Lake Saint Louis Boulevard Extension

This project involves extension of Lake St. Louis Boulevard from Laurel Willow Drive south to Route DD and Diehr Road. This project will meet with the City of O’Fallon’s project to the north that is extending Lake St. Louis Boulevard from its current terminus at the roundabout intersection with Paul Renaud Boulevard. Proposed improvements include:

  • New 2-lane roadway with curb and gutter and an enclosed drainage system.
  • New bridge to cross the floodway south of Preston Woods subdivision.
  • Realign intersection of Route DD and Diehr Road into a new roundabout intersection with Lake St. Louis Boulevard to improve traffic flow and access to Route DD.
  • New 10-foot multi-use path along the east side of Lake St. Louis Boulevard.
  • New 5-foot sidewalk along the west side of Lake St. Louis Boulevard.

The project is fully funded by the St. Charles County’s ½-cent Transportation Sales Tax. The engineering design consultant is Bartlett & West. The project is estimated to cost approximately $450,000 (design services only).

Contact Chris Bostic, Engineering Design Manager, at 636-949-7305 or, with questions about the project. 

Project Information

Conceptual Project Map (PDF)

Current Phase

The intersection work for Diehr Road, Lake St Louis Blvd, and Route DD has been added onto the current Lake St. Louis Boulevard Extension Project. The consultant is Bartlett & West. They have wrapped up Preliminary Plans, but are currently on hold as environmental concerns are being worked out with US Fish & Wildlife and Army Corps of Engineers. Once that is complete, the consultant can move forward with Right-of-Way Plans. Construction will start late in 2023 at the very earliest; likely 2024.

Updated 12/15/22 

Project Location Map