SUBURBAN PONDS REDUCE NITRATE LOSS FROM LAWNS TO STREAMS

Loss of nitrogen and phosphorus fertilizer from Midwestern watersheds, e.g., agricultural fields and lawns, is a major contributor to the dead zone in the Gulf of Mexico. The dead zone is an area the size of the state of New Jersey in the Gulf of Mexico that no longer supports life near the bottom. Loss of nitrogen from Illinois and other Midwestern states is a major cause of the dead zone. Excess nitrates in water is also a problem in municipal water supplies especially for infants under six months of age. Although we have identified the problem, it is unclear how to reduce the loss of nitrate to streams that drain to the Gulf while maintaining green lawns and productive agricultural fields. We examined the potential of suburban water retention ponds to reduce nitrate loading to streams by examining the loads of nitrate entering and leaving the pond. We sampled the inflow and outflow of Tipton Lakes weekly for 3 months to estimate the change in nitrate and phosphate loads as they moved through the pond. We also examined the ability of the ponds to reduce sediment loading to the stream. The ponds at Tipton Lakes reduced nitrate loads by approximately 50%. These ponds are an effective tool to reduce nitrate loss from suburban areas. The inclusion of these systems in urban planning has the potential to significantly reduce nitrate loads in streams draining suburban systems while also increasing areas for recreation and wildlife