Mark - If you are referring to a mini hydro generator that spins with water flowing through it - that sounds like a neat idea, however it may be rather limited.
Hydro in and of itself isn't a bad idea, however if you can combine a generator to use other forms of powering that would be ideal. For example - use a larger paddle wheel of some kind to turn a generator that can also be converted to run off of wind blades. If you aren't camped next to an appropriate stream for the hydro generator to run you would have the option of wind blades to power it.