Building an earth dam requires a variety of considerations in order to create a solid dam that won’t potentially create a hazard later on. Those considerations start with site selection. Usually, the smaller the dam, the better, which is why it is recommended to pick the narrowest point of a valley or gully in which you’d like to place a pond.
From there, some excavation will be required to make sure that clay soil extends below the level of the pond’s basin to prevent leaks. The dam wall will also require a clay-based core to prevent leaks. Over that, you will need a layer of topsoil, and that topsoil should be planted with vegetation or covered in riprap to prevent erosion. Dams should be built wide enough that heavy machinery can drive along the top—and you’ll also need to create a spillway for your pond so that you don’t risk water spilling over the top of the dam and potentially damaging it during a flood.
