If the stream has some elevation drop over the property and the flow is decent most of the year, then the answer is that if you can meet the legal requirements, its possible to make electricity, and that it can be quite cost effective.
|Quite a nice underflow water wheel.|
But, if the stream has no elevation drop, and you just want to make use of the velocity of the stream water to make electricity, then its more challenging. I've added a new section that goes into what's involved in generating electricity only from the water velocity. It covers how to estimate the amount of power your stream might generate, provides a bit of design information, and it lists all of the home scale example projects I could find that seemed like they might actually work. Its a place to get started on your quest for free no pollution energy from your stream.
One of the reasons getting power from your stream is difficult is that while its clear that there is energy in that flowing water, it not nearly as dense as the energy you can extract from water dropping through an elevation difference. This plot shows you roughly how much power you can get from 1 sqft of flow area at various stream velocities.
Just a glance will tell you that if you have a 2 mph 6 inch deep stream, your power generation possibilities are pretty limited. But, if you have a deep 5 mph stream, there is some worthwhile power there.
I found a few commercial and few homemade examples of flow of river turbines and water wheels -- the link below provides pointers to all the ones I could find. If you know of others please let me know.
The new section on Flow-Of-River hydro installtions...
The micro-hyro page for info on more conventional hydro...