Mar. 29, 2023, 08:00 – 09:30 (Beijing Time)
Mar. 28, 2023, 20:00 – 21:30 (Eastern Time)
Mar. 28, 2023, 17:00 – 18:30 (Phoenix Time)
Managing excess nutrients remains a major obstacle to improving ecosystem service benefits of urban waters. We have been taking a small-watershed approach to address water quality impairment of surface waters in the Minneapolis-St. Paul metropolitan area in Minnesota, USA. We have shown that watersheds retained only 18% of net phosphorus (P) inputs versus 78% of net nitrogen (N) inputs, despite relatively low P inputs related to a statewide restriction on lawn P fertilizer use. In contrast to many non-urban watersheds that exhibit high P retention, these urban watersheds have high street and storm sewer densities that enhance transport of P-rich materials from landscapes to stormwater and local lakes. Further work showed that tree litterfall into streets can account for 40-60% of P transport from land to stormwater, and that targeted street sweeping can be a cost-effective method for managing urban P pollution. Working with the Minnesota Pollution Control Agency, we helped develop a new, data-driven pollution crediting approach that is being emulated in other states. Our work shows that advancing ecosystem-level understanding of urban watersheds can generate insights that promote novel solutions to solving urban water quality challenges.