The Short Version
Mason's own M-1 and M-2 ordinances define "light industrial" uses as those that are "clean, quiet, and free from objectionable external effects such as noise, fumes, vibrations, odors and traffic patterns." The City's own FAQs for the proposed M-3 ordinance acknowledge that data centers produce all of these impacts. By Mason's own definitions, data centers are not light industrial.
What Mason's Ordinances Actually Say
Let's look at how Mason's existing zoning ordinances define light industrial uses:
M-1: Light Manufacturing District
"It is the purpose of this district to provide opportunities for a variety of industrial activities that can be generally characterized as being of low intensity, including the absence of objectionable external effects such as noise, fumes, vibrations, odors and traffic patterns, and resulting in limited demands for additional public services."Mason M-1 Ordinance (emphasis added)
M-2: General Manufacturing District
"Light manufacturing activity which by the nature of the materials, equipment, and processes utilized are to a considerable extent clean, quiet, and free from any objectionable or dangerous nuisance or hazard including any of the following goods or materials: Furniture and fixtures, paper and paperboard products, jewelry, silverware and plated ware, musical instruments and parts, toys and sporting goods, signs, advertising displays and canvas products, office computing and accounting equipment, jobbing and repair machine shops."Mason M-2 Ordinance (emphasis added)
The key criteria are clear: light industrial uses must be absent of objectionable external effects and must be clean, quiet, and free from nuisance or hazard.
What the City's Own FAQs Admit
The City of Mason released a Frequently Asked Questions document for the proposed M-3 ordinance. Remarkably, this document acknowledges that data centers produce the very impacts that disqualify them from being "light industrial":
Noise
The City's FAQs mention the topic of noise at least seven times, including references to:
- "noise management"
- "enforceable performance standards-such as noise limits"
- "address[ing] visual and noise impacts"
- "Compliance with existing ordinance standards related to noise"
- "reducing noise exposure"
- "noise transfer to adjacent properties"
City's FAQs, pp. 8-9, 13, 17-20
The conclusion: If data centers were "quiet" and "absent of objectionable external effects such as noise," the City wouldn't need to address noise management seven different times. The need for decibel limits proves these facilities are not "light industrial."
Fumes & Emissions
The City's FAQs directly acknowledge the health risks from data center emissions:
"Diesel backup generators, which are commonly used by data centers and can emit fine particulate matter (PM2.5) and nitrogen oxides (NOx). These emissions are known to affect public health, including increased risks for respiratory problems, cardiovascular diseases, and lung cancer... The World Health Organization (WHO), the EPA, and other health authorities classify diesel exhaust as a human carcinogen, meaning exposure to diesel emissions from backup generators can raise cancer risks if exposure is high and prolonged."
City's FAQs, p. 5
The City also acknowledges that current infrastructure is insufficient:
"To support future data centers, public utilities like DTE Energy and Consumers Energy will need to build new infrastructure to expand their service capacity."
City's FAQs, p. 3
Michigan utilities have confirmed this will require new fossil fuel power plants:
"Indeed, both DTE and Consumers say their long-term plans to absorb data center load involve building new fossil fuel power plants. Consumers Energy President and CEO Garrick Rochow said Thursday that the utility will file a long-term power plan with state regulators next year detailing plans for 'both battery capacity and natural gas capacity. . . . The more we add, in terms of data centers, that will continue to grow,' Rochow said."
The conclusion: Facilities that emit WHO-classified carcinogens and require new fossil fuel plants to power them are not "clean" or "free from objectionable or dangerous nuisance or hazard."
Vibration
According to Informa TechTarget, a company whose "editorial mission is to help executives navigate new technologies, regulations and market dynamics to make wiser business decisions," vibration from server noise contributes to external data center noise pollution. They offer suggestions for mitigating "echoes and traveling sound" due to vibration.
TechTarget: Understanding the impact of data center noise pollution
The conclusion: The tech industry itself acknowledges that data centers are a source of vibration and noise pollution, the opposite of "quiet" and "absent of objectionable external effects."
Traffic
The City's FAQs acknowledge that citizens have:
"identified prolonged construction timelines as a significant impact."
City's FAQs, p. 18
The City states that municipal ordinances and state law already address "large-scale construction," "noise, dust control, and hours of operation," with provisions "intended to minimize impacts on surrounding neighborhoods."
Traffic issues from data center development have been documented as dangerous elsewhere:
Construction of a Meta data center has been causing "dangerous and reckless" road conditions according to local residents.
The conclusion: The City implicitly acknowledges that construction will be "disruptive, burdensome, and intrusive" and requires special regulation. These are not characteristics of "light industrial" uses with "limited demands for additional public services."
The Bottom Line
By Mason's Own Definitions
According to the City's definitions in its M-1 and M-2 ordinances, a data center facility would not be considered "light manufacturing" or "light industrial" because it produces "objectionable external effects such as noise, fumes, vibrations, odors and traffic patterns" and is not "clean, quiet, and free from any objectionable or dangerous nuisance or hazard."
That's why the City needs to create an entirely new M-3 zoning classification: data centers don't fit the existing definitions.
The question Mason residents should ask: If these facilities don't qualify as light industrial under our own ordinances, should we be creating a new classification to accommodate them?
The Emergency Generator Loophole
The proposed M-3 ordinance states:
"Generators shall be operated only for the purpose of performing periodic testing and exercising as allowed under this section or for the purpose of supplying electricity during an emergency disruption in supply from the normal electricity supplier. Under no circumstances shall any generator be operated for the purpose of supplying electricity for ongoing operations except during an emergency disruption in supply."
However, the ordinance fails to define "emergency disruption in supply." A data center operator could reasonably interpret any disruption as an "emergency."
Currently, there are peak periods when utility supply cannot meet demand, often during weather-related "emergencies" like extreme heat or cold. Service interruptions during these periods can last several days, meaning prolonged diesel generator operation that produces fumes, odors, and noise far exceeding "light industrial" standards.
Make Your Voice Heard
The City Council will vote on the M-3 zoning ordinance on February 2, 2026. If you have concerns about allowing industrial uses that exceed our own ordinance definitions for "light industrial," now is the time to speak up.