Characterize phosphorus (P) Release from Ponds

The primary purpose of stormwater detention ponds is to trap and immobilize pollutants, including phosphorus (P). As ponds age, they fill up with P-rich sediments and become shallower, which may decrease P retention or even lead to net P release. Little information exists on pond P retention as a function of season, pond age, site and watershed conditions, and pond water quality, especially at the annual time scale. This information is crucial for the development of guidelines for the management of ponds for improved P retention. Researchers will obtain samples of sediments along with pond water from 5 stormwater detention ponds around the state of Minnesota and will analyze them for the transfer of P between sediment and water. In addition, three ponds will be intensively monitored over a one-year period to measure an annual cycle of P dynamics, including winter and spring snowmelt. The results of the project will provide initial data for decision support systems to manage P levels in urban watersheds.