Pete
Trout Hunter
Earlier in this topic, I compared a nearby pond to a cesspool...C.........Could a man-made lake made by damming a sediment rich river be designed to minimize sedimentation? Small dam first that slows the speed of the water, sediment falls out then water continues to the large main lake. The small sediment catching pre-lake is dredged or pumped out frequently to keep the build up down.
What you're designing is a full fledged septic system. Unfortunately, you'd be using the river as a leeching field.