Why this score?
Four weighted factors drive the Mercer County risk score. Methodology is fully documented — each input is public data or a reasoned proxy.
Moderate transmission capacity. Hyperscale-scale loads would require new substation work.
Limited water capacity. Cooling-tower designs face significant constraints; closed-loop or air-cooled would be required.
Limited large-parcel availability. Brownfield redevelopment is often the only viable path.
No documented activity in or near the county.
Water infrastructure
Any hyperscale data center in Mercer County would need an Ohio EPA NPDES permit and (for surface water) coordination with the relevant watershed authority. The water source is Grand Lake St. Marys (impaired by algae blooms) and Wabash River headwaters.
Grand Lake St. Marys has chronic harmful-algal-bloom impairment. Ohio EPA review of any significant new withdrawal or discharge in this watershed faces additional scrutiny under existing TMDL conditions.
A single hyperscale data center using evaporative cooling can require 1–5 million gallons per day. Closed-loop and air-cooled designs reduce that draw at higher capital cost — a tradeoff that becomes more relevant as Ohio's water-permitting reviews lengthen.
Electric infrastructure
Grid capacity and transmission access are the single biggest driver of where hyperscale developers actually site projects. Mercer County is served by AES Ohio + Midwest Electric Cooperative.
AES Ohio (formerly Dayton Power & Light) serves the Dayton region. AES has less surplus transmission capacity than AEP or FirstEnergy, which is a structural constraint on hyperscale siting in its territory. Midwest Electric Cooperative serves portions of west-central Ohio. Cooperative board structures make rate decisions more localized but slower-moving, a structural constraint on large new loads.
A single major substation upgrade or new transmission-line announcement can change the power factor significantly without any public proposal having been filed. Utility-survey activity at specific industrial parcels typically precedes a hyperscale proposal by six to twelve months.
Adjacent county activity
Hyperscale campuses cluster near existing transmission and water infrastructure. Activity in adjacent counties is the single best predictor of where a developer will look next.
Shelby County — Project Galaxy — Amazon AWS's $3B Sidney campus — is the largest tax-abatement deal in Shelby County history.
Miami County — Project Klondike — the $1B Meta data center in Piqua, traced via Hunterbrook investigation through J5 LLC's Nevada filings.
State legislative context
Ohio's 2025–2026 legislative session has produced multiple bills targeting hyperscale data centers. Each affects Mercer County directly, regardless of whether a project is currently proposed here.
HB 15 (signed into law in 2025) created the "behind-the-meter" generation framework allowing data centers to install on-site generation that bypasses some local zoning review and PUCO oversight. HB 695 (in committee) would prohibit local officials from signing non-disclosure agreements with data-center developers, with $1,000 fines per violation.
The proposed Ohio Constitutional Amendment from Ohio Residents for Responsible Development (ORRD) would ban hyperscale data centers above 25 MW absent a county-level vote. The campaign needs 413,488 valid signatures from at least half of Ohio's 88 counties by July 1, 2026.
No active data center in Mercer County — yet.
The fastest available policy lever is the Ohio constitutional amendment that would ban hyperscale data centers above 25 MW absent a county-level vote. Ohio Residents for Responsible Development needs 413,488 valid signatures by July 1, 2026 to put it on the November ballot. Find a signing event in your county.
Find a signing event →Independent. Reader-supported. Free to participate.
Compare with other counties
See how Mercer County's score compares to the rest of Ohio's 88 counties.
See all 88 counties ranked →A preparation brief written for your address in Mercer County. Includes your public comment letter, hearing script, public records templates, and county officials. Delivered in 60 seconds.