STEWART
SubstationArizona · SULPHUR SPRINGS VALLEY ELECTRIC COOPERATIVE
At a glance
STEWART is an electric transmission substation in Arizona, on SULPHUR SPRINGS VALLEY ELECTRIC COOPERATIVE's transmission network. It is classified as unclassified and connects 3 transmission lines. Substation proximity is one of the strongest speed-to-power signals for siting a datacenter — interconnection distance to an energized, high-voltage bus is often the binding constraint on time-to-energization.
Voltage & classification
Ownership
Connected transmission lines
Lines terminating at or passing through this substation, by HIFLD line ID, highest voltage first.
| Line ID | Voltage | Owner | Status | Length |
|---|---|---|---|---|
| #313968 | 230 kV | GRAHAM COUNTY ELECTRIC COOPERATIVE INCORPOR | IN SERVICE | 28.2 mi |
| #313969 | 69 kV | SULPHUR SPRINGS VALLEY ELECTRIC COOPERATIVE | IN SERVICE | 7.5 mi |
| #313967 | 53 kV | SULPHUR SPRINGS VALLEY ELECTRIC COOPERATIVE | IN SERVICE | 7.7 mi |
Nearby datacenter candidate sites
Scored candidate sites within roughly 25 miles of STEWART, ranked by DC Readiness. Sites this close to an energized substation carry a strong speed-to-power advantage.
| Site | Type | State | County | Voltage | Capacity | Queue wait | Score |
|---|---|---|---|---|---|---|---|
| WINCHESTER | Substation-Adjacent | AZ | Cochise County | 345 kV | 600 MW | 3.5 yrs | 57.4 |
| BUTTERFIELD | Substation-Adjacent | AZ | Cochise County | 230 kV | 300 MW | 3.5 yrs | 57.2 |
| APACHE | Substation-Adjacent | AZ | Cochise County | 230 kV | 300 MW | 3.5 yrs | 56.5 |
| RED TAIL | Substation-Adjacent | AZ | Cochise County | 230 kV | 300 MW | 3.5 yrs | 55.5 |
| ADAMS | Substation-Adjacent | AZ | Cochise County | 115 kV | 100 MW | 3.5 yrs | 52.8 |
| Greenfield (TAP306867 - None) | Greenfield | AZ | Graham County | 230 kV | 300 MW | 3.5 yrs | 49.5 |
| UNKNOWN300824 | Substation-Adjacent | AZ | Graham County | 69 kV | 50 MW | 3.5 yrs | 49.5 |
| Greenfield (TAP306867 - None) | Greenfield | AZ | Graham County | 230 kV | 300 MW | 3.5 yrs | 49.2 |
Who owns the transmission lines at STEWART?
The 3 connected lines listed above are owned by GRAHAM COUNTY ELECTRIC COOPERATIVE INCORPOR, SULPHUR SPRINGS VALLEY ELECTRIC COOPERATIVE. Line voltages range from 53 kV to 230 kV. Their combined recorded length is about 43.4 miles.
How do candidate sites near STEWART score?
The 8 highest-scoring candidate sites within about 25 miles range from 49 to 57 on the 0–100 DC Readiness scale. They fall in Cochise County, Graham County. The Arizona average across 3,816 scored sites is 48.5. 614 of those Arizona sites are classed as substation sites (candidate locations generated at an existing substation).
Frequently asked questions
How many transmission lines connect to STEWART substation?
3 transmission lines terminate at or pass through STEWART in the HIFLD line data. The connected lines listed here run at 230 kV, 69 kV, 53 kV. Together the listed lines cover about 43.4 miles.
Who owns STEWART substation?
HIFLD does not publish substation owners directly. Most of the transmission lines that end at STEWART belong to SULPHUR SPRINGS VALLEY ELECTRIC COOPERATIVE, and others to GRAHAM COUNTY ELECTRIC COOPERATIVE INCORPOR. GridCensus derives this from the line data, so confirm ownership with the utility for anything contractual.
Where is STEWART substation located?
STEWART is in Arizona at 32.3408, -109.8926. The datacenter candidate sites closest to it are in Cochise County, Graham County.
Are there datacenter candidate sites near STEWART substation?
GridCensus lists at least 8 scored candidate sites within roughly 25 miles of STEWART. The highest-scoring is WINCHESTER at 57/100. Across Arizona, the average DC Readiness score is 48.5.
More in Arizona
About this data
Source: HIFLD Electric Substations and Transmission Lines (U.S. Department of Homeland Security), as published June 29, 2026. See the methodology for how records are matched, cleaned and scored.
Cite as: GridCensus, “STEWART substation, Arizona”, https://gridcensus.com/substations/arizona/stewart-713e51fd (data as of June 29, 2026).
Dataset updated . Screening estimates derived from public data sources.
Substation attributes are derived from public HIFLD / EIA infrastructure data and may lag real-world upgrades or retirements. Voltage and connected-line counts are screening figures — confirm available capacity and interconnection terms directly with the operating utility and ISO.
Go deeper than the public screen
Every site and score for STEWART substation, Arizona is free to browse. Pro adds Watchtower on 25 sites, alerts when new candidate sites, datacenters or interconnection-queue requests appear in your markets, score and capacity history, and CSV export. Enterprise adds team seats, weekly data files for all 147,272 sites, the REST API and an MCP server for AI tools.