The eelgrass is back. Oysters are abundant. And the water is so clear you can see straight to the bottom.

The Edgartown Great Pond has seen a rebound in health and water quality from ten years ago.

That’s when a benchmark report by the Massachusetts Estuaries Project found the pond was in a notable state of decline. The pond was perilously near its limit for nitrogen loading and eutrophication was well under way. Eelgrass beds were disappearing or gone and the health of the ecosystem was at a tipping point. Shellfish populations were on the wane. Algae blooms were on the rise. Residential septic systems and poor circulation were flagged as the main source of the problem.

The report recommended curbing the amount of nitrogen entering the pond by upgrading septic systems or tying homes into the town sewer, and also better flushing by opening the pond to the sea more frequently.

Now a new report released last week by the nonprofit Edgartown Great Pond Foundation documents the turnaround: nitrogen levels have dropped significantly, eelgrass beds are coming back and water quality is vastly improved.

The reasons are mainly twofold: a dredge purchased by the foundation has been in active use, helping to keep the pond well flushed with circulating saltwater, and Island shellfish groups have reseeded the pond with oysters.

“The balance is back but we have to be diligent,” Martha’s Vineyard Shellfish Group director emeritus Rick Karney told the Gazette, speaking of the Edgartown Great Pond. He noted that a single bad winter several years ago proved a serious setback to the once-rebounding Tisbury Great Pond. “You can’t just declare victory,” he said. “Ponds need to be in balance so they can be resilient and that requires constant attention.”

That advice can well apply to the sixteen coastal ponds around the Island. These ponds are among the Vineyard’s signature features and all are in varying states of decline. And the primary culprit is still nitrogen from residential septic systems.

The Island towns and the Martha’s Vineyard Commission are stepping up to address nitrogen problems at their source. Oak Bluffs and Tisbury are in the midst of a multiyear effort to improve sewering and wastewater treatment, and the MVC is revising its Islandwide water quality policies.

But one lesson from the Edgartown Great Pond is that projects actively backed by the people most affected by them have the great possibility of success.

The story of the Edgartown Great Pond is a story of stewardship, dating back more than two decades ago when the late Gray Bryan led early efforts to map water quality by studying the pond with the help of marine biologists from Woods Hole. Because of that work, the Edgartown Great Pond was the first pond to be included in the Massachusetts Estuaries Project.

Today the work continues with the Great Pond Foundation, funded primarily by riparian owners.

There are other examples of similar pond stewardship, including the Friends of Sengekontacket and the Lagoon Pond Association.

The health of the Island’s coastal ponds is of critical importance to the continued vitality of the Vineyard. Thanks to those who are not content to make this a government concern and are actively engaged in saving them.