During the past five years Didymo (also known as “rock snot” has been found in rivers in New York and Vermont. Now, Didymo has been confirmed by the Connecticut DEP in the Farmington River from Riverton to New Hartford. If it’s found in those stretches of the river it will likely be found in other areas of the river as well.


Every time you come off the water, CHECK, CLEAN AND DRY.

CHECK: Before leaving the water, remove all obvious clumps of algae and plant material from fishing gear, waders, clothing & footwear, canoes & kayaks and anything else that has been in the water. Leave them at the site. If you find any later, clean your gear and dispose of all material in the trash

CLEAN: Soak/spray & scrub boats and all other “hard” items for at least one minute in either very hot (140°F) water, a 2% bleach solution, or a 5% dishwashing detergent solution.  Absorbent materials such as clothes and felt soles on waders should be soaked for at least 40 minutes in very hot water (140°F), or 30 minutes in hot water (115°F) with 5% dishwashing detergent.

Rock Snot

Source: Biosecurity New Zealand

What is a 2% solution? Three ounces in a gallon of water (which is 128 ounces)*. There are eight ounces in a cup, so that’s around a half cup of bleach to a gallon of water.

What is a 5% solution? Seven ounces in a gallon of water*. That’s around a cup of detergent in each gallon of water.

FREEZING THOROUGHLY WILL ALSO KILL DIDYMO. (if you’re allowed to put your waders and boots in the freezer)

DRY: Drying will also kill didymo, but items must remain completely dry (inside and out) for at least 48 hours.


Downloads – Posters, Flyers and Cards
Help Knock the Snot out of Didymo Blue 

Help Knock the Snot out of Didymo Yellow

Connecticut DEP press release

Sign posted by the DEP along the Farmington River

Business Card (Yellow Card)

Front: Yellow Card

Back: Check, Clean, Dry Detail


Other Websites with important reference information
Federation of Fly Fishers Didymo Page 

Fact Sheet from Sea Grant at Penn State

Federal EPA Information

BioSecurity New Zealand – great resource site

West Virginia DNR – nice page that details cleaning methods


* Yeah for you math nitpickers, it’s 2.56 ounces per gallon for a 2% solution and 6.4 ounces per gallon for a 5% solution. I rounded up to make it easier for folks.