Average E. coli Concentrations at Sampling Sites in June of 2020

The month of June was selected based on Somviz results to represent the effects from activites during the pre-planting season. The spatial distribution and magnitude of average total E. coli concentrations at specific sampling sites are shown using proportional symbols. The basemap is a choropleth map showing the distribution of total swine animal units per square mile within each watershed. This map answers two questions:

  1. What specific locations in Iowa experience the highest average concentrations of E. coli in June?
  2. Do these locations with high concentrations correlate to the spatial distribution of swine densities in Iowa watersheds?

In June the locations having the highest average concentration of E. coli are located on the eastern edge and near the center of the state. The location near the center of the state sits directly south of a watershed unit with high swine density. This may indcate that byproducts and waste originating in this watershed, are flowing down and accumulating at this specific site. The sites with high concentrations on the eastern edge of the state are stacked on top of one another, following close to where the Mississippi river is located. These sites may be showing increased contamination from areas upstream of Iowa, in Minnesota or Wisconsin. This hypothesis could be further explored by extending the study area.