Is there something wrong with re-establishing the natural flow of river systems? I have two examples that show the current policies towards them are not just ecologically destructive but economically as well.
First, the Colorado River. It no longer runs to the sea because so much water is diverted for Las Vegas, Phoenix, Lake Mead, etc. This impacts Mexico, who gets no benefit from the diversions. So, at the Colorado Delta, there are wetlands where endangered species live, and it's Mexico's job to protect them, but they're not the ones destroying the habitat by drying up the river. So they convinced the US to find a way to preserve the wetlands which was done by rerouting some of the diverted water directly to the wetlands instead of just letting the river flow, costing a significant amount of money.
The Mekong is the other example, where China's rapids blasting and damming has severely reduced the size and quantity and variety of fish which can be caught downriver in areas like Laos and Cambodia that rely upon their fishing industry. As the right to swing my fist ends at your face, should not the right to dam a river end when it impacts other countries who share that waterway? China isn't doing any kind of reparations, unlike the US, so it's not costing them a cent, but it definitely has an economic impact.