My country has 40% of electricity generated by hydro power but believe me it is not easy. let me tell you the reasons.

1. you need to have consistent water supply throughout the year. (but its not the case - summer no water , in rainy time too much water and it create huge problems with mud extracting through tunnels . winter - lakes are frozen )

2. Very Costly to install. - You have to carve a tunnel through a lake. and lake should build by a river which have constant water supply.

3. Your power generation is static.

True . After initial investment . its going to be less maintenance. still with my life experience other power options have much more reliability than hydropower

subd :)