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An excavator opens Sesachacha Pond to the ocean on April 12.

A rite of spring on Nantucket: Pond openings.

Pond water flowing out to sea.
Because Hummock Pond was so full and the beach between it and the ocean so narrow, the pond water came charging out.

Attending Nantucket's annual Town Meeting is an imperative for living on this island.

Equally vital to your Nantucket experience is witnessing the biannual opening of Sesachacha Pond or Hummock Pond, or both in the spring and the fall. For you recently new Nantucketers, Nantucket opens two of its seven great ponds — a pond occuping 10 acres or more of area is a great — in early April and early October because unlike the rest of the state, Nantucket holds sovereignty over its ponds, having it wrested them from state control in 1993. As a result, Nantucket is the only municipality in Massachusetts in which you don't need a fishing license fish in its ponds. 

Originally, New York claimed ownership of all the islands in the waters off southeastern Massachusetts, along with Nantucket, until relinquishing them. In Nantucket’s case, the 27 original settlers of the island, the Proprietors of the Common and Undivided Lands of Nantucket, took possession of all rights to the island from the government of the Province of New York in1691, including rights to the ponds. A special act of the Massachusetts Bay General Court confirmed this transfer of jurisdiction over Nantucket from New York in 1693. Since the adoption of that act through present day, ownership of the island’s ponds has held up in all court challenges and was reaffirmed in 1993. Today, the town opens Sesachacha and Hummock ponds at will, operating only under a recurring permit from the Army Corps of Engineers.

But why open them at all? The Native Americans, the first humans to populate Nantucket, discovered that blueback herring need to swim into these ponds to spawn as they do rivers on the mainland by watching them do so during natural wave-actuated openings. They also found that American eels swim into the great ponds, after spawning in Sargasso Sea, to live the rest of their lives. These early island inhabitants would dig open the great ponds to allow these fish species to enter the pond and then the Native Americans used nets and weirs to trap the fish for eating. And in Sesachacha Pond, they made crude piers consisting of large rocks laid onto the pond bottom and then each other allowing the Native Americans a way to wade out to the deeper water of this pond to spear the larger fish. They built one on the north and south sides of this pond, and the south side's pier is visible when the water is calm with good sunlight several days after the pond's been opened.

The pond openings also flush out excess nutrients that have built up in the pond since the last opening, replenishes its salt content and brings food into the pond for marine species that live there. The Native Americans likely also opened Squam, Tom Nevers, Capaum and Miacomet ponds, but the town doesn't open these other ponds, as they've all evolved into fresh water systems that would perish if flushed with salt water. 

The town opened Sesachacha Pond to the ocean yesterday, April 12, and Hummock Pond today, April 13. Both remain open at the time of this post, so I urge you get out there and see the unique merging of salt and fresh water environments. For me, as a naturalist who's made Nantucket's natural world his life, it's something I need to see every spring and fall. I hope it becomes that way for you.