Forest Service Asks Public to Help Stop Spread of Invasive Didymo Algae

This is a press release from the U.S. Forest Service:

Redding, Calif.,  – Fishermen and other Trinity River users are being asked to clean their clothing and gear to help stop the spread of Didymo a.k.a. “Rock Snot”, which is a type of invasive algae produces thick mats that cover stream beds, making swimming, fishing and other water activities undesirable.

“People, including fishermen, are thought to be the main way that Didymo is being spread from one place to another,” explained botanist Lusetta Sims. “Recreational equipment, including clothing, can become contaminated and encourage the spread of Didymo if not cleaned properly before being used in another body of water.”

Didymo (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. Land managers are concerned that Didymo could become established in other Forest Service tributaries, potentially altering the natural ecosystem.

“Didymo has extraordinary capacity to negatively impact river and stream ecosystems,” said Sims. “It is invasive and prevention is all we have to protect uncontaminated water bodies, creeks and tributaries.”

If you think you have seen a Didymo bloom, Sims ask that you please write a brief description of what you saw and where. If possible, take GPS coordinates as well. Drop off your information at a Weaverville Ranger located at 360 Main Street Weaverville, CA 96093.

Sims explained these steps river users can take to stop the spread of Didymo:


  1. INSPECT clothing, shoes, waders, and all gear.
  2. Remove all mud and debris that has been in the water.

  3. At home, CLEAN gear with hot water and ONE of the following:a)

    Dish soap: 1 cup per gallon waterb)

    Bleach: 1/2 cup per gallon water

    c)Table salt: 1 cup per 1.25 gallons water

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

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

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



  • Well we’re screwed then. Unfortunately, asking all fisherman to be that extensive when cleaning gear is asking alot. Has anyone ever walked the river bank down stream from madd river hatchery? Those jerks can’t even packout soda bottles, trash, or their derelict fishing gear. People bitch about homeless making messes around here…. When I leave the river, I can see the nice dodges and Tacoma’s alot of the litterbugs are driving.

  • “Drop off your information at a Weaverville Ranger…” really? How many people are going to walk their information in to the ranger station? How about the Pony Express?

    Mailing address at least. Maybe you’ll get some real data with an email option.

  • I find this to be extremely bias and racist against certain types of mammals. Have they notified the other mammals? Will discounts be provided for those who will be expected to comply with the methods suggested?

  • I’m mean who’s not bleaching their gear and freezing it anyway as a precautionary measure?

  • And then there’s this-

    “An invasive freshwater algae with blooms so nasty they are called “rock snot” has provided an unusual (maybe even unique) surprise in the struggle against imported species: Scientific sleuthing found that it’s not invasive after all, but has actually been lurking unnoticed in New England longer than humans have been here.”

    “A type of freshwater algae, known as “rock snot,” that infiltrates river bottoms and clumps on rocks is not an invasive species introduced into waterways by humans, a new study finds. The organism has actually been native to much of the world for thousands of years.”

  • “Bleach is one of the most corrosive and deadly chemicals and still it can be found at every supermarket and drugstore in the nation, and under countless kitchen sinks. With such broad household use, it’s important to remember the risk it poses to children (especially because small amounts will affect them more than adults) or anyone unaware of its effects.”

    How many babies crawled on the healthy clean and sanitized floors, put the sanitized toys in their mouths, and grew up full of cancers?

    • Lost Croat Outburst

      Children should never have access to medicines and household chemicals and recreational drugs and other dangerous things. It’s called “parenting.” Substitute “fluorine” for bleach and you have the fluoridated-water stupid debate all over again. Many things are dangerous when pure or concentrated; useful when compounded or diluted. Regular, plain, unadulterated chlorine laundry bleach can disinfect drinking water in an emergency, a few drops per quart. Look it up. Chlorinated public drinking water has saved multiple millions of people of people from agonizing diseases and horrible deaths. Gosh, it might be dangerous. Try “cholera” and a host of other maladies for danger.

      How many babies have blah blah blah and grown up full of cancers from the floor? Probably zero to none.

      • Probably? You mean, that as long as the masses can be convinced to overlook a known and obvious hazard, by blaming their neighbor’s nasty habit on everything under the sun? Good grief, those nasty horrible fishermen in the waters of our planet!

        By the way, the courts have found enough evidence to allow the people to sue the flouride pushers in the water tanks. Life is good again.

        Updating the local slush fund puppies:

  • I mean why did we let the poison oak get so prolific? I mean why don’t they declare an earth day celebration and destroy all the poison oak? Maybe it’s a government plot to give you a herpes like infection and keep you out of the woods?

    • Deer, birds, and other wildlife eat the leaves and berries of poison oak and ivy, because poison oak has high concentrations of phosphorous, sulfur, and calcium.
      Reintroducing wolves, osprey, and other predatory species, helps balance the eco system by thinning out the poison oak carnivores.

    • Lost Croat Outburst

      Poison oak is a native plant. The alga apparently is not.

    • Bleach works great on poison oak. I grew up constantly getting bad cases of poison oak so If it blistered I’d pour bleach on it….dried up in one-two days!! Great stuff and I don’t even have cancer.

    • Poison Oak is an asset. It is higher in protein than 2nd cutting alfalfa. Goats especially like it, and it can transfer an immunity to the drinkers of the milk.

  • Veterans friend

    It is a small planet. Are there REALLY invasive species or do things just move around and inhabit new territories. Like the humans, the most destructive species ON the planet?

  • I’ve used Simple Green (50-50 solution) for years to prevent the spread of Sudden Oak, and I’m betting it is a saner, easier solution for clothing, etc. contaminated with Snot Algae. Anything is better than BLEACH.
    When I have tree work done, I have a litter box (cat person here) 3/4 full of the 50-50 solution for the workers to step into with their boots just before they get back in their truck to leave. I keep a handy dish-washing brush available to get into the boot cracks and cleats, too. I watch, and if needed, I help. I believe it has worked sufficiently for my purposes. At the very least, I know I’ve done what I can with what I have.
    The Snot Algae referenced in the article appeared in our “Dotted Blue Creek Bed” after the first septic tank was installed.
    I suspect it was always there, but not abundant until the squeamish citified retards up-stream started flushing their poop back into the water table. (Sigh)
    With Simple Green, it is possible to act – at least to do SOMETHING to acknowledge the problem and TRY to address it…. simply.
    It’s clearly our responsibility to act; we’re the ones on the Front Line. Bottom Line: DO something!
    BTW: When I dump the dip-water, I put it on/in my compost pile. I’ve never observed negative effects. Earth worms are fine with it.
    “I asked: Why doesn’t somebody do something? And then I realized I AM somebody.” You are, too.
    NOTE: Full strength Simple Green will strip paint…

    • Thank you for your very helpful and thoughtful post, AF.

    • The articles mention that elimination of the flushing of nutients as a result of faster snow melt is a likely cause of didymo out growing more usual algaes. It’s designed for out competing in low nutrient waters.

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