Union Bay Natural Area and Constructed Ground

Ecological Design and the Ephemeral Nature of our Cities

The Union Bay Natural Area is an elementary example of what Andrea Kahn would call Constructed Ground. For Kahn, this term is a lens for calling into question our understanding of urban sites and the interplay between what is natural and what is man-made. The Union Bay Nautral Area (UBNA) is a constructed site:once urban fallow ground, it is now given over to natural systems, and is a landmark of the University’s educational landscape.

Much of what is today called the UNBA was under the surface of Lake Washington until 1916 when the Montlake Cut was opened. The water level of the Lake dropped by nine feet when engineers opened the canal, exposing nearly 200 acres of flat land. A canal was dug to connect Ravenna Creek with the lake which now emptied into the Puget Sound via the Cut and Lake Union. (Before 1916, the drainage flow went through the south end of the lake into the Black River which flowed into the Duwamish and then into the Sound. When the cut was opened, the Black River was gone.)

For decades after, this sunken topographical feature was used as a landfill, serving the geographic area extending from the U-District northward to the city limits, growing as the city did. If you can imagine a watershed of garbage, the city sub-region drained into what is now the UBNA. The city had other landfills, notably at Miller Street and along the south shore of Lake Union. These were low-lying places, usually a marsh or slough or estuary. Use of the Miller Street site was abandoned soon after the Montlake Landfill was opened. City organizers buried the dump site under a cap of dirt and turned it into the Washington Park Arboretum.

In a matter of decades, the Miller Site went from a small ravine draining into the pristine waters of  Lake Washington to a city landfill then to a constructed natural area, prefiguring the nearly exact same evolution of the UBNA site.

The UBNA is managed by the University of Washington and is home to diverse populations of birds and other animal species. It is also home to the Center for Urban Horticulture and the University of Washington Farm. During the 100 years since the terrain was exposed, nearly 1 million cubic yards of earth and other material has been brought to the site and pushed around, including maintenance dredging of the shifting, artificial canals which drain Ravenna Creek. The site has been used for university housing, utility yards and ball fields, even a large Victory Garden during World War II.

The idea of Constructed Ground becomes a very important tool in ecological design because it sees snapshots of a site within the wider narrative evolving through time and the growth of the city. Knowing that all urban sites are constructed, we can understand urban ecologies as constructed systems responsive to modification and adaptation. The narrative of landfills converted to park space may be among the earliest kinds of constructed ground to have an ecological design.