CLWA plans treatment of invasive Eurasian Watermilfoil
The CLWA’s comprehensive three-year (2016-2018) survey of the aquatic plants in Crystal Lake revealed a generally healthy lake, and identified Eurasian watermilfoil (“EWM”, Myriophyllum spicatum) as the only invasive plant species currently present. The invasive here is limited in extent – just 6.05 acres of Crystal Lake’s total area of about 10,000 acres, primarily in the east end. The CLWA will begin treatment late this spring in order to halt the spread. Most authorities recommend treatment before it reaches an advanced stage where control becomes impossible. CLWA will pay costs, estimated at up to $10,000.
EWM is widespread in Michigan and Crystal’s situation is much better than many lakes in the state. The highest density is found at the entire drop-off surrounding the Beulah village boat launch, where it was likely originally introduced by itinerant boats. There is intermittent colonization along the southeast shore up to and past the DNR launch and around Railroad Point into Onkeonwe Bay. Additional colonies are established at the Lobb road-end launch but none west of the Disciples of Christ Conference Center on South Shore Rd. The west end and north shore appear to be virtually EWM free. DNA analysis shows that Crystal’s milfoil fortunately has not yet hybridized into variant species for which effective treatments are not available.
None of these colonies has yet begun to interfere with recreational activities, but left unchecked, EWM can out-compete native beneficial plants, and overwhelm all other lake biology including fish and amphibians. It forms a dense canopy of vegetation that blocks light from native aquatic plants. It can grow so thickly that it requires mechanical harvesters to clear the top few feet of water for a short period of time before it grows back, interfering drastically with recreational boating, swimming and fishing.
After thorough investigation of all available treatment methods, CLWA has determined that treatment with chemical herbicides is the most cost effective and suitable one for the existing conditions on Crystal Lake. The most widely used treatment, it is quick and has proven successful in controlling (but not totally eliminating) the invasive plant. The specific agents used for EWM, 2,4-D or Triclopyr, do not aﬀect the native plants or animals of the lake. They are fully registered by the EPA, EGLE, and MDA for aquatic use in the State of Michigan. Both have undergone comprehensive testing and decades of safe usage in U.S. waters.
To perform the treatment, CLWA has retained Clear Water Lake Management, Inc., of Rochester MI, a professional pest management contractor, licensed by the Michigan Department of Agriculture and Rural Development (MDARD). A boat-based technician will dispense the product in a controlled fashion directly on the plants at close range and it sinks to the lakebed. The process will be guided in real time by aerial drone photography that facilitates precise placement of the product without excess exposure.
Effective treatment usually requires two treatments per year in our climate. The first treatment will take place on Wednesday, June 24 (weather permitting), and the second on July 29. Residents and property owners will receive notice of the dates for the treatment. To insure maximum safety, swimming will be restricted for 24 hours in the immediate treatment area. Monitoring results over time will be needed: many lakes that have a regular program for control.
The use of herbicide in inland lakes requires an Aquatic Nuisance Control Permit from the Department of Environment, Great Lakes and Energy (EGLE), which must be obtained for the specific project by the applicator. To obtain the permit, the riparian landowners whose lake bottomland will be treated must give their written permission.
Much of the area to be treated is under public ownership of Beulah Village, the Michigan DNR, and Benzie County: these entities have all given their appropriate permissions. The CLWA is now contacting the affected private riparians to explain the proposal and request their agreement.
The CLWA Aquatic Plant Survey was led by CLWA board member Jim Hamp, assisted by the drone technology of Zero Gravity Aerial, and conducted under the auspices of the Michigan Cooperative Lakes Monitoring Program. The identification and control of invasive species has been a long-time concern of the CLWA, leading to the construction of the boat washing station at the Mollineaux Road launch site in 2013.
For more information on Eurasian watermilfoil, its threats and treatment, see the following sources:
Michigan Invasive Species: Eurasian Watermilfoil
State of Michigan’s Status and Strategy for Eurasian Watermilfoil Management (DEQ)
Weed Risk Assessment for Myriophyllum spicatumL.(Haloragaceae) – Eurasian watermilfoil (Michigan Department of Agriculture)