People who use the Trinity River are being asked to help stop the spread of Didymo, otherwise known as “Rock Snot”. It’s an invasive algae that makes thick mats covering stream beds. It’s a slimy substance that attaches to submerged plants, rocks and logs. It’s difficult to dislodge because the stalk is resistant to degradation by bacteria and fungi. It’s been seen in the Trinity River from Trinity Dam to Helena. It’s believed to be spread by hitchhiking on the gear and clothing of fishermen and other river users. It can be stopped by washing materials with dish soap, bleach or table salt, and then freezing.