Heavy rains impacting Milwaukee wastewater treatment

After a wet August, the heavy rains are having an impact on our fresh water. Millions of gallons of storm and wastewater are going untreated and being dumped into Lake Michigan. 

"If we get an inch or two of rain over 24 or 12 hours, typically that's not a problem," Bill Graffin with Milwaukee Metropolitan Sewerage District (MMSD) said. "When you get two inches of rain in 20 minutes, you're going to have issues somewhere."

MMSD says their tunnels and water treatment facilities are at or near capacity after the rains. So that means millions of gallons of water are going untreated. 

"If we get an inch of rain over our service area, that's 7.1 billion gallons of water," Graffin said. "For comparison, the deep tunnel holds 521 million gallons."

At the end of August, those storms produced combined sewer overflows of 295 million gallons. It also produced less than a million gallons of isolated separate sewer overflow. All of it was pumped into the lake. 

However, Graffin says it's not as bad as it sounds.

"Even with this wet year we've had, we've captured and cleaned 98.5 percent of every drop of water that's gotten into the regional sewer system," Graffin said. "That's been the track record since 1994."
Before 1994, the deep tunnel was not around and even more untreated water was dumped into the lake. So it was a much different scene with the fresh water.

"This was an open sewer," Graffin said. "All of the rivers were. It supported hardly any aquatic life because every time it rained, there would be a sewer overflow. Prior to the sewer systems being put in, all the sewage was just dumped straight into the rivers."

But despite the advancements, the care of our fresh water is still a concern for one local group. Cheryl Nenn with Milwaukee Riverkeeper released the following statement about the overflow:

"Milwaukee Riverkeeper is concerned that MMSD has had their 5th sewage overflow of 2018. Not including the combined sewer overflow event  that started last night, there has been over 750 MG of untreated sewage  and stormwater released into our rivers since June (and this figure  does not include partially treated sewage that has also been released directly from Jones Island). We have had 4 CSOs  events in August alone, which is unprecedented. Although our region has  been blanketed by unprecedented rain, having 5 overflows since June  harms our waterways. Untreated sewage and stormwater impacts water quality and aquatic life and affects the ability of our  community to safely use our rivers and beaches for recreation.

In  addition to MMSD, many local municipalities have also released large  volumes of untreated sewage to prevent basement backups in their communities.  We, as a community, need to come together with our city leaders and  leaders at MMSD to aggressively address this problem and devise  innovative solutions to fix our old and failing infrastructure. Efforts to install more green infrastructure and practices to collect,  treat, and infiltrate storm water need to be massively scaled up to make  a difference. In addition to green infrastructure, we also need to  protect our wetlands, floodplains and riverfront natural areas, which help protect our cities from flooding impacts and  sewage overflows by soaking in more rain water. We urge all community  members to get involved in being part of the solution"

"We want to get the tunnel pumped out and get everything ready to go for the next storm," Graffin said. "No one wants this but at the same time, when it gets into a basement and it's not properly cleaned up, that can cause health issues."

With a stretch of dry weather ahead of us, MMSD says they should be well on their way to getting back to normal processing.

"During bouts of dry weather, [we process] anywhere from 50 to 80 million gallons a day at each plant," Graffin said. "During wet weather, those plants will ramp up to 300 million gallons per day."
 

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