Mark the area for dam construction with stakes and clear away all vegetation.
Remove and pile all of the topsoil from the dame site below where the dam wall will be. This fertile soil will be spread over the completed dam to help vegetation re-growth.
Make a cut-off trench at least one foot deep and nine feet wide in the ground the dam will be over.
Fill the cut-off trench with clay from the excavation and compact it by driving over it several times.
Build the dam wall with layers of clay soil and rock. Each layer should only be half a foot height and compacted by the bulldozer before adding another layer of material. Soil that does not have clay in it should be placed on the downstream side of the wall. Rocks larger than three inches in diameter should not be used.
Make an earthen spillway by constructing a channel that is big enough to allow overflow water to pas the dam without erosion. This spillway can be made from a large pipe, compacted clay or poured concrete lining and should be at least six feet from the top of the dam wall.
Spread the topsoil over the dam wall and spillway and plant grass right away to help stabilizing vegetation to grow.