USGS -- Water Resources of the United States
- Information about water resources from the U.S. Geological Survey. Topics include ground water, surface water, water use, water quality, acid rain, toxic substances hydrology.
- http://water.usgs.gov/

Great Lakes Aquatic Habitat Network and Fund
- Provides information and financial support to those working to protect and restore shorelines, lakes, rivers, wetlands, and other aquatic habitats in the Great Lakes Basin. Includes news and grant information.
- http://www.glhabitat.org/

Ground Water Atlas of the United States
- Online USGS publication describes U.S. ground-water resources by region. Covers the 50 states, Puerto Rico, and the U.S. Virgin Islands.
- http://capp.water.usgs.gov/gwa/gwa.html

USGS - Arsenic in ground water of the United States
- Publications, maps, and data on arsenic in U.S. groundwater.
- http://co.water.usgs.gov/trace/arsenic/

Center for Environmental Education and Information
- CEEI documents polluted streams in the United states by publishing on the web all the Clean Water Act 303(d) lists and documentation.
- http://www.wcei.org/