State Water Resources 

• Alaska's Water
• Arizona Department of Water Resources
• Arizona Water Resources Research Center
• California Department of Water Resources
• U.S. Geological Survey, Water Resources of California
• CERES (California)
• Colorado Department of Natural Resources
• Colorado State University - Water Center
• Colorado Water Knowledge
• Colorado Water Resources Research Institute
• Florida Water Facilities Online
• Idaho Ground Water Association
• Johnson County Wastewater (Kansas)
• Kansas Rural Water Association
• Northwest Kansas Goundwater Management District #4, Colby, Kansas
• Kentucky Division of Water
• Maine Department of Environmental Protection, Bureau of Land & Water Quality
• Missouri Dept.of Natural Resources - Div. of Geology and Land Survey - Water Resources Program
• Missouri Freshwater Springs
• Montana Water Center
• Nebraska Water Center / Environmental Programs Unit
• New Mexico State Engineer
• New Mexico Water Resources Research Institute
• North Carolina Water Resources Research Institute
• Oklahoma Water Resources Board
• Powell Consortium. Alliance of seven Water Resources Centers and Institutes (AZ, CA, CO, NM, NV, UT & WY) cooperating on water issues related to the Colorado River and Great Basin.
• South Carolina Department of Natural Resources Climatology
• Texas Environmental Center
• Texas Water Resources Institute
• Utah Water Research Laboratory
• Western Governors' Association
• Western States Water Council
• Wyoming Water Resources Data System

Federal Water Resources

• EPA'S Office of Water
• EPA's Office of Ground Water and Drinking Water
• EPA Office of Wetlands, Oceans and Watersheds
• EPA Science Advisory Board (SAB)
• EPA's Surf Your Watershed
• Hydrologic Information Center - Office of Hydrology, National Weather Service, National Oceanic and Atmospheric Administration, U.S. Dept. of Commerce
• Office of Environmental Protection Agency
• Tennessee Valley Authority
• U.S. Bureau of Reclamation
• USDA Forest Service
• U.S. Geological Survey
• U.S. Geological Survey, National Water-Quality Assessment (NAWQA) Program
• U.S. Geological Survey Real-Time Water Data - Monitor stream levels in the U.S. and watch as floods evolve.
• U.S. Geological Survey - Water Science for Schools
• U.S. National Biological Survey
• Western Water Policy Review Advisory Commission

International Water Resources

• CSIRO Land and Water
• Environment Canada: Freshwater Web Site
• Freshwater Integrated Resource Management with Agents (FIRMA) (UK)
• Groundwater Remediation Project, Environment Canada
• International Boundary and Water Commission
• International Groundwater Modeling Center (IGWMC)
• LakeNet
• Lifewater Canada
• Living Water (Kenya, Central America)
• Middle East Water Information Network
• National Water Research Institute (Canada)
• Water Conservation and Demand Management (UK)
• Water Conservation Research Database (UK)
• University of Western Australia - Centre for Water Research
• Water Resource Systems Research Laboratory
• World Bank

Professional Water Resources

• American Water Resources Association (AWRA)
• American Water Works Association (AWWA)
• CSO News Stormwater and sewer overflow solutions
• Engineering E-journal Search Engine
• Farm*A*Syst/Home*A*Syst Pollution prevention for farms and homes
• Irrigation Association
• National Ground Water Association
• Pipe Association Global
• Software for Ground Water Scientists
• Wasser & Boden (Water & Soil), a German magazine of the Association of Engineers for Water Sciences, Waste Management and Cultivation.
• Water Conditioning and Purification Magazine
• Water Environment Federation

Non-Profit Water Resources

• American Backflow Prevention Association
• AWWA Research Foundation
• Educating Young People About Water
• Freshwater Society
• Healthy Water, Healthy People Education program based at Montana State University
• H.E.L.P. Hudson (River) Environmental Legislation Project
• Lifewater International
• National Library for the Environment
• National Small Flows Clearinghouse (NSFC), West Virginia University
• NSF International - development of standards, product testing and certification services
• River Network Online
• Rural Community Assistance Program - free assistance concerning drinking water supply and wastewater treatment needs
• Small Water Systems Website
• Water Environment Federation
• Water Systems Council - focused on individual wells and other well-based water systems
• Waterlife Foundation
• WaterPartners International - water supply and sanitation needs in developing countries

General Water Resources

• Air and Water Quality (Environment) Directories
• Amazing Environmental Organization WebDirectory
• America's Threatened Streams
• Bottled Water Web
• Cadillac Desert - history and consequences of the stuggle for water in the American West.
• EcoIQ Water & Wastewater
• The EnviroLink
• Encyclopedia of Water Terms
• Geologic Resources
• Hydrogen Peroxide Online
• Long Island Water Corporation
• National Drought Mitigation Center
• National Extension Water Quality Database
• Selected Water Resources Abstracts
• Sewage Net
• Universities Water Information Network (UWIN)
• Water Publications Digest
• Water Quality Topics
• WaterWiser - The Water Efficiency Clearinghouse
• WWF Global Network
• WWW Virtual Library: Environment