Various components of the overall pollutant loading picture of the Lake are known or have recently been estimated from data that is available. For example, there are quite a few spot or point analyses of pollutant levels at most of the significant inflows into the Lake, such as at municipal discharge points and mouths of major tributaries. Generally lacking at these points to establish pollutant loading levels are volume flow measurements and a statistically significant number of samples over an extended period of time. Also notably lacking are measurements of non-point source inputs along the perimeter of the Lake.?