The Tahoe Keys from Mt. Tallac - photo: Glenn Gould, licensed under CC BY 2.0


The Tahoe Keys Property Owners Association (TKPOA) has applied to the Lahontan Water Board (LWB) and the Tahoe Regional Planning Agency (permitting agencies) for a permit to use aquatic herbicides for the very first time in Lake Tahoe’s waters. There have been many claims made about the need for this proposed one-time use of herbicides in the Tahoe Keys lagoon waters to treat the out-of-control invasive aquatic weeds there, which have been spreading to other parts of the Lake threatening the health of the crown jewel of the Sierra Nevada and national treasure that is Lake Tahoe. However, few if any answers have been provided. For instance:

  1. Why are the permitting agencies insisting on herbicides when the draft environmental document clearly stated non-chemical methods testing was the environmentally superior alternative?
  2. Everywhere else in the country where aquatic herbicides are used to control invasive weeds, herbicides are applied on a routine, regular basis. Why do the permitting agencies think that the Tahoe Keys would be any different unless they truly plan on using them on an on-going basis?
  3. Why use herbicides in this “test” project when the use of herbicides going forward would be prohibited under federal non-degradation regulations that apply to Lake Tahoe’s waters; i.e., why test it if on-going use is not intended or even an option?
  4. Where is the anti-degradation analysis, critical for justifying degradation of Lake Tahoe’s waters, that the permitting agencies stated one and a half years ago would be included in the draft environmental document? 
  5. And where’s the justification for exempting this “test” project under LWB’s Basin Plan regulations when TKPOA’s application doesn’t even mention laminar flow aeration and ultraviolet light, promising newer non-chemical technologies?

Very little to nothing has been said or provided to answer these questions, even the very lengthy Draft EIR/EIS, which was clearly intended to justify the use of herbicides. The permitting agencies should issue a revised Draft EIR/EIS, one that includes the anti-degradation analysis, before reaching a decision on the TKPOA permit. 

Nutrients from Tahoe Keys lawns and South Lake Tahoe stormwater have been accumulating in the lagoon waters and bottom sediments and fueling weed growth for 60 years.  Herbicides don’t kill the turions and seeds. The weeds in the lagoons have become a self-sustaining ecosystem. The only thing this one-time herbicide test will do is offer a few private homeowner’s false hope that there is an easy button to push for the inconvenience of weeds obstructing their boating pathway from their backyards to the Lake, all at the cost of the Lake’s natural habitat and balance. The use of herbicides in no way benefits the general public, water quality or the health of the Lake.

The Sierra Club’s primary concern is the health of the Lake. The Sierra Club believes that LWB and TRPA need to direct their staff toward a longer-term solution to the Keys’ weeds nightmare – one that actually solves the weed problem instead of just managing it forever, and one that preserves Lake Tahoe’s nationally treasured waters.  This solution would be to restore the lagoons to marsh (i.e., the waterways, in particular the dead-end stagnant sections – leaving the houses intact) in order to provide filtration for the nutrient-rich stormwater that runs off the Keys’ lawns, houses and streets as well as the surrounding community. 

Tobi Tyler, Vice Chair Tahoe Area Group, Sierra Club Toiyabe Chapter is a career environmental engineer focused on protecting wetlands and other water resources. She retired from the Lahontan Water Board in 2017 and began contributing her time to the Sierra Club, her North Star on environmental issues.

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