2 locks opened during record rainfall

July 25, 2011

A swim ban remains in place at Oak Street Beach due to water quality as of Monday afternoon. A swim advisory- where swimming is permitted, but caution is advised- is in effect at Rainbow Beach, 12th Street Beach, Montrose Beach and Osterman (Hollywood) Beach.

Opening the locks likely saved the city from an even more serious flooding event. It works like this: Whenever Chicago gets a major rainfall that causes flooding, people start pointing fingers as to who is to blame. The antiquated sewer system? The water reclamation district?

On Monday, a civil engineer explained the procedure to ABC7 at the command center.

"There is no magic button to relieve flooding. And there are no magic gates either," Ed Staudacher, Metropolitan Water Reclamation District, said.

When nearly seven inches of rain fell in the span of two hours in the city and suburbs over the weekend, the control room at the metropolitan water reclamation district went into action. They monitor the storm through radar, an on-call meteorologist, and the rising levels at their different waterways to make sure they didn't overflow. At 2:30 a.m., the call was made to open the locks at Wilmette. At 3:30 a.m., the locks at the Chicago River downtown were opened. But this isn't a decision they made lightly.

"It's a last resort to prevent any type of overbank flooding and the reason why it's a last resort is because we get our drinking water from Lake Michigan, so we're trying to protect Lake Michigan and at the same time protect the homeowners along those waterways from flooding," Staudacher said.

The locks are only opened when the river levels, which are usually kept lower than the lake level, threaten to overflow. That's when the district allows the storm water to go into Lake Michigan. However, even once the locks are opened, relief isn't be immediate

"A lot of people believe if you open these gates it's going to stop flooding in their basements. These systems don't have the capacity to get the storm water to us," Staudacher said.

Furthermore, the locks will only impact the communities that are adjacent to the waterways controlled by the district.

"You have areas that drain into Des Plaines and Salt cCreek and nothing we do with the locks will affect those areas. We have no effect on those natural rivers," Staudacher said. "By us opening the gates, it has very little impact on the homes in these outlying suburbs."

A recently built deep tunnel system that increases the reclamation district's storm and sewage capacity is functional, but Staudacher said it was already half full from a previous storm when Chicago was drenched. A system of reservoirs is currently under construction. Those will increase capacity tenfold. However, the first one won't be open till 2015.

Official say that Saturday's rainfall was so intense that even had the reservoirs been built, there would still be flooding.

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