Most thermal imaging satellite instruments have relatively high sensitivity (0.1°C for AVHRR and MODIS) but poor spatial resolution (1km or more). The eTM sensor aboard Landsat-7 has a thermal channel with 60m spatial resolution. Although not as sensitive as the AVHRR's, this capability can provide images of temperature signals from sources undetectable with other satellites. Ocean Imaging uses eTM thermal data to document the pread trajectories of offshore sanitation outfall plumes (shown here) and cooling water discharges from coastal power plants.