The Water Log

Sewage dumped in the East River meanders with the tide

Sometimes people tell me that the East River is not technically a river. Or they write East “River,” then in parentheses, explain why that’s actually a misnomer. (It is in fact a tidal strait connecting New York Bay and Long Island Sound). It always gets to me. It’s a narrow body of moving water, it’s got “River” in its name, for God’s sake. Why split hairs?

Then one night last week I took a bike ride along my favorite tidal strait. The water was undulating slowly like thick cookie batter that’s almost too much for the egg beater, but I couldn’t focus on any one ripple because the swells were gliding by at a pretty good clip. And they were moving… north. I’m awful at geography, easily turned around, but it seemed to me that the river should not be rushing away from the harbor. (Similarly, at low tide in the Hudson, the ocean rushes in and pushes north. The Hudson is not your average river, either, but a tidal estuary, where salty sea water meets fresh water.)

Suddenly that tidal strait business made sense. The East River isn’t fed by freshwater streams, like a normal river. It’s connected to the Atlantic Ocean at both ends; on the north, through the Long Island Sound, and on the south, through New York Harbor. So it’s open at both ends to tidal influences. In other words, it flows both ways.

The East River’s un-river-like behavior is not news, but a hundred years ago it was. In the first decade of the 20^th century, when New Yorkers were getting typhoid from swimming in the increasingly polluted rivers and eating locally farmed oysters, the Metropolitan Sewerage Commission – composed of a handful of engineers and a physician – was formed to figure out what was happening to the raw sewage being dumped into the rivers.

At first, the commission was optimistic that the sewage would eventually flush into the ocean. “It may possibly be found that we are fortunate enough to have a harbor that flushes itself,” the president of the commission, Dr. George Soper, told the New York Times in 1909. “There are two outlets to the ocean, and the high tide at the Narrows does not correspond with the high tide at Hell Gate. It may be proved that there is a slight excess movement of the current south, and careful observations are now being made to verify this surmise.”

Over the next few years, the commission conducted experiments that included releasing floats – some say the floats were barrels – from different points, following them on a launch, and mapping their progress.

One float was dropped in the water three miles north of where the Harlem River meets the Long Island Sound. Over the course of three and a half days it floated 108 miles, traveling down to the Brooklyn Bridge, then back. It was picked up within a mile of its starting place.

A Times reporter in 1910 described the maps of the floats’ progress as “prints on which were traced zig-zag lines resembling more than anything else the erratic movements of an undecided crab. There were many of the prints and not one of them bore a straight line, as if the float had made up his mind not to go any way in particular.”

Like the floats, the commission determined that “in most cases the sewage that flows into the two rivers at the upper part of Manhattan drifts down to the Battery or a little below, then turns and goes back again.”

Headlines became increasingly panicky: “Typhoid and Outbreaks of Other Diseases Traced to Evil Conditions in the Rivers and Harbor”; “Metropolitan Commission Gives Warning That Remedial Action is Imperative”; “Menace to Public Health; “HARBOR WATER POLLUTED; Sewage Commission Suggests Reforms and Abolition of River Bathe.”

The commission’s gloomy final report was a far cry from Dr. Soper’s blithe hypothesis. “It has been proved that, contrary to popular belief, the tidal currents do not flush out the harbor satisfactorily, but cause the sewage to oscillate back and forth near its points of origin.”

Today, the East River remains mysterious, and contaminated. And ninety-some-odd years after it was thought up, variations of Dr. Soper’s experiment are still being done to map the river’s idiosyncrasies. In lieu of barrels, researchers now inject sulfur hexafluoride “tracers” into the river to dye the water, but even now they follow the meandering path of their tracers the old fashioned way: they zigzag alongside in their boat.

Posted by Tucker on Friday, January 26, 2007 at 12:24 PM | Permalink