Songo River 2015 Progress Report

"Success on the Songo River and Brandy Pond!" was the headline for the LEA Milfoil Team in 2015. After 11 years of hard work, the Milfoil has finally been beaten back to manageable levels in the river and the pond. We declared victory on the Songo for two main reasons.  First, the early-season density of Milfoil on the entire length of the river was much lower than we had seen in previous years.  Even at the peak of the 2015 growing season, there was only one plant for every 100 feet of shoreline, or less.  Four years ago, there would have been hundreds in the same stretch of water.  Secondly, even when we started the season, there was no Milfoil remaining in the main channel for boat propellers to chop and spread.  The majority of the plants seen this year were confined to the remote backwaters, well away from boat traffic.

            The 2015 season on the Songo River was a season of adaptation. In the past, there have always been large patches. This year was the first year when there were no patches left, and our goal became the much broader and more difficult task of bringing the Songo River back to its natural state before variable leaf Milfoil took root. After we pulled last year’s tarps, we used the DASH boat to get any re-growth around those areas. We quickly realized that the volume of plants was so low that the harvester was unnecessarily cumbersome. We could cover more area by hand pulling rather than dragging the boat around with us. We took this as a very good sign.

Milfoil Diver

Even our measures of success changed. In the past, we looked at large numbers of bags pulled as a positive, whereas this year we saw that as a negative. If we pulled a lot of plants from an area it meant we had missed plants or root fragments the last time we came through. We would prioritize those sections and hit them again until only small numbers of plants were found. This year, more area covered also became a sign of success.  Because we weren’t using the harvester, the whole crew was in the water at all times. This had the benefit of covering more area with higher accuracy; however, it was much more difficult for the crew. People were cold and tired, which resulted in some shorter days. 

Despite the fact that we did not pull hundreds of bags of milfoil, 2015 proved to be one of the most successful years. The infestation is now manageable, which means that a crew can efficiently survey the area and remove any plants brought in from Sebago Lake, along with any rogue plants that may have re-generated. This will take less time and require fewer people than previous years, resulting in a lower cost to LEA, and freeing the crew to work on other infestations. Milfoil will probably always be in these waterways, but we can manage plants in such low concentrations, allowing native plants and animals to re-populate previously infested areas.

            Success against Milfoil is largely due to the hard work and ingenuity of the Milfoil Team and strong support from foundations and landowners.  Six veteran crew members returned in 2015 including Tyler Oren, Tom Chagrasulis, Derek Douglass, Sullivan Tidd, and Lucien Sulloway. Christian Oren led the team. Years of hard work were rewarded when our year-end surveys revealed less than a dozen plants in the entire river and Brandy Pond!

            What was most exciting in 2015 was how the ecosystem in the Songo River is recovering. Now that the Milfoil is gone, native plants are able to return to their old habitat.  Also, the ecological impact of removing the Milfoil was greatly diminished this year. Benthic barriers have the unfortunate side effect of killing off existing native plants where they are deployed and suction harvesting causes re-suspension of bottom sediments in the water column. This year these methods were only used sparingly. The surveys and hand pulling are more precise, and do not cause the same negative side effects. Even our experiment with burlap barriers is working. We started to lay burlap over patches of Milfoil in 2013 as a potential alternative to the plastic and metal barriers. The burlap can be laid over the Milfoil, and then left in the water. This is unlike the plastic tarps that need to be removed. Results were promising. The burlap we deployed in 2013 and 2014 was almost entirely decomposed, and was host to thousands of native plants. The summer of 2015 saw the resurgence of native plants on the Songo and Brandy Pond. 

            There are no longer any patches of Milfoil in the river, and better still, we managed to prevent any new patches from developing. This proves we are capable of transitioning from a removal team to one focused on long-term maintenance of drastically reduced plant density. We know how to use a scaled-back version of our crew to maintain these low densities, but we also have the ability to utilize the DASH if any patches arise in the future. Continual monitoring will need to be done into the foreseeable future to maintain the current status of the Songo River and Brandy Pond. But, this constitutes a major victory.

Click on the different areas in the map for information about milfoil conditions and control work .

Following the success of the past summer, LEA was left with a dilemma for 2016: We have a great Milfoil Control Team, but little Milfoil left to work with.  Instead of dismantling the crew and losing all of their experience, LEA chose to expand its program to Sebago Lake. As long as Sebago Lake remains heavily infested, it is a significant threat to all area water bodies.  Milfoil fragments continue to make their way into the Songo River and Brandy Pond from the lake, and other clean waters like Long Lake are at risk. The crew will service several areas on the Sebago, but the focus will be on Sebago Cove, where the worst infestation is. Sebago is larger and will be more complicated than the Songo, but our success in 2015 gives us confidence in our ability to replicate that success on Sebago Lake.

In 2016, we expect to continually re-visit the Songo and Brandy to conduct surveys and maintenance work. 

Lakes Environmental Association, 230 Main Street, Bridgton, Maine, 04009