I have wanted a dam ever since I bought the 'stead. I know right where it should go. I don't really think I'd get enough head to drive a turbine very often, but I sure would like to try it. The creek is named Mill Creek, and I think that means that at some point somebody had a dam that generated water power nearby. But so far I have not uncovered the history of the local mill that must have once existed.
If your head is too low, there are still ways to get small scale hydro power. Forget the math for sufficient head for a moment. All you need is 3 or four gallons per minute of MOVING water.
I think you have that, do you not?
There are two ways to handle that.
1. A bullet shaped submersible electric generator is fastened to a post in the stream. You then use that electricity to run an electric centrifugal pump from the stream to a reservoir.
2. Skip the electric generator and put a hydraulic ram pump in the stream to pump water up to a reservoir. Ram pumps can, with very low stream velocity, pump water up as high as 40 FEET! This is a 1973 article but the principle involved in hydraulic ram pumps is the same. Perhaps they are cheaper now than they were then: The Hydraulic Ram Pump: Perpetual Motion for the Homestead
Although water won't run uphill, some exceedingly clever soul discovered a long time ago that H2O can be persuaded to pump itself in that general direction. The hydraulic ram pump makes it possible.
... if your property contains a spring, creek, small stream, or other source with a flow of at least three gallons per minute (gpm) you can probably solve your problem easily and inexpensively with a hydraulic ram pump.
All that time the device has been pumping clear, cool spring water up over a 25-foot hill—a distance of 150 feet—and into our farm pond, without the use of any fuel whatsoever. In short, we're getting about 500 gallons of water per day at an operating cost of zero ... and we expect this to continue for ten years or more.