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Official websites use .gov
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United States.
Secure .gov websites use HTTPS
A lock (
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Monitoring location Illinois River at Henry, IL - USGS-05558300
Important for you to know:
- Big changes are coming soon to NWISWeb websites and services. Attend our webinar, January 15, 2026 at 2:00 PM EST, to learn about the impacts. Learn more about our modernization plans and timeline.
