Pumps that are best suited to dirty water are called Ditch pumps, they generally have a high flow rate with a small lift capability.
Ram pumps are really neat but they have a low output capability and a low lift capacity, they siphon off a large volume of water to move a smaller volume of water, they don't work well with dirty water.
If your river has a significant drop in it, you could just locate your water intake far enough up stream to use gravity feed, guessing that is not an option here.