Tahoe Keys Property Owners Association wants to use herbicides in 2018 to kill invasive weeds that are choking the canals of this South Lake Tahoe development.

TKPOA has applied for a permit for a small-scale demonstration that would take place next year. Lahontan Regional Water Quality Control Board would be the one to issue the permit. While that board has OK’d the use of herbicides in theory, each application must be approved on a case-by-case basis.

Curly leaf pondweed and Eurasian watermilfoil have taken over more than 90 percent of the 172-acre Tahoe Keys lagoon system. They have spread into other parts of Lake Tahoe.

If permitted, the plan is to apply low levels of Endothall, Triclopyr and Penoxsulam at nine test sites that would cover 13 acres, or 8 percent of the Keys. 

The process would include an impermeable barrier between the lagoons and lake, monitoring, and numerous safety measures to ensure that these substances would not reach the lake. The demonstration would also include using non-herbicide control methods in the years following the herbicides to keep the plants under control.

The herbicides are nontoxic to humans, fish and wildlife, and would be diluted to between 0.02 and 2 parts per million, or about half the maximum concentrations allowed by the EPA.

— Lake Tahoe News staff report