In this article, I compare two accounts of how biodiversity restoration, flood protection and bio-physical models are co-produced in the Netherlands. Both are historical accounts of the interplay between research practices, policy discourse and intervention practices, one focusing on rivers and the other on the coastal environment. Three questions will be central to my comparison of the two paths of co-production. First, how have institutional conditions of research contributed to shaping the bio-physical models? Second, how has epistemic indeterminacy been tamed in the two cases? Third, how do the models of rivers and coasts perform biodiversity? I conclude by arguing that adaptive approaches to biodiversity restoration require an adaptive epistemology, which implies tolerating a certain degree of epistemic indeterminacy. © 2013 SAGE Publications.