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Uncovering the contours of the Narrowsburg Deeps

As someone new to paddle boarding, I’ve become fascinated with rivers. My curiosity leads me to test out questions like, “is that rock close enough to the surface to bonk my fin” or “is this spot deeper than my paddle is tall?” Though I might fall off my board or chase after some gear, I rarely leave a river journey without an answer to a new question.

A marker and a mystery

The Delaware River town of Narrowsburg, New York, is a good place for questions and curiosity. There’s little cell service there, so instead of turning to the internet, it’s easier to ask nearby friends, look to the places around you, or delve inside your own head for answers.

Questions about the river abound here — in part because it’s home to the deepest and narrowest points in the Delaware's 330-mile course. A historical marker on a public deck overlooking the “Big Eddy” shares stories from the past, theories about the bathometry, and a simple map with a cross section diagram of "The Deeps”. For a pedantic person like me though, it invited more questions than answers.

"113 feet deep, whoa! Is that in the narrowest part? It’s not? But isn’t that what that Catskills map said? Wait, the deep part is in this wider area here? Then where is that cross section going through? …is the scale off? Where exactly is the deepest part?"

There was no information on the marker about where these illustrations had come from. However, the Upper Delaware Council's office was just two blocks away: maybe our local river keepers would have some more context.

 Laurie Ramie, Executive Director of the Upper Delaware Council, was kind enough to dig into the UDC archives for me. An issue of their newsletter from 1993 featured The Deeps, with in-depth speculation about its formation and interviews with divers who had been to the bottom. Accompanying the article were two familiar, more detailed illustrations:

It seemed that who ever copied the map and cross section had left off some important information, including key geography in the Big Eddy and a helpful note that the cross section had been compressed in width by a factor of ten. The mystery of the context-less cross section had been solved! But in the process, the article’s author, Keith Fletcher, had pointed out a new one:

"So which theory is right, glacial waterfall or the swirling rocks? Small details are the key to answering this question, the kind of details that only divers can provide. A detailed and accurate map of the river bottom is also very important. No such map now exists—an illustration based on the best one available accompanies this article. 
But thanks to inquiries made on behalf of the Upper Delaware Council for this article, the interests of staff members at the New York State Geological Survey have been piqued. And perhaps, with the help of Park Service personnel and the Council, we will one day determine what made the hole in the river."

More than thirty years had passed since Keith mused about a missing map and what it might lead to. I asked Laurie if she'd come across one. She hadn’t, but suggested that I reach out to the Upper Delaware Scenic and Recreational River National Parks Service office or the Delaware River Basin Commission

An expedition on the internet

When I had internet connection again, I checked the map resource sections of each group’s website — and a few others, for good measure. Finding a lot of nifty resources but nothing from around Narrowsburg, I emailed them all. Of those who responded, no one had made such a map. So I scoured the wider internet; someone, somewhere, had to have mapped this feature. While the county GIS map had contour lines, they stopped at the riverbank. Everywhere else seemed to be a dead end, too. 

Until I circled back to Keith’s hint about the Geological Survey and found a 2012 USGS LiDAR scan of the upper Delaware River, published in 2020 by a research biologist. It had to be in there! Except the many files were all meaningless without the correct program to open them. So I emailed the research biologist to see if he had a .jpeg of just the Big Eddy. Three weeks later, I had a response:

Hi Lisa, Sorry, your email got routed to my spam folder.  We did do some bathymetric mapping about 10 years ago of the Narrowsburg area. Here is a quick and dirty map. It appears that the "hole" at the narrows is over 110 feet deep!  Hope this helps. -John

I was ecstatic. The detailed data of the river bottom Keith had dreamed about had been scanned, 19 years later! Had anyone else in the watershed even seen this? I didn’t know, but it didn’t seem right to have answered these questions for myself alone and to move on.

There were plenty of public topobathymetric maps of nifty places. The deepest and narrowest part of the Delaware River should have one, too. Surely other Narrowsburg-visiting nerds without an internet connection would want to see one.

Making a map

Gathering together everything I’d learned, I designed an 11 x 17 topobathymetric map and had posters made at a print shop in the neighboring watershed that I call home. I'm giving copies away to those who provided insights along the journey — and those who reviewed the resulting map to make it better. The rest are for the Upper Delaware Council to share as they’d like.

I tried to make a map that was easy to understand. There are 10ft contour lines and to-scale cross sections of The Narrows and The Deeps. Additional features like roads, buildings, and boat launches help one to understand the context around the Big Eddy Narrows. It’s all based on the best data I have available in 2024: satellite images, LiDAR scans, and local experience. Yet any map, no matter how detailed, is a rough facsimile that could never capture the fullness of the place it is meant to represent. The Big Eddy Narrows is a performance of water’s dramatic relationship with rock: a poster is nothing without the show, and the show should be seen live.

This project was a collaboration with many people across time, and the resulting map was designed to invite more questions. It leaves ample room for curiosity and speculation. Perhaps it can be another step toward a final ruling on the formation of The Deeps: the "hole" in the Big Eddy. If nothing else, I hope it invites you to be more curious about your local landscape, and that your curiosity takes you into uncharted territory.

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