Major Flood
23 ft
Current Water Level
Gage Height
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Streamflow
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Last Reading
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FLOOD STAGES
Know the flood categories.
Flood stages defined by the National Weather Service. Gage height data from USGS Water Resources.
Moderate Flood
17 ft
Minor Flood
12 ft
Action Stage
10 ft
What Floods at Each Level
25 ft
Extreme flood, extensive residential flooding begins, especially upstream from Union Street bridge. Some evacuations necessary. Serious flooding upstream through Portville. Dikes overwhelmed.
23 ft
Major flood, protective dikes begin to be topped. Some roadway flooding in residential areas of city begins, especially upstream. Serious flooding in areas unprotected by dikes including portions of Portville.
17 ft
Moderate flood, water affects Riverview School of Aviation, 1.5 miles upstream of Union Street bridge. Local flooding occurs in areas unprotected by dikes including portions of Portville upstream.
12 ft
Flood stage, flooding possible on Union Street in Allegany and East Riverside Drive 1 to 3 miles upstream of Olean. Some farm lands along the river are also impacted.
10 ft
Action stage, high flows. No flooding.
Impact statements from the National Weather Service, describing what typically happens at each water level.
7-Day Water Level Chart
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Historic Crests
| Date | Stage | Flow |
|---|---|---|
| Jun 22, 1972 | 26.2 ft | 60,000 cfs |
| Jul 18, 1942 | 23.3 ft | 44,000 cfs |
| Mar 7, 1956 | 19.5 ft | 30,700 cfs |
About This Gauge
USGS Site
NWS LID
OLNN6
River
Allegheny River
County
Cattaraugus, NY
Coordinates
42.0722°N, 78.4519°W
Get Flood Alerts for Allegheny River
StormCast monitors this gauge and sends a push notification to your phone when the water level crosses into a new flood category — even at 3 AM.
Frequently Asked Questions
What is the current water level of Allegheny River at Olean?
The Allegheny River at Olean gauge is maintained by USGS (site 03010820) and reports water levels every 15 minutes. Visit this page to see the latest reading updated live, or download StormCast to get push alerts when levels rise.
What is flood stage for Allegheny River at Olean?
The NWS-defined flood stage for Allegheny River at Olean is 12 feet. Action stage begins at 10 feet. Moderate flooding starts at 17 feet, and major flooding at 23 feet.
How do I get alerts when Allegheny River rises?
Download StormCast free on Google Play, go to River Gauges, and add Allegheny River at Olean to your watchlist. StormCast will send a push notification to your phone whenever the water level crosses into a new NWS flood category.
Where is the Allegheny River at Olean gauge located?
The gauge is located in Cattaraugus County, New York at coordinates 42.0722°N, 78.4519°W. USGS site number: 03010820. Data is provided by the U.S. Geological Survey and the National Weather Service.
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Source & Notes
Data provided by: USACE Pittsburgh, USGS & Olean, Observations courtesy of U.S. Geological Survey
- Stage may be affected by ice during winter months.