Not sure what you'd call it but a knowledgeable friend mentioned something he saw a few years ago and it created a spawning habitat for brookies.

The land owner had an intake trickle of a stream from a swamp, to clean the water before it got to his pond he filled the small valley with about 6 feet deep of varying screens or sand and gravel which was about 20 feet long, covered the sand and gravel over in a small layer of topsoil and planted trees on it. clod clean water comes out the other side to pea gravel...

Is there any documentation of this technique - sounds credible and effective.

The also plant evergreens all around their ponds to retain water and help cool water from the hard wood runnoff.

Cheers.

L