In the latest issue of Home Power magazine, I found three adds specifically addressing hydro electric power, though almost all renewable energy dealers can probably sell you something.
Harris Hydroelectric
632 Swanton Rd.
Davenport Ca 95017
408-425-7652Power Pod Corporation
888-786-3374Energy Systems & Design
P.O. Box 1557
Sussex, NB, Canada EOE 1PO
506-433-3151
506-433-6151 fax
Offered by Steve.