First, contact faculty from your undergraduate or master's program to see if they have any suggestions, given your research interests. This may or may not provide you with some good leads, but never fear, there is a way to do this for yourself.
Think back to your undergraduate courses and research that you have read. Are there any books or articles that pose intriguing questions that made you want to go find an answer? If so, they can lead you to an appropriate advisor and graduate program, and you should make a note of who wrote them and where they were employed at the time.
If you can't remember or find any of those materials, I'd advise you to do some searching in Google Scholar (http://scholar.google.com/). Of course, journal indexes and abstracts are also great sources, if you have access to them. For example, let’s say that after reading a lot of articles about the drought in the southern United States this summer and fall, you decide that one topic that interests you is how natural resource managers can best adapt their management practices in times of environmental stress. You would type in a search such as [drought "environmental management"], and when you get the results, limit it to more recent articles by using the pull down menu (say, to since 2008).
Then you start exploring. It’s a good idea to try several different versions of search terms for each of your areas of interest, and be as specific as you can. For example, one problem with the example search is that it will include aquatic, terrestrial, and, perhaps even, atmospheric subjects. You would want to specify that in your search. You might not be ready to do that right away, but once you do enough reading, you will be able narrow your searches to reflect your more specific interests.
Once you find books/articles that are central to your research interest, look for the place of employment of the authors (it’s almost always there somewhere). Then you can use Google (or any search engine) to find that faculty member’s university page, his/her individual page, and, most likely, the page of the graduate program(s) in which he/she teaches.
The biggest advantage of doing your search this way is that you are much more likely to find the full range of graduate programs that cover some element of what you want to study. Graduate programs in areas related to the environment are named in many different ways, and, because they are interdisciplinary, they can be found in a range of departments (i.e. in addition to a department such as NRES, you might also find that your area of interest is researched by people in departments of geography, plant science, fish & wildlife ecology, sociology, etc.).
Once you have found the faculty members who research what you want to study, you must begin contacting them. This is extremely intimidating, but for many research based programs, it is an absolute necessity for admission. On some faculty member's lab group pages, you will find specific instructions for how the prospective advisor wants to be approached, and some graduate program web pages will provide suggestions. In most cases, you will be asked to contact faculty via e-mail. In my experience, the most effective e-mail to a faculty member whom you want to enlist as your advisor is one that contains the key elements of
- demonstrating a well-reasoned interest in their research (and reference to previous publications can be good evidence of that),
- briefly discussing why their current projects interest you (especially if they have a section on it on their web page or list their current graduate students and their projects), and
- outlining the skills that you already have and that you would want to develop in graduate school in order to pursue that research area.
Prospective students sometimes tell me that this sounds like a lot of work, and they are correct. This is a TON of work. Graduate school is even more work, though, and research based programs require the kind of self-direction and willingness to dig into a problem that this process requires. If you don't have the skills and perseverence to research potential advisors and the initiative to contact them, you should seriously rethink whether a research based graduate program is the best choice for you. As I discussed in a previous post, there are different types of graduate programs, and it may be that one of the others would better suit your interests. On the other hand, you may find that, in the process of doing all of this advance work, you find the research area that ignites your passion and sets the stage for a great career and life. It's worth some effort to find out, don't you think?