Skip to main content
Official websites use .gov
A .gov website belongs to an official government organization in the
United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Monitoring location Lake Michigan at Chicago Lock Wall at Chicago, IL - USGS-415322087362801
Important for you to know:
- How are we doing? We want to hear from you. Take our quick survey to tell us what you think.