Answer
Getting better drains
Knowing where most of the water is coming from, so you can make your own observations on how the water can be harmful.
make sure to properly dispose things.
Explanation:
There are drains all over streets, not all of them are the same though.
The water ending up in the river can come from anywhere, so having an idea where the water comes from can make you know where to improve, like making sure the streets are being keept clean, or pet waste is beings properly disposed of.
