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Peak Streamflow for Pennsylvania

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[!] Over the next year, the USGS Pennsylvania Water Science Center will be updating the geodetic vertical elevation (gage datum) for many locations. Click HERE for additional information including a current list of streamgages with upcoming datum changes. This update in gage datum does not affect the location of the streamgage, nor the observed local gage height or discharge recorded at the streamgage.

[!] ICE EFFECTS ON STREAMFLOW -- During cold weather, stage and discharge values may be affected by ice at some streamgages. Streamgages experiencing ice conditions will have the discharge record temporarily disabled to prevent the display of erroneous discharge values. Display of discharge record will resume when it is determined that ice conditions are no longer present. Adjustment of data affected by ice can only be done after detailed analysis.

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Output formats help Codes help Parameter help

This section provides for the display of annual peak streamflow values for both continuous and partial-record gaging stations. Annual peak flow values are the maximum instantaneous streamflow values recorded at a particular site for the entire water year from October 1 to September 30.

A note of caution that the annual peak flow value may not occur at the same time the maximum water level occurs due to conditions such as backwater, tidal fluctuations, etc.


The following codes are used to indicate special conditions that affect how the peak streamflow value may be interpreted

Code Meaning
1Discharge is a Maximum Daily Average
2Discharge is an Estimate
3Discharge affected by Dam Failure
4Discharge less than indicated value which is Minimum Recordable Discharge at this site
5Discharge affected to unknown degree by Regulation or Diversion
6Discharge affected by Regulation or Diversion
7Discharge is an Historic Peak
8Discharge actually greater than indicated value
9Discharge due to Snowmelt, Hurricane, Ice-Jam or Debris Dam breakup
AYear of occurrence is unknown or not exact
BdDay of occurrence is unknown or not exact
BmMonth of occurrence is unknown or not exact
CAll or part of the record affected by Urbanization, Mining, Agricultural changes, Channelization, or other
FPeak supplied by another agency
OOpportunistic value not from systematic data collection

Peak flow data for gaging stations can be selected as follows:
  1. Start at the peak streamflow search page
  2. Specify one or more search criteria, such as "Drainage Area".
    • The definition of each of these search criteria can be seen by clicking on the Help next to each option.
  3. Click submit to proceed further with the search.
    • The ability to set specifications according to the selected search criteria is given on the next page.
    • The next step is to decide upon how your results should be displayed.
    • You can select how the results are grouped and sorted by clicking on the appropriate dot.
    • The data period allows for a specific time frame of data retrieval for the stations peaks.
    • The output format are different computer file formats which allow for easy input into certain software packages, such as a spreadsheet.
  4. Click submit once your specific criteria are set.
  5. A list of all stations that have peak streamflow values for the criteria you set are then provided in the output format you selected.


The following codes are used to indicate special conditions that affect how the peak gage height value may be interpreted

Code Meaning
1Gage height affected by backwater
2Gage height not the maximum for the year
3Gage height at different site and(or) datum
4Gage height below minimum recordable elevation
5Gage height is an estimate
6Gage datum changed during this year
7Debris, mud, or hyper-concentrated flow
8Gage height tidally affected
BmMonth of occurrence is unknown or not exact
BdDay of occurrence is unknown or not exact
FPeak supplied by another agency