Tahoe Keys answer to invasive weeds — herbicide

Milfoil is is choking the canals of the Tahoe Keys. Photo/LTN file

Milfoil is is choking the canals of the Tahoe Keys and spreading to Lake Tahoe. Photo/LTN file

By Kathryn Reed

It’s time to do something different.

That was the overriding message delivered Tuesday night regarding invasive weeds that are taking over of the Tahoe Keys canals in South Lake Tahoe. Twenty-five years of various methods – most notably harvesting – have not solved the problem.

The Tahoe Keys Property Owners Association has spent about $250,000 developing a multi-year plan to control Eurasian milfoil, curlyleaf pondweed and coontail – the three primary invasive weeds. Estimates are that treatment could cost as much as $1 million.

Today the association spends about $400,000 a year on the harvester, which essentially is mowing the milfoil. It also upends particles that drift into Lake Tahoe proper – 4,000 per acre. Boat propellers are another way the weed gets into the bigger body of water.

The plan is to use herbicides over the course of five years to get rid of the bulk of the invasive weeds. It would be applied in conjunction with continued harvesting and placing barrier mats in locations to suffocate plants.

The draft plan was released Aug. 11, with comments on it being taken until Sept. 15. The plan has been vetted by a panel of five scientists, three who were at the meeting in person, with the other two participating remotely.

Joe DiTomaso, Joel Trumbo, Sudeep Chandra

Joe DiTomaso, Joel Trumbo, Sudeep Chandra

They are:

·      Joe DiTomaso, non-crop weed specialist at UC Davis.

·      Joel Trumbo, senior environmental scientist for the Lands Program for California Department of Fish and Wildlife.

·      Kurt Getsinger, chairman of the Technical Advisory Committee of the Aquatic Ecosystem Restoration Foundation, member of the USDA’s IR-4 Project Aquatics Committee, and expert to the EPA Office of Pesticide Programs.

·      Sudeep Chandra, at UNR does limnological studies related to the restoration or conservation of aquatic ecosystems.

·      Pat Akers.

Collectively, they agree the plan is solid, especially liking that it is science based, there will be monitoring, and adaptive management will be used. That latter means if things aren’t going as planned, changes will be made mid-course. Using herbicides in the spring and not everywhere were also praised.

“The plan is well-thought out and researched. We feel the problems in the Keys are significant and some action has to be taken, and quickly,” DiTomaso said.

It was noted that these plants are invading waterways throughout the United States and that chemical applications have been used elsewhere. While each body of water is different, the Keys is not starting from scratch in terms of finding solutions.

Ultimately it will be up to the Lahontan Water Quality Control Board to issue a permit for the use of any herbicides, so it is not definitive this will happen. However, TKPOA would like to implement the plan in 2017. Environmental analysis would take place between now and then.

Many questions came up from the more than 80 people who attended Tuesday’s meeting regarding the safety of applying chemicals to the lagoons in terms of drinking water, and other plant and aquatic life.

John Larson, president of the TKPOA board, said if contaminants are found in the drinking water, one of the three wells the self-contained water company uses could be taken off-line. In a worst-case scenario, the Keys water system could get its water from South Tahoe Public Utility District.

As for killing native plants, it was noted the more than a dozen EPA approved herbicides that could possibly be used have particular attributes. It would be like applying a chemical to kill dandelions on a yard, but not killing the grass at the same time.

“Herbicides are toxic to plants. The converse is they are less risky to things that aren’t plants,” Trumbo said.

Killing the non-natives should also allow the natives to be healthier. These invasives are habitat for warm water fish, so eliminating their food source could help curtail their population.

No one expects the plants to be eradicated, but instead reduced to a level they can be controlled.

Still needing to be worked out is getting all the property owners on the same page. Within the Keys, besides the TKPOA, the Tahoe Keys Beach and Harbor Association, Tahoe Keys Marina, California Tahoe Conservancy, Tahoe Keys Village and lawyers who own the lagoon all have a say. And not all back the TKPOA plan.



·      The plan is online, as is the ability to comment.

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Comments (21)
  1. old long skiis says - Posted: August 12, 2015

    Milfoil is a problem and it’s spreading thru out the lake. Harvesting spreads the seeds after the weed has been cut and then the weeds are to be hauled away. Putting herbicides in the lake has been talked about in the past but so far has been rejected for water safety concerns and putting a toxic chemical into the lake.
    I hope they find a solution to this growing problem.
    Maybe we could dry it out to be a food product…LOL.
    Take away the weeds , OLS

  2. Hmmm... says - Posted: August 12, 2015

    Monsanto to the rescue!

  3. What? says - Posted: August 12, 2015

    Hard to believe that Herbicides will be allowed to be intentionally put in our drinking water. Milfoil is an issue, it now exists to the base of the mountain in the Upper Truckee River. How is treating the Keys going to eliminate it if it is prevalent upstream? Go back to the drawing board and find a better solution!

  4. Local2 says - Posted: August 12, 2015

    Yes let’s kill the Lake more with toxic additives why don’t we.
    The damage is all ready done, I believe it’s irreversible at this stage. Unless you restore the Keys to it’s natural state which it may save itself; which WAS South Lake Tahoe’s largest natural run off water infiltration eco system. Instead it got totally got obliterated.
    Nice Job Developers.

  5. J&B says - Posted: August 12, 2015

    Shut the Keys off from the Lake for a year (can we drain them?) and see what can be done without more chemicals. The Keys has been the gift that keeps on giving – why do we let this continue to get worse when we know it’s harming the entire lake? The Keys owners will live. The rest of us have to deal with certain regulations and limits, sometimes we have to deal with things like construction next door, ongoing road construction, utility upgrades…all things that inconvenience us for months or longer. We survive it; they can too. More chemicals in our water – seriously?

