Each blue dot represents a single secchi disk reading- typically 2± weeks apart through the spring, summer, and fall. Turbidity varies over the years due to summertime growth of algae, etc.

The green “linear” trendline shows a slow and disturbing decline in turbidity. The red curved trend line shows an alarming downward trend in turbidity. Anything less than 2 meters (6.6′) represents an algae bloom.