U.S. River Conditions, July to September 2021
This is an animation showing the changing conditions of USGS streamgages from July 1, 2021 to September 30, 2021. The river conditions shown range from the driest condition seen at a gage (red open circles) to the wettest (blue closed circles). A purple outer ring around a gage indicates it is flooding.
In early July, high water levels spread throughout the Midwest while severe to exceptional drought spread in the Southwest. Tropical Storm Elsa brought rain to Florida and New England starting on July 5th and continued through the middle of the month. In the Midwest and Southeast, frontal systems brought rain for over a week in late July. Monsoons brought temporary relief to drought conditions in Arizona and New Mexico, while deepening drought continued in the Northwest. From August 16-20, Tropical Storm Fred brought rain to the Southeast and New England, followed by catastrophic flash flooding in Tennessee. Tropical Storm Henri brought high water to the East Coast in late August. Shortly after, Hurricane Ida impacted the Gulf Coast and New England with flooding. Tropical Storm Nicholas also brought high water to the Gulf Coast while drought in the West continued through the end of September.
Note that both USGS gage height and National Weather Service flood stage levels are necessary to determine flooding conditions and were available for 38% of streamgages at the time this graphic was produced. Only publicly available data from the National Water Information System Website was used and some gages are missing gage height even when they have flow.