Squantz Pond State Park - Water Quality

Water Quality

The water of Squantz Pond is moderately productive, and of suitable quality for all recreational water uses, including swimming, boating, and fishing. The productivity, or ability to support plant life, is due to the concentrations of nutrients, such as nitrogen and phosphorus, found in the water. The Connecticut Department of Environmental Protection has classified Squantz Pond, as mesotrophic, due to its moderate nutrient concentrations, good clarity, and other water quality characteristics.

Dissolved oxygen (DO) is a requirement for the respiration of fish and other aquatic organisms. The concentration of DO depends, in part, on water temperature, as cold water can hold more DO than warm water. Because of this, season also affects the distribution of DO in the lake. In the fall, as temperature decreases, the cooled DO-rich surface waters begin to descend toward the bottom because of the difference in density, (water density increases with falling temperatures until it reaches its maximum density at 39 degrees Fahrenheit (4 degrees Celsius), below which it decreases). This mixing of the water due to the difference in density, along with mixing by wind, transports DO to the deeper waters of the lake and results in relatively uniform conditions from the surface to the bottom of the lake by winter. This condition can be seen in the winter profile of DO and temperature (Winter Profile), where the DO concentrations are relatively uniform with depth.

In the spring and summer, the surface waters of the lake are warmed by increasing temperatures and the sun. This warmer, less-dense water remains at the surface, and the lake becomes thermally stratified. As a result of this stratification, there is little mixing of the shallow and deep water in the lake. Thus, DO, which enters the water primarily from the atmosphere and from photosynthesis carried out by aquatic plants, is not transported to deeper water. Near the bottom, the consumption of DO by aquatic organisms and chemical reactions exceed the rate of replenishment, resulting in lower DO levels. This condition can be seen in the summer profile of DO and temperature (Summer Profile), where the DO concentrations decrease rapidly below about 18 feet and are less than 1 milligram per liter below 24 feet. During periods when these low DO conditions exist, there is insufficient DO to support most types of game fish in deeper waters of the lake, and they will normally move to upper layers of the lake where higher DO concentrations are found.

The pH of the water indicates whether it is acidic or alkaline. The pH level is measured on a scale from 0 to 14, where 7.0 is considered neutral, less than 7.0 acidic, and greater than 7.0 alkaline. Highly acidic or alkaline water can be detrimental to aquatic organisms. The ideal range for most freshwater game fish is from 6.5 to 9.0, however, most adult game fish can tolerate pH as low as 5.5. The pH of Squantz Pond ranges from 6.8 to 8.9, which is adequate for most gamefish.

Alkalinity, which is a measure of the ability of water to neutralize acid, is relatively high in Squantz Pond. For this reason, the lake is not very susceptible to acidification.