By 400 AD York's fortunes had changed for the worse. The town was undergoing periodic winter floods from the rivers Ouse and Foss, its wharf-side facilities were buried under several feet of silt and the primary Roman bridge connecting the town with the fortress may have become derelict. By this time Eboracum was probably no longer a population centre, though it likely remained a centre of authority. While the "colonia" remained above flood levels, it was largely abandoned as well, retaining only a small ribbon of population for a time.