In the past 50 years, freshwater and estuarine harmful algal blooms (FHABs) have been increasingly studied in California. FHABs can be found across the entire state affecting rivers, streams, lakes, and estuaries and with some occurring year-round. FHABs negatively impact the safety of our drinking water, tribal subsistence fishing, tribal tradition and cultural practices, fish and mussel consumption, recreational uses, and ecosystem health throughout the state and tribal lands. With greater than 3,000 lakes, 190,000 river miles, diverse ecosystems ranging from deserts to temperate rainforests, and over 40 million inhabitants, California faces a complex management issue for FHABs. These impacts translate to the loss of attainment of up to ten beneficial uses in the California Water Code, and economic impacts are estimated to be in the millions of dollars. With the loss of these beneficial uses, comprehensive statewide monitoring and management efforts are necessary to inform the public of potential health risks and  reduce the occurrence, duration, and severity of FHABs in California.