2008 was another grim year for water quality as combined sewer overflows were up slightly from last year in the Metro Detroit area.
A combined sewer overflow is when the sewer system gets overwhelmed during a storm and the storm water and sewage from homes releases into the waterways rather than back up into the streets.
In recent years many local projects have been aimed at helping the overburdened Detroit Wastewater Treatment Plant with the construction of retention ponds. Without a doubt it has helped, when there is a heavy rain these retention ponds act as holding tanks to hold the overflowed storm water and sewage. The solids are allowed to settle and then the water is treated with chlorine to kill bacteria, then the water is released into the waterways. This is called partially treated sewage.
Another big project that is in its early stages is the $600 million Upper Rouge Tunnel project. The project calls for a tunnel adjacent to the banks of the Rouge River and is designed to hold 218 million gallons of storm water at 28 combined sewer overflow locations throughout the Detroit area.
So how did Metro Detroit do this year?
The grand total for all categories of sewage releases, (including raw sewage, partially, treated sewage, and diluted raw sewage) for St. Clair, Macomb, Oakland, and Wayne counties was over 26 billion gallons of sewage.
Metro Detroit releases far more sewage into the waterways than anywhere else in Michigan. Last year Wayne county released 23 billion gallons of sewage while the rest of Michigan released only 3 billion gallons.
These large sewage releases are of concern in light of a recent Metro Times article reporting that the USGS is shutting down water quality testing in the Rouge River due to budget cuts. The problem with this is it will be impossible to gauge any future water quality progress or deterioration in the years to come.
Another interesting aspect of this is that Canadian sewage overflows are not publicly reported. The Canadian Ministry of Environment collects some data but it is often inconsistent. In 2006 a Canadian environmental organization; Ecojustice rated Windsor as the third worst city in the Great Lakes for combined sewer overflows. This is an important thing to keep in mind when looking at the numbers.
Here is how the individual numbers break down for each county.
Partially Treated Sewage: 23.2 Billion gallons
Diluted Raw Sewage: 1.2 Billion Gallons
Raw Sewage: 103 million gallons
Partially Treated Sewage: 119 million gallons
Raw Sewage: 4 million gallons
Partially Treated Sewage: 1.3 billion gallons
Raw Sewage: 2 million gallons
St. Clair County
Partially Treated Sewage: 60.7 million gallons
Raw Sewage: 3.9 million gallons