Water Quality Report Card - North Coastal Basin Rivers Cyanobacteria

The North Coastal Basin covers approximately 8,540 square miles along the north-central California Coast, including all of Mendocino County as well as major portions of Humboldt and Sonoma counties. Most of the North Coastal Basin consists of rugged forested coastal mountains dissected by six major river systems: the Eel, Russian, Mad, Navarro, Gualala, and Noyo rivers, and numerous smaller river systems. While cyanobacteria can be found throughout the region, three rivers in the North Coastal Basin, the South Fork Eel, Mainstem Eel, and the Russian, experience annual seasonal blooms of toxin producing benthic cyanobacteria. All three of these watersheds are known for their recreational opportunities: State and County Parks, white water kayaking, fishing and summer festivals that draw international and local visitors alike. Under typical conditions, cyanobacteria, commonly known as blue-green algae, starts to appear in late July or early August, coinciding with increased solar intensity, warmer water conditions, and popular water contact activities. The North Coast water Board is employing different methods of sampling and testing for cyanobacteria and associated toxins to provide a better picture of the public health risks associated with cyanoHABs Data Sources: Surface Water - Freshwater Harmful Algal Blooms (FHAB) Northern Region Harmful Algal Bloom Program Total Daily Maximum Load (TMDL) Contact Information: Beverley Anderson-Abbs Office of Information Management and Analysis State Water Resources Control Board [e-mail]