Here is the funnel for collecting the water upstream.
18" wide to 3" wide, 24" long, 6" deep with a 1 1/2" hose. With the drop in elevation available to me, I figure about 63 gpm., plenty to run my 21 ft. "Long Tom". The hose connects to the back side of the home made grizzley at the top end of the sluice.
This will easily convert to a garvity dredge/sluice when the Calif. ban on dredging is lifted.
G-pa made me do it, he gave me my first "Steel" pan.