by Nick McMahon from Pond and Lake Connection

In 2020, eight lake treatments were performed from 4/23 – 9/24. They included algae and/or aquatic plant treatments.

Our lake has Curly-Leaf Pondweed (CLP), the amount of which has generally decreased each year but, in 2020, there was a rise in the CLP present at the time of the first treatment. Nick explained the life cycle of CLP, their treatments, and said he does not expect a higher growth again next year. There was a positive increase in native plants. The aquatic plant Coontail is native and generally good for a lake but can grow floating mats which are a nuisance. The mats were treated. Invasive Phragmites is becoming particularly dense in some areas, especially by the boat launch, but also in other areas. This plant has always been around the lake but is extending its growing areas into more shallow areas. Its roots are deep and hard to remove. PLC has a systemic herbicide that is applied on the leaves, then kills the roots. This product is effective such that 75% of plant does not return. The best time to treat is August to October.

Nick reported that the amount of algae this year was fairly good. The lake did have a brown algae, or Diatom, bloom in the summer, a time when it is usually suppressed. This diatom bloom turns the water brownish for several weeks.

Nick outlined four options to reduce nutrient load (generally phosphorus) in the lake.

– Dredging
– Phoslock treatments to reduce the amount of phosphorus in the lake.
Can do 5-10% of lake per year to make product affordable.
– EutroSorb – a phosphorus mitigation product that is a continuous application
to incoming stream water
– Aeration System

Note: A full report is on file.

PLC 2021 Contract
The PLC lake contract is similar to last year’s contract and the cost is in the same range.



We anticipate receiving more donations after the November fundraising letter goes out.

The Thrift Shop grant application is due at the end of January.



Trees in the Lake

As noted numerous times, many full trees and large branches in the lake were felled by the May 2018 microburst. Our Thrift Shop grant included $1,000 for tree removal. The situation of trees in the lake has been reviewed, and several tree companies have been contacted for cost proposals. The three locations selected for tree removal are at the Marcus property, the Beach Club and at the end of Sixth Lane. After much discussion, it was decided to negotiate a shared cost with the owners for the removal of these particular trees.



A mockup of the fall newsletter was reviewed. It included a description of the Earth Day Poster Contest, which is a way to get more Ridgefielders involved and knowledgeable about the lake. Dean will make a special donation to MLIF to fund the prizes. The Board was pleased with the newsletter. The newsletter will be distributed with the November fundraising letter.


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Mamanasco Lake Improvement Fund P.O. Box 246 Ridgefield, CT06877

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