Treatment methods for aquatic weed control included in the proposed test project are organized into two groups:
- Group A – Large-scale treatment methods for addressing target aquatic weeds using aquatic herbicides*, large scale UVC light** and LFA***.
- Group B – Small-scale, localized treatment methods for addressing target aquatic weeds including UVC light spot treatments, bottom barriers, diver-assisted suction and diver hand pulling techniques. Group B treatments are designed to be used as a follow up treatment to Group A methods.
*Only California and U.S. Environmental Protection Agency (EPA) approved aquatic herbicides are being considered in the analysis. Three aquatic herbicides have been identified as potential methods of treatment based on the weeds they are intended to target: Endothall, Triclopyr, and ProcellaCOR (ProcellaCOR is approved by the U.S. EPA and awaits approval by California EPA. It will only be included in tests if California EPA approval is granted).
** Ultraviolet (UVC) light is an emergent technology for treating aquatic weeds. This innovative technology has only been tested on a small scale at Lakeside Marina in an unobstructed environment (no docks or rock walls to maneuver around). While initial tests in 2018-2019 show promising results, tests in the Tahoe Keys lagoons are needed to understand how effective this technology might be in that specific environment.
*** Laminar Flow Aeration (LFA) is a technique that has been used to improve water quality in water bodies with low levels of oxygen. Anecdotal evidence suggests that LFA can also result in reductions in aquatic weed densities. A pilot project at Ski Run Marina is showing promising results, triggering the inclusion of LFA into the proposed test project. A small scale pilot project in the Tahoe Keys lagoons began in April 2019 and is currently underway (with support from The League to Save Lake Tahoe).
In addition to weed control methods, long-term water circulation and water quality improvement methods will be tested to evaluate how best to control environmental factors favorable to aquatic weed growth. Methods to control the spread of fragments that break loose from aquatic weeds and start new infestations will also be tested. These methods include LFA to improve water quality (and to reduce plant populations) and Bubble Curtains + Sea Bins for fragment containment and collection.