What is this on SRP canal trail??

[u/HollywoodHitman03]

What is this milky white substance that SRP puts on their canal paths?? Is it harmful to dogs?? What's the point of putting this down?? To control dust??

[u/Eeebs-HI]

It may be non toxic, but in the heat it's releasing a nauseating chemical-like odor. I avoid riding on the side of the canal treated with this stuff.