Arsenic in Groundwater Wells

Analytical results for arsenic in water samples from 5,023 wells obtained during 1969–2007 across Pennsylvania were compiled and related to other associated groundwater-quality and environmental factors and used to predict the probability of elevated arsenic concentrations, defined as greater than or equal to 4.0 micrograms per liter (µg/L), in groundwater. Arsenic concentrations of 4.0 µg/L or greater (elevated concentrations) were detected in 18 percent of samples across Pennsylvania; 8 percent of samples had concentrations that equaled or exceeded the U.S. Environmental Protection Agency's drinking-water maximum contaminant level of 10.0 µg/L. The highest arsenic concentration was 490.0 µg/L.

Press Release | Report (SIR 2012-5257)

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

• Baseline Streamflow Estimator (BaSE)
  Estimate baseline streamflow for ungaged streams in Pennsylvania
• StreamStats
  Delineate watersheds and estimate streamflow
• NWIS Mapper
  View the locations of sites with USGS water data
• WaterWatch
  Compare current streamflow to historical record
• WaterQualityWatch
  View stream-temperature and water-quality monitoring data
• Groundwater Watch
  Compare current groundwater levels to historical record
• Groundwater Recharge
  Compare aquifer recharge for 197 watersheds
• WaterAlert
  Get condition updates by text message or email

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.

Surface Water

Streamflow, lake, reservoir, and precipitation data

Groundwater

Water levels in wells and other aquifer data

Water Quality

Chemical and biological quality data for surface water and groundwater

Newsroom

• Citizen Cooperation Requested in Lake Erie Yellow Perch Tagging Effort (Mon, 29 Apr 2013 13:00:00 EDT)
• High Arsenic Levels Found in 8 Percent of Groundwater Wells Studied in Pennsylvania (Wed, 17 Apr 2013 9:00:00 EDT)
• Measuring Landscape Disturbance of Gas Exploration in Allegheny and Susquehanna Counties (Mon, 25 Mar 2013 12:03:26 EDT)
• Tool Estimates Streamflow for Pennsylvania Waterways (Fri, 22 Feb 2013 7:51:22 EDT)
• Mining Waste Byproduct Capable of Helping Clean Water (Mon, 17 Dec 2012 13:49:17 EDT)

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

1. Send a text message to WaterNow@usgs.gov containing the USGS Site Number of the gage you want to query
   
2. Send an email message to WaterNow@usgs.gov 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?

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 http://pubs.usgs.gov/gip/106/.