South Central/Southwest Wisconsin and North Central Illinois
Zone 3

Transmission system characteristics in Zone 3

ATC delivers power in Zone 3 with various transmission facilities including:

  • Columbia-North Madison 345‑kV lines,
  • Columbia-Rockdale 345‑kV line,
  • Paddock-Rockdale 345‑kV line,
  • Paddock-Wempletown 345‑kV line,
  • Rockdale-Wempletown 345‑kV line
  • Rockdale-Cardinal 345-kV line, and
  • 138‑kV facilities from Nelson Dewey, around the Madison area, and in the northwest and southeast portions of Zone 3.
Transmission system limitations in Zone 3

In our analysis of Zone 3, we identified a number of transmission facility overloads. These overloads are due to new generation in the Janesville and Darlington areas. In addition, other emerging issues resulting in facility overloads include steady growth in certain areas and different generation dispatches. The most severe limitations occur during both peak and off-peak periods.

Electric system overview

Increases expected in population, employment Population in Zone 3 is projected to grow about 0.8 percent annually between now and 2026, and employment is projected to grow about 1.3 percent each year for the same time period. Dane County is projected to realize the largest increase in population and employment. Dane County is also projected to have the highest growth rate in population while Dodge County is projected to have the highest growth rate in employment.

Electricity usage growing

Electric load is expected to grow approximately .09 percent annually through 2027.

Transmission projects in Zone 3

The most notable planned, proposed and provisional network projects and asset-renewal projects in Zone 3, along with their projected year of completion and the factors driving the need for the projects, are listed below.

Zone 3 includes the counties of:
  • Columbia , WI
  • Crawford (S) , WI
  • Dane , WI
  • Dodge , WI
  • Grant , WI
  • Green , WI
  • Iowa , WI
  • Jefferson , WI
  • Lafayette , WI
  • Richland , WI
  • Rock , WI
  • Sauk , WI
  • Walworth , WI
  • Winnebago (N) , IL
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Zone 3 Provisional Projects

Project DescriptionIn-service yearNeed driver
Cardinal - Blount 138‑kV line construction2029Overloads and low voltages