By Lake Tahoe News
The Tahoe Keys Property Owners Association is going forward with plans to use an herbicide to rid the canals of invasive species, Eurasian milfoil and curly leaf pondweed in particular.
It will be up to the Lahontan Water Quality Control Board to issue the permit.
In December 2011 the water board voted to allow herbicides to be used on a case-by-case basis. If this is permitted, it would be the first time.
TKPOA wants a permit to use aquatic herbicides in 2018 on 13 of its 172 acres. The plan is to apply low levels of the herbicides Endothall, Triclopyr and Penoxsulam on nine sites. None of the chemicals should reach the lake, according to officials.
The two plants being targeted have taken over more than 90 percent of the Tahoe Keys lagoon system.
“Comprehensive dye studies conducted in 2011 and again in 2016 have shown that water movement will not carry the herbicides out of the back channel lagoons into Lake Tahoe during the test period. Surface-to-bottom curtains and/or other barriers will be placed at select sites as an extra layer of precaution to isolate the herbicide demonstration areas,” TKPOA officials said in a statement. “Secondary barriers will be ready to be deployed as contingency measures in case trace amounts are detected during the test, ensuring no movement of herbicides into Lake Tahoe.”
The plants have been choking the canals and have spread to other parts of the lake. They affect the lake’s ecosystems and clarity.
The warming shallow waters are helping the plants to proliferate.
Herbicides are not the only mechanism being used. TKPOA has made improvements to its harvesting and collection of the fragments. However, this is just like mowing – the plant keeps growing. Bottom barrier mats and dredging are also methods to curtail the weeds.
TKPOA also installed a boat backup station that is designed to reduce the spread of weeds, and purchasing the Lake Tallac lagoon in part to better control the infestations.