One method of controlling pollutant escape is by capturing waterborne chemical and sediment wastes and retaining them for appropriate periods in artificial lakes. Chemical pollutants, such as nitrates from agriculture or phosphates from domestic detergents, can be broken down over time by aquatic plants, and sediments can be trapped in deep ponds for future dredging and disposal in, for example, landfill. A potent tool to help planners design such pollution-control ponds called NESSIE (a two-dimensional vertically integrated resistive flow model) has been developed by the CSIRO Division of Mathematics and Statistics.