How to Stop Ponds From Releasing Phosphorus

Authored by: Vinicius Taguchi, St. Anthony Falls Lab, University of Minnesota

Stormwater ponds are designed to leverage the natural relationship between phosphate, iron, and oxygen. In the presence of oxygen, iron maintains a 3+ charge, which binds it to the 3- charge of phosphate, allowing them to precipitate out of the water and remain in the sediment. However, in an anoxic environment with strong temperature stratification, the water does not maintain sufficient dissolved oxygen at the bottom, and iron changes to a 2+ charge. This no longer fits with the phosphate 3- charge so the iron and phosphate are released into the water. This webinar discusses the recent research on the impact of chloride introduced from winter road treatment, the relationship sheltering from trees has on stratification, and the importance of mixing the water column throughout the year.