Ground-water age dating in community wells in Oswego County, New York

Open-File Report 2001-232
Prepared in cooperation with the Oswego County Department of Health



Officials in Oswego County, in north-central New York, have been concerned about potential contamination of community wells. Many of these wells are completed in unconfined glacial sand-and-gravel aquifers, although some are finished in till or in the underlying fractured and jointed bedrock of Late Ordovician and Early Silurian ages. Local shallow ground-water flow is affected by the orientation and hydraulic characteristics of the local topography and surficial sediments, whereas deeper regional flow is toward Lake Ontario. Concentrations of chlorofluorocarbons and tritium in water samples from 28 wells in the county were measured in 1999 for ground-water-age dating; results yield recharge dates ranging from about 1955 to 1994.

The presence of water older than about 15 years in the sand-and-gravel aquifers differs from previous concepts of recharge sources and ground-water movement that were based on numerical modeling of ground-water flow. Young ground water (1 to 5 years old) probably represents recharge from recent precipitation and seepage from streams, whereas the oldest ground water (more than 40 years old) probably is derived from the fractured bedrock that underlies the glacial sediments or has moved along long flow paths in unconsolidated deposits, or through poorly permeable material. Some sand-and-gravel aquifers in Oswego County contain mixtures of old and young water. Wellhead-protection efforts need to focus on protection of the quality of young water in the sand-and-gravel aquifers because young water is more likely to be contaminated than old water.

Suggested Citation

Komor, S.C., 2002, Ground-water age dating in community wells in Oswego County, New York: U.S. Geological Survey Open-File Report 01–232, 16 p.,

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Hydrogeology
  • Field and laboratory methods
  • Ground-water-age dating
  • Conclusions
  • References Cited

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Ground-water age dating in community wells in Oswego County, New York
Series title Open-File Report
Series number 2001-232
DOI 10.3133/ofr2001232
Year Published 2001
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) New York Water Science Center
Description iv, 16 p.
Online Only (Y/N) Y
Additional Online Files (Y/N) N
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