Seattle leaves room for existing data centers to expand, while tightening rules for larger projects

Status: In effect · moratorium effective 11 June 2026 for 365 days; City Light rules enacted July 2026 · Next: Seattle Public Utilities water proposal due 30 October 2026; permanent zoning rules expected early 2027 · Checked: 12 October 2026

Planning a data center expansion in Seattle? Facilities operating when the pause began have an exception for adding up to 20 megavolt-amperes (MVA). Larger projects may face the zoning pause, currently scheduled to run into June 2027 unless ended sooner or extended.

A separate City Light rule introduces special contracts and upfront grid upgrade costs for qualifying new loads of 10 MVA or more. Whether it covers your company’s own facility needs confirmation with the utility.

1. The zoning moratorium (Ordinance 127447)

The city will not accept, process or approve applications to establish or expand data centers, or to change a use to a data center, “either as principal or accessory uses”, in all zones. It applies whether the data center is part of a project or the whole project.

• Who: a “data center” is a facility used primarily for computer and networking equipment and data handling, with capacity over 20 MVA, generally needing UPS, cooling, backup power and battery storage.
• Existing facilities: the pause does not apply to an application to expand a facility’s capacity by no more than an additional 20 MVA, if the facility was operating on the effective date. That includes facilities at or below 20 MVA today. The text does not say whether the 20 MVA is per application or in total.
• How long: 365 days from 11 June 2026, unless extended (in six-month periods) or ended sooner. No extension had been filed when we checked. The required public hearing was held on 15 July 2026.
• Land use permit applications must now state electrical capacity in MVA.
• The city’s work plan: Seattle Public Utilities’ water proposal is due 30 October 2026; zoning and development standards (separating large data centers from small, medium and co-located ones) are due January 2027, with Council action expected March 2027; a community benefits framework covering noise, heat and limits on fossil-fuel backup generation is due 1 February 2027.

2. The City Light contract rule (Ordinance 127473)

This is a utility rule, separate from the zoning pause.

• Who: a “new large data center load” is service to a data center “fed from an expanded or a new installation equal to or greater than 10 MVA of capacity installed within any consecutive five-year period after January 1, 2027.” Here a data center is a facility primarily providing services under NAICS code 518210 (computing infrastructure, data processing and hosting). The ordinance does not say whether a company’s own data center counts, and City Light may combine service entrances when deciding whether the threshold is met.
• What changes: such a load cannot use general service rates. It is served only under a contract (up to 20 years) that must include a guaranteed minimum demand, curtailment provisions, full upfront responsibility for the cost of any feeder, transmission or substation upgrades, and full recovery of the cost of new power. Service starts only when the contract is signed and the infrastructure and power are in place.
• The 300% charge: it applies only to a customer on one of these contracts whose metered demand (the highest 15-minute demand) exceeds the demand specified in the contract. The charge is the kW above the contract demand × the contract’s demand charge ($/kW) × 300%. The demand charge itself is set in each contract from City Light’s marginal cost of capacity and transmission, so no published dollar figure applies.

If you operate or plan a data center in Seattle, check

1. Your facility’s capacity in MVA, and how much of the 20 MVA expansion allowance a planned project uses.
2. For any connection after 1 January 2027, whether City Light treats your facility as a NAICS 518210 data center and whether your new capacity reaches 10 MVA within five years.
3. Whether the moratorium is extended before June 2027, and what the permanent zoning standards say.

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