Mainly, I'm referring to purposely submerging structure (like a tree, or some rocks maybe, etc.) to create something like a small artificial reef that wouldn't disturb the ecosystem. I was thinking about possibly making a fish hang out at a nearby pond and casting a few texas rigged soft plastics on it weeks later. I literally just thought of this a few minutes ago. It happens all the time in salt water fishing, so...

any thoughts? has anyone ever done this?

Back when I lived in the DFW area of Texas, my dad and I lived about 80 yards down the street from a channel that ran into Lake Arlington. For three years straight, we tossed our xmas tree in a 3 different spots. Each location eventually turned into a Crappie magnet! Right around April we would do our best crappie fishing right around those trees. I'm sure building some cover for bass could yield the same results. Good luck!

You can make PVC-pipe "trees" with a concrete bottom so it lands correctly

Yep, we do it a lot in this area. Some produce, some don't.

I've heard stories from guides on Kentucky Lake throwing out piles of old toilets to create structure. They claim it works well.

Good answers so far. I've bundled oak branches up and made brush piles using a half cinder block tied on the bottom.You can also take these and christmas trees and stand them in a 5 gallon bucket with a little concrete in the bottom One thing about christmas trees though is that they don't last long before they deteriorate. If you can get a hold of one of those giant wooden spools that phone wires and such come on then they are killer if you make a reef with pvc pipe.Piles of cinder blocks and chunk concrete work well in muddy ponds. I am not a big fan of pallets. Too snaggy.

In most areas it would be considered dumping to add thse kinds of items. Always check to see if it is leagl if you can. If private property then by all means dump away. 8-)

Yes!

And it can work.

Be sure to anchor what you put in the water so it stays where you place it. 

Really like the responses so far guys.  Whatever I use I'll definitely make sure it is legal.  My only other concern would be whether or not the structure is too "snaggy" like Bass Finatic said about pallets.