Skip to main content

An official website of the United States government

Here’s how you know

Here’s how you know

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 Chicago San & Ship Canal at Sag Bridge, IL - USGS-05536152

WDFN Home

Important Inventory Page

Questions or Comments

DOI Privacy Policy | Legal | Accessibility | Site Map | Contact USGS

U.S. Department of the Interior | DOI Inspector General | White House | No Fear Act | FOIA