Samuel A. Miller Larry B. Barber Nicholas Workman Albert Richlie 20260114 tabular digital data Reston, Virginia U.S. Geological Survey https://doi.org/10.5066/P14VQQKK This data release presents concentration results obtained using an enzyme-linked immunosorbent assay (ELISA) method for imidacloprid and other neonicotinoid insecticides from samples collected in 30 urban streams across Virginia between August 2024 and July 2025. ELISA analyses were conducted at the U.S. Geological Survey Strategic Laboratory Science Branch in Boulder, Colorado. The ELISA method uses antibodies to detect target compounds and is designed for imidacloprid; however, the antibodies also respond to structurally similar compounds to varying degrees, a phenomenon known as cross-reactivity. Reported cross-reactivity values indicate the relative sensitivity of the assay to other neonicotinoids compared to imidacloprid (100%). For example, clothianidin exhibits 121% cross-reactivity, meaning the assay is slightly more sensitive to clothianidin than imidacloprid, while thiacloprid (13%), acetamiprid (4%), and thiamethoxam (<0.1%) show progressively lower responses. These values are important for interpreting results because the reported concentrations represent the combined response from all compounds that cross-react with the antibody, not just imidacloprid. Quality assurance results, which include blank, replicate, laboratory reagent spikes, and environmental matrix spikes, are provided. Additionally, the dataset provides water-quality measurements recorded at the time of sampling, including water temperature, specific conductance, dissolved oxygen, turbidity, pH, and gage height. These data were used to support the development of an ELISA method to determine imidacloprid and other neonicotinoid insecticide concentrations from surface water samples. 20240808 20250716 ground condition Complete None planned 30 select Virginia streams -80.2991 -76.9922 39.0192 37.1516 USGS Thesaurus pesticide and herbicide contamination surface water quality None Urban Imidacloprid USGS Metadata Identifier USGS:68b97d57d4be0247d9634a6c None Virginia Fairfax County, Virginia City of Roanoke, Virginia Reston, Virginia No access constraints. Please see 'Distribution Information' for details. These data are marked with a Creative Commons Zero v1.0 Universal (CC0-1.0) public domain dedication and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Samuel A Miller USGS - Northeast Region Hydrologist mailing and physical

