In 2014, EPA documented the relative lack of nutrient data from waste water treatment plant effluents, even though development of surface water quality standards for nitrogen and phosphorus has been a stated priority for more than a decade.

  A new shiny app lets users explore effluent nutrient concentrations from an existing data set by waste water treatment plant type, and by nutrient of interest.  When the number of available observations is sufficiently high, the app plots the IQR of the data by month, to show seasonal effects in treatment efficiency.  The app also shows the results in tabular form so users can incorporate the results into water quality models or watershed planning.

You can see the app here.  There is also a companion report with more information about data processing and results.