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An excavator prepares to open Hummock Pond to the ocean.

Pond openings this weekend!

Hummock on Saturday and Sesachacha on Sunday

Sesachacha Pond empties out into the ocean.
Sesachacha Pond's temporary channel widening as the water flows out.
The last few bucketfulls of sand remove a berm keeping the pond at bay until the operator is ready to connect pond and ocean.
Out goes the water.
Fresh meets salt.

Attention all of you natural historians and pond opening junkies out there, and for owners of flooded basements near these ponds, the town is going to be openings Hummock and Sesachacha Ponds to the ocean this weekend. Late Friday afternoon, the Natural Resources Department announced the opening of Hummock Pond on Saturday and the Sesachacha Pond on Sunday. An excavator will start digging a trench between Hummock Pond and the ocean around 8am on Saturday, the same for Sesachacha on Sunday. Expect both ponds to be opened to the ocean between 11am and 1pm on their respective days. The

An excerpt from the Water: Salt and Fresh chapter of "Nantucket: A Natural History", my second book published in June 2008, explains the orgins of opening the ponds in the spring and fall, which today includes boosting salinity and oxygen levels in the pond to help sustain some forms of pond life, flushing out excess nutrients and lowering the water table to help dry out basements. At one time, Sesachacha, Hummock, Miacomet, Squam, Long and Capaum Ponds were all opened to the ocean for various reasons. The town no longer opens Miacomet Pond to the ocean because it has evolved into a freshwater system that would be severely damaged by infusions of salt water

"...Native Americans and European settlers learned to open these
and other ponds to the ocean by digging a trench in the beach between
pond and ocean in the spring and again in the fall, in order to trap and
harvest blueback herring (sometimes confused with alewives), white perch,
American eels and probably other species no longer in great abundance.
The European farmers learned this practice from the Wampanoags, and it
enabled them also to drain meadows and to attract game birds to mudflats
for hunting. The herring are anadromous fish, meaning that they migrate

up into rivers, streams and freshwater ponds to spawn. Their young, called
fry, swim out of these waterways in the fall and reside in the ocean until
they reach sexual maturity and can migrate inland to spawn. Catadromous
fish, including eels, spend most of their lives in these freshwater to brackish
places, leaving only in the fall as adults to swim out to spawn in the
Sargasso Sea, west of Bermuda in the middle of the North Atlantic Ocean.
In the spring, adult blueback herring, alewives and shad run up into
mainland rivers from the ocean to spawn from late March through mid-
May. Alternately, the herring also swim into Nantucket’s salt ponds when
they’re opened in April to spawn as the yellow-flowering forsythia blooms
on island. Juvenile eels swim into the pond to begin their freshwater lives.
And when the ponds are opened in the fall, juvenile herring on their way
out to the ocean join adult eels swimming to the Sargasso Sea to spawn.
Additionally, white perch, another anadromous fish species, also find their
way into the island’s great ponds, commuting for sex, along with the herring.
Depending on how long a pond remains open to the ocean—up to
two weeks, but usually less than a week—other fish species, namely saltwater
fish like striped bass, bluefish and tomcod, have been documented
in these ponds after ocean currents have sealed them shut with sand. Sesachacha
Pond stayed open for five months during the summer twice in the
past, but as usual, longshore currents eventually closed it over with sand..."


Peter-- Bill Ferrall posted this link to a contemporaneous article in Yankee Magazine that gives the full background to the pond opening controversies of twenty years ago.