You are here:
EPA’s National Coastal Condition Assessment: Pilot research in Great Lakes connecting channels
Citation:
Wick, M., M. Pawlowski, Dave Bolgrien, T. Angradi, J. Scharold, M. Pearson, M. Nord, E. Hinchey, AND R. Ellison. EPA’s National Coastal Condition Assessment: Pilot research in Great Lakes connecting channels. Binational meeting of the Lake Erie Millenium Network, Windsor, ON, CANADA, February 21 - 23, 2017.
Impact/Purpose:
not applicable
Description:
The EPA Office of Water’s 5-year cycles of national surveys of wetlands, lakes, rivers, and coastal areas help satisfy the assessment and antidegradation provisions of the Clean Water Act. Measuring extant conditions precedes measuring change in conditions. Surveys are challenged to adequately sample extreme conditions occurring in small areas. Extremely bad conditions are targets for remediation. Extremely good conditions are targets for protection. In 2010, the National Coastal Condition Assessment (NCCA) found the majority of the coastal Great Lakes (by area) was in good condition for water (60%) and sediment (51%) quality but not benthos (20%) and fish tissue contaminants (<1%). Low sampling success for biological sampling was an issue. As part of the 2014 Lake Erie CSMI field year, EPA’s Great Lakes National Program Office, working with the Office of Research and Development, began pilot research to integrate connecting channels into Great Lakes surveys. Assessments of the Huron-Erie corridor (HEC; 2014, 2015) and St Marys River (SMR; 2015, 2016) which have previously gone unassessed by NCCA, are being developed. Water, sediment, and benthic quality data from the 2014 HEC survey (n=60) were compared to 2010 NCCA data from adjacent lakes. Water quality rated “poor” (as % area) in HEC was intermediate compared to Lake Huron and Erie regardless of which lake-specific thresholds were used. However, the amount of area classified as “good” was highly dependent on which thresholds were used, with 11% of the HEC classified as good using the Lake Huron thresholds, and 76% classified as good using Lake Erie thresholds. Sediment quality (based on chemistry and sediment toxicity data) was estimated at 48% good which was intermediate to the adjacent lakes. Rocky substrates, hard-bottom and swiftly flowing river channels, and shallow sites meant that 9% of HEC area could not be assessed. While this is less than the 22-25% of Great Lakes nearshore area left unassessed in 2010, sampling success represents an ongoing challenge for connecting channels assessments. Benthic quality (based on the Oligochaete Trophic Index) was classified as poor in 55% of the HEC (by area) in 2014 which was worse than either of the adjacent lakes. However, comparisons of benthic condition between the HEC and adjacent lakes were also obscured by the lower rates of sampling success in the lakes compared to the HEC.The probabilistic survey design allowed separate estimation of conditions in the Detroit River, an Area of Concern under the Great Lakes Water Quality Agreement. Sediment quality was estimated as 11% of area good, 56% fair, 6% poor, and 27% missing (n=18). Analysis of sediment chemistry, alone, found 28% of area good, 56% fair, 0% poor, and 16% missing. A comparison between survey results and recent targeted (or hot spot) sampling found similar spatial patterns of good sediment quality within the channel and upstream of Detroit. Fair conditions were more common downstream of Detroit. However, the survey underestimated the extent of poor conditions clearly present in the targeted data. This may improve when 2015 survey data become available. Both the population-based estimates and site-based spatial patterns of condition are consistent with the Detroit River’s situation within a highly urbanized and industrialized region and in-channel processes that tend to redistribute sediment and contaminants. While targeted sampling identified areas of severe contamination, our system-wide survey showed that these areas represented a small portion of the total system. Overall, the probabilistic design allows us to evaluate the entire Detroit River and HEC system providing previously unavailable and highly valuable context for local managers. Analysis of 2014-2015 HEC data and 2015-2016 St Marys River data is ongoing and results of the connecting channel assessm