Urban Creeks: Protecting Water Quality AND Urbanism

 

By Dom Nozzi

November 9, 2001

As an urbanist, I often make the point that “the pedestrian is the design imperative” within the urban core zones of the rural to urban community transect.

A crucial way to deliver a walkable, high-quality urbanism is to use modest, human-scaled dimensions.

Unfortunately for this design objective, environmental scientists (and arborists) often call for relatively large dimensions to achieve environmental conservation objectives (big stream setbacks, large tree planting areas, etc.).

The objectives obviously clash.

I enthusiastically support efforts to design walkable cities, and argue that successfully doing so results in better long-term regional environmental conservation, because designing great cities reduces the desire to flee the city in order to buy a home in remote residential subdivisions in sprawlsville. For this reason, it seems reasonable to me that those strongly seeking environmental conservation should buy into the urban-rural transect concept — the pedestrian/human is the design imperative in the core zone of the transect, and “the trout” (nature) is the design imperative in the rural conservation zone of the transect.

A dilemma here is that water in streams is flowing water — sometimes from the urban zone to the conservation zone. If the water is degraded in the urban zone with its pedestrian imperative, it can degrade the conservation zone when it reaches that zone, thereby harming the trout imperative. Nature often does not respect transect boundaries…

In my humble opinion, we should strive for a middle ground. That is, a stream within the urban zone needs to respect the pedestrian imperative by not creating pedestrian barriers. Yet the stream cannot be significantly degraded to the point of harming outlying conservation zones.

Must urban zone reaches of streams be “piped” or “paved over” to be walkable? Will they inherently suffer from ugly littering and dumping if they are not covered up? I don’t believe so.

Seems to me that a middle ground design would be to leave narrow, vegetated banks along the streams, and include a paved, hard-surface path along side it, as well as fairly closely urban-creekspaced pedestrian bridges over the creeks (say, every 200 feet, as we often call for such cross-access distances within a block).

By doing so, we achieve at least two things: First, the stream is walkable and does not create meaningful inconveniences to the pedestrian. Second, by establishing a hard-surface path nearby, we encourage a regular flow of pedestrian traffic along the stream. Such pedestrians become “eyes on the stream,” so to speak. They end up providing regular monitoring and voluntary clean-up when littering or dumping occur (or the “pedestrian police” will call city hall and demand that the clean-up be done). Greenways built around the nation have demonstrated the effectiveness of this form of citizen surveillance. A sense of stream/path ownership by path users typically results in clean up of litter problems that has sometimes persisted for decades before the path was installed. The key is that a formerly hidden, neglected stream is now visible to people on a daily basis, which means that we’ve created a chance for knowing about and caring for the stream. “Piping” or “paving over” a stream creates “out of sight, out of mind” problems, not to mention externalities that we would be blissfully unaware of…

Finally, I believe that the urban stream design I recommend above, while not creating a pristine water quality filled with healthy trout, will at least minimize exporting environmentally harmful water to outlying conservation zones.

 

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1 Comment

Filed under Environment, Urban Design, Walking

One response to “Urban Creeks: Protecting Water Quality AND Urbanism

  1. Great topic and one we frequently think about when we’re in developed areas be they large cities where the stream or river in question might be neglected or abused, or in more rural communities where, too frequently, otherwise healthy streams are run through culverts and subject to pollution and siltation from road runoff. Understanding of the measures required to keep a stream or river healthy has grown considerably over the past couple of decades, but what is understood is too seldom put into practice. The chief setback seems to be cost. Flowing water put into a channel and run through a culvert – or paved over entirely – is less expensive (at least in the short term) than creating a green zone around the water and with proper bridges. We’ve thought long and hard about sustainable, sufficient sources of funding… Do you have any thoughts on this?

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