Assessing sediment quality in the Great Lakes Connecting Channels using National Coastal Condition Assessment protocol
Citation:
Wick, M., M. Pawlowski, Dave Bolgrien, T. Angradi, J. Scharold, M. Pearson, M. Nord, E. Hinchey, Jim Lazorchak, AND R. Ellison. Assessing sediment quality in the Great Lakes Connecting Channels using National Coastal Condition Assessment protocol. SETAC North America, Minneapolis, MN, November 12 - 16, 2017.
Impact/Purpose:
We will present results of our sediment quality assessment for the connecting channels of the St. Marys River and Huron-Erie Corridor. Our probabilistic study will be compared to targeted sampling efforts in areas of known concern for contaminants to evaluate how the probabilistic study design captures the range of known conditions within the system. Our results will help managers improve restoration and remediation design and evaluation efforts in the Areas of Concern in Great Lakes connecting channels.
Description:
The EPA Office of Water’s National Coastal Condition Assessment (NCCA) helps satisfy the assessment and antidegradation provisions of the Clean Water Actby estimating water, sediment, and benthic quality conditions in the Great Lakes nearshore on a five-year cycle starting in 2010. Beginning in the 2015 NCCA cycle, the connecting channels of the Huron-Erie corridor (HEC; 2014, 2015) and St. Marys River (SMR; 2015, 2016) were assessed through a partnership with Great Lakes National Program Office and Office of Research and Development. Great Lakes connecting channels include Areas of Concern designated under the Great Lakes Water Quality Agreement due to legacy contamination and are the focus of ongoing remediation and restoration efforts. The NCCA probabilistic survey design allows estimates of condition based on water, benthic, and sediment quality. These condition estimates offer the opportunity to understand current conditions across the connecting channels and can aid in the design of restoration efforts and assessment of restoration success. To assess sediment quality, NCCA uses an index based on sediment chemistry and sediment toxicity. We compared population estimates to targeted sampling of sediment in AOCs in the HEC and SMR to better understand how the NCCA probabilistic design captures the range of conditions present in each system. For example, preliminary results from the 2014 HEC survey suggest that sediment quality was good in 48% of the survey area and that only 2% of the area was in poor condition.Targeted sampling of sediment chemistry in depositional areas of the Detroit River AOC showed that poor sediment conditions were underestimated in the 2014 survey. The area with poor sediment quality conditions was approximately the same as the error of the population estimates. An increase in point density or intensification in depositional areas would allow the assessment to capture fine-scale variability in the population estimate, but increase cost and effort. At the system-wide scale of the assessment, which included the navigational channel, the sediment quality conditions were fair to good.Sediment chemistry and toxicity data collected in 2015/2016 in HEC and SMR will be compared to respective targeted sampling efforts. Our findings highlight limitations of probabilistic sampling but also show the importance of system-wide studies for a holistic perspective of each connecting channel system.