Inexplicably fishy spots

There's this one spot on a small stream by the house that reliably yields trout. In my younger days (okay, last year), I passed by this water as a place between good fishing spots.

With keener more experienced eyes I realized that it's actually quite fishy looking. There's a large boulder near the tail of the pool that has deep water around it. Definitely fishy.

But I never catch fish near that boulder. The fish all come from an area in the middle of the pool that looks shallow. Regardless, I've always enjoyed the bounty of the spot and moved on.

The current comes in equally around the snowy boulder
and exits just to the right of the black boulder at the tail.

I caught one fish from the pool on Sunday and before making another cast decided that I'd creep up on the thing and try to discern its secrets.

As I approached, I saw two trout dart from the middle of the pool to a hiding spot near the head. So much for stealth. I then waded in and discovered that the middle of the pool appears shallow due to a large slab of a rock canted on an angle to the current. Behind it's lip there must be just enough shelter for trout to sit at precisely the spot where two currents intersect. Low energy. Good eating.

Perhaps those trout aren't as dumb as they seem. Though they do reliably suck on a #18 Copper John.

The angle of the ledge is a lot shallower than
illustrated. Just enough for a trout to duck under.

Inexplicable Brown Trout