Originally published on Terra Fluxus – 01/21/2011

Over the next week, I have been outlining some of the inspirations and precedents related to the idea of Hidden Hydrology of Portland, as this project has been shaped and has evolves across many years to it’s present incarnation.  As I mentioned in the preliminary overview, one of the main inspirations was the map of ‘Disappeared Streams’ that was produced by Metro.  My first encounter with this map was during a presentation at DaVinci Arts middle school, as part of the preliminary planning for what would become their beautiful water garden.  At the time I was working with local non-profit Urban Water Works – and the students were showing off many of their water-related side projects, including hand-made flowforms, studies of water movement, and mapping.   One student had a GIS application that was showing the disappeared streams – which has stuck in my brain every since.  Metro now publishes it in map form – available at the Data Resource Center – along with many other great maps.

As I mentioned there are a few methodological caveats to this map – as it is not a historical representation of actual streams, but looking more specifically at locations of potential water routes.  From the map, some of this language:

“Development patterns in the Metro region have historically resulted in piping, culverting, or filling of streams and stream beds.  A computer mapping program was used to evaluate the terrain in the region, and to generate areas where major streams (those draining 50+ acres of land) may once have existed.  While this does not represent an authoritative analysis, it does visually describe the effects of urbanization on the regions natural systems.  This exercise indicates that an estimated 388 miles of previously existing streams are now underground.”

The coding of the map is pretty striking (the choice of ‘blood’ red I think fitting) when viewed as a whole (above) particularly noting the core area of Portland that has been denuded of streams over the course of 150 years (below, closeup of City of Portland), where flatter areas were developed for Eastside residential, and margins on the Willamette filled in for industrial development.

You can also get a close-up view,including the central business district – seen in closeup below.  Notice the existing pattern, where streams are kept somewhat intact in the west hillsides (topography being somewhat of an antidote to piping), then quickly buried when they reach the urbanized area.  Tanner Creek, one of the hidden streams we will be studying closer, is captured as it originates from the Oregon Zoo and cuts through the northwest corner of downtown.

A relatively simple map that is more evocative than accurate, but does much to reinforce the ideology of what is hidden beneath our developed urban areas.  As I mentioned, it has stuck with me (and I’m glad Metro still has these available).  One of the stronger and original inspirations for the project, it continues to entertain and inspire investigation into our hidden hydrology.