MMSD issues Water Drop Alert as steady rain passes through

 

MILWAUKEE (CBS 58) -- With rain in the forecast throughout the day Monday, Aug. 14, and the potential for much of the rain to be heavy, the Milwaukee Metro Sewerage District (MMSD) asked people to use less water throughout the day.

As of early Monday evening, the MMSD's Deep Tunnel system was filled beyond half of its capacity. The Deep Tunnel can hold 521 million gallons of water. As of 6 p.m. Monday, the district's real-time tracker reported 293 million gallons in the tunnel. At noon, the tunnel was holding 12 million gallons.

MMSD Public Information Manager Bill Graffin said while the Deep Tunnel, which opened in 1994, greatly limits the frequency of overflow events, they can still happen where there is sustained heavy rain over a widespread area.

"Intensity is key," Graffin said. "I always tell people if we get 1-2 inches of rain in 12-24 hours, it's typically not a problem. It's when you get two inches of rain in 20 minutes, it can inundate the sewer system and end up causing problems."

Graffin said MMSD experiences one or two overflow events per year. When that happens, the sewerage system is overwhelmed; MMSD responds by releasing untreated wastewater into surrounding rivers.

The wastewater ends up in Lake Michigan, and while that's not ideal, Graffin said the district is more concerned with preventing widespread flooding in people's homes.

"Our highest priority during a storm is to keep it out of people's basements," he said. "And so, the only option we have is to have an overflow."

To reduce the risk of an overflow event, MMSD issued a Water Drop Alert, which is a call to everyone in the district's service area to use a little less water.

"Do not do your laundry," Marissa Jablonski, executive director of the Freshwater Collaborative of Wisconsin, said. "Wait until the alert goes away and try not to do your dishes. Use as little water as possible."

MMSD serves 28 municipalities; most of them are in Milwaukee County, but the district also reaches into Brookfield, Mequon and Muskego. 

While heavy, widespread rain will stress the sewer system, Graffin said one thing that helps during Monday's event is that Southeast Wisconsin has seen less rain that usual so far this summer. While dry, hard ground could worsen a flooding event, Monday's rain started out fairly light, softening the ground without flooding it. 

"If the ground was completely hard and we got a ton of rain, it would just all wash downhill," Graffin said. "But now that we're softening up that ground, it's gonna help penetrate some of that water into the ground, which is a big help." 

Graffin added MMSD has recorded rain events with a rate of 13 billion gallons per 24 hours, so even with the Deep Tunnel, there are storms that are too much for the system to take.

With 1.1 million customers, Graffin said a collective effort to limit water usage can go a long way.

"Every drop counts, so what you can keep out of the system during times like these when the system can get overtaxed, please do," he said. "It'll help everybody."

Prior to Monday, MMSD has had one overflow event so far this year. That was back in February. Prior to the Deep Tunnel's construction, MMSD reported 50-60 overflow events per year.