Difficult Run near Great Falls, VA Water Level Today

NWS river forecast

Forecast from the NOAA National Water Prediction Service. Issued a few times a day and only while a forecast is active. Not for navigation.

Last 30 days

About this gauge

USGS gauge 01646000 sits on Difficult Run and reads everything draining 58 square miles of the Middle Potomac-Catoctin basin. Its datum sits 151 feet above sea level NAVD88. Daily flow has been on record here since 1935, 91 years of it.

Where this gauge sits in the drainage

One gauged site sits upstream of here. The closest is Difficult Run above Fox Lake near Fairfax, VA, reading 5.5 square miles. This gauge adds the 52 square miles that drain in between. Downstream the next reading comes from Potomac River near Wash, Dc Little Falls Pump Sta at 11,560 square miles, so what passes this gauge is about 0% of the water measured there.

Normal flows here

Difficult Run runs a median of 37 cfs at this gauge across 91 years of record. March is the fullest month at a median 60 cfs, and September the leanest at 18 cfs. The highest daily mean on record is 25,000 cfs in 1972, and the lowest is 0.1 cfs in 1966.

Medians from the USGS daily-statistics record, 1935 to 2026. A month at 100% is running at its own long-term median.

Flood stages and record crests

Difficult Run reaches flood stage at this gauge at 11 feet. NWS starts watching it at 9 feet. The highest crest on record is 21.4 feet, in June 1972.

Flood categories and crest history from the NOAA National Water Prediction Service, gauge GFLV2. Stages are gage height, not depth. Not for navigation.