All lots, regardless of size, are required to install settling basins to remove solids from the runoff before they leave the lots. The captured runoff in the detention basin must then to be pumped or hauled for application to agricultural land. The permit allows the lot to discharge whenever a large enough rain occurs, but not at any other time. Although the laws have been in place for nearly 30 years, they haven t been rigorously enforced. COD is the amount of oxygen required by microbes in the water.
Total ammonia is of concern because of hypoxia issues in the Gulf of Mexico.
High COD deprives the water of oxygen, suffocating the fish. The size of settling basins and detention basins is defined by IDNR requirements. Detention basins should hold from 5 to 17 inches of runoff, depending on the frequency of pumpout. In both cases it s obvious that the smaller the lot, the smaller the control facilities. Iowa State University Extension, Natural Resources Conservation Service, and private consulting engineers can help with specific basin designs.