Rivers and lakes are, as well as ground water, are very important for us, because they are the main sources of our fresh water.
Out of 100% total water on the planet, thereof only 0,009% are fresh waters from lakes and only 0,0001% are fresh waters from rivers. The majority of water (97,2%) is the ocean. The rest is atmospheric, ice/snow or seasalt lakes.
So you see, there is no big surplus already. Minimizing the fresh water volume will cause supply issues.
What are the threats?
- Industrializing: Dams and straightenings prevent natural tide, cut off fish routes
- Pollution: Chemical waste, plastic, microplastic are a thread for humans and animals. Turning fresh waters into toxic waters leads to water shortages.