From the 1960s to the 1990s Ballston lake had a long history of copper sulfate treatments to control excessive algae levels in the lake. There were whole lake treatments after 1973 and in some years multiple treatments. Typically 1200 pounds of copper sulfate were applied in late June and early July. Here were the results:
1. Water clarity in the late 1970s was from 5 to 7 feet. In 2012 it was 4 to 6 feet.
2. DEC did a study in the mid 1990s and found the sediment copper levels were 175 mg/kg. Untreated lakes were 10-20 mg/kg.
3. Copper levels of 175 mg/kg is considered a “contaminated” sediment.
4. Excessive copper levels can be toxic to some fish species.
5. Blue green algae levels dropped immediately after application. This resulted in an increase in 1 foot of additionalclarity.
6. Within a week the water clarity readings had returned to pre treatment levels.
7. Within a week blue green algae concentrations increased, “rebound effect”.
8. Conclusion: copper sulfate is not a long term solution to algae control.In addition the following information about copper sulfate is a concern:
1. Copper sulfate works best in water that has a pH below 6.5. The pH of Ballston lake is 7.5.
2. People cannot go in the water for 2 days after a copper sulfate treatment.
3. Copper sulfate causes eye irritation
4. Copper sulfate breaks apart algae cells and the contents in the cells is released into the water. This results in anincrease in microcystin toxin concentrations.
5. Copper sulfate is toxic to the zooplanctin that consume algae.
Studies show that humans influence the frequency of algae blooms. Our actions have a potential to alter the balance between having a bloom or not. Steps to reduce phosphorous from entering the lake will reduce the incidence of algae blooms. Old failing septic systems contribute to phosphorous levels. In addition, minimizing erosion, controlling storm water runoff, not using fertilizers, and maintaining a shoreline vegetative buffer, all help to limit our impact and preventing algae blooms