Carrying capacity: what a place can hold

In my first year at what is now Thompson Rivers University in Kamloops, I answered an anthropology exam question on carrying capacity by defining it as the amount a person could physically carry. I pictured a hiker on a long trail. I was thinking of the treks I had taken with my father and older brother through the sagebrush hills above the city.

Most of my classmates wrote about land, population and ecological thresholds, which was what the question was after: how large a population an environment could sustain with the resources available. I still scored four out of five, which only deepened the impression the moment left. I had been thinking about an individual’s load while the concept concerned collective limits.

I grew up on that high interior plateau desert, where water scarcity was a daily reality. I live now on southern Vancouver Island, where winter rain can make summer drought feel distant. In both landscapes, the question of what a place can sustain has practical consequences for how people live.

Carrying capacity belongs at the centre of community planning. A community depends on the land and water supporting it, alongside systems that require continuing investment and care. Decisions about growth need to account for those dependencies and what happens when demands exceed them.

As a child, I read my parents’ copy of the Whole Earth Catalog, which sat among books about living off the land on the bricks-and-boards bookshelves that wrapped what felt like every wall in our living room. The spine was already worn, the pages dense with small type, diagrams and descriptions of tools for living differently.

Stewart Brand organized the catalog around subjects including “Understanding Whole Systems,” “Shelter and Land Use” and “Community.” Influenced by Buckminster Fuller, it brought practical tools together with an interest in how people could understand and change the systems around them. I could not have explained all of that as a child. I was drawn to the possibility that people could learn enough to make deliberate choices about how to live.

In the mid-1990s, I attended a summer solstice party near Lillooet, where people I knew lived on neighbouring farms. Van Andruss and Eleanor Wright were there, along with other free spirits and intellectuals. Andruss and Wright had co-edited Home! A Bioregional Reader with Christopher Plant and Judith Plant. We gathered around a fire in the clean mountain air, sparks rising beneath the stars, talking about building a better world. Bioregionalism was part of those conversations, connecting our hopes for change to how we lived in the places sustaining us.

Peter Berg and Raymond Dasmann described a bioregion through both its geography and the understanding people develop about living there. Their idea of reinhabitation included learning to restore damaged places and developing ways of life that could endure within them.

I found it useful then. I find it more useful now, when considering how a community’s decisions relate to its watershed and the lives already depending on it. Administrative boundaries assign responsibilities, but the systems we depend on do not necessarily stop at those lines.

That makes carrying capacity a demanding concept. It requires attention to the relationships between systems, as well as the limits of each. Increasing the capacity of a water treatment plant does not, by itself, establish how much water a watershed can supply.

Geographer Nathan Sayre’s history of carrying capacity adds an important caution. He questions the assumption that a changing environment can be assigned a fixed capacity, and examines how the concept has been used to justify control over people and land. That criticism deserves consideration, particularly when a calculation is presented as though it settles a political decision.

I take it as a reason to examine how capacity is assessed and whose needs are considered. We still have to account for what sustains us. Difficulty establishing an exact threshold does not relieve us of the responsibility to recognize strain and respond before the consequences become harder to reverse.

In 2015, I helped a municipal chief administrative officer with an op-ed answering a question residents kept asking at budget time: why do local taxes rise faster than inflation? Much of the answer was underground. Facilities and networks of water and sewer pipes were aging, replacement funding had not kept pace, and residents expected services to continue.

The op-ed ended by acknowledging that local governments needed to do a better job of explaining those costs. The pipes were largely out of sight; the tax increase was not. Understanding what the community depended on meant making that connection visible.

There are choices about how much infrastructure to build and how to pay for it. Those choices sit within a larger question about what a place can sustain. Bioregionalism asks us to keep that relationship in view, including when an investment appears to solve the immediate problem.

Buckminster Fuller’s trim-tab image helps me think about how people can influence decisions on that scale. A trim tab is a small control surface on a larger rudder. Moving it changes the pressure around the rudder, helping it turn and change the direction of something much larger. Fuller used it to explain how an individual could affect a system without having the power to move the whole thing directly.

I think public conversation can work in that way. When people begin asking what their water supply can sustain, that question can influence which proposals they support and what they expect councils to consider. A change in what a community regards as reasonable can affect its direction.

Systems thinker Donella Meadows gives this connection further substance in “Leverage Points: Places to Intervene in a System.” She distinguishes adjustments to a system’s infrastructure from changes to its goals and the assumptions guiding it. Her argument also challenges the expectation that more growth will resolve problems created by growth.

That matters when growth is described as good news while the demands accompanying it are treated as problems to be managed later. We need to consider what is growing, what supports it and who carries the consequences when that support is insufficient.

For communicators and planners, this means making those relationships understandable while decisions can still change. People need enough information to consider trade-offs and an opportunity to contribute what they know about the place. The experience of someone watching a well run low belongs alongside the assessment of future demand.

Before the next growth plan goes forward, ask which system reaches its limit first and who will notice when it does. Then make sure those people are part of the conversation.

The question I keep returning to is what this place actually needs from us. I first encountered it through the landscapes I walked and the books on our living-room shelves. My work has given me other ways to consider the responsibilities it carries.

My answer on that exam was wrong. Still, the term began in the 1840s as a measure of how much cargo a ship could carry, and when a community runs past its limits, the load still has to land somewhere.

Further reading

• Van Andruss, Christopher Plant, Judith Plant and Eleanor Wright, Home! A Bioregional Reader. Essays connecting ecological place with community life, culture and the practice of reinhabitation.

• Donella Meadows, “Leverage Points: Places to Intervene in a System.” On how changes to information, goals and underlying assumptions can influence a system’s direction.

• Nathan Sayre, “Carrying Capacity” (2012). A critical history of the concept, from shipping to ecology, examining the assumptions and consequences of assigning limits.

About the author

Alesha Hayes, MA, APR, is principal of A. M. Hayes & Associates, a communication and public relations practice based in Victoria, British Columbia. Her work brings together strategic communications, organizational development and public engagement, with attention to how decisions are made, how people become involved and what it takes to earn their trust.

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