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 2007. 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 twenty-three 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 thirteen 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 twenty 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 April 29 to September 15 at all 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 nine near shore and seven off shore sites.  Sediment chemistry samples were collected at thirteen near shore locations. Aqueous samples for trace mercury analyses were collected at ten sites on the lake and six sites in the watershed.

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

Bathing beach water and sediment sampling was conducted at fifteen 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 twenty 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 2007 Lake St. Clair Assessment

(See cover for sample site locations)

The annual geometric mean did not exceed the 30 day Total Body Contact Standard of 130 E. coli MPN/100 mL at any Lake St. Clair sample site during 2007, nor did the geometric mean for all Lake St. Clair sample sites exceed this standard during any individual sampling event.  The highest Lake St. Clair sample site annual E. coli Geomean was 119 E. coli MPN/100 mL at the Milk River (n1). 

The daily geometric mean for E. coli samples taken from all Lake St. Clair sample sites shows a statistically significant decrease over the period from 1998 to 2007. 

The Clinton River (n23) had the highest annual average nitrate level (0.45 mg/L) of any Lake St. Clair sample site.  This is the ninth consecutive year this has happened. 

A statistically significant downward trend in aqueous mercury concentration was noted at the Clinton River Spillway (n19) from 2001 to 2007. 

The highest aqueous mercury concentration (7.0 ng/L) found in 2007 was found at the Clinton River Spillway at the Weir (w43).

The highest 2007 total phosphorous concentration (0.183 mg/L) in the Lake St. Clair samples was found at the St. Clair Shores Coast Guard Station site (o10).

The highest 2007 orthophosphate concentration (0.39 mg/L) in the watershed samples was found at Red Run Drain at Utica Rd. (w55) in a dry weather sample.

The highest 2007 sediment PCB concentration (0.95 mg/kg) was found at Milk River (n1).

The highest PNA level detected in 2007 in the Lake St. Clair sample sites was 12 mg/kg,   found at the Stephens Relief Drain (n4). The highest concentration of PNAs found in the watershed (18 mg/kg), was found at Bear Creek at Old 13 Mile Rd (w82).

Dissolved oxygen and water temperature were found to be directly related at the Irwin Branch Relief Drain (n24).

TO VIEW THE 2007 SITE SUMMARIES click here

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