It then began the review process for the balance of Indiana's waters. Save the Dunes Council and other environmental groups hoped this process would result in better water quality protection, building on the standards developed in 1990. To protect human health and aquatic life, the 1990 standards placed severe limits on the discharge of toxic pollutants, as required by the 1987 amendments to the Clean Water Act. The rules also banned the use of mixing zones in all Indiana lakes including Lake Michigan. Mixing zones allow polluters to meet water quality standards by diluting contaminants and toxics in a larger waterbody before measuring their concentration.
Current rules measure pollutants at the end of the pipe.
Removing the mixing zone ban for Lake Michigan generated strong protests in Northwest Indiana that extended beyond environmental groups. Over our objections, however, IDEM's Great Lakes Basin rules include this retreat from protecting Lake Michigan. EPA has yet to approve or disapprove Indiana's GLI rules. The proposed rules IDEM has just made public contain more bad news for Lake Michigan and its tributaries. No increases in pollution were allowed, except for short-term, temporary increases.