Green River at Mammoth Cave, KY 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 03309000 sits on the Green River and reads everything draining 2,020 square miles of the Upper Green basin. Only 1,539 square miles of that contributes flow in a normal year; the rest is closed basin that does not drain to the river. Its datum sits 409 feet above sea level NAVD88. Daily flow has been on record here since 1938, 25 years of it.

Where this gauge sits in the drainage

One gauged site sits upstream of here. The closest is Green River at Munfordville, KY, reading 1,673 square miles. This gauge adds the 347 square miles that drain in between. Downstream the next reading comes from Green River at Hwy 259 at Brownsville, KY at 2,762 square miles, so what passes this gauge is about 73% of the water measured there. Water passing here goes on to Green River at Lock 4 at Woodbury, KY.

Normal flows here

The Green River runs a median of 1,130 cfs at this gauge across 25 years of record. February is the fullest month at a median 4,650 cfs, and October the leanest at 302 cfs. The highest daily mean on record is 55,700 cfs in 2025, and the lowest is 86 cfs in 2006.

Medians from the USGS daily-statistics record, 1938 to 2026. A month at 100% is running at its own long-term median.

Flood stages and record crests

The Green River reaches flood stage at this gauge at 32 feet. NWS starts watching it at 20 feet. The highest crest on record is 59.7 feet, in April 2025.

Flood categories and crest history from the NOAA National Water Prediction Service, gauge MMCK2. Stages are gage height, not depth. Not for navigation.