Internships in American Government
There are more internship opportunities in American government than can possibly be listed. Some are paid, many are not. Internships with national or state agencies are often paid, often quite well (New York agencies can pay $14 an hour). Political internships with elected officials are usually not.
State and Local Governments
Less glamorous, more substantive, less expensive?
State Governors Internship programs- most state governors have internship programs. Below are some links, but if you google state governor internship, you will find one in your state.
City Mayoral Internship Programs - Most big city mayors have official internship programs. Here are a few, you can google Atlanta, Boston, Portland at your leisure.
State and Cities Agency Internship Programs States and cities have a wide variety of internships. Google the name of the state, internship program and you will find options.
Lobbying/Public Affairs/Government Relations
If you are interested in working as a lobbyist for public, nonprofit, or private interests, there are countless opportunities at the national and state level. Google the name of the interest and government relations or public affairs or lobby and you will find many organizations that you could potentially intern for.
-American League of Lobbyists (ALL) http://www.alldc.org/
-Public Affairs Council (http://pac.org/jobs)
-Women in Government Relations (http://www.wgr.org/)
-State Government Affairs Council (http://www.sgac.org/)
Here are a list of different job posting sites. Some are DC specific, but many have jobs listed across the country. LOTS of good campaign jobs and internships.
http://publicaffairsjobs.blogspot.com/ - Typically updated with new postings every day. Not environmental specific, but there's typically a few environmental jobs posted every week.
http://www.opajobs.com/index.php - Public policy and Congressional job postings.
There's also a few job databases that require a paid subscription. I haven't used them personally, but have heard that they are very useful, and that some organizations will post listings to them if they are looking for more serious candidates.:
https://groups.google.com/forum/#!forum/jobsthatareleft - Jobsthatareleft - Primarily campaign-oriented jobs for various progressive candidates and organizations
https://groups.google.com/forum/#!forum/noi-jobs - New Organizing Institute - Similar to jobs that are left, primarily campaign jobs with a progressive slant.
http://orise.orau.gov/science-education/internships-scholarships-fellowships/recent-graduates.aspx - Fellowships with the EPA, CDC, DHHS, FDA and others. All are paid, usually last 1 yr with the option to renew for longer.
http://www.ecojobs.com/index.php - Environmental-specific job listing site. I've found it's easiest to sort by geographic area.
https://docs.google.com/spreadsheet/ccc?key=0AuwBTPUVhNwqdHJRWnRGNTRBeWRtcmhtSloxcTNoY0E&usp=sharing#gid=0 - Large listing of different career resources for environmental jobs.