I work for a small privately owned hydroelectric facility that is LIHI certified and does not impact the ecosystem or environment at all. The Low Impact Hydropower Institute certifies qualifying projects as "Low Impact" based on an arduous and thorough certification process. The solution is to require that hydro projects be certified, thereby insuring low-impact to ecosystems. It isn't and shouldn't be either/or. It should be clean energy with low impact. Check out the LIHI website for more understanding of what clean hydro is, and can be.