Making 'green' fit in a 'grey' accounting system: The institutional knowledge system challenges of valuing urban nature as infrastructural assets

Nature is increasingly enrolled as a functional component of infrastructure in cities as municipal governments attempt to cost-effectively replace and repair deteriorating engineered infrastructures. Green infrastructure (GI) is a popular incarnation of this enrollment, most often defined in the United States (US) as the use of vegetated land (e.g. street-trees, bioswales, parks) to provide stormwater management services. However, GI is far from mainstream. While many municipalities cite technical performance uncertainty as a primary reason for this lag, institutional challenges of knowledge system integration also create road-blocks to GI management. In this paper, I argue that financial asset management (AM) standards are an important, but obscured, institutional barrier to the mainstreaming of GI in the US. I use Knowledge Systems Analysis to illuminate the institutional tensions that emerge from attempting to fit nature into existing AM practices. Primarily, tensions stem from the inability to book natural components of GI (such as trees, soils, vegetation) as assets as they are not recognized by US financial accounting rules and standards; this has encouraged a proliferation of highly engineered GI that contain human-made components at the expense of more ecological GI that do not contain human-made components. I first review the use of corporate AM practices in North American municipalities, and outline the general motivations for including urban nature in AM. I then zoom in on a case study in Portland, Oregon where a 2016 effort to create a city-wide Green Asset Plan encountered road-blocks that reflect the wider national knowledge system challenges surrounding making nature into infrastructure. In particular, different valuation methods (i.e. the use of replacement value vs service value) are at the heart of the conflict between accounting and ecological knowledge systems. I conclude with a discussion of the political implications of GI's increasing standardization to fit grey infrastructure knowledge systems more broadly and the ways that this movement leads to a depoliticization of nature.