UC Riverside Public Policy and Environmental Science

Is it possible to double major in Public Policy (Health/Population Policy and Urban/Environmental Policy) and Environmental Science (Natural Sciences Option)?
Also, is it allowed to enroll in a community college class the summer before your freshmen fall quarter?
I’ll be starting my college apps in the fall so I’m wondering whether I should do dual enrollment but I have 3 AP Classes, 3 College Prep Classes, ROP EMT class after school, President of a Club, VP of a SoCal based organization, Facilator for a political organization, Hospital Volunteer in the mother/baby unit, and a camp counselor so it won’t be easy to juggle this courseload. The community college classes I want to take is the English series, Psychology, Sociology, or History to fill up my GE credits before entering UCR in the fall (hopefully I make it in)

Any other important info that you have in regards to the Public Policy and/or Environmental Science major will be appreciated.