Study Design

A water quality monitoring program was conducted on Lake St. Clair and the Clinton River Watershed during the spring, summer and fall of 2004. The overall purpose of this project was to collect data and characterize water and sediment quality in the Lake and Watershed.  

The project included five complementary monitoring activities; near shore, off shore, watershed, bathing beach and wet weather.  The near shore testing was conducted at 23 major inputs to the lake, including the mouths of the Clinton River and Spillway, urban storm drains, smaller rivers and creeks and retention basin discharge points.  Near shore sampling was conducted adjacent to the outfalls, however, many samples were collected further from the outfalls than during previous years due to lower lake levels.  Off shore sampling was conducted at 13 sites.  Seven of the off shore locations corresponded to major near shore sample locations, two were adjacent to public beaches, two were municipal drinking water intake sites and the mouths of the North and South Channel.  Water chemistry samples were collected during the spring, summer and fall seasons at 20 near shore and all off shore sites. Aqueous bacteriological samples and water quality meter readings (temperature, dissolved oxygen, conductivity, pH and turbidity) were collected weekly from May 6 to September 30 at all 23 near shore sites. Off shore water bacteriology testing and water quality meter readings were collected during the spring, summer and fall seasons.  Sediment E. coli samples were collected during the summer and fall from 9 near shore and 7 off shore sites.  Sediment chemistry samples were collected at 13 near shore locations. Aqueous samples for trace mercury analyses were collected at 10 sites on the lake and 6 sites in the watershed.

Concurrent sediment and water samples were collected at 20 locations in the watershed for bacteriological examination during the spring, summer and fall.  Sediment chemistry samples were collected at 5 locations.  Water chemistry samples were collected at 5 locations during wet and dry weather conditions. 

Bathing beach water and sediment sampling was conducted at 15 sites on the public beaches along Lake St. Clair (Blossom Heath, Memorial Park, HCMA Metropark, and New Baltimore).  The sampling was performed at locations established for the Bathing Beach Water Quality Monitoring Program.  Samples were collected monthly from July through September, and analyzed for water and sediment bacteriology. 

Event sampling was conducted in the watershed in response to rain events exceeding one half inch in a 24-hour period. Water samples were collected for bacteriological analysis at 20 strategic locations between April and September. Sample locations were selected based on three criteria: proximity to known sewer overflows, locations of frequently high bacteria counts and at the most downstream sample site of each major sub-watershed drainage area of the Clinton River.

Executive Summary

Key Findings in the 2004 Lake St. Clair Assessment

The annual geometric mean did not exceed the 30 day Total Body Contact Standard of 130 E. coli CFU/100 mL at any Lake St. Clair sample site during 2004, nor did the geometric mean for all Lake St. Clair sample sites exceed this standard during any individual sampling event.

The statistically significant decrease in near shore daily all-site E. coli geometric means, which was first noticed last year, continued for the period 1998-2004.

Statistically significant decreasing E. coli counts were noted at the Clinton River (n23) for the period 1998-2004.  A significant relationship between rainfall and E. coli levels was also noted at this site over this time frame.

A statistically significant correlation (r = 0.99) was found between E. coli counts in the foreshore sand and aqueous E. coli monthly geometric means at Metropolitan Beach.

A statistically significant correlation (r = 0.99) was found between sediment and aqueous E. coli monthly geometric means at St. Clair Shores Blossom Heath Beach.

A statistically significant correlation (r = 0.78) was found between aqueous E. coli counts and turbidity at the Salt River (n28).  This relationship was also found in last year's data.

The average annual nitrate concentration exceeded the critical value of 0.3 mg/L at the Clinton River (n23), Metropolitan Beach (06), Salt River (n28), Crapeau Creek (o2), Dykeman Drain (n27) and the South Channel (o13).  The average concentration at the Clinton River (n23) (1.32 mg/L) was more than twice as high as the nitrate concentration at the next highest site, Metropolitan Beach (o6) (0.59 mg/L), which lies directly in the downstream path of the effluent from the Clinton River.

The aqueous mercury concentration at Liberty Drain (n2) was 1.25 ng/L, just beneath the critical value of 1.3 ng/L.  This was more than twenty-five times lower than last year's value of 33 ng/L (which was four times higher than that found at any other Lake St. Clair sample site).  

Sediment metal levels at the Milk River (n1) and Liberty Drain (n2) exceeded Ontario Ministry of the Environment Low Effect Levels for all seven of the metals with published critical values (arsenic, cadmium, chromium, copper, lead, mercury, and zinc).

Statistically significant downward trends in nitrate, total phosphorous, chloride, total organic carbon, and E. coli  were noted at Crapeau Creek (n29) for the period

1998-2004.

A statistically significant downward trend in sediment chromium was noted at Martin Drain (n6) for the period 1998-2004.

TO VIEW THE 2004 SITE SUMMARIES click here

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