Inside the command center of the Metropolitan Water Reclamation District of Greater Chicago (MWRD), it has been all hands on deck.

Between July 2 and July 4, about 8-10inches of rain fell over 48 hours, creating a precarious situation at two of the district’s large deep tunnel reservoirs.

John Murray, MWRD’s executive director, spoke to WGN-TV on Thursday about the work being done.

“This is trending downward,” Murray said. “We’ve opened up some gates down at Lockport to let some water out so that if a storm comes in the next day or so, we have capacity in our waterway.”

McCook’s reservoir was 98% full as of Monday, and hit capacity on July 6. 

The Thornton reservoir was 94% full earlier in the week— the highest level it’s reached since it was built in 2015. 

“With McCook full and also the Thornton system being almost full, we collected 13 billion gallons, which is the equivalent of 20,000 Olympic-sized swimming pools,” Murray said. “It’s been a record time period for us.”

As of Thursday, the McCook reservoir is at 66% capacity. Thornton sits at 88%, thanks to a careful and calculated balancing act. 

“As soon as the storm is over and conditions have subsided and we’re sure the sewer levels are where they should be, then we start to turn on big pumps and take water out of the reservoirs,” Murray explained.

“Pulling a billion and a half gallons out of the deep tunnel system to make room if another storm comes through.”

According to the WGN Weather team, since June 1, the area has received nearly 12 inches of rainfall, making this the second wettest start to summer in the past 100 years, keeping John Murray and his team on their toes. 

But is it exciting or nerve-wrackingly stressful? It’s all of that, Murray says.

“We want to help the people of Cook County,” Murray said. “We worry they could flood, so yes, it’s all of that.”

In six years, the second phase of the McCook Reservoir expansion will be complete, Murray says, adding another 6.5 billion gallons of water storage.

Watch the program