uses consistent with the General Plan. Under this approach, only projects that increase the rate of VMT generation would be considered to have significant impacts. Since VMT fluctuates with population and employment growth, economic changes, and evolving travel behavior (e.g., ride-sharing, autonomous vehicles), an efficiency-based VMT threshold provides a more reliable means of comparison.
A project will be considered to have a significant project-generated VMT impact if either of the following conditions is met:
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The baseline project-generated VMT per service population exceeds the City's baseline VMT per service population.
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The cumulative project-generated VMT per service population exceeds the City's baseline VMT per service population.
Similarly, the project's effect on VMT is deemed significant if it results in either of the following conditions:
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The baseline link-level boundary VMT per service population (for the City or subregion) increases under the "plus project" condition compared to the "no project" condition.
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The cumulative link-level boundary VMT per service population (for the City or subregion) increases under the "plus project" condition compared to the "no project" condition.
The cumulative "no project" condition should align with the adopted Regional Transportation Plan (RTP) Sustainable Communities Strategy (SCS). If a project is consistent with the RTP/SCS, then its cumulative impacts should be considered less than significant, subject to additional substantial evidence.
VMT Mitigation Measures
When a project is determined to have significant VMT impacts, various mitigation strategies can be applied. The following options provide a range of potential solutions:
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Project Modification: Adjust the project’s built environment characteristics to reduce the amount of VMT it generates. This may include revising the project design to encourage mixed-use development, increasing accessibility to transit, or implementing pedestrian and bicycle-friendly infrastructure.
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Transportation Demand Management (TDM): Implement TDM measures aimed at reducing VMT. Examples include providing incentives for carpooling and telecommuting, offering transit subsidies, and enhancing bicycle and pedestrian facilities. These measures require ongoing monitoring and performance metrics, which must be a required condition for any project choosing this option.
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Impact Fee or Exchange: Participate in a VMT fee program or a VMT mitigation exchange/banking program, if available. These programs allow developments to offset their VMT impacts by funding off-site mitigation projects or contributing to citywide transportation improvement initiatives.
TDM measures are aligned with the City's Development Code and Climate Action Plan and are designed to promote sustainable transportation. Evaluating VMT reductions should use state-of-the-practice methodologies while recognizing that many TDM strategies rely on long-term performance by building tenants. Because actual VMT reduction outcomes can vary, ongoing monitoring is necessary to assess effectiveness. Additionally, regional TDM measures identified in the WRCOG Implementation Pathway Study can further support mitigation efforts.
CEQA Assessment – Active Transportation and Public Transit Analysis
Projects may also impact public transit, pedestrian travel, and bicycle facilities. These potential impacts should be evaluated using the following criteria:
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A significant impact occurs if the project conflicts with adopted policies, plans, or programs related to public transit, bicycle, or pedestrian facilities, or if it decreases the performance or safety of such facilities.
The Transportation Impact Analysis (TIA) should include a review of whether the project is inconsistent with existing or planned infrastructure for active transportation and public transit. If a project is found to conflict with or negatively impact these facilities, further analysis is necessary to determine its potential effects and identify appropriate mitigation strategies.
By establishing clear VMT thresholds and mitigation strategies, the City of Murrieta ensures that new developments align with state sustainability goals while maintaining efficient transportation operations. VMT-based CEQA assessments provide a more holistic approach to evaluating environmental impacts by focusing on reducing reliance on single-occupancy vehicles and encouraging alternative transportation options. Through careful planning, monitoring, and mitigation efforts, the City can support sustainable growth while minimizing adverse transportation impacts.
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