Development of a Selenium TMDL for the San Joaquin River

The objective of this study is to devise a user-friendly, reliable method to calculate a screening-level 'Total Maximum Daily Load' (TMDL) for the San Joaquin River and similar western rivers. The proposed method is a simple calculator model in spreadsheet format. It is based on the theory that, given western river conditions, the greatest gain in accurately predicting dilution capacity comes from breaking the data set into seasonal and year-type subsets. The TMDL is also sensitive to the choice of flow averaging period and excursion rate. Correcting for changes in dilution capacity as a result of decreased effluent flows in this case is important, but not crucial.