Deep water scooper el JUMBO size?

Got a river where many crossings were used from the mid 1700's to early 1900's.  River for the most part has a sand bottom probably not far from the bedrock in some cases. Ranges form 15 to 25  feet deep and is very dark tanic water. Trying to come up with some type of basket scoop to drag along the bottom and recover from above....could be on a rope or long pole.

Anybody got any ideas or seen some sort of "bottom scoop dragger thing"?

P