with flow ,head height vs outlet height calculate how much available power can be extracted.
beavers are some of the best dam builders there are so live trapping can be worthwhile if you need to for smaller creeks.
squirrel cages from old furnaces work well for keeping batteries charged.
grey water systems can be designed to collect hydropower or clean surfaces. in some homes this can be used to flush toilette.
rainwater can be harvested and used to prevent drought and lack of water in populated areas. gutters can be easily converted to do this for you. have seen stacked 45 gallon blue plastic rain barrels used for this.