"I want to graduate and get a job right away."
That's great, so does every other undergraduate student in the country. What makes you better than all of them? To be more marketable, you need to gain experience working in your field. Don't spend the summer flipping burgers, spend the summer working in Colorado, Wyoming, Florida, Maine, etc. gaining real-world experience in your field of study, be that environmental sciences or biology. Don't wait till your senior year to work on this, there are three summers in your undergraduate career, use them wisely. There are many places to look for summer jobs, ask your professors.
"I'm about to graduate, now what?"
Ideally, approximately 8 months before you graduate you start your job search. The department subscribes to a publication called The Job Seeker, that is full of environmental and biological jobs. This comes to Dr. Wymer on the 6th and the 20th of each month. You should come by the day it comes out to see what is available. Here at UWA we take the shotgun approach to job hunting, we apply to every job that we are marginally interested in. The end product of this approach is that we may get to choose from several offers. We don't apply for one job and wait around.
"But I don't know what I want to do!"
If you don't know what you want to be when you grow up, The Job Seeker is a good place to start. Leaf through the notebook and read the description of any job that sounds interesting. This will give you a good idea of the types of jobs that are out there and the requirements for those jobs.
Useful Job Hunting Sites
State of Alabama Personnel Department