Land management impacts on water quality following fire in a major water supply catchment

Salvage harvesting and land clearance to re-establish radiata plantations in the lower catchment followed the January 2003 bushfires in the Cotter River water supply catchment. We report impacts of post-fire catchment disturbance on water quality and preliminary results of a recently completed works program to improve water quality. Suspended sediment concentrations as high as 39,000 mg/L and massive annual specific sediment yields between 520 and 950 t/km²/a from the 42 km² salvaged pine area occurred over three low-intensity rainfall years following the fire. In contrast, reservoir turbidity profiles in naturally-regenerated, upper-catchments returned to pre-fire conditions within 12 to 18 months.