Joliet weighs water footprint of massive data center amid aquifer depletion fears

Joliet weighs water footprint of massive data center amid aquifer depletion fearsDevelopers of the proposed Joliet Technology Center are promising a closed-loop cooling system capped at 150,000 gallons per day to protect the city’s strained deep well aquifer ahead of a 2030 transition to Lake Michigan water.

The proposed 24-building data center campus will utilize a closed-loop chilled water system to avoid the high water consumption of traditional evaporative cooling.

The annexation agreement caps average daily water use at 150,000 gallons, enforceable by fines of three times the water rate and potential service shutoffs.

Industrial discharge from the cooling system is prohibited without specific city pretreatment permits, and unapproved waste must be trucked off-site.

The council also approved a 0% interest IEPA loan for 2026 lead service line replacements and a low-interest IEPA loan for water main replacements.

Joliet City Council held a marathon public hearing on March 16, 2026, regarding the annexation and development of the Joliet Technology Center, an 800-acre, 24-building data center campus proposed by Hillwood and Powerhouse. A major focal point of the debate was the facility's water consumption and its impact on the city's depleting deep well aquifer, which Joliet relies on ahead of a planned transition to Lake Michigan water in 2030. To mitigate water stress, the developers abandoned initial plans for direct evaporative cooling, which could have consumed up to 5 million gallons per day during peak heat. Instead, they are proposing a closed-loop chilled water system. Todd Sworniak, a mechanical technical manager with Siska Hennessy Group representing the developer, explained that once the system is filled, the water remains in the pipes with no evaporative blowdown required. Under the proposed annexation agreement, the campus would be capped at an average of 150,000 gallons per day (GPD), with a maximum peak day usage of 300,000 GPD. Director of Public Utilities Allison Swisher noted that the city's metering technology provides data points every six minutes to monitor compliance. If the developer exceeds the cap, the city can impose fines of three times the standard water rate, and ultimately retains the right to terminate water service. Swisher also clarified the site's wastewater discharge rules. The annexation agreement only permits the discharge of domestic wastewater into the city's sanitary sewer. Any non-domestic wastewater—such as water drained from the cooling system during maintenance or lease turnovers—must be tested and permitted under the city's pretreatment ordinance. Depending on the wastewater's characteristics, it may require on-site pretreatment, incur treatment surcharges at the city's plant, or be rejected entirely, forcing the developer to truck the waste off-site at their own expense. Despite these technical assurances, dozens of residents voiced fierce opposition, citing fears over localized well drawdowns, the fragility of the local aquifer, and the potential for chemical leaks from the cooling loops. The council ultimately recessed the meeting to March 19 without taking a final vote on the annexation. In separate utility business, the council approved two Illinois Environmental Protection Agency (IEPA) loans for 2026 capital projects: a 0% interest loan for lead water service line replacements, and a 2.16% low-interest loan for water main replacements. The council also approved a $49,995 contract with Gasvoda & Associates for ISCO portable sewage flow meters to diagnose collection system issues.