a. The lead agency will examine project to see if it qualifies for a categorical or statutory exemption. If so they may issue a notice of exemption.
b. If not exempt the lead agency performs an initial study to determine if the project will have any significant negative impacts on environmental quality. If no the lead agency will issue a negative declaration. The lead agency may also issue a negative declaration with mitigation measures.
c. If the initial study indicates potential negative environmental impacts the lead agency will order an environmental impact report. This report will study the impacts in more detail and suggest mitigating measures if any to reduce the effects.
Exemptions or Negative Declarations allow the project to move forward. Negative Declarations with Mitigation Measures requires changes to the project, but it moves forward. EIR requires significant project delay and potentially renders the project infeasible, significantly changes the project, or kills it entirely.