A Brief History of the Big Marine Lake Association:
Eurasian Water Milfoil (EWM) was first discovered in BML by scuba divers and reported to the DNR in 2004. There were rumors about the presence of EWM in BML, but there was no lake association at the time. In 2009, a few neighbors formed the BMLA and confirmed the rumor with the DNR. The few plants found in 2004 had taken hold and 10.5 acres were found and treated with herbicide in 2009. The DNR advised the best that could be done was try to keep navigation and some areas for recreation open. They said the EWM would grow into every area of the lake less than 15 ft deep where the sediment could support its growth. There are 1170 littoral acres (less than 15 ft deep) in BML, so the situation looked dire. The BMLA hired a licensed herbicide applicator and a consultant to help prepare permit application maps. Unfortunately, the EWM ballooned to 40 acres by late 2013 and 2014.
What did we learn between 2009 and 2014?
- A sick relative in the hospital needs an advocate. So, the BMLA became an advocate for the lake. We attended seminars, read research papers; worked with applicators, consultants, and the DNR; purchased mapping software and sophisticated GPS equipment; and started questioning everything. The herbicide being used was supposed to kill the EWM, but it wasn’t working.
- We received written permission from the DNR to spot treat EWM. To our knowledge, the BMLA is the only lake association in the state with this status.
- The major difference between herbicide application on land or lawns is that, in the water, the herbicide is diluted because the water moves. Drop-offs, wave action, boats, underwater springs, etc. cause dilution of the dosage. We learned through our own work and research papers that the herbicide must stay in contact with the plant at a threshold dosage for 18 to 24 hours to kill it.
- When you have an infection that is treated with antibiotics, the dose is kept high enough for a long enough time by taking several pills a day for a given number of days. That idea led to the protocol to treat the targeted areas on the calmest possible day in the a.m. and again in the late afternoon, just before the usually calm evening and night. The max allowable dose was applied in two doses, the first dose higher than the kill threshold and a second, smaller dose to spike it back up to or above the kill threshold.
- EWM spreads by rootlets formed in late August. They selffracture and float some distance, sink and take root. Single plants or small groupings are always ignored since they are so hard to kill. Why? If the herbicide moves just five or ten feet, the dose at the plant(s) fall below the kill threshold. That led to the idea of injecting herbicide directly into the root balls. The DNR was concerned about the safety of the method and the MAISRC (U of M research) had no idea if it would work. The first tests with DNR personnel accompanying a boat the BMLA had rigged up for herbicide spot application were conducted in spring 2017. It worked very well; no dilution, targeted and less herbicide needed than when the whole water column is treated. It took the entire season to refine the equipment and the procedure so we were able to use this method far more effectively in 2018.
- So far, the EWM in BML has been reduced to about five acres of dense growth. That was the original goal, but there are still too many small spots, that if not killed, could blossom/spread and set us back to 2014. A new herbicide, Procellacor, reputed to work far better than existing product in small spots will be used in 2019. If so, long term reduction to under five acres may now be more feasible. Approximately 6 acres are planned to be treated by PLM, our licensed applicator, in 2019.