Shallow basins can be easily formed by building berms between the road and the lake. These berms prevent dirty runoff from entering the lake by creating areas where rain and snowmelt can soak into the ground, be filtered and deposit solids such as road sand. Because the basin is open, it’s easy to remove accumulated sediments each year or more often, as needed.
Construction is quite straight forward. A triangular stack of poles or logs forms the base of the berm, which is covered with soil material retrieved while cleaning the lake shore. The soil on the side of the berm is planted and/or seeded, providing useful habitat (turtle nesting beside one basin) that needs little or no maintenance.
Seven simple basins were built by volunteers for under $500 and capture over 10 tons of sediments a year. The top photo shows a three-year old sediment basin during a rainy day. The bottom photo shows six-week old construction – riprap will be placed on each end.