To provide data to investigate hypotheses about the evolution of channel networks, specifically the optimal channel network concept, discharge and channel properties were measured at 336 sites in a 121 km2 basin over a 5-day period of reasonably steady flows. The data are also suitable for investigating how discharge increases down river channels. The data collection was a major logistical exercise which involved 80 person-days in remote field locations. In the expectation that the data will be of use to other researchers, this paper describes how the data were measured, checked and archived. The archive is available at http://www.niwa.cri.nz/hydrology/ashpage.htm and includes the associated time series of streamflow at the basin outlet and the channel network as plotted on 1:50,000 scale maps. ¿ 1998 American Geophysical Union