Rivers in Pennsylvania

Allegheny River at Natrona Lock and Dam

Allegheny County, PennsylvaniaNWS NATP1USGS 03049500Moon Township office

Below flood stage
12.50ftStage

Observed Thu, Sep 24, 6:15 PM EDT

Flood stage
21.00 ft
Forecast crest
12.50 ftThu, Sep 24, 8:00 PM EDT
Record crest
32.10 ft1936

Open the live map with the river flood outlook

Flood stages and impacts

CategoryStage
Major flood26.00 ft
Moderate flood24.00 ft
Minor flood21.00 ft
Action17.20 ft
  1. 29.40 ftPennsylvania Railroad main line and sidings affected at Tarentum PA, 3 miles downstream floods.
  2. 21.50 ftThe Natrona Water Company is affected.
  3. 21.30 ftWater begins to back up into the sewers at Braeburn Steel Co.
  4. 21.00 ftLock walls overtopped.
  5. 18.00 ftNavigation suspended, lock out of service.

Flood outlook

Chance of flooding, September to November

CategoryChance
Minor floodingUnder 5%
Moderate floodingUnder 5%
Major floodingUnder 5%

The three-month chances are the River Forecast Centers’ long-range flood outlook, issued September 22, 2026.

Crest history

15 crests on NOAA’s list since 1936.

#DateStage
1March 18, 193632.10 ft
2December 30, 194228.40 ft
3January 22, 195927.60 ft
4June 23, 197227.50 ft
5March 10, 196426.40 ft
6September 18, 200424.20 ft
7January 20, 199623.10 ft
8February 14, 196622.10 ft
9February 17, 197621.80 ft
10March 16, 200721.40 ft
11December 31, 199020.70 ft
12January 7, 200520.00 ft
13February 9, 201918.63 ft
14February 19, 202218.52 ft
15March 24, 200717.84 ft

Most recent crests

  • February 19, 2022: 18.52 ft
  • February 9, 2019: 18.63 ft
  • March 24, 2007: 17.84 ft
  • March 16, 2007: 21.40 ft
  • January 7, 2005: 20.00 ft
  • September 18, 2004: 24.20 ft
  • January 20, 1996: 23.10 ft
  • December 31, 1990: 20.70 ft
  • February 17, 1976: 21.80 ft
  • June 23, 1972: 27.50 ft

Nearby

Upstream, downstream and the gauges around this one.

What this means

Forecasts by the Ohio River Forecast Center. Forecasts are issued routinely year-round. The above river forecast includes future rainfall/snowmelt. Forecast stages may be different if the actual rainfall/snowmelt is different than the forecast rainfall/snowmelt. Stage may be affected by ice.

Sources

Stage, flood stages, impacts and crest history from NOAA’s National Water Prediction Service. Streamflow and the daily record from the U.S. Geological Survey.