If you want control of your future trout project, you may need to eliminate the "stream-fed" option from your pond water supply. Your "recipe" for trout ponds can easily be ruined by allowing invasive fish from the stream to enter your trout ponds. You want to be able to control the inputs as much as possible since pond management is difficult enough to optimize.
Will your ponds stay full with just the water from the springs?
Perhaps the creek connection is just to allow water movement in the middle trout run pond so you can effectuate spawning during the season. You can either buy trout fingerlings and skip the spawning step, filter the entering creek water (difficult to avoid plugging), or set up a recirculation pump to re-create the current.
Do you have AC electricity near the ponds from the cabin? That would make a recirculation pump an affordable option. More importantly, it would allow you to much more economically provide aeration to your trout (which is their most critical health need).
Finally, your best option may be to kill all of the existing fish in your ponds and start over. As an outdoorsman, that always sounded terrible to me when I first joined Pond Boss, but the experts all agree on that topic if you are serious about your management goals.
I would follow the good advice your received above to determine the actual depth profiles in your ponds and also start taking temperature measurements at various depths. If your trout budget is large, then you should also consider buying a dissolved oxygen meter - but they ain't cheap.
Good luck on your projects, and I hope you enjoy reading up on trout fishery topics!
