Hello out. Near my place is this wetland/overgrown former park. I grew up near here, I remember when it was vibrant when I was a kid. Alas, as an adult it has fallen victim to time. The spot where I’m standing at and taking this photo is an old trolley interchange. You’re looking at some kind of dam or something that was placed here many years ago for some reason. As you can see, the earth around the dam eroded, restoring the flow of the river. I would like to re-fill in around the edges of this dam to make a nice waterfall and pond area. What would be the best material to dump in there with a wheelbarrow? Something that will stand up against the water flow and not get me in trouble with the town. Thanks.