The United State Geological Survey is the place to start water research!
It contains a wealth of info about water in the United States, such as national water surveys, current water and stream flow conditions (e.g. floods, droughts, water quality, ground water), science topics, water resource programs. And it links to State USGS offfices throughout the nation, plus browse for state & local info via maps.
Main topics include:
- Streams, lakes, and reservoirs (Science to observe, analyze, and understand the movement and condition of surface water)
- Groundwater, aquifers, and wells (Science to discover and describe the location, condition, and behavior of water in the ground)
- Quality of water resources (Science to monitor and evaluate biological, chemical, and environmental factors affecting water quality)
- International water activities (Ongoing water projects of international interest)
- Floods & droughts (Study the conditions and consequences of water over-abundance or scarcity)
- Water use (Information about how water is used now and in the past)
- Contamination & pollution (Study the existence and results of harmful substances in water, produced by humans and natural processes)
- Methods & Models (Available tools and expertise to conduct water resources science)