By A.J. Arias
Montclair State University recently concluded a three year study of the contents of Greenwood Lake. The results of the study were presented by Meiyin Wu, the Director of the Passaic River Institute, at Greenwood Lake Commission on Wed., Mar. 28.
The results of the study covered multiple areas of concern for the lake including Phosphate, which is a reactive that occurs naturally for plants and fish to perform their natural tasks; total phosphorus (TP), which shows levels for algae and dirt in the water; E. coli, which shows bacteria levels in the water, temperature, suspended solids, and other pathogens in the lake. These were tested at several different sites spanning the lake.
A concerning find in the study was the E. coli pathogen indicator. The New York side of the lake recorded levels that are all under the Environmental Protection Agency’s recommended threshold for pathogen levels of 126 CFU/100ml. However, the New Jersey side of the lake had two areas that recorded levels above that threshold.
These two points were the most southern data point researched in the main body of the lake at slightly below 140 CFU/100 mL, as well as at the mouth of Belchers Creek around Brown’s point at 3,638 CFU/100 mL, nearly 30 times over the recommended threshold.
Wu said that at the threshold 126 CFU/100 mL mark any place for recreation, including a beach, should be shut down. It should also be noted that these points were recorded in late September, whereas the height of pathogens tend to be around July and August.
While discussing the lake’s phytoplankton levels, Wu noted the discovery of microcystis and anabaena, which both create microcystins. Symptoms of microcystins exposure include diarrhea, vomiting, goose bumps, weakness, and liver hemorrhaging/toxicity. Microcystins were found at the most northern data point of the main body of the lake, which is around the Stow Away Self Storage Facility, in 2015.
The study only presented results from 2016 in Belchers Creek on the Jersey side of the lake, where the amount of microcystins was 3.2 µg/L, which is above the NJ threshold of 3 µg/L. Going over this threshold would normally call for the immediate closure of a beach.
In 2017, the study took samples from the most northern tip of the northeast arm, where the levels were found at 0.050 µg/L and 0.071 µg/L on either side of the bridge. The reason for the low levels of microcystins is most likely thanks to the presence of plants and green algae in the area, which block sunlight that the pathogens need in order to grow and flourish.
The total phosphorus levels for the lake exceeded the recommended threshold of .1 mg/L in two points on the most northern points of the northeast arm at around just above .15 mg/L in both areas. Additionally, the most northern data point on the main body of the lake had recorded levels two times above the recommended threshold at around .21 mg/L. All points were slightly improving over the course of the study but were still over the listed threshold. The existence of phosphorus leads to the growth of algae and plants in the lake.
Another contributor to algae and pathogen growth is phosphate. Phosphate levels in the lake have been increasing over the course the three years of the study and are currently just slightly below the recommended level from University study.
Potential causes of these problems include runoff of fertilizer from surrounding lawns, animal waste from anything including dogs, deer, geese, or other farm animals, and the possibility of septic tank leaks into the lake. Commissioner Eric Hastings noted the potential of sewage bypass by the West Milford sewage plant.
In terms of temperature, the lake overall dropped in temperature in 2017 from previous years. Additionally, all areas of the lake recorded temperatures underneath the recommended threshold of 23 degrees Celsius. The temperature for the main body of the lake had a seven day average of 21 degrees Celsius and the northeast arm of the lake had average temperatures ranging from 19 to 20 degrees Celsius. The coolest site was the most northern point of the northeast arm. It should once again be noted that the study was done on Sept. 30 and that in summer months the lake is most likely dramatically warmer, putting the lake at risk for having a higher temperature than the recommended maximum of 25 degrees Celsius.
Further research into the issues of the lake was called for by the Commission. The possibility that most of the data points are actually dramatically higher in summer months due to warmth and recreational activities in the lake was a cause for a concern. Wu did give some comfort to the Commission by letting them know that other lakes are much worse and that Greenwood Lake isn’t that bad according to her.