Aquatic Plant Survey – August 2019

In May 2019 BLIA received a $3800 grant from DEC through the Capital Mohawk PRISM to conduct an Aquatic Plant Survey of Ballston Lake. In August scientists from Darrin Fresh Water Institute were on the lake conducting this survey. Link to the report. They employed a rake-toss point intercept methodology to record their data using GPS to develop the points. They surveyed 125 points in the littoral zone (depths of 11 ft or less) around the lake.  Results are as follows:

1. 44 different aquatic plants were identified. Most lakes in our area have 15
2. Of these 3 were invasive, water chestnut, curly-leafed pondweed, and Eurasian Watermilfoil
3. Eurasian Watermilfoil was present at 19% of the 125 points
4. Only 5 species occurred in more than 5% of the 125 points
5. 35% of the 125 points had invasive plants
6. Water Chestnut very scarce due to aggressive pulling by BLIA volunteers
7. Most prevalent plant in August was coontail
8. Most aquatic plants grow in water less than 11 ft deep
9. Lack of aquatic plants in south half of the lake due to shale substructure, steep slopes, and small littoral zone
10. Curly-leaf Pond Weed was dense in early summer and was replaced by coontail after the lake got warm in July

Conclusions:

1. Large number of native plants suggests that if any invasive plant were eliminated it would be replaced by another aquatic plant
2. Aquatic plants can be reduced in density by pulling and disposing of the debris
3. Plant free areas around docks can be developed by placing a benthic barrier. This will kill the plants in 4-5 weeks. See: Seaweed Mat Systems
4. If plants are cut you must remove all the pieces since some invasive plants propagate by fragmentation
5. Herbicides are controlled substances and must be applied by a licensed application company. Some Herbicides can be used for specific species of aquatic plants. Lake use restrictions may apply after Herbicide use.

The BLIA board believes that by decreasing phosphorous coming into the lake when the unwanted aquatic plants and algae will decrease in abundance. Once this phosphorous input is decreased then lake bottom sediment with its enriched phosphorous can be addressed.