Abstract Digital data from Landsat's Multiple Spectral Scanners (MSS) are used to calculate the amount of radiation received from sea level at the position of the satellite. We investigated the atmospheric degradation of the signal because very little is known about it, and because it is needed for eliminating atmospheric effects on the radiance data. The magnitude of degradation is estimated for clear sky and stable conditions, and is subtracted from the total radiance to give that fraction of the radiance which contains information of oceanographic interest. This amount of radiance is then related to sediment concentration. An error analysis for calculating the remotely sensed radiance and relating it to the ground truth is also presented in the paper. As a result, maps of the surface radiance and sediment distributions near the mouth of the Fraser River are produced from Computer Compatible Tapes (CCTs). These maps are not only useful in monitoring the flow characteristics, they also show detailed features which are very difficult to detect visually in the satellite images.