Great Island Pond
Water Quality Monitoring
The Pinehills LLC, under it's Groundwater Discharge Permit with the Commonwealth of Massachusetts (#0-680), is required to monitor groundwater and surface water around the Pinehills, primarily to determine if nutrients from the treatment plant are contaminating the water, including Great Island Pond.
NOTE: Nutrients from the treatment plant could increase the algae and aquatic plants in Great Island Pond. In addition, over fertilized lawns could runoff into the pond and increase algae and aquatic plant growth. The Pinehills Initial Use Restrictions and Rules limit the application of fertilizer at more than 3.5 lbs/1,000 sf/yr nitrogen.
Removing ground-cover, shrubs and trees from the 100' buffer around the pond or any of the community's other six (6) wetlands will damage the buffer zone's ability to protect the pond.
According to Horsley & Witten. 2007. 2006 Annual Report for The Pinehills Groundwater Discharge Permit 0-680. Horsley & Witten, Inc. Sandwich, MA.:
"The concentration of most nutrients and chlorophyll-a were similar to concentrations observed in previous years and/or fell within the range of variability seen in previous years. This suggests that there has been little or no change in overall water quality and productivity over time and/or the variation falls within the amount of variation observed in previous years."
You already know that Great Island Pond is crystal clear. Horsley & Witten documented that you can see 18 feet to the bottom during the winter!
They measured how clear the water is in Great Island Pond using a standard measure of visibility called a secchi dish.
| Secchi Disk |
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Here are the visibility measurements at the two Great Island Pond sampling location;
| How clear is the water in Great Island Pond? |
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GIP-1 |
|
2006 |
2007 |
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| January |
10' |
18' |
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| March |
5' |
8' |
|
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| June |
9' |
12' |
|
|
| July |
12' |
13' |
|
|
| August |
9' |
11' |
|
|
| November |
10' |
15' |
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|
|
|
|
GIP- 2 |
|
2006 |
2007 |
|
|
| January |
10' |
18' |
|
|
| March |
12 |
14' |
|
|
| June |
16 |
11' |
|
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| July |
12' |
12' |
|
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| August |
13 |
10' |
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| November |
18 |
17' |
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Here are the sampling location in Great Island Pond;
Here are 2004 to 2007 comparisons for some of the basic nutrients;
NOTE: Chlorophyll is a measure of the amount of algae in the water. Total Nitrogen and Phosphorus measure nutrients in the same way as you would choose a fertilizer for your lawn based on its Nitrogen and Phosphorus content.
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