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Tahoe Keys Herbicide and UV Trials for Aquatic Weed Control

Subject: Tahoe Keysherbicide and UV trials for aquatic weed control 

Dear Tahoe decision makers, 

This letter is written in strongsupport of the proposal to do a herbicide and UV trial applications to several of the sealed off Tahoe KeysLagoons. Over my sixty years of research as former Director of the UC DavisTahoe Research Group I have watched the aquatic weed problem in the Tahoe Keysescalate until it has become a lake wide problem. Over the years the aquatic weed fragment from mowing have takenhold around the margins of the lake andparticularly in marinas. Invasive warm fish from the Keys have followed thesepatches of weeds and now can be observed as far from the keys as Star Harbor onthe north shore.   

Over many years the Lahontan Water Control District has requireda strict ban on the use of any herbicides in the basin and this was areasonable, conservative course of action before the Keys weed problem becameso critical. I have tried over the last decade to convince the leadership thatit was time to consider the reality of the aquatic weed problem and take moredrastic action. Over the years herbicides which degrade in days not weeks havebeen developed and would be used in the current application. The UV light weed eradication trials needs to be further tested at the same time which I understand will be tested with and without herbicides.  I have seen objections expressed as if thelake was to be poisoned when in fact the keys is the controlled target and the areas treated are to be double screen in order to contain the herbicide test application areas and not allow aquatic herbicide to enter the lake.    

Climate Change should also be considered in support of adecision to allow for the proposed controlled test treatments. Tahoe is measurably warming with the weedchoked warmer pockets in lagoons warming more than the lake. These warmer areasare already promoting the growth of cyanobacteria which tend to flourish bybenefiting from warmer water, nutrients and lack of circulation from themassive weed growth. It is important to note that these cyanobacteria produceneurotoxins that are harmful to both humans and animals and are a seriousindication of the eutrophication of our waterways. One positive step that the Keys could also take to suppress toxic algal growth is to do away with irrigated and fertilized grass lawns.   

In summary I believe that the time has come to allow thistesting of what promises to be a more effective water management of the TahoeKeys. It is important to give lake science a chance to prove that this is notonly a safe and desirable approach but also a very important one for the goodof Tahoe, our increasingly threatened lake ecosystem.    


Charles R. Goldman 

Distinguished Professor of Limnology Emeritus 

Dept of Environmental Science and Policy 

University of California Davis 

Currently adjunct Prof DRI and UNR 


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