Environmental Indicators Gateway
http://www.epa.gov/indicators/

The Environmental Indicators Gateway features information on EPA’s environmental indicator projects. These projects provide information on environmental conditions and trends over a range of geographic scales and time periods. The Gateway provides summaries of the indicator projects and links to the related reports and Web sites developed by each project. You can search these summaries by geographic location, keyword, and topic. This has been added to Reference Resources Subject Tracer™ Information Blog. This has been added to the tools section of Research Resources Subject Tracer™ Information Blog.