Huron-Erie Corridor: P mass balance and climate impacts on the Lake Huron load

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

Donald Scavia, University of Michigan, [email protected]
Serghei Bocaniov, University of Waterloo, [email protected]
Awoke Dagnew, Environmental Consulting and Technology, [email protected]
Colleen Long, University of Michigan, [email protected]
Yu-Chen Wang, University of Michigan, [email protected]

Abstract

To support the 2012 Great Lakes Water Quality Agreement to reduce Lake Erie’s phosphorus inputs, we integrated US and Canadian data to update and extend total phosphorus (TP) loads into and out of the St. Clair-Detroit River System for 1998-2016.  The most significant changes were decreased loads from Lake Huron caused by mussel-induced oligotrophication of the lake, and decreased loads from upgraded Great Lakes Water Authority sewage treatment facilities.  By comparing Lake St. Clair inputs and outputs, we estimated that on average the lake retains 21% of its TP inputs.  We also identified for the first time that loads from resuspended Lake Huron sediment were likely often missed by monitoring programs due to mismatches in sampling and resuspension event frequencies, substantially underestimating the load. This additional load likely increased over time due to climate-induced decreases in ice cover and increases in storm frequencies.  Given this more complete load inventory, we estimated that unless the extra Lake Huron load is taken into account, other sources would have to be reduced by at least 50% to reach a 40% Detroit River TP load reduction.  We also discuss the implications of discontinuous monitoring efforts.

Twitter handle of presenter
@Dscavia