Lots of reservoirs or mining pits basically aren't suitable for life, and there are even more bodies of water that have areas that aren't. Sometimes that's beca

Lots of reservoirs or mining pits basically aren't suitable for life, and there are even more bodies of water that have areas that aren't. Sometimes that's because of pH or salt concentrations, but more often it's because they dry out seasonally, they're very low oxygen, etc. Many of those areas are large enough to get substantial power out of, and in the case of the seasonally dry reservoirs you might even be building a better ecosystem by reducing evaporative loss.