Pond Boss Forums POND CONSTRUCTION Selecting a site Topsoil How Close to Waterline?

Hi. I am excavating a dugout pond in an area with a 1 foot thick layer of topsoil and then all clay below that. I need to dig down roughly 2 to 3 feet to where the water level will be. My current plan is to strip the topsoil back and then cut the clay down to the water level, but then have a flat “bench” spot at the water level, before continuing down to the bottom of the pond. My thought for this bench is it can help hold the topsoil I put back on the pond bank down to the waters edge, and then have just clay below that. I’m hoping this will give a natural look above water level, and less weeds below water level.

I’m wondering what you all think of this idea. I’m also wondering at what elevation I should place the bench. I’m thinking perhaps just above the water level, so the topsoil stays a bit more dry, but perhaps it should be just below the water level, so I don’t have a small ring of visible clay around the pond between the water level and the topsoil. Your thoughts are appreciated.

I'd put the clay bench at about 6 to 10 inches above the full pool line and place the topsoil right down to the water. Some of the topsoil will get into he water, but you will get plants (grasses I presume, or whatever) to grow up to the waters edge. This will allow you to try and control what grows there and it will be easier to mow or weed-wack without being saturated and swampy. Most plants that like wet clay soils are typically considered weeds and adding the top soil to the water's edge will help prevent a line of tough plants. If your feeling ambitious, consider adding rip-rap at the shore at the full pool line down about 2 foot into the water to divide the bench vegetation from the water vegetation. This rip-rap will slow erosion and somewhat limit the vegetation at the bank by covering the up sub-water soils.

Thanks Quarter Acre. I like the idea of keeping the clay bench a bit above water level to keep the topsoil dry. In this scenario how do you think I finish the space between the bench and the waterline? Just a couple inch layer of topsoil? Or just leave it as clay and leave it to Mother Nature? What do you think? I’m hoping to avoid having to replace rip rap, and make it work with just topsoil and clay.

I envision you pushing/dumping/spreading the replaced topsoil with a skid-steer, or the like. It's been my experience that controlling the topsoil with powered equipment will be rudimentary at best. That being said, I would do my best to keep from pushing much of it into the the waterline. Some will go beyond, but I cannot think of a reason to add topsoil to the water on purpose. You could try to stop short of the waterline and come back with a hand rake and feather it in giving that taper of the topsoil from full thickness down to an inch or two at the water line. Even that is hard to control once your back starts feeling it. It is a fair amount of work, I know, as I did that along my 100' long dam. The important thing is to get grasses growing in the topsoil sooner than later. Some folks even get grasses growing below the waterline before the pond fills to stabilize the pond bottom as it fills. If rip rap might be an option, I would recommend at least a row or two of larger rock between the topsoil and the waterline. This gives a barrier that serves a couple purposes, but is not real critical. My dam does not have the bench such as yours and the large rock gives me some comfort in not sliding my mower into the pond and it helps resist any wave action that would erode the bank (and I like the aesthetics). Leaving exposed clay between the topsoil and the waterline may stay barren for a season (or three). My pond is 4 years old and I still have some steep slopes of clay that are bare, maybe 10% of what was originally left exposed. Some topsoil will migrate to that clay strip anyhow and who knows what will grow in the exposed clay when it does become seeded. Either way you go will not be bad. It's really a matter of how much effort you can put into it and how "finished" you want it to look upon completion.

That’s helpful Quarter Acre, thank you. I like the idea of putting a small layer to below the waterline, and then get grass growing before it fills. That way hopefully the grass goes down right to the waterline, but the topsoil doesn’t go too much past it. Let me try that. Thank you for the advice.