This paper explores how environmental policy is implemented and enacted through the management of technical and institutional knowledge at the local level. We use the conservation of the freshwater pearl mussel in the River Esk, North Yorkshire, UK, as an empirical case study to examine the interaction that takes place between professionals from different institutional and disciplinary backgrounds as they come together to work on a common problem. We focus on two aspects: the way in which an institutional context was created; and the interaction between the professionals involved. Our analysis demonstrates that the strategic intermediary role of professionals is vital to policy implementation. The intermediary uses their strategic vision and undertakes political manoeuvring following the presentation and interaction of different knowledges and evidence to ensure a certain course of action. This is different from a knowledge broker. The role of the professional is to draw on expertise, both formal and tacit, to interpret and judge data in relation to decision making. Those individuals participating in decision making of this nature have multiple histories, roles and motivations which enables innovation in the creation of meaning within environmental management. The quality of the evidence can be assumed adequate once subject to diverse professional scrutiny. These findings are important since innovative behaviour that creates new structures and practices is becoming central to delivering good management of land, water and biodiversity.