Feds OK herbicide use near Lake Tahoe’s South Shore
October 1, 2015
SOUTH LAKE TAHOE, Calif. — Tahoe Keys, a series of man-made canals and small lagoons created in the 1960s on Lake Tahoe's South Shore, are infested with the Eurasian water milfoil and the curlyleaf pondweed.
According to scientist Lars Anderson, the Tahoe Keys provide the perfect spawning ground for invasive species. Weeds reduced water clarity and became home to aquatic species like giant goldfish, largemouth bass and bullfrogs.
"The waters hardly move and have good conditions to grow aquatic invasive plants because they are warm and shallow," Anderson said.
A new tool may help reduce the dense underwater jungle of weeds in the Tahoe Keys lagoons following a Sept. 10 U.S. Environmental Protection Agency decision. The decision allows the Lahontan Regional Water Quality Board to approve herbicide/pesticide use on a case-by-case basis in the Lake Tahoe Basin.
"Our action makes it possible for the Tahoe Keys Property Owners Association to apply for an exemption and a discharge permit for the application of herbicides to control invasive weeds," said EPA public affairs specialist Soledad Calvino.
Anderson was recruited to help create Tahoe Keys Integrated Weed Management Plan that addresses the weed problem.
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"It's another tool that we can apply," Anderson said of the EPA decision at a Sept. 23 Tahoe Regional Planning Agency board meeting.
Tahoe Keys Integrated Weed Management Plan also includes several non-chemical solutions to remove weeds over the next five years. The plan goes before the Lahontan Regional Water Quality Board in January.
Proposed methods to reduce or remove weeds include barrier mats, which suppress or kill weeds, driver-assisted hand pulling and mechanical harvesting.
The Tahoe Keys Property Owners Association already uses mechanical harvesters to combat weeds. The association spends approximately $400,000 per year for plant removal.
Anderson said the harvesting process generates approximately 4,000 fragments per acre of weeds removed. The fragments, if not removed, can spread and create new weed blooms.
He added that the weed management plan tracks the effectiveness of methods so the Tahoe Keys Property Owners Association can adjust its techniques appropriately.
"Every year we are going to know the effectiveness of the various approaches," Anderson said.
Proposed herbicide use for the Tahoe Keys weed management plan faces some public challenges.
Madonna Dunbar, executive director for the Incline Village General Improvement District in Nevada, said herbicides should only be used when other methods fail; and non-mechanical methods like bottom barriers should be used on a much larger scale.
"The Tahoe Keys plan fails to detail and documents how drinking water will be affected," Dunbar said. "Our treatment process in Lake Tahoe is not designed to remove chemicals like herbicides."
Tahoe Keys still needs to apply for exemptions from the EPA, according to Calvino
And Lahontan Regional Water Quality Board assistant deputy director Lauri Kemper said exemptions must be specific.
"They will have to make a justification to use herbicides and show that other methods aren't as effective," Kemper said.
Requirements include public outreach and proof that water quality won't be affected.
Even if the Lahontan Regional Water Quality Board approves initial justification for herbicides,Tahoe Keys Property Owners Association still needs to conduct additional environmental reviews and prepare another plan for herbicide use. Both the water board and the TRPA will need to approve it.
For more information on the Tahoe Keys Integrated Weed Management Plan, visit http://www.keysweedsmanagement.org.
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