Not sure I'd feel comfortable within 20 m of it...

They've been talking about the need to clean up the Ganges River in India for years, possibly decades, but here we have another lengthy article at the BBC about the dire condition it's in.  How's this chart, for example:

And after that appears the line:

Here in Varanasi it is sometimes more than 150 times the recommended safe level for bathing, yet vast numbers of people bathe away regardless.