Image taken from the LANDSAT-7 satellite. The image is of the discharge of the Fraser River into the Straight of Georgia near the city of Vancouver, British Columbia, Canada. Different color bands collected by the satellite are used to discriminate forest and soil types, and water body characteristics. Color composite images are useful for getting acquainted with the area in the image. In these images, vegetation will be green, water will be blue, and urban areas will have mixed colors, usually shades of gray. These types of images are useful for the analysis of lake water parameters, such as turbidity, chlorophyll, suspended sediments, and Secchi depth. Using thermal bands also allows for the measurement of surface temperature. These images are useful for assessing land cover types and area, and how forest clearcuts or agricultural development can impact a watershed. However, these analyses have to be validated by using ground-truth data by collecting water samples and water spectral characteristics at approximately the same time of the image acquisition (satellite overpass). Picture donated by Eddie Loos.