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This probabilistic forecast is issued by the Ohio River Forecast Center.
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About this graph
Forecasts for the Allegheny River at Olean are issued routinely year-round.
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Upstream Gauge - at Eldred Upstream Gauge Downstream Gauge Downstream Gauge - at Salamanca
Zoom Level:16
Flood Categories (in feet)
Major Flood Stage: 23
Moderate Flood Stage: 17
Flood Stage: 12
Action Stage: 10
Low Stage (in feet): -9999

Historic Crests
(1) 26.20 ft on 06/23/1972
(2) 23.30 ft on 07/19/1942
(3) 19.50 ft on 03/08/1956
(4) 19.30 ft on 05/29/1946
(5) 18.60 ft on 01/20/1996
Show More Historic Crests

(P): Preliminary values subject to further review.

Recent Crests
(1) 13.33 ft on 02/19/2022
(2) 13.91 ft on 01/14/2018
(3) 14.17 ft on 01/13/2017
(4) 17.74 ft on 12/03/2010
(5) 12.34 ft on 03/11/2009
Show More Recent Crests

(P): Preliminary values subject to further review.

Low Water Records
(1) 0.50 ft on 08/03/1999
(2) 1.00 ft on 09/01/1998
(3) 1.15 ft on 08/10/2016
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Gauge LocationGauge Map Marker
Latitude/Longitude Disclaimer: The gauge location shown in the above map is the approximate location based on the latitude/longitude coordinates provided to the NWS by the gauge owner.
Flood Impacts & Photos Collapse
If you notice any errors in the below information, please contact our Webmaster
25 Extreme flood, extensive residential flooding begins, especially upstream from Union Street bridge. Some evacuations necessary. Serious flooding upstream through Portville. Dikes overwhelmed.
23 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 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 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 Action stage, high flows. No flooding.

Other Real-time and/or Archive Data Sources:

Additional Information Collapse
Potential River Levels - Used to
Potential River Levels
Used to Estimate the Chance of Flooding and the Range of Possible River Levels
10 Day (HEFS) 7 Day (NAEFS) 7 Day (GEFS)
HEFS Ensemble NAEFS Ensemble GEFS Ensemble

Note: Use the official hydrograph at the top of this web page for river levels within the next 48 hours.

See the Product Description Document link for more details on the interpretation of the 3,7 day graphics.

Click individual graphics to enlarge.

Observations courtesy of the town of Olean.
Collaborative Agencies Collapse
The National Weather Service prepares its forecasts and other services in collaboration with agencies like the US Geological Survey, US Bureau of Reclamation, US Army Corps of Engineers, Natural Resource Conservation Service, National Park Service, ALERT Users Group, Bureau of Indian Affairs, and many state and local emergency managers across the country. For details, please click here.
NWS Information
National Weather Service
Buffalo Weather Forecast Office
587 Aero Drive
Buffalo, NY 14225-1405
(716) 565-0204
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Page last modified: 2-Nov-2020 7:30 PM
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