Algae is a ubiquitous feature in waterways throughout the globe, including western North America. Slippery, green epilithic algae is a familiar sight on river rocks. Toxic blue-green algae—cyanobacteria—is a visually interesting, yet worrisome phenomenon. Increasingly prevalent filamentous algae , with its long, voluminous green strands joins the picture, and is presenting new questions for scientists, recreationalists and land managers. ...read more read less