When Salt Water Floods a Farm

May 17, 2018

The flooded property in Truro.
Credit K.C. Myers

If you live on the Cape, you’ve maybe heard of the Ballston Beach overwash. It’s the spot on the ocean side in Truro where the Perfect Storm broke through in 1991. One relatively low sand dune is the only thing here between the ocean and the Pamet River, which cuts through Truro east to west from Cape Cod bay. George Mooney’s family farm is a quarter mile inland from the ocean beach.

 

George’s grandfather came here from the Azores, sometime in the mid-1800s, and he started farming the land. He had a dairy, and big gardens, and would take vegetables into Provincetown with a horse and buggy. He’d also take the produce up to the cottages in Ballston Beach.

 

George and his wife Janet took over the farm in the late 1960s. George estimates they grow about 80 percent of what they eat—they have a big garden and his grandfather’s orchard, and they keep sheep, pigs, and cows.

 

This winter though, when we had those bad storms in a row, the water kept coming on their property. The cow’s shelter, which is up on a knoll even got flooded, and the area where George loads the cows into a trailer was under a couple of feet of water. It did a lot of damage to the cow pasture and to his gardens.

 

George sent his cows to slaughter early right after the storm, because they had nowhere to live, stranded on that little island of high ground surrounded by water. Now he’s spreading gypsum on his gardens, a soil amendment that can help pull out salt. Like many coastal estuaries, the Pamet River was diked in the early 1900s. There’s a clapper that lets water flow from the bayside estuary into the Upper Pamet River Valley, toward the ocean, and over the winter it got broken.

 

“It wouldn’t have been too bad if it was like before, where the water didn’t stay on the ground for that long,” said George. “But this time it was on the ground for probably a week or so.” 

 

Long standing salt water flooding like what the Mooney’s land experienced this winter is challenging because it damages soil structure and pulls water out of plant roots. If the roots dry out enough, the plants die, and if they do survive, they’re more susceptible to drought, because they have fewer living roots to take up water. 

 

Overwashes have happened on the ocean side here for decades— there are reports of big flooding events during storms in 1897, 1938, 1978, and again in 1990s. Luckily, most of the salt water flooding has happened in the winter, when the fruit trees George’s grandfather planted over a hundred years ago are dormant and the rest of the garden is empty. But in the past decade, overwashes have happened at Ballston beach multiple times: once in 2013, twice in 2015, and three times this winter in 2018. 

 

George describes what his family remembers, “I’m sure it will keep happening to some degree, my mother and my oldest brother remember it you know way back then it slopping over the path up here where people would walk down to the beach, it would spill over there a little, but not to this degree. You know four storms in a row, four big storms in a row, that doesn’t usually happen.”

 

I talked to two coastal researchers in Truro and Provincetown and they said it’s hard not to see some influence here of climate change—causing more frequent and stronger storms—but that also the Upper Pamet River Valley is at an unnaturally low elevation because of the river being diked. Without tidal restriction, saltwater estuaries are actually pretty good at keeping pace with sea level rise and protecting the coast from storm surges—with regular tidal flow, twice a day when the water comes in, a little sediment gets deposited. Over time this builds up the land, which makes it higher and less likely to flood. But this can’t happen when there’s a dike like the one on the Pamet. Like many towns, Truro is working to find a way everyone can agree on to restore tidal flow.  

  

In the meantime, George knows it’s likely the overwashes at Ballston Beach into the Pamet Valley will keep happening. But tradition is tradition, and he and his son are busy rebuilding. They’ve been mucking out ditches, spreading gypsum, fertilizing and planting.

  

“I’ve got a lot of work to do in the cow pasture before I get more cows, but the grass is growing down there, I’ve spoken to one guy he’s holding a couple Herefords calves for us, so another couple weeks I’ll probably get those have a chance to get the pasture straightened out and go at it again,” said George. “It’s just uh, just farming. You know.”   

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Here are some helpful links: 

  This is the Rutger's paper on salt water flooding. 

  This is on sea level rise, tradition, and salty soils along the Atlantic Coast from the Atlantic

  And this is on sea level rise and using natural sediment deposition and restoring wetlands to try to build up land.