I have a spring-fed, concrete pond approx. 18' x 18' that sits at the edge of some woods and was overhung by a large walnut tree until a storm brought that down.
Normal procedures for cleaning a pond are to drain it to remove sediment that has built up over time. Since the spring can not be controlled, emptying the pond would be a very difficult task.
I typically resort to a rake and pool net, however, this will only get you so far. The rake could get the large debris and the net the very small floating debris. The muck and silt just run through the rake or out of the net.
Well this year things just got too far along to keep working with the same old cleaning procedures. The muck and silt built up to such a depth on the bottom that they could only be removed by extraordinary measures.
Hence this Instructable.
I needed something that was somewhere between a rake and a net so as usual I looked around at my salvaged bits of materials and came up with the following.

Step 1: Dredge Basket

I had an old piece of perforated aluminum plate left over from an architectural sample of a building sunscreen.
I cut the perforated sheet with a cut-off wheel in my angle grinder and folded the sheet to make a box or basket with a bottom approx. 16" x 16" and 3 upturned sides approx. 4" high.
It was very heavy gauge aluminum, so bending was a bit difficult.
If I had to do this again, I would go find a perforated steel of thinner gauge.
The bottom of my (cement) pond is flat, so I made the front edge of the dredge straight.
I suppose the front edge could be curved to suit curved ponds.

Step 2: Pole Bracket

The bracket was fabricated with steel sheet metal that I found a few months ago.
I cut 2 pieces of sheet steel approx. 4 1/2" x 5".
This sheet steel was also pretty heavy gauge, so I scored the sheet with the cut-off wheel on my grinder before bending.
The idea was that each side of the bracket would get bolted to the pole and then the brackets would get bolted to the dredge basket.
I drill holes in the sides of the brackets to support the pole at a right angle to the bottom of the basket and then drilled another hole so the pole could be angled.

Step 3: Pole and Bracket Mounting

I used a 3/4" EMT (electrical metallic tubing or thin-wall conduit) that I had lying around for the pole.
I pounded down the last 6 inches or so of the pole to fit more firmly between the 2 bracket pieces than the round tubing profile.
I used (1 1/2" long ) #10 machine screws to secure the bracket pieces to the pole (in the 90 degree position).
I then positioned the pole and brackets onto the dredge basket and marked the locations of perforation holes on the bracket bottoms for drilling and mounting the brackets to the basket with more (3/4" long this time) #10 machine screws.

Step 4: Finished

I used the dredge he pole in the 90 degree position for now.
The pole and perforated metal are sturdy enough to carry the load of the muck.
The size is pretty good since any larger load would be difficult to lift.
I guess a dredge with some sort of nylon mesh could be used, however, based on the weight of the muck and silt, I think perforated metal is the way to go.
Works great as you can see in the photo.