National Association of Science Writers (NASW)
http://www.nasw.org/
The National Association of Science Writers was created in 1934 to strengthen and improve science reporting in order to better inform the public. Science reporters and public information officers on science are invited to join the association, which provides contact information of other science reporters, organized regional meetings, quarterly newsletters, and financial sponsorships.

Society of Environmental Journalists (SEJ)
http://www.sej.org/
The Society of Environmental Journalists is a United States-based organization dedicated to advance environmental reporting. It provides a better-educated network of professional journalists and editors who seek to improve public understanding of environmental journalism. For journalists, publications, conferences, and memberships are among SEJ’s efforts to achieve its goals.