ROCK BRANCH
SubstationWisconsin · AMERICAN TRANSMISSION CO
At a glance
ROCK BRANCH is an electric transmission substation in Wisconsin, on AMERICAN TRANSMISSION CO's transmission network. It is classified as distribution (69–115 kv) and connects 4 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 |
|---|---|---|---|---|
| #159906 | 69 kV | AMERICAN TRANSMISSION CO | IN SERVICE | 7.7 mi |
| #166814 | 69 kV | AMERICAN TRANSMISSION CO | IN SERVICE | 8.4 mi |
| #166817 | 69 kV | AMERICAN TRANSMISSION CO | IN SERVICE | 3.6 mi |
| #166825 | 69 kV | AMERICAN TRANSMISSION CO | IN SERVICE | 14.1 mi |
Nearby datacenter candidate sites
Scored candidate sites within roughly 25 miles of ROCK BRANCH, 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 |
|---|---|---|---|---|---|---|---|
| BLACK EARTH | Substation-Adjacent | WI | Dane County | 69 kV | 50 MW | 4.3 yrs | 59.7 |
| TAP138067 | Substation-Adjacent | WI | Sauk County | 138 kV | 100 MW | 4.3 yrs | 59.5 |
| TAP162959 | Substation-Adjacent | WI | Sauk County | 69 kV | 50 MW | 4.3 yrs | 59.4 |
| WALLY ROAD | Substation-Adjacent | WI | Dane County | 69 kV | 50 MW | 4.3 yrs | 59.4 |
| MOUNT HOREB | Substation-Adjacent | WI | Dane County | 69 kV | 50 MW | 4.3 yrs | 59.1 |
| EC Near Argyle | Greenfield | WI | Lafayette | — | — | 4.3 yrs | 58.9 |
| EC Near Argyle | Greenfield | WI | Lafayette | — | — | 4.3 yrs | 58.9 |
| SPRING GREEN | Substation-Adjacent | WI | Iowa County | 138 kV | 100 MW | 4.3 yrs | 58.8 |
How does ROCK BRANCH compare with other substations in Wisconsin?
Wisconsin has 1,930 substation records in HIFLD, of which 768 carry a station name; the rest are unnamed tap points, risers and line ends. 340 named substations in the state are in ROCK BRANCH's 69–114 kV band (44% of named stations). 370 sit in a higher band. 34 named substations in Wisconsin 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 ROCK BRANCH?
The 4 connected lines listed above are owned by AMERICAN TRANSMISSION CO. Line voltages range from 69 kV to 69 kV. Their combined recorded length is about 33.8 miles.
How do candidate sites near ROCK BRANCH score?
The 8 highest-scoring candidate sites within about 25 miles range from 59 to 60 on the 0–100 DC Readiness scale. They fall in Dane County, Sauk County, Lafayette, Iowa County. The Wisconsin average across 3,340 scored sites is 55.4. 1,248 of those Wisconsin sites are classed as substation sites (candidate locations generated at an existing substation).
Frequently asked questions
What voltage is ROCK BRANCH substation?
ROCK BRANCH has a maximum voltage of 69 kV. That places it in the 69–114 kV band. The median named US substation in this dataset is 115 kV, so ROCK BRANCH is below the national midpoint.
How many transmission lines connect to ROCK BRANCH substation?
4 transmission lines terminate at or pass through ROCK BRANCH in the HIFLD line data. The connected lines listed here run at 69 kV. Together the listed lines cover about 33.8 miles.
Who owns ROCK BRANCH substation?
HIFLD does not publish substation owners directly. Most of the transmission lines that end at ROCK BRANCH belong to AMERICAN TRANSMISSION CO. GridCensus derives this from the line data, so confirm ownership with the utility for anything contractual.
Where is ROCK BRANCH substation located?
ROCK BRANCH is in Wisconsin at 42.8582, -90.1078. The datacenter candidate sites closest to it are in Dane County, Sauk County, Lafayette.
Are there datacenter candidate sites near ROCK BRANCH substation?
GridCensus lists at least 8 scored candidate sites within roughly 25 miles of ROCK BRANCH. The highest-scoring is BLACK EARTH at 60/100. Across Wisconsin, the average DC Readiness score is 55.4.
Other 69 kV substations in Wisconsin
- EAST CAMPUS· 6 lines
- DAM HEIGHTS· 5 lines
- HILLTOP (ALTE)· 5 lines
- WEST MIDDLETON· 5 lines
- BERLIN· 4 lines
- CHAFFEE CREEK· 4 lines
- COLUMBUS MUNI 1· 4 lines
- DEFOREST· 4 lines
- All named substations in Wisconsin· 768 stations
- Datacenter candidate sites in Wisconsin· 3,340 sites
- Brownfield and retired plant sites in Wisconsin
- 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, “ROCK BRANCH substation, Wisconsin”, https://gridcensus.com/substations/wisconsin/rock-branch-b8021058 (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 ROCK BRANCH substation, Wisconsin 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.