Streamflow information provided by the U.S. Geological Survey is used in many ways and often the information from any give streamgage is used for not just one of the following but for many of the following purposes:
Water resource appraisal and allocations - how much water is available and how is it being allocated?
For water supply plans
Streamflow information is required to determine how much water is available in different locations so the citizens can make informed decisions about growth and to help assure there is an adequate water supply even during periods of drought. Today, the effects of climate change on the water available could become an issue in certain regions of the nation, and accurate long-term streamflow information is required to determine what if any impacts.
As part of interstate agreements, compacts, and court decrees
Because of growing populations, contaminated supplies, and potentially changing supplies, the amount of water crossing political boundaries has come under much more scrutiny in recent years.
Bridges, roads, culverts
Streamflow information is used for many of our nation's infrastructure designs. It is important to have accurate information because to over design is very costly, but to under design can be even more costly
Most of the nation's reservoirs relay on streamflow information to know how much water to release and when to release it, whether for flood control or for aquatic habitat. Hydropower producers also rely on streamflow information to regulate the amount and timing of releases.
Identifying changes in streamflows due to changes in
Major changes in land use can have significant effects on streamflow, as can even more obvious changes in water use. In the near future it will be the effects of climate change on the amount and timing of streamflow that will get the most attention.
Flood planning and warning
Streamflow information is used by the National Weather Service in making flood forecasts. The streamflow information is used to check the model results and to help calibrate the models. The Federal Emergency Management Agency uses streamflow information in delineating flood prone areas to help protect citizens from building or developing in areas that have a high probability of being flooded.
To help water management agencies do a more efficient job, more are relying on computer models to forecast the amount of water that will be available for different time periods (week, months, seasons). Streamflow information is used to help calibrate the models and to provide verification checks.
Support of water quality sampling
Water quality conditions and trends
Total Maximum Daily Loads (TMDLs)
Streamflow information is required to determine the load, or amount, of a contaminant that is moving past a given point.
Characterizing and evaluating instream conditions
Instream flow requirements
Streamflow information is required to determine the amount and timing of streamflow to assess habitats and to develop instream flow requirements. In addition, many boaters, swimmers, and fishermen use streamflow information to decide if the streamflow is appropriate for them to visit their favorite locations.