Water Quality Monitoring

Since 1983, each month from May through October, the Candlewood Lake Authority heads out to the water to conduct water quality testing and monitoring. Historically there have been four sites tested on Candlewood and one on Squantz Pond.  


What do we test for?


At each site, we lower a probe into the water at 1- meter intervals and record readings on the following:

- Water Temperature

- Dissolved Oxygen

- Conductivity

- pH

- Relative Blue Green Algae Concentrations

- Chlorophyll-a


In addition, at each site we take a Secchi disk reading. A Secchi disk is a black and white disk that is lowered in to the water until it is no longer visible. The depth of the disk is recorded and that is how we measure water clarity in the lake. High water clarity is usually an indicator of better water quality. When clarity is lower, that could mean that there are high levels of particulate matter (like soil and other solids) in the water, or it can be an indication of increased algae in the water, causing the water to appear green and less clear.


At each of the sites we also take multiple water samples to bring to the lab for analysis. Samples are taken from three depths at each site using a Van Dorn Bottle, which is a specialized instrument that captures water at specific depths. The depths the samples are taken from are: the surface, the bottom, and a middle depth in between determined by where the warmer upper water layer ends and the layer of colder water beneath it begins (namely, where the largest change in temperature between meters is).


The various samples are brought to the lab and tested for
- Nutrients: Phosphorous and Nitrogen

- Ions: Calcium, Potassium, and Sodium

- Chlorophyll - a