A massive bloom of the cyanobacteria (blue-green algae) Nodularia on the surface of Farmington Bay, an enclosed embayment of the Great Salt Lake, Utah (USA). The bay receives extensive nutrient loading from Salt Lake City. The Secchi disk photo demonstrates how massive cyanobacterial and algal scums can limit light penetration and shade underylying waters. Salinity at the time of the photo (15 April 2005) was 1% (10 ppt).