purplehelmet mentioned about chemicals that get dumped in sewers & make it's way into the Brunette R.
Worked at a site right at the mouth of the Brunette R. back in the 70's for 2 yrs. A sawmill called Lamford Cedar..I think the owner also had a mill near Sooke.
Anyways the mill was built right over the river...logs being pulled up into the mill from the Brunette R.
Also looked at the river just east of the mill & the bottom had like rainbow colors. At one time a pallet of paint cans must of be dumped into the river (accidently???) Ya could see the cans as well.
When working as a commercial floorwaxer ,made sure I dumped the janitor bucket that was full of stripper chem/removed old wax/floorsoap etc.... into the toilet.
It takes longer & sure enough some gets spilt so one has to clean the outside of the toilet. Sadly many many floorwaxer crews are dumping full buckets of soap/stripper chem/old wax removed from floors or even new left over sealer or wax right into the sewer drains in the parking lots. Or they will fill their bucket 3-4 times with fresh water & rinse out their mop heads...then dump water into the parking lot drain. Goes on all the time.
Floor crews are out there late at night & no one is seeing them do this !!!!