Eurasian water milfoil (EWM) is an aggressive aquatic invasive species (AIS). Invaders like EWM enter mainly via boats traveling from lake to lake, transported on boat bottoms, trailers, in bilge water, motors, in bait boxes and on fishing equipment. Once established, it can be easily spread by boat props, fishing lines and anchors. Eurasian water milfoil was first seen in Higgins Lake in the late 90s but was introduced in the U.S. in the 40s. EWM in Higgins Lake is found primarily along the drop off areas.
Identify Eurasian Watermilfoil
PAST: Since the initial introduction of EWM, various methods of removal and control have been tried. Asking residents to hand pull any EWM on their property was the first recommendation presented by Brad Jensen of Huron Pines. The next effort was the introduction of miniscule weevils expected to devour the EWM. The weevils were costly and results disappointing. The Higgins Lake Foundation funded a chemical test site in Higgins which proved ineffectual due to the depth and water movement in Higgins Lake. The next method was the use of benthic barriers, large tarps that are placed directly on top of the infestations for six to eight weeks to kill all vegetation beneath it. The Higgins Lake Foundation funded the purchase of the barriers with grant funds provided by EnTrust Foundation, RCCF and the John Morley Fund. The divers used air tanks as they placed the barriers. They were secured to the bottom by pounding them in with j-pegs. It was a laborious process however progress was made. It was difficult to firmly secure the barriers at the drop-off locations where the milfoil is most prevalent and the system was not selective, extinguishing native vegetation along with the EWM. The work was done by a volunteer team led by Marv Bolton who did much of the work himself.
In 2010 board members of the Higgins Lake Foundation with the HLPOA Milfoil team of Marv Bolton, Pat Springstead, Rick Meeks and Laurie Smith, learned about the DASH (Diver Assisted Suction Harvester) boat at the annual Michigan Lakes and Streams Convention. This vacuum-like method had been used on the East Coast with a record of proven success. By 2012 a DASH boat was funded by the Higgins Lake Foundation, permitted, insured and operating on Higgins Lake with a paid crew of two divers and two deck hands. This “harvesting” system involves actual underwater hand pulling of the weeds and placing them in a suction tube that transports the weed into onion bags where it is contained and deposited at an approved land site at the end of the day.
PRESENT: Darcia Little, Geographic Information Specialist from Camp Grayling, completed a survey of Eurasian water milfoil in Higgins Lake this summer. She mapped locations and coordinates, providing a current record of locations and size of infested areas. This data will help our management plan.
The DASH boat system removes more milfoil in a day than the barriers could extinguish in a month. The DEQ permit allows the use of a small tool to remove the root, although in areas of soft sand, the root easily comes up along with the weed. EWM is an aggressive invasive; it spreads easily by props, anchors and fishing lines; stems and cuttings easily break off with any disturbance and it replants quickly. There are challenging areas in the lake where constant mooring and recreational activity disturb the lake bottom and cause cuttings to occur. The DASH team has been successful in controlling, reducing and removing EWM in Higgins Lake; however, due to the nature of this invasive, our work is not done.
The Higgins Lake Foundation is the first in the State to own and operate a DASH boat. The HLF Board has provided demonstrations of the DASH Boat to many other lake groups; some are renting DASH Boat services to remove their EWM. Houghton Lake will be removing twenty-seven acres of EWM from their lake bottom this fall using the DASH method. Other lakes that have shown interest, and some who are using the system, are Eagle, Perry, Marcellos, Margrethe, Pentwater and Maceday.
It costs approximately $20,000 per year to operate the DASH boat. The Higgins Lake Foundation has funded the DASH boat with generous help from grants given by the Roscommon County Community Foundation, the John Morley Foundation, the Thalner Fund, EnTrust Foundation, the Rotary Club of Roscommon and private donations. The DEQ permit for operation was recently renewed. Support letters for use of the DASH system on Higgins Lake were provided by Huron Pines, the DNR, US Fish and Wildlife and others. Chemical use is extremely expensive and can have a negative impact on the lake’s delicate eco-system. Chemical treatments have not proven to eliminate EWM. Houghton has invested six million dollars in chemicals in the past fifteen years, and EWM remains a problem there.
How many invasive species are there in Higgins Lake? HLF is funding an analysis of plant life in Higgins Lake to answer that question. Currently EWM and zebra mussels are the only known AIS species in Higgins Lake.
The DASH Boat on Higgins Lake
FUTURE: In the first five years of use, the DASH boat system has successfully controlled, reduced and removed EWM in Higgins Lake. The DASH crew works Monday-Thursday, and Fridays when boat traffic permits. Left unchecked, EWM can overtake a lake very quickly. In some areas of Higgins, the EWM has been totally eradicated; in other areas it is necessary to repeat the harvesting to eradicate it permanently. During the recent survey, a few small patches were spotted in shallow areas between the drop off and the shore. The locations have been recorded, and the DASH Crew will be removing as many of them as possible before weather prohibits their work. An additional tool to eradicate the smaller patches is the benthic barriers. The Higgins Lake Foundation has applied for the required permit to use benthic barriers in the spring. Once the weed has been identified as EWM, a small barrier can be used when the patch is located on a flat area. Most EWM is found in the drop-off where the barriers cannot be secured.
Flag Point has been a difficult area to battle EWM due to ongoing boat mooring and recreational activity that disturbs and spreads the weed. Anchors are often dropped directly on top of the EWM and lines pulled around it. The DASH team will continue work at Flag Point this fall and focus on it when first growth appears in the spring.
There are 188 known aquatic invasive species in the Great Lakes. There is not a guaranteed eradication method known for any of them. The boat wash movement is growing in Michigan inland lakes. Many lake associations have visited Higgins Lake to tour the boat wash stations funded by the Higgins Lake Foundation. The HLF is working with the DNR to use Higgins Lake as a pilot program for mandatory boat washing at state launch sites. Toward that goal a survey was distributed to boaters this summer to determine public awareness of the aquatic invasive species problem and willingness of boaters to wash their boats when launching and leaving lakes. Results of the survey will be available soon.
Love Higgins Lake? What can you do to help? Prevention is the best defense! Do not transport aquatic hitchhikers from lake to lake. Wash your boat, your trailer and fishing equipment, empty bilge water, live well, motor and bait boxes. Omit use of fertilizer; if it makes your grass grow, it is also feeding weeds in the lake. Phosphorous is banned in Michigan. If you are starting a new lawn or garden, have your soil tested. The HLF office has a limited supply of MSU Extension Office soil test kits for sale for $12.50 – half off the full price. Maintain your septic system. Nutrient loading from faulty systems in the Higgins Lake watershed promotes weed growth in the lake. Do not anchor on top of EWM; it will break off and spread. Report EWM locations to the Higgins Lake Foundation. If you are unsure if it is EWM or native milfoil, please take a picture and send it to the Higgins Lake Foundation. Email firstname.lastname@example.org, 989 275-9183, open Tuesday-Wednesday-Thursday 9am-3pm.