Is it safe to harvest mushrooms near quarries or mines?

Someone recently asked about harvesting mushrooms near a quarry and wondered if I had any specific guidelines surrounding this. I asked a friend and soil scientist for his feelings on this. Here are some of the things he had to say about it

What was quarried? Usually quarries are for stone or sand, so there should be minimal environmental contamination associated with them.  If it is a quarry of this type I would be comfortable foraging around it.

How close are you to the quarry? Most contamination that is “off-site” will be in the groundwater. As I understand it, mycelia don’t typically penetrate to this depth. Any foraging in the vicinity should be ok.

Important caveat, I would not recommend mushroom foraging at or immediately downhill of old mines. This areas often have mine tailings piles, which can have a variety of heavy metals.

These pollutants can be washed downstream by rain or by water that is leaching out of the old mine itself.  Most of the time these areas are easy to ID because nothing is growing. They’re often ID’d on old topo maps too.

The main take away: don’t worry too much about old quarries but don’t harvest mushrooms where it looks gross/unhealthy.

Here is a link to some maps that show near surface soil contamination from smelters in Washington.https://apps.ecology.wa.gov/dirtalert

This is a link to known coal mines in Washington.

https://geologyportal.dnr.wa.gov/2d-view#coal?-13707225,-13462626,5914461,6073450

Here’s a map showing known contaminated sites in Washington. You can filter by contamination type.

I personally don’t harvest mushrooms near busy roadsides, industrial areas, or places that might be regularly sprayed with herbicides and pesticides. I don’t have any evidence that this is a problem but it’s just a personal preference.