This is the project plan that was submitted and approved by Belchertown Conservation Committee

A benthic barrier, in this application, is an expanse of fabric (permeable geotextile) weighted to the lake floor to kill invasive weeds. The weeds are flattened and denied sunlight, in 4 – 8 weeks they are dead. This technique is described in The Practical Guide to Lake Management in Massachusetts (The Guide) for control of invasive weeds such as milfoil. The Guide recommends this technique for small areas of dense weed growth for effective total control.

Target Area

Much of the area around the lakefront at 21 Channel Drive on Lake Holland is being choked by invasive milfoil stands that are filling the water column and growing along on the surface. The water is hot and stagnant, it does not circulate, and is a noxious habitat favorable to insect breeding.

The area is about 3,000 sq ft. (1/15th of an acre).

According to The Guide, there are seven factors favoring this technique; this site meets them all:

1. The target area has dense plant growths of undesirable species
2. The target area is small (<1 acre) and relatively free of obstructions (stumps, logs, boulders, pilings and moorings)
3. The target area represents only a small portion of the whole lake (<10%)
4. Long-term control is sought over a small area with recognition of necessary maintenance needs
5. Inexpensive labor is available
6. No significant shellfish resources are present in the target area
7. A favorable plant assemblage is expected to develop (or can be encouraged by planting).

The area is bounded by a thick wetland, deep water, the west shore of Lake Holland, and my lakefront. See attached map. Within these boundaries the milfoil stand is very dense.

Much of area is 100% infested with invasive milfoil. The water column is filled and the plants are emergent, growing on the surface with large flowers. Picture attached.

Some of the area also has two types of water lilies. One is a broad leaf variety that I understand is also an invasive. The other has much smaller leafs and is native. Both species exacerbate the milfoil infestation because they tend to combine, entangle and develop into mats. I have been working against that tendency in my area by hand-pulling milfoil among the water lilies especially where I see tangling, with some success, but it is impossible to eradicate the milfoil in this area by hand-pulling. Therefore my target area includes some water lilies.

There is an area around my dock which is about 80% native, 10% milfoil and 10% fanwort. This is not the target area. This area was similarly choked with milfoil, but I have restored it by hand, and it will play a role in post-treatment. The fanwort in this region is not currently a nuisance.