"Cleaner water on tap as Skokie’s O’Brien treatment plant breaks ground on $400 million upgrade," Chicago Tribune

_{From left: U.S. Environmental Protection Agency Region 5 Administrator Anne Vogel, Metropolitan Water Reclamation District of Greater Chicago Board of Commissioners President Kari K. Steele, Board of Commissioners Vice President Patricia Theresa Flynn, Commissioner Cameron Davis, Commissioner Beth McElroy Kirkwood, Commissioner Eira L. Corral Sepulveda and Commissioner Precious Brady-Davis break ground on Battery E at the Terrence J. O’Brien Water Reclamation Plant in Skokie on Oct. 8, 2026. (Claire Murphy/Pioneer Press)}

Nearing 100 years of operation at its Terrence J. O’Brien Water Reclamation Plant in Skokie, the Metropolitan Water Reclamation District of Greater Chicago (MWRD) is investing in a new water treatment system, one officials say will ensure cleaner water and prepare for future regulatory requirements and another century of service for more than a million people across 143 square miles to whom the plant serves every day.

Battery E, as the district labels it, is the fifth battery, or group of treatment tanks and associated infrastructure equipment, to be constructed at the site.

The project, which broke ground Oct. 8, is a nearly $400 million investment by the water district, one of the largest to date in MWRD’s 137-year history, according to officials.

“O’Brien Plant was opened in 1928 and a lot of the infrastructure you see around here has been around since 1928, so it’s aging, it needs maintenance and rehab,” said Aruch Poonsapaya, a managing engineer for the plant.

“But also the key driver [in this new battery] is nutrient removal,” Poonsapaya told Pioneer Press.

Battery E will utilize advanced technology to significantly reduce the amount of phosphorus present in the waste and stormwater the plant treats and later returns to the North Shore Channel of the Chicago River system from residents’ sinks and drains, Poonsapaya said.

“Phosphorus is essential to life, but too much phosphorus, as most of us know…can fuel excessive algae growth, reduce oxygen levels and harm aquatic ecosystems,” MWRD Board of Commissioners President Kari K. Steele told leaders from Skokie, Evanston and the U.S. Environmental Protection Agency at Battery E’s Oct. 8 groundbreaking ceremony.

_{A construction worker stands in the field where the new Battery E treatment system is set to be constructed at the Terrence J. O’Brien Water Reclamation Plant in Skokie on Oct. 8, 2026. Battery E is the fifth battery, or group of treatment tanks and associated infrastructure equipment, to be constructed at the site. (Claire Murphy/Pioneer Press)}

“This impact on water quality can impact downstream North Shore Channel, to the North Branch of the Chicago River, all the way south to the Des Plaines River and the Mississippi River,” she added.

“This project reminds us that we are all tied together by water.”

Water that flows down the drains of approximately 5.19 million people’s homes, or about 90% of the Cook County area, will eventually come to one of the district’s seven water reclamation plants before it is later cleaned and sent downstream, Steele said Thursday.

The plant works to screen, filter and settle out waste and sewage through a complex mechanical process, Poonsapaya clarified. This is known as primary treatment.

Primary treatment removes about 60-70% of contaminants in the water, before a secondary treatment system, which is what Battery E will help support, filters the water to about 97-99% clean.

“We’re removing pretty much all the contaminants so that the water that goes back into the river is clean. It’s not necessarily drinkable, potable, but it’s very safe for human contact,” he said.

_{An above ground air main pictured at the Terrence J. O’Brien Water Reclamation Plant in Skokie on Oct. 8, 2026. An air main is a large-diameter pipeline system responsible for distributing compressed air to the plant's biological treatment systems. (Claire Murphy/Pioneer Press).}

As environmental standards become more stringent, Battery E will also help the O’Brien plant meet new phosphorus discharge limits taking effect in 2027 and 2030, according to Steele.

“We are dealing with unpredictable flows, changing weather patterns, emerging pollutants and excessive nutrients,” Steele told officials at the groundbreaking ceremony.

“Our infrastructure must evolve with that. Our treatment of wastewater must evolve with all the changes in our environment.”

Skokie Mayor Ann Tennes, whose municipality houses the water treatment plant, said in her public address Thursday that the groundbreaking marks an important step in keeping the village’s water quality safe while also ensuring that “critical infrastructure is prepared for the future.”

_{Skokie Mayor Ann Tennes speaks at a groundbreaking ceremony for the construction of Battery E at the Terrence J. O'Brien Water Reclamation Plant in Skokie on Oct. 8, 2026. (Claire Murphy/Pioneer Press)}

Skokie has worked with MWRD on multiple sustainability goals throughout the decades, Tennes said, including helping the village to reduce its community-wide water usage by 7.5%, which is nearly 200 million gallons annually, by 2030.

“Wastewater infrastructure may not be glamorous or something that most of us think about every day, unless you live near it… but it’s absolutely essential,” Tennes added.

Battery E will take about four years to complete, according to the district, likely employing hundreds of tradespeople throughout its multi-year construction process.

https://www.chicagotribune.com/2026/10/12/cleaner-water-skokies-treatment-plant-upgrade/