Water Resources Investigations Report 96-4319 "Evaluation of selected wells in Pennsylvanias observation-well program as of 1993 " by R.W. Conger       In 1993, the U.S. Geological Survey operated 62 observation wells in 60 of Pennsylvania's 67 counties in cooperation with the Pennsylvania Department of Environmental Resources. These wells attempt to monitor an aerial extent of 45,000 square miles and penetrate 39 geologic formations or water-bearing units of 14 physiographic provinces. Some wells were drilled specifically for the observation-well program, some were drilled for other U.S. Geological Survey projects, and some were drilled for other purposes and were no longer used. Approximately 3 percent of the network wells have less than 5 years of record, 5 percent have 5 to 15 years of record, and 92 percent have greater than 15 years of record.       The older the observation well, the greater the possibility of water levels being affected by physical deterioration of the borehole. Therefore, it is necessary to periodically conduct a series of physical, chemical, and hydraulic tests to determine changes in the physical condition of the well and local land-use practices that may affect water-level response.       Nineteen wells were selected for evaluation on the basis of past questionable water-level responses. These wells were evaluated for functionality by analyzing historical water-level fluctuations, geophysical logs, single-well aquifer tests, and water-quality analyses. These parameters indicated that well Je-23 (Jefferson County) is affected by coal-mine pumpage, well Bt-311 (Butler County) is periodically affected by strip mine activities, well Gr-118 (Greene County) and Mc-110 (McKean County exhibit unexplained fluctuations not desirable for an observation well, and 15 wells show no obvious problems or degradation that would affect their functionality to monitor natural water-level fluctuations. Return to the Water Resources of Pennsylvania Home Page or go directly to: The URL for this page is http://pa.water.usgs.gov /abstracts/wrir_96-4319.html Please note our privacy statement and disclaimer Accessibility Answers to many common questions can be found on our Frequently Asked Questions (FAQ) page. Please direct content comments or questions to: Information Specialist U.S. Geological Survey 215 Limekiln Road New Cumberland, PA 17070-2424 Phone: (717) 730-6916 FAX: (717) 730-6997 Email: is_pa@usgs.gov or contact: Director, USGS Pennsylvania Water Science Center U.S. Geological Survey 215 Limekiln Road New Cumberland, PA 17070-2424 Phone: (717) 730-6960 FAX: (717) 730-6997 Email: dc_pa@usgs.gov Please direct web related comments to webmaster@pa.water.usgs.gov vaww50