High spatial resolution airborne imagery has been acquired at anniversary dates and processed to produce monitoring information for vegetation on the Gnangara Mound. The Mound, located north of Perth Western Australia, is of great importance to the city's water supply and retains significant biodiversity values. An effective monitoring system for vegetation is a priority for multiple agencies concerned with management and regulation of the Mound. Individual tree deaths and spatial patterns across the area were detected using the image sequences. Spatial analysis showed no associations with borefield pumping, but active disease processes were identified Methods and results are presented.