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 the Nelson Dewey Power Plant, 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 low voltages, high voltages and transmission-facility overloads. Low voltages are located in the Verona, Lake Geneva and Hustisford areas. Several overloads on 138-kV and 69-kV facilities in Zone 3 are emerging concerns. The causes of these emerging issues include steady growth in certain areas, power plant retirement and different generation dispatch scenarios.

Electric system overview

Increases expected in population, employment – Population in Zone 3 is projected to grow about 1.0 percent annually between now and 2023, 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

Electricity usage growing

Electric load is expected to grow approximately 1.2 percent annually through 2024 for all of Zone 3.

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 on the next page.

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

Zone 3 Planned Projects

Project DescriptionIn-service yearNeed driver
Colley Road - Brick Church 69-kV line2018Overloads, low voltages, condition, rebuild and provide line sectionalizing

Zone 3 Proposed Projects

Project DescriptionIn-service yearNeed driver
Badger Coulee: La Crosse area u2013 North Madison u2013 Cardinal 345-kV line construction2018Reliability, economics and public policy
Spring Valley u2013 North Lake Geneva 138-kV line construction2019Overloads and low voltages, provide network service
Cardinal u2013 Hickory Creek 2020Reliability, economics and public policy

Zone 3 Provisional Projects

Project DescriptionIn-service yearNeed driver
Cardinal-Blount 138u2011kV line construction2025Overloads and low voltages
West Middleton-Pheasant Branch 69u2011kV line rebuild2028Overloads and low voltages

Zone 3 Asset Renewal Projects

Project DescriptionIn-service yearNeed driver
Dam Heights u2013 Dane 69-kV line re-route at dam2015Condition and performance
Belmont - Rewey 69-kV line rebuild2015Condition and performance
Concord - Rubicon - Butler Ridge - nHartford 138-kV line rebuild (portion of Quad Counties project)2016Condition and performance
Dam Heights u2013 Portage 69-kV line rebuild2017Condition and performance
Boscobel u2013 Lone Rock 69-kV line rebuild2018Condition and performance
Related Resources