Huron-Erie Corridor: Assessing urban P loads

Session: Great Lakes Tributaries: Connecting Land and Lakes (3)

Yao Hu, University of Michigan, [email protected]
Yu-Chen Wang, University of Michigan, [email protected]
Colleen Long, University of Michigan, [email protected]
Branko Kerkez, University of Michigan, [email protected]
Donald Scavia, University of Michigan, [email protected]

Abstract

The Huron-Erie Corridor (HEC) watershed, a binational watershed draining into the connecting channel between Lake Huron and Lake Erie, contains large urban areas where runoff from impervious surfaces, combined sewer overflows (CSOs), and point source facilities can generate phosphorus loads that can degrade water quality In this study, we analyzed spatial and temporal dynamics of phosphorus loads from these three sources in the three largest urban areas in the watershed: southeast Michigan, Windsor, Ontario, and London, Ontario. Results indicate that point sources are the primary source of urban total phosphorus (TP) loads, contributing, on average, 75% (516 MTA) of the annual urban TP load, while CSOs and runoff contribute an average of 15% (104 MTA) and 10% (69 MTA), respectively. The TP loads from the point sources decreased significantly from 2009-2014, due largely to improved treatment of wastewater discharged from the Great Lakes Water Authority Water Resource Recovery Facility. On the other hand, TP loads from CSOs show large variation from 2009-2014, driven mainly by rainfall. The findings of this study can help guide actions to reduce TP input to Lake Erie.