What is an EIR, an EA or an EIS, and when is it required?
An environmental impact report (EIR) is a detailed report written by the lead agency describing and analyzing the significant environmental effects of a proposed project, identifying alternatives and discussing ways to reduce or avoid the possible environmental damage. An EIR is prepared when the lead agency finds substantial evidence that the project may have a significant effect on the environment. An environmental assessment (EA) is a substitute for the EIR under the Certified Regulatory Program. An environmental impact statement (EIS) is an environmental impact document prepared pursuant to NEPA, in place of the term EIR which is used in CEQA.
