Analysis of reports filed with the state Department of Environmental Quality indicate that Jackson bypassed treatment at its Savannah Street Wastewater Treatment Plant about one day in eight, according to The Clarion-Ledger (http://on.thec-l.com/Q4q9HD).
Such bypasses often occurred after a half-inch of rain or less, the newspaper reported.
The sewer system is old and failing. Safeguards no longer function properly because of years of neglect.
However, DEQ officials say health risks appear minimal. It has found bacteria levels too high for swimming or wading in the Pearl River only four times since 2009. Nine other water contact advisories — eight of them in the last two years — were issued for creeks.
Before diverting excess sewage, the city dilutes it with treated water, adds chlorine to kill bacteria, then dechlorinates the mixture so chemicals don't go into the river.
Sewage dumps can kill off fish or cause a spread of bacteria, but DEQ spokesman Robbie Wilbur said the metro area had only two mass fish kills since 2009. Nor has it found any increase in human digestive diseases that might be caused by raw sewage, he said.
Sometime this month, The Jackson City Council is expected to approve an agreement to spend hundreds of millions of dollars on sewer system upgrades and to pay the EPA a fine for violating the Clean Water Act.
Negotiations have been going on for two years. The consent decree would be the first of its kind in Mississippi, but similar agreements have become common around the country.