What is Significant Impact?

The determination of whether a project may have a significant effect on the environment is a critical step in the CEQA process. This determination should be based on information in the record and on scientific and factual data. The CEQA Guidelines Section 15382, sets forth the following definition for significant effect:

“Significant effect on the environment” means a substantial, or potentially substantial, adverse change in any of the physical conditions within the area affected by the project, including land, air, water, minerals, flora, fauna, ambient noise, and objects of historic or aesthetic significance."

The Guidelines also indicate that an ironclad definition of significant effect is not possible because the significance of an activity may vary with the setting.

However, according to CEQA Statutes Section 21083, (Significance Guidelines) and CEQA Guidelines Section 15065 (Mandatory Findings of Significance), if any of the following impacts would result from a proposed project, the project is considered to have a significant effect on the environment:

• The project has the potential to substantially degrade the quality of the environment, substantially reduce the habitat of fish or wildlife population, cause a fish or wildlife species to drop below self-sustaining levels, threaten to eliminate a plant or animal community, significantly reduce the number or restrict the range of an endangered, rare, or threatened species, or eliminate important examples of the major periods of California history or prehistory.
• The project has the potential to achieve short-term environmental goals to the disadvantage of long-term environmental goals.
• The project has possible environmental effects which are individually limited but cumulatively considerable. “Cumulatively considerable” means that the incremental effects of an individual project are considerable when viewed in connection with the effects of past projects, the effects of other current projects and the effects of reasonably foreseeable probable future projects (as defined in Guidelines Section 15130).
• The environmental effects of a project will cause substantial adverse effects on human beings, either directly or indirectly.