Some Success in a Tough Fight

By Peter Lowell, Director,
Lakes Environmental Association, Bridgton

In October, experimental blue tarps began coming out of the Songo River. LEA devised this method LEA's Supersized Mainer Tarp is rolled on swim noodles so it can be floated into position. of covering and killing Milfoil on the river bottom. Because the infestation in the river above the locks is extensive (perhaps as large as three acres), we needed an affordable way to kill the plants. The tarps are each 2,400 square feet. Four were installed this past summer to test the technique. When the first tarp was removed, a barren sandy bottom was revealed where there had once been dense plant growth, giving us hope that the tarps can be used effectively on more of the river next season.

In addition to the tarps, a grant from Maine’s Libra Foundation funded full-time boat inspections at the locks and hand removal and bottom barriers at the infestation in Brandy Pond at Causeway Marina. Plants were discovered there in the fall of 2004 and through repeated work at the site by LEA divers, the situation seems manageable and diminishing in scope. A final assessment of this site will be done in November. The other marinas have been surveyed with only one plant found.

LEA's rolled and ready barrier floats as diver-director Peter Lowell discusses the next step with boaters.

Despite the apparent success of the tarps, it will be a daunting task to eliminate Milfoil from the upper river. A sweep of the river by four divers in October revealed only a few plants had made a foothold within 1,500 feet of Brandy Pond. This is good news and those plants were removed. Below this point, it’s a different story. There, some of the plant beds rise to the surface and look dense enough to walk on.

Ken Wagner, a well-known lake scientist visited the Songo this fall to assess the infestation. Following discussions with Wagner, Portland Water District staff and Maine DEP staff, LEA has made preliminary plans for a four-stage program for the Songo:

1. Attempt to draw the river down to the maximum extent in November and hope for late snow cover and minimal precipitation. Although this “freeze the plants” approach is highly weather-dependant, it is a low cost and effective way to reduce the size of the infested area.

2. Design a suction barge that would assist in the hand harvesting by suctioning the plants pulled by divers to the surface and bagging them for disposal. Little Sebago Lake has successfully built such a device. We may be able to utilize a pontoon boat donated by Naples Marina. If it is not possible to build the barge by spring, we may need to contract with a commercial harvester for one season.

3. Continue to use the tarp barriers on the sections of the river where the bottom contour is relatively flat.

4. Continue diver monitoring of the river and marinas with hand-pulling where necessary.

Area-wide, Courtesy Boat Inspectors were trained by LEA to staff a dozen boat launches with Swim noodles on the tarp's leading edge keep it afloat during application. Note floating air compressor at right; financial support from towns and the DEP. New washing stations were built at Trickey Pond in Naples, and Moose Pond in Bridgton and Denmark. Milfoil Day was initiated in August, offering landowners an opportunity to have their shoreline surveyed for invasives.

Milfoil continues to be a significant threat to the Lakes Region. Most of the 26 documented infested lakes and streams in Maine are located within an hour’s drive. Invasive plant control and education is consuming more and more of LEA’s resources and will still need to be intensified. Our priority is to contain the Songo infestation, The Mainer Tarp unrolls upstream on the Songo River.eradicate the plants in Brandy Pond and build a rapid response and prevention program that will keep plants out of other lakes or detect them early enough to be able to control them. Towns may need to consider centralizing access or requiring mandatory inspections in order to prevent this problem from getting out of control. A full blown infestation in any one of our lakes threatens all others and would generate enormous ecological damage and economic costs.