MILL
SubstationColorado · PUBLIC SERVICE CO OF COLORADO
At a glance
MILL is an electric transmission substation in Colorado, on PUBLIC SERVICE CO OF COLORADO's transmission network. It is classified as sub-transmission (115 kv) 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 |
|---|---|---|---|---|
| #201677 | 115 kV | PUBLIC SERVICE CO OF COLORADO | — | 5.3 mi |
| #201678 | 115 kV | PUBLIC SERVICE CO OF COLORADO | — | 8.2 mi |
| #201679 | 115 kV | PUBLIC SERVICE CO OF COLORADO | — | 21.4 mi |
Nearby datacenter candidate sites
Scored candidate sites within roughly 25 miles of MILL, 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 |
|---|---|---|---|---|---|---|---|
| GORE PASS | Substation-Adjacent | CO | Grand County | 230 kV | 300 MW | 4.3 yrs | 57.5 |
| BLUE RIVER | Substation-Adjacent | CO | Summit County | 230 kV | 300 MW | 4.3 yrs | 57.0 |
| UNKNOWN201402 | Substation-Adjacent | CO | Clear Creek County | 230 kV | 300 MW | 3.5 yrs | 56.7 |
| DILLION | Substation-Adjacent | CO | Summit County | 230 kV | 300 MW | 3.5 yrs | 56.6 |
| BRECKENRIDGE | Substation-Adjacent | CO | Summit County | 230 kV | 300 MW | 3.5 yrs | 56.3 |
| FRASER | Substation-Adjacent | CO | Grand County | 138 kV | 100 MW | 4.3 yrs | 54.6 |
| WINDY GAP | Substation-Adjacent | CO | Grand County | 138 kV | 100 MW | 4.3 yrs | 53.6 |
| UNKNOWN205909 | Substation-Adjacent | CO | Grand County | 115 kV | 100 MW | 4.3 yrs | 53.4 |
How does MILL compare with other substations in Colorado?
Colorado has 1,214 substation records in HIFLD, of which 400 carry a station name; the rest are unnamed tap points, risers and line ends. 206 named substations in the state are in MILL's 115–229 kV band (52% of named stations). 148 sit in a higher band. 20 named substations in Colorado operate at 345 kV or above. The highest voltage recorded in the state is 345 kV, and the state median is 115 kV.
Who owns the transmission lines at MILL?
The 3 connected lines listed above are owned by PUBLIC SERVICE CO OF COLORADO. Line voltages range from 115 kV to 115 kV. Their combined recorded length is about 34.9 miles.
How do candidate sites near MILL score?
The 8 highest-scoring candidate sites within about 25 miles range from 53 to 58 on the 0–100 DC Readiness scale. They fall in Grand County, Summit County, Clear Creek County. The Colorado average across 3,428 scored sites is 50.6. 899 of those Colorado sites are classed as substation sites (candidate locations generated at an existing substation).
Frequently asked questions
What voltage is MILL substation?
MILL has a maximum voltage of 115 kV. That places it in the 115–229 kV band. The median named US substation in this dataset is 115 kV, so MILL is at the national midpoint.
How many transmission lines connect to MILL substation?
3 transmission lines terminate at or pass through MILL in the HIFLD line data. The connected lines listed here run at 115 kV. Together the listed lines cover about 34.9 miles.
Who owns MILL substation?
HIFLD does not publish substation owners directly. Most of the transmission lines that end at MILL belong to PUBLIC SERVICE CO OF COLORADO. GridCensus derives this from the line data, so confirm ownership with the utility for anything contractual.
Where is MILL substation located?
MILL is in Colorado at 39.8461, -106.0778. The datacenter candidate sites closest to it are in Grand County, Summit County, Clear Creek County.
Are there datacenter candidate sites near MILL substation?
GridCensus lists at least 8 scored candidate sites within roughly 25 miles of MILL. The highest-scoring is GORE PASS at 58/100. Across Colorado, the average DC Readiness score is 50.6.
Other 115 kV substations in Colorado
- WEST STATION· 12 lines
- FLATIRON· 8 lines
- STORY· 8 lines
- BAYFIELD· 7 lines
- CLIMAX· 7 lines
- MANCHIEF· 6 lines
- MARTIN DRAKE· 6 lines
- NORTH· 6 lines
- All named substations in Colorado· 400 stations
- Datacenter candidate sites in Colorado· 3,428 sites
- Brownfield and retired plant sites in Colorado
- 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, “MILL substation, Colorado”, https://gridcensus.com/substations/colorado/mill-3f027122 (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 MILL substation, Colorado 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.