The curriculum for all engineering is practically the same until your third or fourth year (because of the accreditation and professional licensure processes) so you don’t lose anything if you ending up switching out of CSUF.
That said, I think you might be in for some disappointment. The difference’s between UCI’s EnvE and CSUF’s CEE is very minimal so I highly doubt moving to UCI will change much if what your currently learning is not what you want to do.
Comparing the two majors points to the only differences really being that Environmental offerings are considered major “electives” and the Civil offerings are considered major “requirements” at CSUF while this reversed at UCI where the the Civil offerings are major “electives” and the Environmental courses are major “requirements”. Regardless of “requirement” versus “elective”, you have the same number of courses and similar opportunities to learn the same material at either school.
Comparing both programs to Cal Poly’s program only enforces that the course requirement differences are minimal regardless of the school. (Again due to ABET accreditation)
Sources:
http://www.fullerton.edu/ecs/cee/_resources/pdfs/current/ceeflowchart.pdf
http://plaza.eng.uci.edu/sites/default/files/flowcharts/14-15/environmental-frosh.pdf
http://flowcharts.calpoly.edu/downloads/mymap/15-17.52ENVEBSU.pdf
Wastewater is such a niche subfield that finding employment might be difficult afterwards? What part of wastewater are you interested in? Have you considered general water resources where (from what I’m told) employment is much more likely?