  6. Local2 says - Posted: August 12, 2015

    Thank you J&B, many of us have been saying that for years, and most likely for years to come. It’s the only logical answer we have, tear that development out of there and let mother nature restore herself back to a natural freshwater marsh and let her work miracles, that no human being alive can do!

  7. Tahoereader says - Posted: August 12, 2015

    The folks who live in the Keys need to step up and stop damaging Lake Tahoe. How many millions of public money has been spent mitigating the damage caused by this private development? Now they essentially want to dump poison into the Lake? The poison won’t be 100% effective so it will need to be continued every year.

    None of the proposals in this article seem up to the challenge or the standard of Lake Tahoe.

  8. Steve says - Posted: August 12, 2015

    Time to move from the Keys and buy stock in bottled water.

  9. fromform says - Posted: August 12, 2015

    seems to me that j&b and others have a good idea: isolate the keys from the lake proper, drain the ‘canals’, physically remove the invasive species (plant and animal), use minimal chemical agents as an adjunct to the eradication effort. 2-3 years is a drop in the bucket. the ‘keys impact issue’ is much larger than the list of associations, clubs, lawyers, agencies…the special interest flavor of this means that it won’t be solved without some transcendent approach. joint powers? anonymous? how bout civil unrest…?

  10. Kits Carson says - Posted: August 12, 2015

    I wouldn’t count too much on the Keys marina for any intelligent answer. They are KEY in polluting the lake and never held accountable.

    Then after you people spend Millions of TAX dollars the weeds will return. Your last attempt failed as expected. Nature ALWAYS wins.

  11. rock4tahoe says - Posted: August 12, 2015

    It isn’t just the Milfoil in the Keys, look a Pope Beach. Milfoil is getting a toehold along with Asian Clams. At dusk take a close look at the water at Pope Beach, the “green slime” that was at Round Hill Pines is starting to show up.

  12. old long skiis says - Posted: August 12, 2015

    The dredging of the truckee marsh to make it into the tahoe keys was a huge mistake. Very pollutng to the lake! Yes, I did dock my boat there but now it’s up for sale and I’ll be back in the canoe! Thank you Outdoorsman for letting me make payments on that Grumman aluminium 17 footer all those years ago.
    As far as getting rid of the keys and returning it to it’s natural state? Highly unlikely. Those folks don’t want to sell their homes and where’s the money going to come from to buy them out?
    We are in a constant state of repair with no money to spare and a populace that does not care.
    Be good, Old Long Skiis

  13. LocalFarmer says - Posted: August 12, 2015

    Watch out for these so called “weed specialists”. More often they should be called “Herbicide Lobbyists”. Herbicides are nasty, they don’t break down and remain in the environment for many years. I agree, drain the keys and dry up the weeds. Can we get the names of the proposed herbicides please (and a link to the material data safety sheets)?

  14. gigguy says - Posted: August 13, 2015

    What? & J&B have it right. The invasives are all the way up the Upper Truckee River and what is being done near the airport is going to make them explode in every direction. The Keys are the breeding grounds.
    Shouldn’t there be a vote on this? Why do the Keys entities continue to keep damaging OUR Lake while they practice controlling non-native, invasive weeds? They have been 100% unsuccessful, so far, and draining and walling-off this environmental nightmare seems to be a reasonable next alternative.

  15. Sailermon says - Posted: August 13, 2015

    It is obvious that the naysayers that continue their ranting about turning the Keys back into a marsh don’t have a clue about Lake Tahoe ecology, herbicides or reality itself, for that matter. Unless you are green and produce your food by a process called photosynthesis, herbicides can’t harm you or any other living thing. Herbicides can be contained in the Keys, but even if they weren’t, one swimmer pissing in the lake would do more harm than herbicides that break down, decompose and become so diluted you couldn’t find a trace if your life depended on it. If the uninformed stop the use of approved herbicides to manage aquatic invasive weeds, they will do far more harm to Lake Tahoe. Unfortunately some are just too dumb to realize this, but fortunately, there are enough smart people in the basin that do understand and will prevail.

  16. AROD says - Posted: August 13, 2015

    Sail boy must be a lobbyist for Monsanto. We should just take his uninformed word that unless you are a plant herbicides do no harm. How about drinking a bottle of Roundup?

  17. Level says - Posted: August 13, 2015

    Arod, glyphosate, the active ingredient in Roundup is 25 times less toxic than acetylsalicylic acid, the active ingredient in aspirin.

  18. Sailermon says - Posted: August 13, 2015

    Sorry AROD… We are talking about aquatic herbicides here. Roundup is not approved for aquatic use and therefore, your point is mute.

  19. Old Tannenbaum says - Posted: August 14, 2015

    Since we have a drought and the water in the keys is low, why not drain them completely and let all this bad stuff die out? It’s a pity to pollute Tahoe and drinking water with herbicides. I simply don’t trust the notion that plants can be killed without harm to other life. And I certainly don’t trust the judgment of our state and federal agencies.

  20. Sailermon says - Posted: August 14, 2015

    Old Tannenbaum… Have you ever dug a hole in the sand on a beach? If you did, you would have noticed that the hole keeps filling up with water. That’s what would happen if you tried to de-water the Keys lagoons, because of the ground water connection to Lake Tahoe. It would be next to impossible to dry out the bottom sediments and even if you could, there is a substantial seed bed that would allow the weeds to return as soon as the area was flooded. Your statement that herbicides would “pollute” Lake Tahoe and drinking water cannot be substantiated and is totally unwarranted fear mongering.