Using water quality to assess ecological condition in the St. Marys River and Huron-Erie Corridor

Session: Poster session

Molly Wick, EPA, Oak Ridge Institute for Science, wick.molly@epa.gov
Matthew Pawlowski, ORISE, pawlo023@d.umn.edu
Theodore Angradi, U.S. EPA Mid-Continent Ecology Division, angradi.theodore@epa.gov
David Bolgrien, US Environmental Protection Agency, Bolgrien.Dave@epa.gov
Mari Nord, U.S. EPA Region 5, nord.mari@epa.gov
Elizabeth Hinchey Malloy, U.S. EPA GLNPO, hinchey.elizabeth@epa.gov
Jill Scharold, US EPA, scharold.jill@epa.gov
Anne Cotter, EPA, anne.cotter@epa.gov
Mark Pearson, US EPA, pearson.mark@epa.gov
Will Bartsch, Oak Ridge Inst. for Sci. and Education, EPA-MED, bartsch.will@epa.gov
Julie Lietz, EPA, ORISE, lietz.julie@epa.gov
Tim Corry, Environmental Protection Agency ORD-MED, Corry.Timothy@epa.gov

Abstract

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.

1. Keyword
water quality

2. Keyword
phosphorus

3. Keyword
assessments

4. Additional Keyword
connecting channel