I can't imagine that we would allow sewage into our wild spaces, but it happens every day. In North Vancouver our sewage treatment plant was going to change from tertiary and go upwards. It was one of our local streamkeepers who led the charge on getting a substantial increase in the amount of debris that would be taken out of the water before it entered our wild spaces.
We cannot count on dilution any more to be the solution. We can be the solution by taking out the pieces that we know about.