Water School

The United States Geological Survey (USGS) is a federal scientific agency that works in biology, geography, geology and hydrology. USGS is the nation’s primary civilian mapping agency. The agency also monitors streams and other bodies of water across the country for flow and depth. Among its other activities, USGS also monitors earthquakes and volcanic activity.The USGS web site may be found by clicking here.

A measure of water’s alkalinity or acidity is called pH. Water with a pH of 7 is neutral; lower pH levels indicate increasing acidity and higher pH levels indicate increasingly basic solutions.

A 500-year flood is a high streamflow that overflows the natural or artificial banks of a waterway and has a two-tenths of 1% chance of occurring in any given year.

A 50-year flood is a high streamflow that overflows the natural or artificial banks of a waterway and has a two percent chance of occurring in any given year.

A 10-year flood is a high streamflow that overflows the natural or artificial banks of a waterway and has a 10% chance of occurring in any given year.

Datum is the basis for relating a river's stage to mean sea level. (datum + stage = elevation in feet above mean sea level)