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 2006. 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 April 29 to September 15 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 ten sites on the lake and six sites in the watershed.

 

Concurrent sediment and water samples were collected at 14 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 five 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 2006 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 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 highest Lake St. Clair sample site annual E. coli Geomean was 123 E. coli CFU/100 mL at the Clinton River (n23).

 

The 2006 average annual nitrate level (1.3 mg/L) at the Clinton River (n23) was twice    the 2005 average annual nitrate level (0.67 mg/L) at this site and more than twice the level (0.50 mg/L) of the next highest site, the Salt River (n28).  Historically, the levels of nitrate at the Clinton River (n23) correlate significantly with total phosphorous, but they do not correlate with any rainfall levels, as measured at Selfridge Air National Guard Base.  This tends to undercut the fertilizer runoff explanation for the high nitrate levels at this site.

 

Statistically significant downward trends in aqueous mercury levels were noted at the Clinton River (n23) and the Milk River (w58).

 

A statistically significant downward trend in E. coli concentration at the Mt. Clemens Water Treatment Plant Intake (o7) was noted from 1998 to 2006.

 

Lead and PNA levels decreased dramatically from 2005 levels in the sediment at the Clinton River at Moravian (w68).

 

The highest PNA level detected in this year’s Lake St. Clair assessment, 26 mg/kg PNA, was found at Stephens Relief Drain (n4).  In 2006, this site also demonstrated the highest annual levels for ten other sediment chemistry parameters, lead, zinc, cadmium, chromium, arsenic, nickel, ammonia, chemical oxygen demand, total organic carbon, and PCBs, ever found at this site.

 

PCBs were detected at Milk River (n1), Liberty Drain (n2), Stephens Relief Drain (n4), Martin Drain (n6), Clinton River Spillway (n19), and Bear Creek at Old 13 Mile Rd. (w82).

 

A statistically significant correlation between aqueous E. coli and foreshore sand E. coli was found at Blossom Heath Beach between 2004 and 2006.

 

Dissolved oxygen and pH were found to be directly related at the Clinton River (n23) and Irwin Branch Relief Drain (n24).

 

A statistically significant decrease in turbidity was observed at Irwin Branch Relief Drain (n24) from 1998 to 2006.

TO VIEW THE 2006 SITE SUMMARIES click here

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