No, they intercepted the water far enough upstream of their settlements. Let's say you have a pueblo on a 200 ft mesa, above a river that's running at a 4% grad

No, they intercepted the water far enough upstream of their settlements. Let's say you have a pueblo on a 200 ft mesa, above a river that's running at a 4% gradient. Your aqueduct needs a 2% gradient to maintain good flow -- the Hohokam were excellent at maintaining consistent gradients over very long distances -- so what you need to do is build a small check dam 200 / (4% - 2%) = 10,000 ft upstream, with the stone aqueduct wending its way "up" the side of the mesa from there. Ruins of these kind of structures can be seen all over the area.