It is so hard for otters in a country such as Nepal outside of national parks, mainly because every ounce of water is used, and therefore polluted by people. The rivers are literally the life of the people; they wash themselves, clothes, cook, fish, toilet all along the river meaning it’s all completely filthy and therefore no life follows it, bar some fish.
But in my opinion, you can’t really blame the people. They don’t have the resources or the finances to provide themselves with proper sanitation so they have no choice but to continually pollute all water supplies.
To me it’s an almost unsolvable issue. It’s almost a humanitarian problem first and foremost and with so many charities working on cleaner water for people. When they are working on clean water it’s more wells, etc. Rivers etc aren’t an overnight job that will be clean with a few days of stopping everything. The pollution would take years if not decades to repair.
To be honest, I think this is going to be the same in a number of “developing” countries. You can’t blame the people but even so the water quality must be bad for them too. But this is why it is important that we have local people doing work on otters rather than us saying how to do things. They will understand these problems.