Pennsylvania Water Science Center


USGS Waterwatch:
Maps of Current Conditions

Pennsylvania Streamstats

Delineate watersheds and estimate streamflow

National Water Information System (NWIS)

View current and historical streamflow, groundwater level, and water-quality data for Pennsylvania

Real-time data

Historical data


Water Resources of Pennsylvania

Highlighted Publications
Science Feature

Conowingo DamConowingo Dam Above 90 Percent Capacity For Sediment Storage

The Conowingo Dam on the Susquehanna River is at about 92 percent capacity for sediment storage.

Since the dam’s construction in 1929, sediment and nutrients have been building up behind it, being released periodically downriver and into the Chesapeake Bay, especially during high flow events. As the reservoir nears full capacity it has begun to lose its phosphorus and sediment-trapping ability, with increasing amounts going into the Bay.

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The Pennsylvania Baseline Streamflow Estimator (BaSE)


  • Estimate baseline streamflow (minimally altered by regulation, diversion, or mining, and other anthropogenic activities) for ungaged streams in Pennsylvania
  • Generate text file of daily mean streamflow for the ungaged site for the period 1960 to 2008
  • Create a report that includes streamflow data, exceedance probabilities, basin characteristics, and hydrographs for the ungaged site

Find out more

Hydrologic Toolbox
The USGS Pennsylvania Water Science Center is your direct link to all kinds of water-resource information. Data collection and interpretive studies are done in cooperation with various local, State, and Federal agencies.
Hydrologic Monitoring Networks

Surface waterSurface Water

Streamflow, lake, reservoir, and precipitation data

Groundwater Groundwater

Water levels in wells and other aquifer data

Water quality Water Quality

Chemical and biological quality data for surface water and groundwater

Of Interest...

alert iconOn-demand, current conditions for water data directly to your mobile phone or email. 2 ways to get started:

  1. Send a text message to containing the USGS Site Number of the gage you want to query
  2. Send an email message to where either the Subject or the first line of the message contains the USGS Site Number of the gage you want to query

Visit WaterNow for more details

Just What Is a 100-Year Flood Anyway?

USGS flood poster

Almost everyone has heard the term "100-year flood", but not everyone knows what it really means. A common question is, "we just had a 100-year flood a few years ago, why are we having another one so soon?" The USGS Office of Surface Water has released a poster that explains the concept, probabilistic nature, and inherent uncertainties of a 100-year flood. The poster, entitled "100-Year Flood—It's All About Chance," can be found at

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