TARKIO
SubstationMontana · NORTHWESTERN ENERGY LLC - (MT)
At a glance
TARKIO is an electric transmission substation in Montana, on NORTHWESTERN ENERGY LLC - (MT)'s transmission network. It is classified as sub-transmission (115 kv) and connects 2 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 |
|---|---|---|---|---|
| #202342 | 115 kV | NORTHWESTERN ENERGY LLC - (MT) | — | 11.3 mi |
| #202343 | 69 kV | NORTHWESTERN ENERGY LLC - (MT) | — | 22.4 mi |
Nearby datacenter candidate sites
Scored candidate sites within roughly 25 miles of TARKIO, 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 |
|---|---|---|---|---|---|---|---|
| TARKIO | Substation-Adjacent | MT | Mineral County | 115 kV | 100 MW | 1.1 yrs | 57.9 |
| TAP204183 | Substation-Adjacent | MT | Missoula County | 69 kV | 50 MW | 1.1 yrs | 57.8 |
| UNKNOWN207786 | Substation-Adjacent | MT | Mineral County | 115 kV | 100 MW | 1.1 yrs | 57.0 |
| TAP207787 | Substation-Adjacent | MT | Mineral County | 115 kV | 100 MW | 1.1 yrs | 57.0 |
| UNKNOWN204168 | Substation-Adjacent | MT | Mineral County | 115 kV | 100 MW | 1.1 yrs | 57.0 |
| UNKNOWN203111 | Substation-Adjacent | MT | Mineral County | 69 kV | 50 MW | 1.1 yrs | 55.0 |
| Mine Site | Former Mine | MT | Sanders County | — | — | 1.1 yrs | 53.6 |
| Mine Site | Former Mine | MT | Sanders County | — | — | 1.1 yrs | 53.6 |
How does TARKIO compare with other substations in Montana?
Montana has 1,211 substation records in HIFLD, of which 149 carry a station name; the rest are unnamed tap points, risers and line ends. 34 named substations in the state are in TARKIO's 115–229 kV band (23% of named stations). 50 sit in a higher band. 5 named substations in Montana operate at 345 kV or above. The highest voltage recorded in the state is 500 kV, and the state median is 115 kV.
Who owns the transmission lines at TARKIO?
The 2 connected lines listed above are owned by NORTHWESTERN ENERGY LLC - (MT). Line voltages range from 69 kV to 115 kV. Their combined recorded length is about 33.7 miles.
How do candidate sites near TARKIO score?
The 8 highest-scoring candidate sites within about 25 miles range from 54 to 58 on the 0–100 DC Readiness scale. They fall in Mineral County, Missoula County, Sanders County. The Montana average across 2,542 scored sites is 54.3. 815 of those Montana sites are classed as substation sites (candidate locations generated at an existing substation).
Frequently asked questions
What voltage is TARKIO substation?
TARKIO has a maximum voltage of 115 kV and a minimum of 69 kV. That places it in the 115–229 kV band. The median named US substation in this dataset is 115 kV, so TARKIO is at the national midpoint.
How many transmission lines connect to TARKIO substation?
2 transmission lines terminate at or pass through TARKIO in the HIFLD line data. The connected lines listed here run at 115 kV, 69 kV. Together the listed lines cover about 33.7 miles.
Who owns TARKIO substation?
HIFLD does not publish substation owners directly. Most of the transmission lines that end at TARKIO belong to NORTHWESTERN ENERGY LLC - (MT). GridCensus derives this from the line data, so confirm ownership with the utility for anything contractual.
Where is TARKIO substation located?
TARKIO is in Montana at 47.0183, -114.7380. The datacenter candidate sites closest to it are in Mineral County, Missoula County, Sanders County.
Are there datacenter candidate sites near TARKIO substation?
GridCensus lists at least 8 scored candidate sites within roughly 25 miles of TARKIO. The highest-scoring is TARKIO at 58/100. Across Montana, the average DC Readiness score is 54.3.
Other 115 kV substations in Montana
- COLUMBIA FALLS· 7 lines
- DILLON-SALMON· 7 lines
- MISSOULA· 7 lines
- HAMILTON· 5 lines
- BIG TIMBER AUTO· 4 lines
- CONRAD AUTO· 4 lines
- KALISPELL· 4 lines
- SHELBY· 4 lines
- All named substations in Montana· 149 stations
- Datacenter candidate sites in Montana· 2,542 sites
- Brownfield and retired plant sites in Montana
- Substations by state
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, “TARKIO substation, Montana”, https://gridcensus.com/substations/montana/tarkio-1cf9ba72 (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 TARKIO substation, Montana 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.