The Minnesota Pollution Control Agency (MPCA) recently circulated a two-page summary of the Bolton & Menk study analyzing alternatives for sulfate in Municipal Wastewater treatment. The study acknowledges the challenge of removing sulfate.  Reverse osmosis is the only method that is close to feasible, but it is not affordable.

Until treatment is more affordable, prevention will be a key strategy. Timing the release from pond treatments is mentioned as one method of diluting sulfate. Variances are also mentioned as a strategy. The MPCA notes that the sulfate study provides better data on which to issue variances.

You can find the underlying study here. Even though it is dated May 1, it was not made widely available until recently.