Re: What Tests can be made to find out how polluted a river is?

There are many tests available to determine the state of a 
river. At all water treatment facilities they monitor the turbidity 
(particle counts that tell you how cloudy the water is), pH, then there are 
numerous tests done for bacteria, viruses, and other water borne diseases 
such as cryptosporidium and giardia.  The bacterial methods mainly look for 
thermal tolerant bacteria numbers as an indirect measure of fecal 
contamination.  Most of the tests are focused on the bacteria, etc. which have 
been shown to cause health problems in humans.  The testing for toxins from 
industry are mostly controlled by monitoring what the company is emitting 
into the river etc.  A good reference site to go to which has a description 
and methods for the tests is located at volunteer monitoring 
network. The program was established by EPA as a partnership between EPA, 
educators and concerned citizens. Groups are established with EPA and receive 
guidance, while providing valuable field data back to EPA.