09/02/2026
WHAT’S THAT SMELL? IS THERE A GAS LEAK? 🤢❓
If you’ve noticed an offensive, gas-like odor over the last couple of days, you aren’t alone! Calls poured into local authorities and local utility companies in Wisconsin and Illinois this week.
After crews scrambled to investigate, they confirmed there was no gas leak. So, what was causing the stink from Fort Atkinson to Edgerton to Janesville, Beloit, and down into Rockton?
The answer: Lake Koshkonong.
Here is what's happening:
🦠 The Cause: A recent stretch of warm, sunny weather and light winds triggered a massive blue-green algae (Cyanobacteria) bloom in the shallow waters of Lake Koshkonong.
💨 The Smell: When these massive algal blooms occur and decay, they release strong, unpleasant gases into the air that smell surprisingly similar to a natural gas leak or sewage.
🌊 Why is it affecting downstream towns? While the bloom originated in the lake, Lake Koshkonong flows directly into the Rock River. As that water moves south, the odor travels along with it—even if the moving river water makes the algae harder to see!
⚠️ HEALTH & SAFETY WARNING:
The Wisconsin Department of Health Services warns that exposure to these harmful algal blooms can cause:
Respiratory issues
Skin irritations and blisters
Gastrointestinal illness
Please keep yourself, your family, and your pets out of the water where blooms or odors are present.
Good news: Satellite imagery and recent monitoring show concentrations are beginning to thin out, so the worst should hopefully be behind us.
Share this post to help clear the air for your neighbors! 👇
