She compiles it and sends it to Project Coordinator Jay Sandal at the Lake Superior Center, where the information is added to a basin-wide data set that will help scientists distinguish changes in water quality over time. Over the last five years, Superior Lakewatch volunteers have recorded 1,700 Secchi disk transparency measurements. The Secchi disk is a simple way to measure water clarity. The cloudier the water, the shallower the depth at which the Secchi disk disappears from view. In clear water, Secchi readings are usually high.
Measurements can vary depending on wind direction and time of year.
Sometimes wind can transfer or stir up sediment from river mouths or the lake floor. Or it can improve water clarity by upwelling clear water from the center of the lake. In the summer, algae growth is another cause of cloudiness. Iversen joined the Superior Lakewatch program because data gathering seemed like a good way for him to be part of the Lake Superior community. But I recently attended a meeting where many of the scientists involved in the program were discussing the project, and I realized the data I collected is an important part of what these scientists were talking about.