User blog comment:Ordeaux26/Pure Evil Proposal - Frozen 2’s Villain/@comment-32583560-20191206082858/@comment-30634893-20191206114559

The dam he constructed was designed to cut off the Northuldrans' resources, which, obviously, would include food and water. The Northuldran leader said something along those lines before being killed. And while he never really says that he's going to kill the Northuldrans, he lays some pretty clear implications of such in planning to know how powerful they are before even building the dam.