Large data centers are springing up across Ohio. They can use huge amounts of freshwater – and may expel huge amounts of wastewater. The wastewater can be hot and contaminated with pollutants.
The Ohio EPA is proposing to issue a new, general permit that would allow data centers to discharge wastewater into Ohio’s rivers, streams, and Lake Erie under a “one-size-fits-all” permit with minimal oversight.
This approach would weaken water protection at a critical time and could put drinking water, public health, and aquatic ecosystems at risk – especially in the Lake Erie watershed, which is already under stress from nutrient pollution and harmful algal blooms.
Ohio EPA’s proposed general National Pollutant Discharge Elimination System (NPDES) permit would:
- Treat all applicable data centers the same, regardless of size, water use, cooling technology, or location
- Allow pollution from chemicals used in data center cooling equipment to enter streams, rivers, and drinking water sources, including Lake Erie, with few limitations or monitoring requirements
- Increase the risk of harmful algal blooms in Ohio’s waterways – including Lake Erie and the Ohio River – by allowing thermal pollution and by not setting any limits for nutrients such as nitrogen and phosphorous, which are already present in freshwater drawn from Ohio waterways and which data centers can concentrate through evaporative cooling
- Raise costs for communities that must treat more contaminated water
- Harm communities, fish, and wildlife, as well as job and recreation opportunities
- Reduce public transparency and accountability
- Require minimal monitoring for a small handful of contaminants
More than half of Ohioans rely on Ohio surface waters for their drinking water. Lake Erie alone supplies water to millions of people and supports fisheries, tourism, shipping, and recreation across northern Ohio. We cannot afford to weaken protections now.
What you can do
Ohio EPA is accepting public comment until 5:00 PM on January 16, 2026. Your voice matters! Contact the Ohio EPA today and urge them NOT to issue a general permit for data center wastewater.
Here’s how to send your comment:
- Draft your note to Ohio EPA.
- Start by explaining why clean water in Ohio matters to you. For example: Your drinking water comes from Lake Erie or an Ohio river or stream. You fish, boat, or swim in local waters. You work in a water-dependent industry (tourism, fishing, shipping, agriculture). You care about public health, wildlife, and the Great Lakes.
- Then ask Ohio EPA NOT to issue a general NPDES permit for data center discharges and instead require individual, site-specific permits that fully protect water quality and uphold strong protections for all Ohio waters. If it’s helpful, use some of the following language and make it your own.
I urge the Ohio EPA NOT to issue a general NPDES permit for data center wastewater discharges. Issuing a broad, one-size-fits-all permit would weaken the protection of Ohio’s rivers, streams, and Lake Erie. These waters are too important to risk through a permitting approach that reduces oversight and accountability.
- Data centers vary widely in size, design, location, and cooling technology, and do not discharge the same types or amounts of pollutants;
- The permit increases the risk of harmful algal blooms in Ohio’s waterways – including Lake Erie and the Ohio River – by allowing thermal pollution and by not setting any limits for nutrients such as nitrogen and phosphorous, which are already present in freshwater drawn from Ohio waterways and which data centers can concentrate through evaporative cooling;
- The permit does not provide Ohio EPA with enough oversight to address the impacts on public health, water quality, and ecosystems that will result from shifting to a general permitting approach;
- Communities, taxpayers, and water customers will face increased water treatment costs and health consequences from a broad authorization of lower water quality; and
- Ohioans have the right to fully understand potential contamination through individual permitting, which allows for site-specific review and public comment.
I urge you to withdraw the proposed general NPDES permit for data center discharges and instead require individual, site-specific permits that fully protect water quality and uphold strong protections for all Ohio waters.
2. Submit your comment to the Ohio EPA. Go to https://ohioepa.commentinput.com/?id=csDN8pRrg and follow the instructions
Take action by January 16th at 5:00 PM! And, if you have a minute, email alliance@greatlakes.org to let us know you contacted the Ohio EPA.
Thank you for speaking out to protect Ohio’s waters!
You can learn more about the demand for Great Lakes water and the potential impacts of data centers in our recent report, A Finite Resource: Managing the Managing the Growing Water Needs of Data Centers, Critical Minerals Mining, and Agriculture in the Great Lakes Region.