How do they Border Wall the Lakes or whatever they’re called ?
Lakes are further down the priority list, because the big open area makes detection easier, and gives intercepting officers a long lead time.
When they do get down the list to those lakeside miles ( like around Falcon Lake in Texas), barrier construction would be similar to how they have to do it along the Rio Grande River - with careful attention to flood control consideration.
Maybe they will rely on technology and CBP humans. In Texas there is Falcon Lake and Amistad Reservoir. Seems like from the south the wall will eventually end at Amistad. Maybe a barren rock desert up there.