Southeast Wisconsin
Zone 5

Transmission system characteristics in Zone 5

ATC delivers power in Zone 5 with various transmission facilities including:

  • Southern portion of 345‑kV lines from Point Beach and Edgewater,
  • The Saukville, Arcadian, Granville, Oak Creek, and Racine 345/138‑kV substations,
  • The transmission lines emanating from the Pleasant Prairie and Oak Creek power plants,
  • 230‑kV facilities near Milwaukee, and
  • A significant 138‑kV network in the Milwaukee area, a portion of which is underground.
Transmission system limitations in Zone 5

Transmission system performance issues in Zone 5 include heavy market flows from and to the south, resulting in high 345-kV and 138-kV line loadings and the need to monitor potential multiple contingency conditions.

Electric system overview

Increases expected in population, employment Population in Zone 5 is projected to grow 0.4 percent annually between now and 2025, and employment is projected to grow 1.1 percent in the same time period. Waukesha County is projected to realize the largest increase in both population and employment. Waukesha County is also projected to have the highest growth rate in employment, while Washington County is projected to have the highest growth rate in population.

Electricity usage

Peak electric demand typically occurs during the summer months. Large industrial loads in the Milwaukee metropolitan area are among the largest electricity users in the zone.

Electric load is forecasted to grow approximately 0.6 percent annually through 2026.

Transmission projects in Zone 5

The most notable planned, proposed and provisional network projects and asset-renewal projects in Zone 5, along with their projected year of completion and the factors driving the need for the projects, are listed below.

Zone 5 includes the counties of:
  • Kenosha , WI
  • Milwaukee , WI
  • Ozaukee , WI
  • Racine , WI
  • Washington , WI
  • Waukesha , WI

Zone 5 Planned Projects

Project DescriptionIn-service yearNeed driver
Oak Creek - Hayes 138-kV upgrade and reconfiguration2018Overloads
Spring Valley - North Lake Geneva 138‑kV line construction2019Overloads and low voltages, provide network service
Mukwonago - Edgewood - St. Martins 138-kV line rebuild2019Condition and performance

Zone 5 Proposed Projects

Project DescriptionIn-service yearNeed driver
Southeast Wisconsin - Northeastern Illinois Interface Project2020Overloads
Port Washington - Saukville 138-kV line rebuild2021Overloads
Arcadian - Waukesha 138-kV rebuild2025Overloads

Zone 5 Provisional Projects

Project DescriptionIn-service yearNeed driver