Minnesota Department of Transportation

511 Travel Info

Hwy 169, Hwy 22 Minnesota River Flood Mitigation

Mankato, Saint Peter

About this project

This project involves raising Hwy 169 and Hwy 22 one foot above the 100-year flood elevation to maintain traffic during high water events. When these highways were originally constructed in the early 1960’s, the Minnesota River high-water elevation was assumed at 751 and the roads were constructed accordingly. The actual 100-year flood elevation in this area ranges from about 756.0 to 756.6. View project overview map (PDF 0.5 MB).

Summary of work

flood mitigation overview mapHwy 169 Saint Peter to LeSueur (2014)

  • Includes raising the grade and reconstructing for two miles (southbound lanes only)
  • Includes nine miles of preservation/resurfacing (southbound lanes only)
  • Includes access revisions in Saint Peter (north and southbound lanes)

Hwy 22 South of Saint Peter (2015)

  • Includes raising the grade and reconstructing from Hwy 169 to the existing Minnesota River Bridge
  • Includes a 120’ span bridge to handle additional water flow during high water events

Hwy 169 Mankato to Saint Peter (2016)

  • Includes raising the grade and reconstruction in four areas, for a total of three miles (north and southbound lanes)
  • Includes six miles of preservation/resurfacing (north and southbound lanes)
  • Includes median barrier for nine miles

Key issues

  • Unsuitable soils in reconstruction areas
  • Impacts to 6(f) environmental properties of Seven Mile Creek and Riverside Park
  • Coordination with rehabilitation of Hwy 99 bridge over Minnesota River at Saint Peter
  • Management of traffic during construction and access to businesses during construction


Cost estimate (millions) 2014 2015 2016
Construction 13.2 2.5 22.6-26.7
Construction-related costs 1.1 0.15 1.6-1.9
Engineering 2.6 0.5 4.5-5.3
Right of way 0 0.05 0.1
Total $16.9 $3.2 $28.8-$34