Proposed Nutrient Criteria for Iowa's Water Resources and How Can Agriculture Meet Them

U.S. EPA is requiring States to develop (or at least have a plan for developing) criteria for total nitrogen (N) and total phosphorus (P) in flowing waters (river and streams) and standing waters (lakes and reservoirs) by the end of 2004. The purpose of these criteria are to protect the designated uses of the States' waters in line with the national goals of the Clear Water Act of 1972 to achieve, wherever attainable, water quality which provides for the protection and propagation of fish, shellfish, and wildlife and recreation in and on the water. To help the States develop their criteria, the EPA is publishing nutrient criteria documents along with recommended criteria by ecoregion. At this point, these criteria are being recommended strictly based on what is believed to be needed to protect against water quality degradation; attainability and possibly economic impacts have not been factored in as yet. Based on the proposed criteria currently available, Iowa agriculture will have to implement additional improved/best management practices to significantly reduce current nutrient concentrations and losses in surface runoff water, with sediment, and in subsurface drainage. Although practices (and systems of practices) are available that will help, it is not clear that the low values being proposed are achievable without major changes, including changes in land-use, that could have a large economic impact on agricultural producers.