"Impacted" meaning that there are more applications from qualified applicants than there are available spaces.
Impaction also means that campuses can--and do--often invoke what's called "supplementary admission criteria" either for the program or for students who don't reside in the campus's local area. This means that the campus requires higher standards for admitting students when it is impacted (e.g. Higher GPA).
CSU Academic Program Impaction for 2025-26
All undergraduate programs, pre-programs, and undeclared/undecided programs are impacted for the following universities:
Cal Poly San Luis Obispo
Cal State Fullerton
Cal State Long Beach
San Diego State
San José State