The "Dilution solution to pollution" remains the greatest challenge to the Goals of the clean water act 

The Clean Water Act (CWA, the Act) was passed in 1972 to restructure the nation's oversight regarding the release of pollutants into public waters.  Beginning in 1948 under the Federal Water Pollution Control Act, states assumed essentially full control over protecting the waters within their borders - and they did an abysmal job.  Dischargers went pollution shopping, always looking for the weakest regulatory environment that would allow the greatest amount of contamination with the least amount of treatment.  Of course those costs would always need to be paid by someone, and by the 1960's, with half of the nation's waters too contaminated to support aquatic life and dangerous to anyone who dared to go for a swim, the bill was delivered, to you and me.  

In 1969 the Cayuhoga River in Ohio caught fire and Congress finally realized it needed to intervene.  Within a few years the CWA was passed, and the new law included a federal permitting program called the National Pollution Discharge Elimination System (NPDES,) designed to put the brakes on this state-by-state race to the bottom.  States were now required to adopt scientifically defendable water quality standards (WQS) that would protect the various uses of the water, such as supporting aquatic life, providing a drinking water source, use for agriculture, etc., and each state had to issue permits to potential dischargers that must be reviewed by EPA and monitored by state regulators on a regular basis.  The NPDES program has been a great success in many ways, but industrial and municipal dischargers wanted, and found, a loophole big enough to absorb hundreds of millions of gallons of contaminants every year - the mixing zone.  

A mixing zone is a volume of public water exempt from the WQS.  Instead of having to meet the WQS at the point of discharge, as the Act clearly intended given the goal of eliminating the discharge of all pollutants into U.S. waters by 1983, the application of mixing zones allows polluters to release waste into public rivers, streams and lakes in chronic and acute amounts, and avoid the development and implementation of better technologies that might eliminate the discharge of pollutants once and for all.  The cost of that pollution continues to be shifted to the public through increases in health problems, loss of fishing habitat, and fewer waters safe for recreation.

We have been fighting against the use of mixing zones for decades, state by state, industry by industry.  To learn more about mixing zones and what you can do to prevent or limit their application in the waters where you live, please read the linked (see below) Mixing Zone Manual, download our Mixing Zone Survey questionnaire and submit it to your state environmental protection agency (and share the results to us!) and read through our earlier Mixing Zone Survey Results to see how your state compares with others in your region and around the country.