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Bacteria Study

High bacteria levels in the St. Lawrence River have had an impact on the use of the river for water contact sports, including swimming, at a number of public sites within the Area of Concern.(AOC map)  Thirty-five of these locations were monitored for faecal coliforms and/or E. coli concentrations in 2003 and it was determined that the criterion for E. Coli in recreational water had not been met in the Area of Concern, although conditions in general appear to have improved since the 1980s. 

“Faecal Bacteria Concentrations in the St. Lawrence River (Cornwall) Area of Concern” prepared by Heather Moore and Jeff Ridal with the St. Lawrence River Institute of Environmental Sciences in March, 2004, provides detailed analysis at the sampling sites including Westley’s Point, Glengarry Park and areas on Cornwall Island where exceedences are most pronounced.  Subsequently there has been some action towards revising the Remedial Action Plan delisting criteria relating to the beach closings/water contact sports Beneficial Use Impairment.

Water sampling conducted during the recreation period in 2007 at Westley’s Point found that at least 75% of samples met the Provincial Water Quality Objective for E. coli.  Because several factors may degrade water quality in the area at different times, it was recommended that the preparation of a pollution plan for the area should include assessments of inputs from nearby tributaries (Raisin River, Finney Creek, Pattingale Creek and Westley’s Creek) on nearshore water quality, relative to inputs from faulty or overcharged septic sources associated with nearshore discharges.

Bacteria sampling along St. Lawrence River (RRCA map) has indicated sporadic high bacteria levels upstream and along the southwest shore of Westley’s Point.  In 2007, sampling in the Westley’s Creek embayment suggested that in addition to the faulty or overcharged septic systems along the shore, upstream tributaries including the Raisin River, Finney Creek and Pattingale Creek may be contributing significantly to the water quality issues at the site.  As well, depending on meteorological and flow conditions, Westley’s Creek located immediately downstream of the subject site may periodically be adding to problems.  Although sampling did not provide evidence that the existing tile drain outlet in the Westley’s Creek embayment area is contributing to bacterial issues, it does provide a potential conduit for contaminants and alternatives should be explored.

Currently, samples are being collected on 4 occasions throughout the swimming season along the St. Lawrence River shoreline and towards mid-stream to assess the impacts of tributary plumes impinging on swimming areas. Sampling are conducted along 5 transects below each tributary.  Each transect consists of 3 sampling sites starting nearshore and moving into offshore waters. Specific conductivity, dissolved oxygen and temperature are being monitored in the field to delineate the plumes. Water samples are being collected for analysis of E. coli, TSS, TP, chl a, algae and optical brighteners.

For additional information, please contact Chris Critoph, Manager of Environmental Services.  chris.critoph@rrca.on.ca.   

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Raisin Region Conservation Authority
18045 County Road #2, P.O. Box 429, Cornwall, ON, K6H 5T2
Tel. 613-938-3611   Fax. 613-938-3221