U.S. River Conditions for Water Year 2018

This is an animation showing the changing conditions of USGS streamgages for Water Year 2018 (October 1, 2017 to September 30, 2018). The conditions shown range from the driest condition seen at a gage to the wettest. There is also an indicator for gages that are flooding, but it is noted that both USGS gage height and National Weather Service flood stage levels are necessary to determine flooding conditions and were available for 38% of gages at the time this graphic was produced. Only publicly available data from NWISWeb was used and some gages are missing gage height even when they have flow. The animation starts with drier conditions throughout most of the west and east coasts through the end of October; frontal systems bring floods to the northeast from the end of October to November 10; most of the Nation experiences lower than normal flows from early December to early January; in mid-February frontal systems and snowmelt cause high flows in much of the east; from early to mid-April, snowmelt and rainfall cause flooding in Illinois and Indiana; from mid-April to early May, flows in Hawaii increase as Hurricane Lane passes nearby; the Northwest experiences snowmelt flooding from early to mid-May; thunderstorms at the end of May and in early June cause flooding in Western North Carolina and Virginia; in mid-June there was flash flooding in Virginia, West Virginia, and Maryland; at the end of July Montana, Virginia, and Maryland had high flows and flooding; in early September, Hurricane Gordon passed by Florida and Mississippi bring high flows and flooding; and mid- to late September, Hurricane Florence hovered over North Carolina and caused flooding.