Pennsylvania Water Science Center

Sampling bacteria in lake water


Eliza Gross


Lower Susquehanna River Basin, National Water-Quality Assessment Project

(click thumbnail for larger image)
(click thumbnail for larger image)
In fractured bedrock aquifers conditions can exist where contaminants such as bacteria are not filtered out by the soil. Once in the fracture system, little additional filtration takes place. The results of the study showed that bacteria concentrations in wells were higher in areas with high levels of agricultural activity, likely due to the application of manure.

Highlights of Study

  • 146 Domestic Supply wells sampled for bacteria.
  • Bacteria were found in 80% of the wells sampled
  • 70% of the samples were positive for total coliform
  • 25% of the samples were positive for fecal coliform
  • 65% of the samples were positive for fecal streptococcus
  • E. Coli were found in water from 30% of the 88 wells
  • Bacteria were more likely in water from wells in agricultural areas
  • Bacteria were more likely in water from wells in the Ridge and Valley Province
  • E. Coli concentrations were higher in areas underlain by carbonate bedrock
  • Weak relations exist between bacteria concentrations and selected well characteristics and selected water-quality constituents

Report online

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