HydroColor: Water Quality
This water quality application uses the smartphone’s camera to determine the reflectance of water bodies. HydroColor can estimate water turbidity (0-80 NTU), concentration of suspended particulate matter (SPM) (g/m^3) and the backscattering coefficient in the red (1/m). The data files are save automatically and can be downloaded on a computer in a text file the information about the measurement: latitude, longitude, date, time, sun zenith, sun azimuth, phone heading, phone pitch, exposure values, RGB reflectance, and turbidity.
Very cool app that provides good data. For more information about the app, see their webpage.