Most lakes in the Lower Hudson Valley must contend with seasonal algal blooms. Kirk Lake is no exception, so KLWA has been collecting water quality data and will also gather New York City's water testing data to develop a watershed management plan to attack this problem.
Occasional blue-green algal blooms are of particular concern. If you see a significant greenish mat-like substance on the water's surface, it's probably a good idea to avoid swimming. Young children -- who tend to ingest more water than adults, should especially avoid swimming during these times.
What causes the the algal blooms in Kirk Lake?
We have an excess nutrient load in the lake. Phosphorus and nitrogen are the main culprits.
Using the funds so generously donated by our members, KLWA has done extensive studies over the years to identify the point sources. (This information is on the KLWA website) Our limnologist has tested various waterflows from around the lake. As would be expected, the areas with the highest home density have shown to have the highest nutrient loads. Most notably on the west side coming from Overlook and Lakeside Roads.
Where does the excess nutrients come from?
2. Septic systems
3. The lake bed, where nutrients have accumulated over time
For more information, see the NYS Health Department PDF below.