In the movie Field of Dreams, a struggling farmer (played by Kevin Costner) repeatedly hears a voice from heaven whisper to him: “If you build it, he will come.” The specific instruction is to build a baseball field instead of growing corn, in the middle of Iowa. Once the farmer builds the diamond after an enlightening visit to Fenway Park, the ghosts of famous baseball players start using the field to play ball. As a result, paying audiences flock to this cornfield, alleviating the farmer's financial struggles once and for all. In restoration ecology, this quote is commonly used to describe the expectation that when physical attributes, like water flow or elevated ridges, are restored, biotic responses will rapidly follow, without any additional human intervention (Hilderbrand, Watts and Randle 2005).

It is common to hear proponents of ESMs use this phrase to describe the hope and expectation that, following the creation of a clear set of rules and measurement systems for an ESM, active credit trading would emerge “naturally” and buyers and sellers would “come.” In the Willamette River basin, the Chesapeake Bay watershed and the Ohio River basin, this prophecy has not been true when it comes to the creation of ESMs. The three reasons ESMs have failed to materialize are widespread concerns about displacement, the inability to produce equivalence and the problems of participation.

This final chapter revisits those three challenges and develops an argument about their continued relevance as well as a set of ideas on how to learn from the obstacles encountered for environmental policy and planning more generally. The attempts to create integrated markets for multiple ecosystem services at the watershed scale are not isolated incidents, but can be seen as part of a broader ongoing experiment with market-based and market-like instruments in environmental policy and planning. In urban planning, for example, the idea behind transferable development rights (TDR) is somewhat analogous to the logic of ESMs. TDR refers to a practice in which one piece of land in a city is not developed but typically turned into a park or some other public benefit, in return for which the development of another property can exceed some regulation, like restrictions on height or density (Linkous and Chapin 2014).