HI everyone
I believe with a little ingenuity one could divert a small portion of the water upstream from the mill.
Lets say that the river or stream has a vertical drop of 8 feet over 1000 or 1500 feet then a small channel's head could be started at this point and end up at the mill with the proper head height to propel the turbine without disturbing the river or stream's ecosystem, and even create a small ecosystem of its own for birds and aquatics.
The water would then reenter the river just below the mill and continue happily on its way.
In Lowell Massachusets many mills were situated on a single canal that diverted a portion of the river's water well above the town, the mills then were able to access a portion of the water as it passed by for powering their equipment.
Even here where I live, the St Lawrence River before the seaway project, had a canal system that served as an inland water route for shipping, the same canal also powered many generators with excess water flow, and there were many vertical blade mills situated on the mouths of the incoming creeks.
I hope this makes some sense.
NH
