Document Type



Marshfield High School, Marshfield, Massachusetts


James Merritt


Corey Rhodes


Located down the street from my house is the Magoon Pond. I conducted an independent Study to determine the relative health of the Magoon Pond. This pond is a tributary of the North River in Marshfield, Massachusetts. To access the health will we be using a macro-invertebrate biological index as our primary tool. We will also be taking depth and flow measurements to conduct a stream profile and discharge value. To start with we scouted the watershed and choose three different test sites to use, an Inlet site, a Pond site and an Outlet site.

The pond was within a few miles of the high school, which allowed us easy access to conduct our testing on school days. The test sites were all relatively easy to reach from our parking spot along the neighborhood road. The easy access we had to all these areas made our testing simple and safe.

On our primary expeditions we observed and sampled from our sites. During this time we created some hypothesis about the integrity of our sites. At first we believed that the sites would be healthier in the inlet since the water would be less subject to pollution. However our conclusions were proven incorrect; in fact it was quite the opposite the site in the outlet of the pond had better water quality then our testing site in the inlet.

After collecting, examining, counting and sorting the macro invertebrates we were able to gain knowledge leading to the answers to our question. We discovered that our outlet was the healthiest of the three with an MGI of 4.12. The outlet also had a higher water quality rating than the pond with an MGI of 5.12. The pond was the worst of the three with water quality fringing fairly-poor with an MGI of 5.76.

This data that we collected was the key to our understanding the integrity of our sites. To determined water quality we gathered our macro invertebrates and calculated the percent of insects that were tolerant to pollution versus those that were not tolerant. For example May flies and Stone flies are not tolerant to pollution, making them good indicators. On the other end of the scale are such insects as leeches and fly larva’s which can tolerate pollution, incidentally making them poor indicators? The percentages are as follows; first is the Inlet, which had 49% of its gathered insects tolerant to pollution and 24% not tolerant. Further downstream at the Pond we found 46% of the macro invertebrates were tolerant and 5% not tolerant; the Outlet was the best quality overall with 4% of the life found being tolerant and 0% was not tolerant.

In conclusion we learned that the water quality was the highest outside of the pond. The information gained from the macro invertebrate sampling were the keys to determining the overall health of the Magoon Pond.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.


Project Location