I am no expert in design or pond construction, but I thought I would give some information on the lake design we have from a highly engineered lake that required state permit and wetlands mitigation. The lake design includes a continuos dirt berm around the lake that channels runoff to large "flats" in the lake proper. These have been designed with a gradual slope of from zero to 24" across a 1/2 acre flat. These areas contain aquatic wetlands plants that absorb excess nutrients as well as drop out silt. The aeas above and with-in the berms have been planted with bermuda grass to act to drop out silt as well. The idea is to allow siltation to take place outside of the lake, allowing for periodic rebuild of the berms with this silt. This also allows for water to migrate through the berms during light rain runoff through a terrace affect, to further clarify the water. Excess runoff flows across the mitigation areas, and wetland plants use nutrients and provide bait fish habitat.
