Coping with Asymmetries in the Commons: Self-Governing Irrigation Systems Can Work

Abstract

"Common-pool resources are natural or man-made resources where exclusion is difficult, and yield is subtractable (Gardner, E. Ostrom, and Walker, 1990). They share the first attribute with pure public goods; the second attribute, with pure private goods. Millions of common-pool resources exist in disparate natural settings, ranging in scale from small inshore fisheries, irrigation systems, and pastures to the vast domains of the oceans and the biosphere.

"The first attribute - difficulty of exclusion - stems from many factors, including the cost of parceling or fencing the resource and the cost of designing and enforcing property rights to exclude access to the resource. If exclusion is not accomplished by the design of appropriate institutional arrangements, free-riding related to the provision of the common-pool resource can be expected. After all, what rational actor would help to provide the maintenance of a resource system, if noncontributors can gain the benefits just as well as contributors? The extent to which a common-pool resource will be provided is a complicated problem, depending on how preferences are articulated, aggregated, and linked to the mobilization of resources.

"The second attribute - subtractability - is the key to understanding the dynamics of how the 'tragedy of the commons' can occur. The resource units (like acre-feet of water, tons of fish, or bundles of fodder) that one person appropriates from a common-pool resource are not available to others. Unless institutions change the incentives facing appropriators, one can expect substantial overappropriation. For example, those who fish from a lake derive all the benefit from catching additional fish. However, the depletion of the fishery is a cost shared with other fishermen. The private gain is thus very likely to overbalance any single fisherman's share of the social loss. Or, to put it another way, no single fisherman can prevent depletion of the fishery by restricting his personal catch. The fishery is thus likely to be pushed to the brink of extinction unless institutions counteract these incentives."