​The filamentous algae in your area is a naturally occurring result of clear water and abundant sunlight. The algae grows on the bottom and as it produces oxygen can rise to the surface and form mats. It is a green algae and is not hazardous to health. Our recommendation to shoreline owners is to take action on their own and rake or skim the algae from their areas and dispose of on land. It is harmless, it just looks icky.