Complex sentence: Record discharge rates were observed at 25 gauging stations, and 27 stations along rivers were at least 100 year events, setting records along the Potomac and Monongahela rivers, among several others.
Split into simpler sentences: Record discharge rates were observed at 25 gauging stations. A total of 27 stations along rivers were at least 100 year events, setting records along the Potomac and Monongahela rivers, among several others.