For those who may not be aware, when water clarity recordings are made, the on-site weather and water conditions are also recorded due to the influence that these have on light penetration in the water column.  Secchi disc depths are dependent on the incident light striking the lake surface travelling down to the Secchi disc and then reflecting back up through the water column to the surface.  Water clarity values should ideally be recorded only from mid-morning until mid-afternoon when the sun is overhead and always recorded from the shaded side of the boat. Along with the Secchi depth, the data and time, the estimated percent of cloud cover, whether it is sunny or dull, surface water conditions, including wave height and / or ripples, estimated wind strength and the water color (is it greenish or brown colored) are all recorded.  Having this field of information assists with the interpretation of the clarity data.