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 to and from 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 0.5 percent annually between now and 2027, 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 Ozaukee 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 0.7 percent annually through 2028.

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
Mount Pleasant Tech Interconnection Project2019T-D Interconnection
Mukwonago–Edgewood–St. Martins 138‑kV lines (3013), (671K61), rebuild2019Condition and performance
Spring Valley–North Lake Geneva 138‑kV line construction2019Overloads and low voltages, provide network service
Juneautown Substation, new T‑D interconnection2020T‑D interconnection
Paris–Burlington 138‑kV line (8962) rebuild2021Condition and performance
St. Lawrence–Barton–Auburn 138‑kV lines (8032), (9752), rebuild2022Condition and performance

Zone 5 Proposed Projects

Project DescriptionIn-service yearNeed driver
Port Washington–Saukville 138‑kV rebuild line 762 to a double circuit2021Overloads

Zone 5 Provisional Projects

Project DescriptionIn-service yearNeed driver