A Shedload of Sheds

The ‘shed is an ecological framework that has expanded into a variety of topics. This post attempts to define all of the known ‘sheds and explore how they impact regional issues such as climate change, economics, and health.

Surface water flowing in a creek in North Carolina.

  • Watershed – this is by far the most well known sort of ‘shed to planners. In North America it is synonymous with a drainage basin or catchment area.  In a sense, this is the “original ‘shed” as many people are exposed to this ecological concept before they learn any others.
    • The watershed often defines where drinking water, wastewater, and drainage (stormwater management /  flood risk) are managed. While these boundaries rarely align neatly with political jurisdictions, other governance structures have been established in key areas to address impacts to these ecological systems.
    • Drainage basins don’t typically align neatly with groundwater systems. This can cause confusion in places that rely on groundwater for drinking and irrigation.
    • Active environmental management of watersheds didn’t start in the US in earnest until the 1970’s with the Clean Water Act.

Rolling clouds, seen from above.


  • Airshed – these exist in places where air currents and geology interact to predictably limit airflow in an area.  For instance in  a U-shaped canyon currents and temperature can trap air inside the valley. Airsheds often have nebulous boundaries.
  • Events like the “great smog” of London have illustrated how local airsheds impact human health.

A farmers market in upstate New York.

  • Foodshed – while this term might seem novel, it was coined in 1929. A foodshed encloses the geographic region which provides food for a specific town or city. As agriculture and transportation have both changed rapidly in the past century, so have urban foodsheds. Cities now rely on agricultural products grown hundreds or thousands of miles away.
    • In the case of subsistence farming, a foodshed is a literal boundary which describes where all of a family’s food is produced.
    • (I also seem to remember this term referring to the theoretical acreage of farmland required to feed one person/household in a given community.)

Passengers boarding and alighting the Red Line in Boston.

  • Walkshed / Bikeshed / Driveshed / Transitshed – these ‘sheds define the typical area accessible by each transportation mode. For instance, planners often cite a quarter mile (400m) as a comfortable distance for an able bodied person to walk – thus their walk shed from a given point (such as home or work location) is defined using that distance as a radius.
    • Mapped transportation sheds should also take infrastructure availability into account. Streets without safe places to walk (such as interstate highways) should be excluded from the walkshed radius calculation. Neighborhoods without bus stops should not be included in transitsheds.

A coal power plant on Lake Superior.

  • Energyshed – does it matter where your home’s power comes from? Depending on the topic and level of analysis, it may be of interest as a policy question. In the event of a heat wave, demands on the power grid due to air conditioning loads can be overwhelming, causing large scale black-outs. An energyshed defines where a community gets its power from.
    • Energy is provisioned at a wide variety of scales: the national grid, regional grids, micro grids, combined-heat-power (CHP) systems, institutional power systems, and off-grid systems.
 Climate ChangeEconomy & EquityHealth
WatershedStrong - the hydrologic cycle is fundamentally connected to climate change.Variable - water availability influences industrial development patterns.Strong - water quality and supply impact public health.
AirshedStrong - air pollution is fundamentally linked to local climateVariable - regulation of the airshed may influence industrial development.Strong- air pollutants impact public health where they are concentrated.
FoodshedModerate - food production and transportation impact carbon emissions. Strong - access to fresh food is highly variable between communities.Strong - the availability of healthy food influences community health outcomes.
Walkshed, Bikeshed, Driveshed, Transitshed, &c.Strong - transportation is a major contributor to carbon emissions.Strong - transportation networks define a community's access to markets and jobs.Strong - active transportation has positive health impacts.
EnergyshedStrong - the majority of carbon emissions are from energy production.Variable - energy prices may influence industrial development.Variable - communities impacted by fuel or energy production may have worse public health.