Selected pesticide concentrations and trends and drainage basin pesticide use in the Little Arkansas River, south-central Kansas, 1995–2023

This data release contains model inputs and outputs for an investigation of temporal changes of selected Little Arkansas River pesticides by Stone and Klager (2026). Continuous streamflow, specific conductance, and turbidity and discrete atrazine data were collected from two Little Arkansas River study sites (USGS stations 07143672 [L Arkansas R at Hwy 50 NR Halstead, KS] and 07144100 [L Arkansas R NR Sedgwick, KS]) and discrete glyphosate and aminomethylphosphonic acid data were collected from one of the two Little Arkansas River study sites from 1995 to 2023. Pesticide trends during 1996 through 2023 in the herbicides atrazine and glyphosate and the herbicide-associated compound aminomethylphosphonic acid (a glyphosate degradate) were evaluated using the R package seawaveQ. Model input data included daily streamflow, specific conductance, and turbidity data (tables 1–4) and discrete results for atrazine, glyphosate, and aminomethylphosphonic acid concentration (tables 5–8). Model output data (for atrazine at both sites and glyphosate and aminomethylphosphonic acid from one site) included model-predicted concentrations and loads at each site (tables 9–12) as well as the percentage and concentration change in atrazine, glyphosate, and aminomethylphosphonic acid, the trend likelihood, and model parameters (table 13). Previously published annual agricultural pesticide-use (table 14) and land use data (table 15) were used to estimate pesticide use for the two study drainage basins (table 16).