Disclaimer: We are not datacenter cooling experts. We are just like everyone else in Ohio and around the nation - trying to understand a complex challenge. These are some of our thoughts.

Ohio has become a Silicon Heartland, but the infrastructure powering it is currently on a collision course with Lake Erie. While data center providers increasingly pitch closed-loop systems as the ultimate conservation win, the technical and regulatory reality is far more complex.

1. The Blowdown Reality: It's Not a One-Time Fill

A closed-loop system is not a permanent vault of water. To prevent mineral scaling and bacterial growth, these systems must be periodically flushed. This process is called blowdown.

  • How often does it happen? Most closed-loop facilities perform a "bottom blowdown" daily or once per shift to remove sediment.
  • Cycles of Concentration: Engineers track how many times water can circulate before minerals reach dangerous levels. In Ohio, most systems are pushed to 4–6 cycles. This means for every 4–6 gallons used, 1 gallon is discharged as waste and replaced with fresh water.
  • The Scale of Discharge: For a large 10 MW facility, even a "water-efficient" closed-loop system can discharge over 3 million gallons of blowdown water every month.

2. The Ohio EPA General Permit

The most significant policy shift of 2026 is the Ohio EPA's proposed General Permit.

  • One-Size-Fits-All: Instead of individual site reviews that account for a specific river's health, this permit would allow data centers to discharge wastewater into Ohio waterways with minimal oversight.
  • Admitted Degradation: The EPA's own draft permit states that a lowering of water quality is necessary to accommodate important social and economic development.
  • PFAS and Thermal Pollution: The permit lacks strict limits on forever chemicals (PFAS) and heat. Discharging hot water into Lake Erie directly fuels the harmful algal blooms that already threaten our drinking water.

The Citizen's Toolkit: Demand Accountability

If a data center is proposed in your community, do not let "closed-loop" be the end of the conversation. Use these contact points to demand transparency.

Call Your Representatives

Ask them to support site-specific environmental reviews instead of blanket General Permits.

  • Senator Kent Smith (D-Euclid): 614-466-4857 | smith@ohiosenate.gov
  • Representative Munira Abdullahi (D-Columbus): 614-466-2473 | Rep09@ohiohouse.gov

Contact the Ohio EPA

The public comment period for General Permit OHD000001 is a critical battleground. Even if the formal deadline has passed, the agency still accepts written comments. Contact the Division of Surface Water and reference permit number OHD000001.

Questions to Ask at Any Public Meeting

  • "What is the facility's daily blowdown volume, and where does it go?"
  • "Has an individual site-specific environmental review been conducted?"
  • "What are the PFAS and thermal discharge limits for this specific site?"
  • "How does this discharge affect the nearest watershed and Lake Erie's algal bloom forecasts?"

Closed-loop is a real and meaningful improvement over once-through cooling. But it is not a silver bullet, and it should not be the end of public scrutiny. Ohio's water is a public resource. The data center boom is a public policy choice. Both deserve the full truth.