The National Status and Trends Program is comprised of three nationwide programs: Benthic Surveillance, Mussel Watch, and Bioeffects. These programs are in place to observe estuarine and coastal waters nationwide to describe the current status and detect changes in the environmental quality using long-term, continuous monitoring. Special Studies is another program which assesses the environmental impacts of different events, such as Hurricane Katrina. Mussel Watch is the longest continuous, nationwide contaminant monitoring program, running from 1986 to present, analyzing sediment and bivalve tissue for organic contaminants and trace metals. Bioeffects Assessment Program has completed over 30 regional studies since 1991, studying sediment contaminants, toxicity, and the condition of benthic communities. Benthic Surveillance monitored chemical concentrations of bottom-swelling fish and sediments, as well as biological effects of contaminant exposure. This project was discontinued in 1993.