This is our contribution to Reimagining Birrarung: Design Concepts for 2070. The exhibition was held at the NGV Australia, Federation Square. The work is a response to the gallery’s request for a new vision for the lands and waterways of Birrarung (the Yarra River). Our project speculates on the design consequences of a simple question: What would it be like if Birrarung became an autonomous territory? To make this speculation urgent, we’ve imagined that the river has seceded from Victoria and that the boundary of this new independent state (it’s catchment boundary) positions Birrarung at the center of a spatial and planning entity rather than at the margins. The work demonstrates how design within the catchment zone could have a demonstrably different outcome and behaviour to design-as-usual outside the zone. The focus of the work is the design of infrastructure. Referencing the ‘before and after drawings’ of Humphrey Repton’s Red Books as a communication tool, we have redesigned three types of infrastructure that currently trespass across and diminish the river – the road, the transmission tower and the drain. Three models show the transition of each type from its ‘before’ state in 2024 to an ‘after’ in 2070. Each realises an ambition for infrastructure to do more than one thing, to accommodate more than one constituent and to host a complex and living whole.