Any pollutants from an airport are unavoidable.
Wash off from taxiways, runways and gates after rainfall inevitably gets into the rivers and streams around airports, especially after very heavy or prolonged rainfall
Airports have special pools to collect the run off but they are frequently missed by the rainfall wash....usually due to being in the wrong place or sediment build up in gullies leading to the pools
There is a legal maximum allowed of pollutants around airports. The local environmental department will be able to give you those and they will, if requested by either the public and/or the airport do extra testing, again especially after heavy or prolonged rainfall. Airport environmental personnel work alongside the State authority and are duty bound to test all local water courses and drinking water wells on a 4 to 6 week basis. Any infraction on the legal maximum allowable always results in very heavy fines...worst case scenario if the usual process has been ignored or test results are not improving sufficiently can lead to the temporary shutdown of the airport til the issues are resolved
A big problem at airports in recent months (same goes with both private and military too) is that due to the pandemic, the airports have been less active, staffing has been stood down so many are in catch up mode now. This can often mean that environmentally sensitive work can go lower on the list of priorities. Airports need revenue first, environmentals take a back seat til everything is back up and running and staffing levels are back to being pre-pandemic levels.
I would not recommend eating any fish caught in waterways close to an airport (or any other industrial facility) for at least a year since all environmental aspects are very much on the back burner for the time being whilst everyone gets back to normal working levels.