Information on Herbicide Applications and Water Use Restriction

Lake Herbicide/Algaecide Treatment Summary and Information
One of the major components of the CLAM Program is aquatic plant management. In the Canadian Lakes water bodies, aquatic plants are managed to minimize nuisances to recreational pursuits within the framework of bolstering biodiversity and ecological stability. When native aquatic plants (Illinois Pondweed, Northern Milfoil, Vallisneria and others) satisfy treatment criteria in treatment zones, herbicides are applied to singe them back. Native aquatic vegetation is never treated with the goal of mortality. This would not only be against DEQ permitting, it would be detrimental to the environmental health and water quality of the lakes. When exotics are identified, they are targeted for eradication via highly specific spot treatments. Summit Laboratory is responsible for assessing the aquatic plant population and producing treatment protocols. These protocol-based treatments are then conducted by the aquatic applicator (Aquatic Nuisance Control) as to remove any potential conflict of interest. Based on herbicide/algaecide treatments applied during the first (3) years of the CLAM Program, the following treatment schedule can be expected for 2007:

Native Aquatic Vegetation:
General Contact Herbicide Treatment
An annual pre-Fourth of July general herbicide treatment is conducted to control nuisances created by native plants. This application is not intended to kill plants, but to singe them down and leave lowering growing plants intact. This is typically a mixture of endothol and or diquat based salts (Reward, Aquathol K, Hydrothol 191). The exact mix is based on availability of product and desired effect and is left to the discretion of the applicator. These products are commonly used EPA permitted contact herbicides The treatment includes the Main Lake chain, the Lake of the Clouds chain, the Laura chain including Golden Pond, and Fawn Lake. Camper Lake and the Camper Ponds, Kitt Lake, Rush Lake, Lily Pond, and Lost Canyon Lake are all assessed each season but typically have not needed treatments.

Exotic Control:
Curly Leaf Pondweed
The CL water bodies are fortunate to currently have only one type of invasive aquatic plant, Curly leaf pondweed. As of the fall of 2006, CLPW has been reduced to a few acres on the Main Lakes (Western Main and East Lake). CLPW is a coldwater plant from Eurasia. It typically emerges in early May before the beneficial natives are up, then drops back out of the water column when water temperatures increase in June. It reappears one more time in the fall as the lake cools before winter. The plant is prolific and quickly displaces native vegetation by forming dense unsightly mats that are too thick for fish and wildlife use. Because it is active and attempting to reproduce while native plants are dormant, selective eradication via herbicide is possible. We conduct a survey specifically for CLPW in the spring and again in the fall. If patches are detected, they are mapped and treated. Typically, the contact herbicide Aquathol K is the product of choice.

Purple Loosestrife
By now most of us are very familiar with this aggressive invasive shoreline plant. Since 2004, it has been targeted for extermination under the CLAM Program and is controlled by Summit Laboratory staff. The PL story has been extensively covered in this Blog. Please review previous Blog posts for more information. The selective specially formulated aquatic herbicide Triclopyr is hand delivered in areas dense with juvenile plants, where hand pulling is not effective, and only after all flowers have been removed and bagged. Because the water is not treated, there are no water use restrictions and no posting is required.

Phargmites (Giant Reed)
Phragmities australis or the Giant Reed is an emergent shoreline plant that grows up to 12 feet tall! There is ongoing debate over the plant being native or invasive but in CL it is controlled as it can quickly spread and create thick monocultures. It can create virtual walls around a lake and with its height views of the lake can be completely lost. This plant is treated with Rodeo (Glyphosate). As of the fall of 2006 Phragmities was limited to small patches on Fawn, Laura, and Sunset Lakes. Treatment was not been necessary in 2006 due to 2005 treatment success. It is likely spot treatments will be conducted during 2007, as some of the patches appear to be slowly trying to rebound. Please note that Rodeo is a specific formulation of glyphosate. It is engineered to break down when it comes in contact with water. Glyphosate is also the active ingredient in Round Up. Never use Round Up near or in aquatic environments as it does not break down and can kill amphibians, fish, and other lake organisms!!! If you fell you really must treat vegetation on your shoreline, use Rodeo. As is the case with Triclopyr, because the water is not treated, there are no water use restrictions and no posting is required.

Algae Control:
Filamentous algae blooms are common following the pre-forth of July general treatment and isolated blooms can occur at anytime at any location if nutrients are supplied. Therefore, whenever we are out on the lakes, we look for these filamentous algal blooms. When these blooms reach treatment criteria, they are treated with chelated copper based algaecides and surfactants. Chelated copper products are more effective and efficient than traditional non-chelated copper sulfate. Though effective on algae, copper based algaecides are not very selective in that they can be lethal to larval fish, aquatic insects and other invertebrates, and amphibians. For this reason, algaecides are only applied when there is no other means of control. The most restrictive water use on any algaecide used in the CL water bodies is a 24-hour ban on swimming following an application. Copper based algaecides settle out of the water column quickly.

Discussion on Restrictions
Often, a specifically formulated “cocktail” of more than one of the above herbicides is applied. When this is the case, the applicator will post the most restrictive water use according to each products label. This is the case for the general pre-forth native plant treatment. The treatment is applied just prior to the 4th holiday as it is the most appropriate time to treat biologically (stage of aquatic plant development) and culturally (just prior to peak of summer use season). All water use restrictions (fishing, swimming, etc.) are lifted by the time everyone is up for the holiday with one exception. Treated water is not to be used for irrigation, household uses, animal (livestock) watering, or similar use for 14 days following the treatment. This needs to be clarified, as there has been some confusion over interpretation of this statement and the mode of action by which contact herbicides work. Contact herbicides are essentially salts that are designed to break down into inert compounds after a specific period of time. Because the formulation and engineered properties of each contact herbicide are slightly different, slightly different water use restrictions apply. The salts are applied into the lake as close as possible to aquatic plant beds targeted for control. Over the next few days, the salts stay in high concentrations around the plants. Because the concentration of salts is higher outside of the plant that inside its cells, water actually flows out of the plant, dehydrating it and singeing apart leaf and stalk tissues. After a few days, the salts break down into inert compounds that settle out of the water column. This mode of action is very similar to the leaf burning and dehydration over-fertilizing (fertilizers are salts too) causes a terrestrial plant. The DEQ (EPA) requires a 14 day restriction on irrigation/livestock watering on members of the Aquathol/Hydrothol family as they are chemically engineered to take two weeks to break up and go inert. If cattle, out in the hot summer sun, were watered solely with lake water that had been treated less that 14 days prior, they would run a high risk of becoming dehydrated. Imagine drinking a nice cold glass of saltwater after being on the golf course all day, and everyday for the next 14 days. This is not good for you, hence the water use restriction. There is no empirical evidence to date demonstrating a significant health risk to humans or pets ingesting small amounts of permitted contact herbicide treated water consistent with swimming activities.

Please contact us if you have further questions or concerns. Prior to any treatment, a map and description of what is being applied are posted on the Blog. Our goal is to use as few herbicides and algaecides as is possible as over use destabilizes the delicate balance of the aquatic ecosystem. We accomplish this by managing the overall aquatic vegetation population. In order to minimize negative ecological consequences of herbicide use, untreated “No Spray” zones are established wherever appropriate. Please refer to past Blogs for more in depth information on aquatic plant management.