But I understand they are bad in ponds filled with runoff that are used for irrigation.
Yes they are, they can cause algae blooms.
But it's no more a run off risk than the farmers putting on their fields.
I bet there is a lot of Organic farms in the area that got it banned.
We have highly protected water bodies up here, and MgCl2 was found to be much safer for aquatic life.
But it does cost more to use.
Surprisingly beat juice is a great road deicer, but people hate it where they use it, as it leaves a nasty residue and smell on everything.
They used it here one year and it didn't go over well and was expensive.