TidalMapLong Green Creek at Glen Arm, MD Water Level Today
NWS river forecast
| When | Stage | Flow |
|---|
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 01584050 sits on Long Green Creek and reads everything draining 9.4 square miles of the Gunpowder-Patapsco basin. Its datum sits 240 feet above sea level NAVD88. Daily flow has been on record here since 1976, 51 years of it.
Normal flows here
Long Green Creek runs a median of 8.5 cfs at this gauge across 51 years of record. March is the fullest month at a median 12 cfs, and September the leanest at 4.3 cfs. The highest daily mean on record is 458 cfs in 2006, and the lowest is 0.8 cfs in 2002.
| Month | Median flow | Share of annual median |
|---|---|---|
| Jan | 9.9 cfs | 116% |
| Feb | 11 cfs | 129% |
| Mar | 12 cfs | 141% |
| Apr | 12 cfs | 141% |
| May | 9.9 cfs | 116% |
| Jun | 8.2 cfs | 97% |
| Jul | 6.0 cfs | 71% |
| Aug | 5.3 cfs | 62% |
| Sep | 4.3 cfs | 51% |
| Oct | 5.2 cfs | 61% |
| Nov | 6.6 cfs | 78% |
| Dec | 8.6 cfs | 101% |
Medians from the USGS daily-statistics record, 1976 to 2026. A month at 100% is running at its own long-term median.
Flood stages and record crests
Long Green Creek reaches flood stage at this gauge at 7 feet. NWS starts watching it at 4 feet. The highest crest on record is 6.7 feet, in July 1984.
| Category | Gage height |
|---|---|
| Action | 4 ft |
| Minor flooding | 7 ft |
| Moderate flooding | 10 ft |
| Major flooding | 15 ft |
| When | Crest |
|---|---|
| July 1984 | 6.7 ft |
| February 2016 | 6.4 ft |
| November 2006 | 6.4 ft |
| August 1978 | 6.3 ft |
| July 1989 | 6.3 ft |
Flood categories and crest history from the NOAA National Water Prediction Service, gauge GALM2. Stages are gage height, not depth. Not for navigation.
Nearby river gauges
- Little Gunpowder Falls at Laurel Brook, MD
- Whitemarsh Run near Fullerton, MD
- Honeygo Run near White Marsh, MD
- Whitemarsh Run at White Marsh, MD
- Minebank Run near Glen Arm, MD
- Long Quarter Branch at Lutherville, MD
- Winters Run near Benson, MD
- Winters Run near Bel Air, MD
- West Branch Herring Run at Idlewylde, MD
- Moores Run at Radecke Ave at Baltimore, MD
- Plumtree Run near Bel Air, MD
- Wheel Creek near Abingdon, MD
Live streamflow and gage height: USGS gauge 01584050. Percentile context computed against the gauge's period of record. Not for navigation.
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