Data on Midwest stream diatom and stressors, 2013

The objective of this study was to assess the comparative influence of multiple stressors on benthic diatoms at 98 sites that spanned a range of stressors that occurred in an agricultural dominated region in the upper Midwest, USA. The primary stressors of interest included: nutrients, herbicides and fungicides, sediment, and streamflow; though the influence of physical habitat was incorporated in the assessment. The study area covered portions of 12 states (600,000 km2), with agriculture the dominate land use. The 98 sites used in this study consisted of 49 randomly selected EPA National Rivers and Streams Assessment sites combined with 49 targeted USGS sites. Thirty-seven of the targeted sites were selected to fill in the agricultural land use gradient that was defined by a combination of the percentage of row crop agriculture and the toxicity-weighted pesticide use (TWU) within the basin. The remaining sites were located at reference and urban settings. Nutrient, pesticide, and suspended sediment samples were collected weekly over a 6-week period from July to early August, 2013, with benthic algae collected and stream habitat quantified at the end of the 6-week period. Streamflow was measured continuously using USGS streamflow gaging stations and pressure transducers at non-gaged sites; water temperature was measured continuously using Hobo sensors.