BIG GRASSY
SubstationIdaho · PACIFICORP
At a glance
BIG GRASSY is an electric transmission substation in Idaho, on PACIFICORP'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
Connected transmission lines
Lines terminating at or passing through this substation, by HIFLD line ID, highest voltage first.
| Line ID | Voltage | Owner | Status | Length |
|---|---|---|---|---|
| #203081 | 115 kV | PACIFICORP | — | 20.9 mi |
| #203101 | 115 kV | PACIFICORP | — | 61.5 mi |
| #203090 | 46 kV | PACIFICORP | — | 0.8 mi |
Nearby datacenter candidate sites
Scored candidate sites within roughly 25 miles of BIG GRASSY, 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 |
|---|---|---|---|---|---|---|---|
| RIGBY | Substation-Adjacent | ID | Madison County | 230 kV | 300 MW | 5.0 yrs | 63.4 |
| REXBURG | Substation-Adjacent | ID | Madison County | 69 kV | 50 MW | 5.0 yrs | 57.8 |
| TAP204706 | Substation-Adjacent | ID | Madison County | 69 kV | 50 MW | 5.0 yrs | 57.8 |
| JEFFERSON | Substation-Adjacent | ID | Jefferson County | 161 kV | 100 MW | 5.0 yrs | 57.3 |
| MENAN | Substation-Adjacent | ID | Madison County | 69 kV | 50 MW | 5.0 yrs | 57.0 |
| EGIN | Substation-Adjacent | ID | Madison County | 69 kV | 50 MW | 5.0 yrs | 57.0 |
| BIG GRASSY | Substation-Adjacent | ID | Jefferson County | 115 kV | 100 MW | 5.0 yrs | 56.8 |
| TAP204993 | Substation-Adjacent | ID | Jefferson County | 115 kV | 100 MW | 5.0 yrs | 56.5 |
How does BIG GRASSY compare with other substations in Idaho?
Idaho has 897 substation records in HIFLD, of which 274 carry a station name; the rest are unnamed tap points, risers and line ends. 149 named substations in the state are in BIG GRASSY's 115–229 kV band (54% of named stations). 44 sit in a higher band. 11 named substations in Idaho operate at 345 kV or above. The highest voltage recorded in the state is 500 kV, and the state median is 138 kV.
Who owns the transmission lines at BIG GRASSY?
The 3 connected lines listed above are owned by PACIFICORP. Line voltages range from 46 kV to 115 kV. Their combined recorded length is about 83.2 miles.
How do candidate sites near BIG GRASSY score?
The 8 highest-scoring candidate sites within about 25 miles range from 57 to 63 on the 0–100 DC Readiness scale. They fall in Madison County, Jefferson County. The Idaho average across 2,171 scored sites is 51.7. 646 of those Idaho sites are classed as substation sites (candidate locations generated at an existing substation).
Frequently asked questions
What voltage is BIG GRASSY substation?
BIG GRASSY has a maximum voltage of 115 kV and a minimum of 46 kV. That places it in the 115–229 kV band. The median named US substation in this dataset is 115 kV, so BIG GRASSY is at the national midpoint.
How many transmission lines connect to BIG GRASSY substation?
3 transmission lines terminate at or pass through BIG GRASSY in the HIFLD line data. The connected lines listed here run at 115 kV, 46 kV. Together the listed lines cover about 83.2 miles.
Who owns BIG GRASSY substation?
HIFLD does not publish substation owners directly. Most of the transmission lines that end at BIG GRASSY belong to PACIFICORP. GridCensus derives this from the line data, so confirm ownership with the utility for anything contractual.
Where is BIG GRASSY substation located?
BIG GRASSY is in Idaho at 44.0011, -112.1705. The datacenter candidate sites closest to it are in Madison County, Jefferson County.
Are there datacenter candidate sites near BIG GRASSY substation?
GridCensus lists at least 8 scored candidate sites within roughly 25 miles of BIG GRASSY. The highest-scoring is RIGBY at 63/100. Across Idaho, the average DC Readiness score is 51.7.
Other 115 kV substations in Idaho
- PALISADES· 6 lines
- ALBENI FALLS· 4 lines
- MACKS INN· 4 lines
- TENDOY· 4 lines
- TINCUP· 4 lines
- CATTLE CREEK· 3 lines
- NORTH LEWISTON· 3 lines
- SAND CREEK· 3 lines
- All named substations in Idaho· 274 stations
- Datacenter candidate sites in Idaho· 2,171 sites
- Brownfield and retired plant sites in Idaho
- 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, “BIG GRASSY substation, Idaho”, https://gridcensus.com/substations/idaho/big-grassy-bdfc4804 (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 BIG GRASSY substation, Idaho 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.