STUDYING MV GROUNDWATER

According to USGS (US Geological Survey)

Groundwater is water that exists underground in saturated zones beneath the land surface. The upper surface of the saturated zone is called the water table.

Contrary to popular belief, groundwater does not form underground rivers. It fills the pores and fractures in underground materials such as sand, gravel, and other rock, much the same way that water fills a sponge. If groundwater flows naturally out of rock materials or if it can be removed by pumping (in useful amounts), the rock materials are called aquifers.

Groundwater moves slowly, typically at rates of 7-60 centimeters (3-25 inches) per day in an aquifer. As a result, water could remain in an aquifer for hundreds or thousands of years. Groundwater is the source of about 40 percent of water used for public supplies and about 39 percent of water used for agriculture in the United States. USGS What is Groundwater?

Great Pond Foundation began a collaboration with The Marine Biological Laboratory, in 2021 to measure and locate nitrogen sources in groundwater surrounding our Island Great Ponds.

Upon completion of the first phase, the study indicated that >50% of nitrogen in our Great Ponds is coming from wastewater and the next biggest contributor is fertilizer. The bad news is that humans caused this problem. The good news is that humans can fix it.

Tracking sources of nitrogen pollution is an iterative process where each round of sampling gets closer to the target of identifying the source. If you think of a pond as a whole and imagine looking at a large circle that represents a concentrated source or plume of nitrogen, with each round of sampling, the circle gets smaller, and you get closer to the target. The next phase of the work, which began in November 2024, is to integrate the targeted transects in Slough and Meshacket Coves into a nitrogen load model for Edgartown Great Pond.

The ultimate goal is to pinpoint the source and magnitude of concentrated nitrogen plumes. Knowing the size, source, and scope of the problem will allow mitigation technologies can capture and transform harmful nitrogen before it reaches ponds.

Learn more in the December 5, 2024 article by Vineyard Gazette reporter, Gwyn Skiles.

If you are curious how individuals can help reduce nitrogen, the Vineyard Conservation Society provides wonderful resources about having naturally beautiful Vineyard Lawns.

For more information about this ongoing groundwater study visit the links below.