The question posed in this article is how shifts in governance ushered in by the sustainability paradigm are reshaping knowledge governance. Drawing on constructivist theories of knowledge, I examine the tension between the sustainability mandate to open up knowledge making to local knowledge, and conventional science policy practice that would see it excluded. I present a water management case study from New Zealand's South Island region of Canterbury, where communities are involved in establishing catchment nutrient limits to manage land use and water quality. It is concluded that although local knowledge was embraced within the knowledge-making process, the pursuit of epistemic authority led to its recalibration, aggregation, and standardization. As such, it was stripped of its complexity. This research highlights the role of politics in anchoring the linear knowledge governance model in place and the challenge for supplanting it.