What is an impaired watershed as listed by the EPA and how can it be approved to use?

Question

Also, on the EPA's website it states that some impaired watersheds are approved TMDLs (Total Maximum Daily Loads).

* Does this mean it's approved to be used as a water supply?

Some are impaired (yet still approved) because of DDT, fecal coliform, toxaphene, dioxin, etc.

* Is this just in low levels that allows them to approve the water?

* What are some causes and solutions to cleaning the water?

I've read stories from my g-g-g-g-grandfather who settled here in the mid 1800's that said the water used to be so clear that you could see your feet in the river, until the timber boom, and the industrial revolution came. Now it's brown.

Thanks for your help!

Answer 1

Approval is for a particular use. Approval as a source of human drinking water requires the highest levels of purity. Approval for industrial use is probably the lowest. However, it gets tricky. Certain contaminants may foul the water for a "lower" use but not for a "higher" one.  Each section of stream is rated for certain uses and there are a lot of uses and a lot of levels of approval. That's why, in the wayer business, TMDL is sometimes joked about as standing for Too Many Damned Lawyers. BTW, brown water can sometimes be purer than clear. Compare water flowing out of a pristine bog with water contaminated with acid.