Very odd looking. I have seen something like this once in person and once here at PB where saturated surface ground water was seeping into the pond. In these cases, the water at the shore was clearer than the bulk of the pond water, being filtered by the surrounding soils.

Your pond's condition far exceeds the above possibility due to the fact that is extends far out into he pond and appears to be coming from one side not the perimeter.

One other guess might be a turnover of the pond moving a bloom or murky waters around. Are the temps conducive to a turnover there?

Fish on!,
Noel