Apponequet Regional High School, Lakeville, Massachusetts
In the summer of 2003, I noticed that the clarity of the water of Long Pond seemed murky with a brownish hue. I remembered as a kid being able to travel around the pond and see the bottom. Back then the water seemed much clearer, which is what provoked me to look further into the causes of the increase of turbidity of Long Pond.
To measure turbidity I used a simple Secchi disk that I made out of the bottom of a bucket and some rope. The rope was marked every six inches and was fourteen feet in overall length. Sampling was generally done at about seven o’clock in the morning. Weather patterns were recorded to help explain any spikes in the data. I choose four sites at various spots, which I felt would provide dependable data for the overall quality of the pond.
The data were compiled into a spreadsheet and then displayed as a graph. The overall turbidity measurements of the four sites showed no irregular spikes or evidence of severe changes. A notable spike occurred on the fourth of May at the site Point of Cove, which could have been caused by an increase in debris entering the water due to the blooming of trees.
Chlorophyll samples were taken on the twenty third of April to provide baseline data of algae concentrations as no previous studies have occurred. The procedure for sampling chlorophyll came from the Massachusetts Water Watch Partnership’s protocol. The result of the chlorophyll tests show that the values were below normal for a mesotrophic lake. Normal values range from 4-12 mg/l. The site north end had a value of 2.5; cove 3.0, my dock 3.9 and point of cove 1.5 mg/l respectively. Since measurements were taken on April 23, 2004, the results show a low value due to the time of year. As the summer months progress chlorophyll values should increase.
The overall turbidity of Long Pond is not as dangerous as I had previously thought. Most of the measurements for turbidity were at least half of the overall depth of the site. It may be possible that an increase in the growth of milfoil may cause an increase in turbidity, however further studies must be done to prove this. The increased turbidity last year may have been caused by high counts of algae as the weather was very hot and rainfall was below normal. Since chlorophyll a was measured in the spring, it is safe to summarize that chlorophyll a did not contribute to the increase of turbidity in Long Pond during the period tested. Other factors may have caused an increase in turbidity; it is my hope, however, that this study will help provide data for further research in the water quality of Long Pond.
— Mike McNally
Apponequet Regional High School, Lakeville, Massachusetts (2004). Turbidity: An In-depth Look at Long Pond. In Watershed Access Lab Projects. Project 11.
Available at: http://vc.bridgew.edu/wal_projects/11
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