I use mesh bags so while I walk I hope the spores are dispersing themselves. Unless I get REALLY buggy shrooms nowadays I simply half them, run under cold water for 5-10 seconds, dry about 25% moisture in dehydrator [1 hr], then vacuum seal in freezer bags and store up to several years. I've learned not to look too hard for critters and never let the wife help me or she'd likely never enjoy them again.
So, yes Tony I think you're right, some spores make it back home and would be in the water. I have read volumes on Morels, and several expert scientists seem to disagree on conditions necessary for propagation...it's one of the wonderful things about Morels, they are mysterious and all our efforts to control or predict them have largely failed. Adds to the intrigue!
FYI, only went out for 30 minutes Monday, nothing yet. I'm checking my hot spot on Friday and should have some action. Next week it will be on I'm hopeful.