Senator Seyarto's environmental quality legislation directs California's Office of Land Use and Climate Innovation to establish standardized criteria for evaluating project impacts under the California Environmental Quality Act (CEQA). The measure requires the office to develop best practices by July 2027 for determining when proposed projects may significantly affect the environment.

The bill mandates that these guidelines incorporate specific thresholds based on three major environmental laws: the California Global Warming Solutions Act for greenhouse gas emissions, the federal Clean Air Act for vehicle miles traveled, and the California Noise Control Act for noise pollution. These criteria would be codified in a new Appendix O of the CEQA guidelines, providing public agencies with concrete metrics for completing environmental impact assessments under Appendix G.

Under the legislation, the Office of Land Use and Climate Innovation may consult with local, regional, state, and federal agencies during the guidelines' development process. The Secretary of the Natural Resources Agency must then certify and adopt the final guidelines, which would establish uniform standards for public agencies to apply when evaluating projects' environmental effects. The measure aims to create consistency in how agencies determine the threshold for "significant effect on the environment" - a key trigger for additional environmental review requirements under CEQA.