There are approximately 10,000 km of streams in the Auckland region (mainland) as mapped on 1:50,000 scale NZMS260 series topographic maps (ARC 2001). This is an underestimate of resource extent because many small streams are not mapped, and the mapping does not include ephemeral and intermittent streams that flow only during certain times of the year or during rainfall events. Research is underway to assess the extent, quality, functions of intermittent and ephemeral streams, and will be reported in future annual reports.