Increasingly, biotoxins, harmful algal blooms (HABs) and bacteria pose threats to human health along the nation's coasts. Potent biotoxins such as ciguatoxins, mercury, DDT, PCBs and domoic acid from HABs are known to transfer up the food chain poisoning seabirds, marine mammals and commercially harvested species. Runoff and spills have periodically resulted in high levels of Escherichia coli (E. coli) bacteria, which is often used as an indicator organism for monitoring nearshore water quality. Municipalities near numerous marine sanctuaries regularly monitor their waters for contaminants and have issued fishing and swimming advisories when HABs or contaminant loads exceed safe limits. Consumption of contaminated fish or exposure to hazardous water in sanctuaries can cause mild to severe symptoms, from headaches to hepatitis. Generally, nonpoint sources (i.e. runoff from urban, suburban and rural areas) are the chief contributors that pollute and contaminate sanctuary waters. Pollution is exacerbated by illicit storm drain connections, improper maintenance, disposal of materials that clog pipes and cause overflows, cracked or damaged pipes, overflow of sewer systems during storm events, and septic system leaching.