How do you know they didn't stop to ask if they should? And concluded after, detailed and deep study, that yes, they should. Perhaps they (or someone else) al

How do you know they didn't stop to ask if they should? And concluded after, detailed and deep study, that yes, they should. Perhaps they (or someone else) already did studies of the impact of blocking rivers partially or totally? Are you, perhaps, making assumptions about what they did without first stopping to think if you should make such assumptions?