Susquehanna River level at Harrisburg
Pennsylvania · Flood watch
Measured at USGS 01570500 — Susquehanna River at Harrisburg, PA · NWS forecast point HARP1
Reading taken · as of 1 hour ago
Running far above normal for the date
At 17,900 CFS, this gauge is running 245% of normal for mid-September — above the 7,320 CFS median USGS has recorded for this date across 135 years of record (1891–2026).
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Flood stages at Harrisburg
National Weather Service categories for gauge HARP1, WFO CTP. Impact wording is the NWS's own, verbatim.
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Major flood 23.0 ft
- 23.0 ft Evacuations are necessary in the Shipoke area of Harrisburg. Listen to local emergency officials for specific details. The water level reaches the corner of Kelker and Front Streets. Delaware Street, Geiger Street and Maclay Streets may also be impacted.
- 24.0 ft The residential section of Front and Second Streets in Harrisburg flood at this level. Cameron Street in Harrisburg floods due to backwater from Paxton Creek.
- 26.0 ft FEMA 2% Annual Chance Flood Level (50-year flood). Flood waters begin to reach the Walnut Street Bridge. Green and Vaughn Streets flood.
- 28.0 ft Widespread flooding occurs in the residential sections of Front and Second Streets and in the Shipoke area of Harrisburg. Flooding reaches Italian Lake Park in Harrisburg.
- 29.0 ft FEMA 1% Annual Chance Flood Level (100-year flood). Flood waters begin to reach the Market Street Bridge.
- 30.0 ft Widespread flooding occurs on both banks.
- 32.0 ft Widespread flooding occurs on both banks. The square and central business district in Harrisburg begin to be affected.
- 33.3 ft Flood of record from Hurricane Agnes in 1972.
- 35.0 ft Flood waters begin to reach the Harvey Taylor Bridge.
- 37.0 ft FEMA 0.2% Annual Chance Flood Level (500 year flood).
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Moderate flood 20.0 ft
- 20.0 ft Riverfront Park in Harrisburg begins to flood.
- 20.5 ft FEMA 10% Annual Chance Flood Level (10-year flood).
- 21.0 ft Homes on both banks are affected by high water. This is the approximate level of Routes 11 and 15, upstream of the Market Street Bridge. Flood waters begin to reach South Main Street in Marysville.
- 22.5 ft US 22/322 in the vicinity of the Dauphin Narrows is impacted by flood waters.
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Minor flood 17.0 ft
- 17.0 ft Basements of residences and businesses on both banks flood. The parking lot on City Island begins to take on water.
- 19.0 ft A number of homes in West Fairview, Dauphin, and Harrisburg flood. Flood waters begin to reach Front Street in East Pennsboro Township in Cumberland County.
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Action 11.0 ft
- 11.0 ft Recreational use of City Island begins to be curtailed. River interests are encouraged to monitor conditions.
- 13.0 ft The recreation area on City Island is evacuated. River interests are encouraged to monitor conditions.
- 15.0 ft The recreation area of City Island is evacuated. River interests are encouraged to monitor conditions.
- Right now 4.13 ft
NWS forecast: 4.10 ft by .
Flow history at Harrisburg
Daily values from USGS 01570500, updated every 15 to 60 minutes; NWS forecast for HARP1 reissued through the day. Provisional.
Highest crests on record at Harrisburg
12 on record
| Stage | Flow | Date |
|---|---|---|
| 33.27 ft | 1,020,000 CFS | Jun 24, 1972 |
| 29.23 ft | 740,000 CFS | Mar 19, 1936 |
| 26.80 ft | 654,000 CFS | Jun 2, 1889 |
| 25.70 ft | 613,000 CFS | May 22, 1894 |
| 25.17 ft | 589,800 CFS | Sep 9, 2011 |
| 25.08 ft | — | Jan 20, 1996 |
| 24.66 ft | 568,000 CFS | Jan 21, 1996 |
| 24.40 ft | — | Sep 19, 2004 |
| 23.81 ft | — | Sep 27, 1975 |
| 21.80 ft | — | May 29, 1946 |
Crests published by the National Weather Service.
About Susquehanna River at Harrisburg
The Susquehanna at Harrisburg drains about 24,000 square miles before it reaches the city, which is why this gauge behaves nothing like a headwater. Rain that fell two days ago in the Chemung or the West Branch is what shows up here, so the river can be rising in Harrisburg under a clear sky. The lag is the whole reason the NWS forecast on this page is worth more than the current number.
It is the most-watched flood gauge in Pennsylvania because of what sits behind the levees: City Island, Shipoke, the Capitol Complex approach roads and the low-lying blocks along Front Street. Winter adds a second failure mode the flow number cannot see, when an ice jam backs water up far faster than the discharge would suggest. The crest table below lists what the river has actually done here, which is a better guide than any percentage.
Susquehanna River at Harrisburg — common questions
5 questions
Why is the Susquehanna rising at Harrisburg when it is not raining here?
Because almost none of the water on this page fell in Harrisburg. The gauge sits near the bottom of a 24,000-square-mile basin reaching into New York, so the rain that drives a rise here landed one to three days ago and several hundred miles upstream. That travel time is what makes the National Weather Service forecast above useful: it already accounts for water that is on its way and has not arrived.
Does this gauge see ice jams?
Not directly, and that is the limitation worth knowing. Discharge measures how much water is moving; an ice jam is a blockage that raises the stage far above what that volume would normally produce, and it can do it in under an hour. In a hard freeze followed by a thaw, watch the gage height and the NWS statements rather than the flow figure.
What is flood stage at Harrisburg?
The National Weather Service sets minor flood stage at this gauge at 17.0 ft, moderate at 20.0 ft, and major at 23.0 ft. Action stage — the level at which agencies begin preparing — is 11.0 ft. The ladder on this page shows each threshold against the current reading, with the NWS's own impact statements at each level.
Is Susquehanna River at Harrisburg high or low for this time of year?
The USGS median flow for mid-September here is 7,320 CFS, from 135 years of record (1891–2026). Today is 245% of it. The comparison is what makes the raw number mean anything: the same reading is a drought on one river and a flood on another.
How often does this reading update?
USGS transmits from gauge 01570500 every 15 to 60 minutes, and the National Weather Service reissues the flood forecast for HARP1 a few times a day — more often when the river is rising. This page refreshes from both when you open it. The timestamp is in the gauge's local time.