William D. Capurso Michael L. Noll Anthony Chu 20221227 Data Release Coram, NY U.S. Geological Survey https://doi.org/10.5066/P9MJCIAS Anthony Chu Michael L. Noll William D. Capurso 2022 publication Coram, NY US Geological Survey https://doi.org/10.3133/ofr20221119 This geospatial data set contains groundwater level contours, well locations, and associated metadata that characterize the potentiometric surface near the Rondout pressure-tunnel in High Falls, New York during November 5–7, 2019, and January 21–22, 2020. The pressure tunnel was shut down and partially dewatered for 74 days from November 11, 2019, to January 23, 2020, for inspection and repairs. The USGS monitored a network of 31 groundwater wells near High Falls, NY to determine the potentiometric surface of the bedrock aquifer adjacent to the Rondout pressure-tunnel during normal tunnel operations and following a tunnel shutdown of 74 days. Water-level differences between the two measurement periods were used to determine the potential influence of tunnel leakage on the local bedrock aquifer. 2019 2020 ground condition Complete None planned -74.22343004508619 -74.08790384114181 41.88455176459686 41.77063183644499 USGS Thesaurus Water levels Tunnel shutdown USGS Metadata Identifier USGS:63509a90d34e47431c15c8ec Getty Thesaurus of Geographic Names High Falls New York Ulster County none none William D Capurso New York Water Science Center Hydrologic Technician mailing and physical

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Coram NY 11727 US 631-736-0783 wcapurso@usgs.gov Water levels were taken to the nearest hundredth of a foot and rounded to the nearest whole number. Water levels and Measuring Points (MPs) were checked by a third party other than the party that entered the data into the database. Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. Data was collected with a Global Navigation Satellite Systems (GNSS) and/or total station survey techniques. Data was collected using GNSS surveying methods as per Rydlund, Paul H. and Brenda K. Densmore. “Methods of Practice and Guidelines for Using Survey-Grade Global Navigation Satellite Systems (GNSS) to Establish Vertical Datum in the United States Geological Survey. Chapter 1 of Section D, Field Survey Methods, Book 11, Collection and Delineation of Spatial Data.” (2012). In some cases a total station was used to establish measuring point elevations as per Noll, M.L., and Rydlund, P.H., 2020, Procedures and best practices for trigonometric leveling in the U.S. Geological Survey: U.S. Geological Survey Techniques and Methods, book 11, chap. D3, 94 p., https://doi.org/10.3133/tm11D3. Potentiometric surfaces were created from measured water levels in a bedrock-aquifer observation-well-network adjacent to the Rondout Pressure Tunnel during fall of 2019 and winter of 2020 using Natural Neighbor interpolation (Sibson, 1981) which was applied in ArcMap 10.8.1. 2022 Contours were created from the surfaces at fixed (20 ft) intervals using the Contour tool in the Spatial Analyst toolbox. 2022 Experienced analysts then reviewed and modified the contours if, for example, an anomaly or erroneous contour line was detected. In some cases, jagged contours were smoothed using GIS contouring tools. 2022 The modified contours, along with the original measured water levels, were then loaded back into the natural neighbor interpolator and reprocessed. This was done to eliminate any artificial interpolation results caused by the Natural Neighbor tool. Similar methodology was done in "Hydrologic Assessment of the Shallow Groundwater Flow System Beneath the Shinnecock Nation Tribal Lands, Suffolk County, New York" (Noll and others, 2016). 2022 This iterative process was continued until experienced analysts were satisfied with the results and no rules of hydrologic contouring were violated. 2022 Water-level measurements collected during the winter of 2020 were subtracted from the measurements made in the fall of 2019 to determine the effect of potential tunnel leakage on the bedrock aquifer adjacent to the Rondout Pressure Tunnel. 2022 Universal Transverse Mercator 18N 0.9996 -75.0 0.0 500000.0 0.0 coordinate pair 198.3 49.2 Meters D_North_American_1983 NAD_1983 6378137.0 298.257222101 North American Vertical Datum of 1988 1 feet Attribute values Well_Network This shapefile contains the water level information used for this study. Measured values FID A value that uniquely identifies a record or feature. System generated 0 30 Record number. Shape Geometry type of record or feature. System generated Point Shape of record is a point. System generated NWIS_Site NWIS site name. Producer defined NWIS site name. NWISNumber 15 digit NWIS site number. Producer defined 15 digit NWIS site number. Fall2019WL Measured water level taken in the fall of 2019, in feet above NAVD1988. U 135 was not measured, as indicated by "Not sampled" attribute. Water levels were rounded to the nearest foot. Producer defined 78 346 Feet, above NAVD1988 Wint2020WL Measured water level taken in the winter of 2020, in feet above NAVD1988. Water levels were rounded to the nearest foot. Producer defined 79 349 Feet, above NAVD1988 ChangeWL Difference between water levels. (Calculation: [Wint2020WL] - [Fall2019WL]) Producer defined -77 22 Feet Lat The latitude in decimal degrees of the associated point. Producer defined 41.796286 41.852338 Decimal degrees Long The longitude in decimal degrees of the associated point. Producer defined -74.188802 -74.108284 Decimal degrees Fall2019_WL_Contours This shapefile contains the water level contours for the measurements taken in the fall of 2019. Measured values FID A value that uniquely identifies a record or feature. System generated 0 68 Record number. Shape Geometry type of record or feature. System generated Polyline Shape of record is a polyline. System generated Contour_ft Contour line elevation, in feet above NAVD1988. Producer defined 80 780 Feet, above NAVD1988 DashedLine Indicates whether the line is dashed, and inferred. Producer defined Yes = line segment is inferred; No = line segment based on point data. Shape_Leng Shape length of contour line. System generated 1245.707086 24957.507681 Meters Winter2020_WL_Contours This shapefile contains the water level contours for the measurements taken in the winter of 2020. Measured values FID A value that uniquely identifies a record or feature. System generated 0 66 Record number. Shape Geometry type of record or feature. System generated Polyline Shape of record is a polyline. System generated Contour_ft Contour line elevation, in feet above NAVD1988. Producer defined 80 780 Feet, above NAVD1988 DashedLine Indicates whether the line is dashed, and inferred. Producer defined Yes = line segment is inferred; No = line segment based on point data. Shape_Leng Shape length of contour line. System generated 1101.304476 17804.91982 Meters ScienceBase U.S. Geological Survey mailing and physical

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Denver CO 80225 USA 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Not for navigational use. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 20221227 William Capurso The United States Geologic Survey Hydrologic Technician mailing and physical

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Coram NY 11727 US 631-736-0783 wcapurso@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998