Driving along Route 139 in Marshfield’s Green Harbor, you might not notice that the road passes over a tide gate, also known as the Brant Rock Dike. The harbor itself lies to the east of the gate, while to the west, the tidal Green Harbor River and its marshes stretch out toward the horizon. Although beautiful, it seems like an ordinary kind of place. You’d never know from looking that the Brant Rock Dike was the site of quite a bit of controversy back in the nineteenth century.

The Green Harbor River rises from springs and ponds near the Garretson Cranberry Bogs on the Marshfield-Duxbury line. It passes under Webster Street, and flows through the Green Harbor Golf Course and Mass Audubon’s Daniel Webster Wildlife Sanctuary. Continuing through a basin of wide, grassy meadows, it enters a tide gate at Turkey Point and empties into the sea via Green Harbor itself, on the Brant Rock/Green Harbor line.

Originally the river’s path to the sea was much less direct. Passing what is now the harbor (which was then just another bend in the river), it continued on a circuitous route through narrow marsh creeks, and eventually into Duxbury Bay.

Ever since the Pilgrims settled in Marshfield, there have been efforts to improve the river’s navigability. In 1633, a canal was dug to better connect the river to the bay. In 1636, this canal was widened and deepened per order of the court. In 1806, a group of Marshfield landowners successfully petitioned the court for permission to dig a more direct canal from Green Harbor to Duxbury Bay. Known today as the Cut River, this canal flowed through the marshes and meadows behind Green Harbor Beach, and out to sea near present-day Canal Street on the Duxbury line. But soon after the canal was complete a November storm closed off its mouth completely.

An even more direct outlet was cut in 1810 – and remains to this day. While prior attempts to improve the river’s navigability had been permitted — or even decreed — by the court, this was a case of townspeople taking matters into their own hands. According to Joseph C. Hagar’s book, Marshfield, 70’40” W, 42’5” N: The Autobiography of a Pilgrim Town, “This labor was done under cover of night and about forty men were engaged in the undertaking.” (This was not an uncommon practice – attempts to improve the outlet for the North River were also made in this fashion.)

By eliminating the narrow last leg of the river, the 1810 cut dramatically increased the incoming tidal flow to the Green Harbor River. This was a boon to local fishermen, as it improved the harbor’s navigability. However the owners of farms bordering the river saw things differently. The increase in both the volume and the frequency of saltwater flooding to their lands was a big problem, as crops don’t like salt water.

So in 1871, a group of farmers petitioned the court to construct a dike, or tide gate, that would block the flow of saltwater upstream, and create more arable land. The dike was constructed in 1872, with the condition that “Should shoaling take place above the level of mean low water in the channel in consequence of dike construction, it was to be removed by the Marsh proprietors.” Shoaling did occur, and thus began the “Brant Rock Dike Feud.”

By 1876, shoaling in Green Harbor was significant enough that the Harbor and Land Commissioners demanded its removal. The fishermen claimed that “the value of the harbor was totally destroyed,” as there wasn’t enough water for their boats to enter the harbor at times other than high tide.

The farmers did not respond to this request. They said the harbor was made illegally, while they followed proper channels to get their dike. They argued that boats had trouble entering the harbor at lower tides even before the dike was built. They claimed that shoaling would have happened anyway, without the construction of the dike, and that if they removed the shoals, the problem would return soon enough.

The situation remained in stalemate until one angry anti-diker, Henry Tolman, contrived to force the issue by blowing up the dike. Word of his plan got out, and a Boston detective firm was hired to keep an eye on him. Marshfield selectmen warned that “No man can catch him but a woman can,” so a female investigator was assigned to the case. After becoming acquainted, Tolman invited her to accompany him to the dike in the middle of the night. He brought along a wheelbarrow of dynamite, fuses and “other equipment necessary to achieve the destruction in view.”

Tolman was arrested. Unfortunately, the police acted too soon. Tolman was stopped while still on the road above the tide gate, not down in the sluiceway where the detonation was to occur. In court he claimed that he was only transporting the dynamite Brant Rock, and he was doing so in the middle of the night so he wouldn’t endanger anyone. He was allowed to go free, but “under bond for the rest of his life.”

The dike feud continued for decades. In 1898, the Massachusetts legislature passed a bill that called for the removal of the dike. But a few days later, Governor Wolcott vetoed the bill, because it included a clause guaranteeing the farmers be paid damages for what would once again be salt-ruined land. So the dike remained.

Really, no one won the Dike Feud. Unfortunately, Hatfield/McCoy-type spats continued in town meetings and other venues for many years. Although the farmers got to keep their dike, the promise of arable lands upstream never did come true, as their crops did not grow the way they had hoped. Meanwhile, the fishermen continued to deal with shoaling in the harbor – a problem that continues to this day. But Green Harbor’s cod and lobster fishing industry has prospered for many years nonetheless.

It is important to know that shoaling has always been an issue on the Green Harbor River, even before the dike was built. According to Jim O’Connell, a Coastal Processes Specialist at the Woods Hole Oceanographic Institution, “the channel would be shoaled with or without the dike.” O’Connell continues, “The harbor tidal prism (volume of water between high and low tide) is too small to flush the channel to a point to keep the channel open; wave and wind dynamics move sand into the channel and current velocities are too low to move the sand back out.”

Does the dike contribute to the need for periodic dredging in Green Harbor? It is certainly a factor, but so many other issues must be considered as well. Professor of Geography Reed Stewart cites a few: sea level rise, the building of seawalls, and the changes in the amount of sand washed south along the beach since the realignment of the North River mouth in 1898.

“Even after extensive study, the Corps of Engineers cannot figure out how to keep the entrance channel from shoaling,” says O’Connell. “Natural coastal processes are at work here that we humans cannot overcome!”

And that’s really what it comes down to. No matter what we do to change the course of a river – dig canals, reroute channels, build jetties, perhaps even blow up tide gates – Mother Nature will always have the upper hand.

Hagar, Joseph C. Marshfield, 70’40” W, 42’5” N: The Autobiography of a Pilgrim Town. Marshfield Tercentenary Committee (Marshfield, MA, 1940).

By Kezia Bacon-Bernstein, correspondent
January 2008

Kezia Bacon-Bernstein’s articles appear courtesy of the North and South Rivers Watershed Association, a local non-profit organization devoted to the preservation, restoration, maintenance and conservation of the North and South Rivers and their watershed. For membership information and a copy of their latest newsletter, contact NSRWA at (781) 659-8168 or visit