We track the movement of contaminants from the land surface into and through aquifers and see if these contaminants are in water withdrawn from wells . A lot of work also goes into studying the quality and chemical makeup of our water resources. The USGS has water-quality laboratories where water samples are analyzed. Stream stage is an important concept when analyzing how much water is moving in a stream at any given moment .
Stage is the water level above some arbitrary point in the river and is commonly measured in feet.
If a big storm hits, the river stage could rise to 15 or 20 feet, sometimes very quickly. How high and how fast a river will rise during a storm depends on many things. Most important, of course, is how much rain is falling. The USGS has studied these things at many places across the country for many years, and thus is often able to make predictions about if and where a flood will occur and how bad that flood will be. With the advent of modern computer and satellite technology, the USGS can monitor the stage of many streams almost instantly.