Forest Service needs Help Stopping the spread of Invasive Algae

Fishermen and other Trinity River users are asked to clean their clothing and gear to help stop the spread of Didymo or Rock Snot.

Posted: Apr 16, 2018 1:41 PM
Updated: Apr 23, 2018 12:24 PM

Redding, Calif.—Fishermen and other Trinity River users are asked to clean their clothing and gear to help stop the spread of Didymo or Rock Snot.

It is a type of invasive algae that produces thick mats that cover stream beds, making swimming, fishing, and other water activities undesirable.


Didymo or Didymosphenia geminate has a slimy appearance and attaches to submerged plants, rocks, and other hard substrates in rivers and streams by excreting a stalk that is resistant to degradation by bacteria and fungi.

It has been documented in several locations along the Trinity River from Trinity Dam to Helena.

According to a local botanist, people including fisherman are thought to be the main way that Didymo is being spread from one place to another.

If you think you have seen a didymo bloom, you are asked to please write down a brief description of what you saw, and where and report it to the Weaverville Ranger Station.

Here are steps you can take while using the rivers to help stop the spread of didymo.

1. INSPECT clothing, shoes, waders, and all gear.

  1. Remove all mud and debris that has been in the water.

2. At home, CLEAN gear with hot water and ONE of the following:

        1. Dish soap: 1 cup per gallon water
        2. Bleach: 1/2 cup per gallon water
        3. Table salt: 1 cup per 1.25 gallons water

3. SCRUB non-absorbent items thoroughly with one of the solutions.

4. SOAK clothes, waders, and absorbent items in HOT soapy or salty water for 30 minutes, then rinse.

5. DRY completely for at least 48 hours or FREEZE gear until frozen solid and completely dry.

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