Stouder, M.D.W. Finkelstein, K.M. Rosen, J.J. Beaulieu, K.M. 20230809 Excel Spreadsheet and Comma Separated Values (CSV) files Troy, NY U.S. Geological Survey https://doi.org/10.5066/P98P1VV6 Stouder, M.D.W. Gifford, S.R. Gutchess, K.M. Finkelstein, K.M. Johnston, B.D. Beaulieu, K.M. 2025 publication Scientific Investigations Report 2024–5118 N/A U.S. Geological Survey https://doi.org/10.3133/sir20245118 From August 2018 to October 2019, the U.S. Geological Survey collected high-resolution spatial water quality from a total of five shoreline synoptic surveys conducted around the perimeters of Owasco Lake, Seneca Lake, and Skaneateles Lake within the Finger Lakes Region. Water-quality data were collected just below water surface utilizing YSI EXO2 multiparameter sondes and portable nitrate sensors paired with real-time GPS data collection as part of an Advanced HABs Monitoring Program in the Finger Lakes Region. In October 2019, water-quality data collection was paired with discrete phytoplankton grab samples on Owasco Lake and Seneca Lake. Phytoplankton grab samples were collected just below water surface with a peristaltic pump at twelve unique locations on each of the two lakes. The data were collected by the USGS New York Water Science Center, in cooperation with the New York State Department of Environmental Conservation, to document the spatial variability of cyanobacteria and nitrate concentrations and phytoplankton population dynamics as part of a larger effort towards the development of a comprehensive monitoring strategy to establish an advanced water-quality monitoring program in three of the Finger Lakes affected by increased occurrence and prevalence of cyanobacterial harmful algal blooms: Owasco Lake, Seneca Lake, and Skaneateles Lake. 20180823 20190626 20190709 20190710 20191008 20191009 20191010 ground condition Complete None planned -77.038879395069 -76.242370606038 42.96816205618 42.354161318633 USGS Thesaurus surface water quality limnology water temperature turbidity water pH dissolved oxygen oxygen content (water) nutrient content (water) algae algal blooms hazards freshwater (surface) lake ecosystems phytoplankton phycology Common Geographic Areas New York United States None Defined cyanobacteria continuously-measured spatial synoptic specific conductance chlorophyll phycocyanin fluorescent dissolved organic matter (fDOM) nitrate genus species taxonomy taxa division class order family USGS Metadata Identifier USGS:602d6d11d34eb1203114a5cb Geographic Names Information System (GNIS) Owasco Lake Seneca Lake Skaneateles Lake Finger Lakes none Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the source of the information. Users are advised to read the data set's metadata thoroughly to understand appropriate use and data limitations. Director U.S. Geological Survey, New York Water Science Center mailing and physical

425 Jordan Road

Troy NY 12180 USA (518) 285-5695 dc_ny@usgs.gov This study was conducted by the U.S. Geological Survey in cooperation with the New York Department of Environmental Conservation, Division of Water, Bureau of Water Assessment and Management, Lake Monitoring and Assessment Section All water quality data were broadly checked for accuracy; erroneous spikes and outliers were deleted from the data. Phytoplankton data were analyzed by a certified aquatic laboratory (PhycoTech Inc.) that does its own quality assurance and quality control practices. No formal logical accuracy tests were conducted but data were checked for consistencies and numerical errors. Data set 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. No formal positional accuracy tests were conducted No formal positional accuracy tests were conducted Prior to data collection, the internal clocks of portable GPS receivers and all continuous water-quality monitors were synched. Continuous water-quality monitors were mounted to a boat at approximately 0.5-meters below the water surface. GPS receivers collected continuous location data while water-quality instruments were used to measure water nitrate, chlorophyll, fluorescent dissolved organic matter (fDOM), dissolved oxygen, specific conductance, phycocyanin, turbidity, pH, and temperature. All parameter values were monitored in real time by the field crew. The boat was piloted as close to the shore as conditions would allow, ideally within 100 meters, while also maintaining a maximum sustained speed, of approximately 5 miles per hour, at which all monitored parameters remained stable and unaffected by turbulence. Where field crews noticed elevated nitrate concentrations, generally near the confluences of tributaries, or visible algal indicators, boat speeds were lowered and attempts to collect higher resolution data as close to the shore as possible were made. 20191010 All data were downloaded from GPS receivers and water quality instruments. Data were aligned to the nearest corresponding values based on synched, recorded times of collection as provided by each instrument and organized to provide approximately 1-minute data intervals. Where GPS location data was not collected within 15-seconds of water quality data collection, no data were included for that interval. All water quality values are reported raw and were not averaged or smoothed across multiple readings. All data were compiled into one spreadsheet for this data release. Data were broadly checked for accuracy and suspected erroneous spikes and outliers were deleted from the final data set. 20210528 Phytoplankton samples were collected using a peristaltic pump. The sampling boat was anchored in place during sample collection. The tubing intake was suspended approximately 0.5 meters below the water surface and pumped to rinse the tubing with approximately 2 liters of native water prior to sample collection. Phytoplankton samples were pumped directly into 250 mL amber HDPE bottles prior to being immediately preserved with glutaraldehyde, homogenized, then stored on ice or refrigerated prior to shipment to PhycoTech Inc. 20191010 Phytoplankton sample results were compiled by the analyzing laboratory into one spreadsheet and organized for the purposes of this data release. Data were evaluated to ensure consistency in naming conventions and presentation of dates and times. 20210428 1.0E-5 1.0E-5 Decimal degrees North American Datum of 1983 (NAD 83) GRS 1980 6378137.0 298.257222101 ScienceBase U.S. Geological Survey mailing and physical

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Denver Colorado 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 on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. 20250910 Michael Stouder U.S. Geological Survey Physical Scientist mailing and physical

425 Jordan Road

Troy NY 12180 US 518-285-5690 mstouder@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998