Watershed v Sewershed

I had the lucky opportunity to paddle with Eric Sanderson last week, the developer of the Welikia project. We  paddled down the length of the Bronx River in the Bronx with some WCS scientists now studying the river and its life in the context of the larger world, some WCS staff and  some other guests (including Carolyn Hall, about whom I learned a very interesting connection! Mills!). The group was seeking a closer look  at the river as well as a deeper connection with the local history.

As we paddled down the river, sharing information about what each of us knew, including long gone mills and communities and well intentioned restoration efforts that have gone awry,  I shared with the group  the damage that occurs to the river and its population every time there is a rainfall due to the built environment that surrounds it.   In Westchester it is due to the fact that virtually all water that falls on impervious surfaces  enters the nearest local water body, and  how in NYC a certain quantity of rain over a given amount of time  in a sewer shed that causes street and sanitary sewage to enter the river.  As this is our lot in today’s world, I often advocate for teaching about the sewershed ( where all of our  neighborhood sewers combine) as opposed to the watershed ( where, in the natural world, all rainfall in a given area eventually comes together). As city dwellers with a constructed sewer system, we have a direct effect on the water that enters our sewers and the watershed is long gone. So, why not teach that fact and base all further understanding off of that position? I can have an effect on what enters the sewers through my apartment pipes, as well as what physical matter (bottles, cans) may enter the sewers through the street, and feeling some control is a feeling of some power. No?

After exiting the canoes at Hunts Pont Riverside Park, watching the river change from (constructed) natural surroundings to the obvious industrial human impacts, Eric asked me if we shouldn’t teach the watershed as the primary focus. “When the sewers were constructed,” he offered, “we took advantage of natural grades as much as possible, placing sewer pipes in streams and slopes.” I argued that some sewer pipes run counter to the apparent grade of the streets, making the watershed seem obsolete, but his firm position that the major factor in deciding sewer placement was existing watershed grades and make more sense as the first step. Eric also put forth that the water shed is the larger community and, at the same time that it ties us in to the historical landscape, encompasses the entire community that has an effect on the water body discussed: The Bronx River.

As a hard head, I kept up my argument, but the walks through the neighborhood, especially Thursday’s walk, have bent me quite a bit. The encounter with the incongruous willow, Josue’s comment of a possible historic stream and a closer look at the surrounding geography; gentle slopes and valleys, point to that watershed and the  sewer shed that follows it below our view.  It may vary depending on the neighborhood, it is necessary to keep it in mind. I am still not sure if there should be a given order to the explanation, but they should be in tandem.

We also had an interesting conversation about relative history and how most of us, upon arrival somewhere, see history beginning at that time. Might make for a nice discussion and a need to layer maps through personal perspective. Eric wants to come along on some part of our walks so I will keep him informed of our planned meetings.

Damian Griffin