[SilverElfin]

But does the amount per liter matter? The quantity matters too right? How much of these substances are being released in total? And since it’s into a drainage ditch that goes past what looks like farmland, does the higher local concentration cause more problems for the population in the area?

[gdudeman]

I think it does. Crops pull up a set amount of water. If it's concentrated, then they'll pull up a lot of heavy metals. If it's at very low levels, then they won't.