The golf course was watered = artifical source of water.
I am not sure that the golf course was watered on those days because there was frost on them. If I recalled he said they closed the golf course on those days because of the frost. If people walked on the greens it would break the grass off.
My point was that it appears there was enough moisture naturally, that if Danielle was there on those days, she wouldn't mummify. She would rot. But if her body was left there after those days it was plenty dry to mummify.