McCavanaugh Ponds: 2013 Aquatic Plant and Water Quality Report

Adirondack Watershed Institute

Corey Laxson & Daniel Kelting

The objective of this report is to describe the water quality status and aquatic plant communities of the water bodies of the McCavanaugh Pond Club currently being managed with grass carp to control aquatic vegetation. Water quality monitoring has occurred at the McCavanaugh Ponds for seven years. However, with the exception of 2006, only one sample is analyzed per year. Given the inherent variability in limnological data, we feel trend analysis on these single samples would be weak, if not invalid, and therefore we did not statistically analyze the time series data. The data and accompanying analysis provided in this report give insight into the water quality and plant community of the McCavanaugh Pond Club’s water bodies, more detailed limnological studies may be necessary to produce management recommendations.

McCavanaugh Pond

1. Since 2006 the trophic status of McCavanaugh Pond has fluctuated between the eutrophic and mesotrophic boundary. In 2013 the Trophic Status Index of McCavanaugh Pond based on secchi disk transparency (63) and chlorophyll (59) suggests a eutrophic classification for the pond, while the TSI value for total phosphorus (46) suggests a mesotrophic classification for the pond. A disparity of this nature typically occurs when the water body is experiencing phosphorus limitation or has elevated levels of dissolved organic matter that reduce the secchi transparency.

2. Vertical profile analysis from September suggests that McCavanaugh Pond provides a suitable thermal environment and adequate dissolved oxygen for brook trout, whose optimal temperature is around 16°C, and optimal oxygen concentration is 5 mg/L and above. However this scenario may be quite different during the warm summer months when brook trout may be restricted to a narrow stratum where temperatures are cool and oxygen is still adequate.

3. McCavanaugh Pond is an acidic water body with a historical average of 6.3 pH units. We observed a decrease in alkalinity over the seven years of monitoring, ranging from values near 20 during the first several years to values below 10 mg/L for the past two years. Water bodies with alkalinity values less than 10 mg/L are classified as being sensitive to acidic deposition.

4. McCavanaugh Pond is a deeply colored water body with a historical average of 79 PtCo units. Elevated color levels are associated with high levels of dissolved organic material in the water. Elevated color values also result in a decrease in secchi transparency.

5. We observed 13 native aquatic plant species in McCavanaugh Pond, the most common being water shield, white water lily, spatterdock and purple bladderwort. The aquatic plant beds occupy a minimum area of 12 acres. We did not detect any change in plant bed area between 2011 and 2013. The slight difference in bed area (0.3 acres) is within the range of error expected when performing a visual survey from the surface.

6. The frequency of occurrence of white water lily and water shield captured by the rake decreased by 12% between 2011 and 2013; however, we found a greater percentage of rakes had dense coverage of water lily in 2013. Lesser bladderwort and common bladderwort were ensnared by the rake in 2013 but not in 2011. The frequency of occurrence of purple bladderwort did not change between years; however greater density of purple bladderwort was captured on the rake in 2013.

Dickman Ponds

1. The trophic status of the Dickman ponds has fluctuated between eutrophic and mesotrophic characteristics since the study began in 2006. However, both ponds are deeply colored, averaging 102 PtCo units; this value is greater than any of the 67 lakes analyzed by the AWI in 2013. Elevated color levels are indicative of high concentrations of humic organic matter. The elevated color and relatively low concentrations of chlorophyll suggests the ponds maybe somewhat dystrophic. Phosphorus and chlorophyll concentrations in the ponds appear to be decreasing over the past several years. However, this cannot be statistically validated due to low sample size.

2. Vertical profile analysis from September suggests that the Dickman Ponds provides a suitable thermal environment and adequate dissolved oxygen for brook trout, whose optimal temperature is around 16°C, and optimal oxygen concentration is 5 mg/L and above. This scenario is likely quite different during the warm summer months when brook trout may be restricted to a narrow stratum where temperatures are cool and oxygen is still adequate; however, because the ponds are so shallow this type of refuge may not exist.

3. The Dickman ponds are acidic and have low acid buffering ability. The historical average pH is 5.8 for Dickman 1 and 5.9 for Dickman 2.

4. We observed 12 native plant species in the Dickman ponds, the most common being water shield, purple bladderwort, common bladderwort, and spatterdock. In 2011 the aquatic plant detected in the surface survey occupied a minimum area of 14.6 acres (84% of surface area), in 2013 we found the minimum surface are occupied to be 9.8 acres (67% of surface area).

5. The frequency of occurrence of water shield captured by the rake decreased by 16% between 2011 and 2013. We also observed that the density of the plants ensnared by the rake was less in 2013. The frequency of occurrence of purple bladderwort increased by 22% between 2011 and 2013 and the density of plants ensnared by the rake also increased.

In conclusion, we found the water quality of the McCavanaugh Pond Club’s water bodies conducive to brook trout growth and survival. However, we surmise that warm summer water temperatures and bottom anoxia may greatly reduce the available habitat for the fish. The Dickman ponds are quite acidic. Although brook trout are the least acid sensitive salmonids, it is likely that the acidity of the Dickman Ponds has negative impacts on juvenile fish. We were unable to detect a substantial difference in the plant community of McCavanaugh Pond in 2013. The Dickman Ponds did see a reduction in water shield and the area occupied by plant beds. The final survey of the ponds will occur in September, 2014.