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Using water quality to assess ecological condition in the St. Marys River and Huron-Erie Corridor
Citation:
Wick, M., M. Pawlowski, Dave Bolgrien, T. Angradi, M. Nord, B. Hinchey-Malloy, J. Scharold, A. Cotter, M. Pearson, W. Bartsch, J. Lietz, AND T. Corry. Using water quality to assess ecological condition in the St. Marys River and Huron-Erie Corridor. IAGLR, Toronto, ON, CANADA, June 18 - 22, 2018.
Impact/Purpose:
We will present results of the National Coastal Condition Assessment in the connecting channels. Water quality thresholds specific to the connecting channels are not currently available but we have defined two methods to identify thresholds in order to assess ecological condition based on water quality in the connecting channels. The poster will summarize those two methods and results of the assessment based on both methods. The methods used to identify thresholds can be applied by NCCA as well as state and local managers to assess ecological conditions in the connecting channels in the future.
Description:
The St. Marys River and Huron-Erie-Corridor were assessed by EPA for the first time in 2014-2016 as part of the National Coastal Condition Assessment (NCCA). NCCA uses a probabilistic survey design to allow unbiased assessment of ecological condition across the entire Great Lakes nearshore. Nearly 100 sites were sampled in each connecting channel. Measured indicators included water quality, sediment quality, benthos, fish tissue contamination, cyanobacteria, algal toxins, and enterococci. Here we focus on water quality. The NCCA has defined thresholds for assessing ecological condition based on total phosphorus (TP), chlorophyll a (chla), Secchi depth, and near-bottom dissolved oxygen in the Great Lakes. Thresholds have not been defined for connecting channels. Based on a review of available federal, state, provincial, and tribal water quality criteria, we defined two sets of connecting channels water quality thresholds: tributary input-weighted thresholds aimed at protecting conditions within the individual channel, and receiving waters thresholds aimed at protecting the channels and their receiving waters. For TP and chla in the Huron-Erie Corridor, input-weighted thresholds were more protective (conditions appear more poor) than receiving waters thresholds. In St. Marys River, receiving waters thresholds were more protective. Water quality assessment results based on these thresholds will be presented.