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Richmond VA 23228 804-592-9813 smiller@usgs.gov Laboratory analyses were run with standard curves, procedural blanks, and reference materials as available and appropriate. The water-quality results were reported directly from the laboratory. If the data files are opened in Excel the reported formatting will be lost. Attribute values were checked for data duplication and omission. 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. No formal positional accuracy tests were conducted. No formal positional accuracy tests were conducted. Gold Standard Diagnostics 20210821 tabular digital data Warminster, PA Gold Standard Diagnostics Gold Standard Diagnostics, 2021, ABRAXIS® Imidacloprid Enzyme-Linked Immunosorbent Assay (ELISA) for determination of Imidacloprid in contaminated samples: Gold Standard Diagnostics User Guide, accessed November 18, 2025, at https://www.goldstandarddiagnostics.us/media/15622/ug-21-039-rev-01-abraxis-imidacloprid-elisa_500800.pdf. https://www.goldstandarddiagnostics.us/media/15622/ug-21-039-rev-01-abraxis-imidacloprid-elisa_500800.pdf Digital and/or Hardcopy 20210821 publication date Gold Standard Diagnostics Enzyme-Linked Immunosorbent Assay (ELISA) for determination of Imidacloprid Samples were collected from 30 predominantly urban streams during low to moderate streamflow conditions. The sampling methods and types of samplers used varied based on site-specific and streamflow conditions to meet project objectives. Water samples were collected from flowing stream water, filtered through a 0.7-micrometer syringe-tip filter into amber glass vials, and stored in a cooler with ice while in the field. Upon return from the field, samples were transferred to a refrigerator before being shipped to the U.S. Geological Survey Strategic Laboratory Science Branch (USGS SLSB) in Boulder, Colorado, for analysis. Individual enzyme-linked immunosorbent assays (ELISA) were conducted using the 96-well microtiter plate format according to manufacturer instructions for the individual kits (Gold Standard Diagnostics, 2021) at the USGS SLSB. The method detection limit was defined as the lowest standard on the calibration curve and was 75 nanograms per liter. Sample results at or below the method detection limit are presented as '<75' in Table1_results.csv. All samples and standards measured by ELISA were analyzed in duplicate and reported as the mean concentration and relative percent difference. Quality assurance samples consisted of negative and positive controls for each kit, laboratory replicates of field samples analyzed using a different kit, field blank samples, field replicate samples, laboratory reagent spike samples, and environmental matrix spike samples. Gold Standard Diagnostics 2025 table1_results.csv Comma Separated Value (CSV) file containing data Producer Defined site_no An official U.S. Geological Survey site number assigned to each sampling site https://waterdata.usgs.gov/nwis Unique strings that are automatically generated station_nm The official U.S. Geological Survey station name for the sampling site https://waterdata.usgs.gov/nwis Unique name describing sampling location date The date of sample collection (MM/DD/YYYY) Producer Defined 8/8/2024 7/16/2025 time The time of sample collection in Coordinated Universal Time (UTC) Producer Defined 11:55 20:00 HH:MM sample_method The U.S. Geological Survey sampling method https://help.waterdata.usgs.gov/code/fixed_parms_query Grab sample (dip) Sampling method code 70 https://help.waterdata.usgs.gov/code/fixed_parms_query Multiple verticals Sampling method code 40 https://help.waterdata.usgs.gov/code/fixed_parms_query Single vertical, depth integrated Sampling method code 30 https://help.waterdata.usgs.gov/code/fixed_parms_query - Not applicable Producer Defined sampler_type The U.S. Geological Survey sampler type https://help.waterdata.usgs.gov/code/fixed_parms_query Grab sample Sampler type code 3070 https://help.waterdata.usgs.gov/code/fixed_parms_query US WBH-96 weighted-bottle sampler Sampler type code 3061 https://help.waterdata.usgs.gov/code/fixed_parms_query US DH-81 with Teflon cap and nozzle Sampler type code 3045 https://help.waterdata.usgs.gov/code/fixed_parms_query - Not applicable Producer defined Open-Mouth Bottle Sampler type code 3071 https://help.waterdata.usgs.gov/code/fixed_parms_query sample_type The type of sample Producer Defined Regular A regular sample Producer defined Replicate A replicate sample Producer defined Blank A blank sample Producer defined concentration Concentration of imidacloprid. Sample results at or below the method detection limit are presented as '<75'. Producer Defined <75 1176 nanograms per liter relative_percent_difference Relative percent difference of concentration result Producer Defined 0 89 percent water_temperature Water temperature Producer Defined - No data Producer Defined 14.0 27.1 degrees Celsius specific_conductance Specific conductance Producer Defined - No data Producer Defined 114 565 microsiemens per centimeter at 25 degrees Celsius dissolved_oxygen Dissolved oxygen Producer Defined - No data Producer Defined 2.90 11.10 milligrams per liter turbidity Turbidity Producer Defined - No data Producer Defined 0.10 31.00 formazin nephelometric units pH pH Producer Defined - No data Producer Defined 5.90 8.50 unitless gage_height Gage height above relative datum Producer Defined - No data Producer Defined -1.49 24.18 feet table2_spike_results.csv Comma Separated Value (CSV) file containing data Producer Defined site_no An official U.S. Geological Survey site number assigned to each sampling site https://waterdata.usgs.gov/nwis NA Not applicable for laboratory reagent spike samples Producer defined Unique strings that are automatically generated station_name The official U.S. Geological Survey station name for the sampling site https://waterdata.usgs.gov/nwis NA Not applicable for laboratory reagent spike samples Producer defined Unique name describing sampling location date The date of sample collection for matrix spike samples and date of analysis for laboratory reagent spike samples (MM/DD/YYYY) Producer Defined 8/8/2024 8/7/2025 time The time of sample collection in Coordinated Universal Time (UTC) Producer Defined NA Not applicable for laboratory reagent spike samples Producer defined 14:35 18:35 sample_type The type of sample Producer Defined matrix_spike A matrix spike added to a regular environmental sample in the laboratory Producer defined lab_reagent_spike A laboratory reagent spike of a known concentration Producer defined expected_concentration The expected concentration of the result Producer Defined 150 600 nanograms per liter measured_concentration The measured concentration of the result Producer Defined 128 701 nanograms per liter percent_recovery The recovery of the spike sample result Producer Defined 82.0 140.7 percent relative_percent_differnence The relative percent difference of the measured concentration duplicate pair Producer Defined 1.3 91.3 percent U.S. Geological Survey - ScienceBase mailing address

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Denver CO 80225 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. Digital Data https://doi.org/10.5066/P14VQQKK None 20260114 Samuel A Miller USGS - Northeast Region Hydrologist mailing and physical

1730 East Parham Road

Richmond VA 23228 804-592-9813 smiller@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999