DEP, Shandaken and agencies slow down Chichester’s ‘Bowl of Doom’

Bowl of doom before

Bowl of doom 1 year after

Since Katsuo Asada bought land in Chichester the early 2000s, he has watched the Stony Clove Creek change course several times, gradually eating away at a section of his property. For years each heavy rain washed mud down a steep, curved slope of bare clay, nicknamed the “Bowl of Doom” by watershed officials, and the creek turned a muddy brown for days or weeks at a time. 

In 2013, a team of local, New York City, and national agencies reconstructed the stream alongside Asada’s property, raising the stream bed, smoothing out the slope, and placing rocks to speed the water down the center of the channel. Five years later, the bowl’s once bare earth is covered with grasses and young trees, and turbidity, or suspended sediment in the water, is way down.

“I couldn’t do anything about it by myself,” said Asada. “They have done incredible work.” But as Dany Davis, Stream Studies Coordinator at the New York City Department of Environmental Protection (DEP), pointed out, there hasn’t been a really big flood since the reconstruction, so we don’t know for sure how a storm on the scale of the 2011 Hurricane Irene would affect the revamped creek.

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The project is just one of nine stream modifications along the Stony Clove that the DEP has designed, with the collaboration of the Town of Shandaken, which has to approve all projects; the Ulster County Soil and Water Conservation District (UCSW), responsible for executing the plans; and the U.S. Geological Survey (USGS), which monitors water quality. The first project was an emergency intervention near Phoenicia’s Main Street bridge, with construction taking place in the week or so after Hurricane Irene sent two feet of water surging down Main Street. When Tropical Storm Lee followed ten days later, other parts of Shandaken flooded again, but Main Street did not. 

Standing near the bridge on a recent autumn morning, Davis said, “Today the water’s running at about 60 cubic feet per second. During Irene, it was 16,000 feet per second.” 

Because the Stony Clove flows into the Esopus Creek and thence to the Ashokan Reservoir, a major source of New York City drinking water, turbidity is of major concern to the DEP. Suspended sediment attracts microbes, and the city is required by the federal Filtration Avoidance Determination (FAD) to reduce turbidity in its water to avoid building a multi-billion-dollar filtration plant. 

The Stony Clove projects, therefore, are primarily aimed at improving water quality. However, they have also been designed to prevent flooding, protect infrastructure and private property, and enhance environmental conditions. Furthermore, DEP is using the stream modification program as a research project, generating detailed data that can be used by scientists across the country.

“The Stony Clove is no longer a chronic source of turbidity,” said Davis, “but there’s still some sediment. Recovery after a storm is now is within hours or days, depending on the size of the storm, rather than days or weeks.” This recovery is often visible to the eye, but DEP decided to quantify the effects by collecting and analyzing data, using USGS monitoring stations that measure such parameters as turbidity and water flow, at multiple points along the Stony Clove and its tributaries. Drones are sent up to take high-resolution photographs at different angles, collecting elevation data and creating 3-D models that help scientists identify erosion and deposition sites and pinpoint the best places to treat with reconstruction.

Project data have been presented at national conferences on water issues, and USGS, a national agency, has heightened awareness of the work. Experts visit the watershed to learn about the methods used on local waterways. Three universities — Cornell, University of Massachusetts, and University of Vermont — have been given access to the findings. “It increases the value of our work by getting it out to researchers,” said Davis. “This is data most scientists can’t afford to get.”

The needs of people…and trout

The conditions that created the Bowl of Doom probably began in the 1970s, when a section of the Stony Clove Creek behind the Chichester Post Office was straightened, for reasons unknown. Curves that formerly slowed the water were eliminated, making the stream steeper and faster, and thereby leading to erosion upstream. The banks became unstable and collapsed, while the stream dug deeper into the ground.

The DEP’s design put a curve, or meander, back into the stream and created a stepped stream bed to dissipate the erosive energy of the water naturally through a series of rapids and pools. Rock vanes were built in the center of the stream to guide the flow down the middle, preventing erosion of the banks. The cliff of clay was converted to a gentle slope that was planted with grasses and weeds to anchor the soil.

“The contractors were artisans,” said Davis. “They could visualize what they were building based on their experience, and they suggested adjustments to our plans. One heavy equipment operator was an angler.”

In the five years since the reconstruction was carried out, with permission from the streamside landowners, the landscape has turned lush. Among the rounded stones and gravel along the bank, willows have taken root and are expected to prevent erosion in the future. The stream features pools that make ideal habitat for trout, and the organic debris that accumulates among the rocks can host the stream insects that fish feed upon.

Chichester resident and Trout Unlimited member Mark Loete stated that the since the restoration projects were completed, the reduction in turbidity and increase in habitat have significantly improved fly fishing along the Stony Clove. “Today we catch lots of smaller trout almost everywhere in the Clove, with an occasional larger fish in the net. The average catch is 4 to 6 inches in the Chichester reaches, reaffirming the Stony Clove’s role as an important spawning nursery for our Esopus trout population. Once again, we find out that the needs of people and trout coincide—a reliable source of pure, fresh, cool water.”

The nine projects, addressing sites along 2.7 miles of the Stony Clove, were paid for with $2.7 million from DEP, the remainder of the total $8.4 million cost coming from federal agencies in response to Irene. Now that the Stony Clove is running clearer, a project is underway near the campground at the end of Woodland Valley, rebuilding a section of stream that has threatened to undermine the road. Next year, two projects will modify sites on Warner Creek, the Stony Clove tributary that runs alongside Silver Hollow Road. “We’re taking care of smaller problems,” said Davis, “before they get bigger.”

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