TS I am a biologist, I don't know what you want to do with your degree but if you want good prospects in the environmental science field I would change majors. Env. Science doesn't have enough math and hard science that makes you appealing to an employer. It also is usually not a good enough degree to get into a graduate degree in the sciences. Biology, Statistics, Economics, depending what it is you want to do one of those might be a better choice.
If you want to do policy then it is probably fine..
Poster above is correct, you will need an advanced degree for a good job with the possible exception that you are superb at selling yourself and you know the right people.
So you better get good grades and do a shitload of networking and get any experience or internships in research, policy or whatever it is you want to do before you graduate. You will need all of that for either a job or to get into grad school.
Oh anyway I worked pretty hard in school, also got tons of experience in the field doing research and working for free/peanuts under researchers, which got me into grad school, and now I fucking love my job. Fishing, diving, enough money to live on also (1/2-2/3 of the time is behind a computer using stats, computer programming, etc.)