Yeah, the great stuff is non-toxic. If you read the whatcha-ma-callit sheet, it has all the non-toxic stuff in it. Not that I personally would be putting it in the pond before it dried and set up; but I've read of folks who have. The crushed coral is used a lot in salt water aquariums, so it is non toxic also. Down here, you could go to the beach and get it. Inland, its cheaper to buy it when you find it at a good price (rather than making a gas special drive to the beach). Don't remember exactly where I got this big, but it was on sale or open bag discount. I looked today at Petsmart and they have it for $12 a bag. Watch the prices though because I have seen it jacked up in some places for close to $30 a bag.
And Cape, that looks like some nasty stuff. Surprisingly, your dog looks happy in it all!