My recommendation is to first pursue an experience in enviromental toxiology before deciding to invest in additional education.
I recommend you look to government Jobs at both national and local Levels, if in the US, locally look to your local water works department as well as local and state Level Departments of Environmental Conservation. At national Level look at the US Fish and Wildlife and US Dept of Agriculture,, i'm not sure about the EPA. Also check local departments of health. Check out NOAA too.
On the industry side, perhaps make some bridges to Agriculture Indusrty (Dave can comment here) and Oil industry as well.
Do alot of Networking - you can even leverage Jobs/opps at Schools that do Research in that area and have specific programs as well.
A key question is what do you want to do exactly? but that's for you to figure out.