Water Quality

Area of Hypoxia

August 1, 2010 — Hypoxia is a condition that occurs in bodies of water as dissolved oxygen concentrations decrease to levels where organisms become physically stressed and ultimately cannot survive. The area of hypoxia in Long Island Sound refers to the number of square miles in which dissolved oxygen concentrations were less than 3 mg/L over the course of a single year. Read More

Duration of Hypoxia

July 30, 2010 — Hypoxia is a condition that occurs in bodies of water as dissolved oxygen concentrations decrease to levels where organisms become physically stressed and ultimately cannot survive. Duration of hypoxia refers to the number of days in a year during which hypoxia was observed in Long Island Sound. Read More

Industrial Chemical Discharges (TRI data – CT and NY)

July 30, 2010 — This indicator compiles the total amount of discharges of toxic chemicals manufactured and used at industrial facilities that are released into the Sound either by air or by water. Read More

Wastewater Treatment Plants Meeting Toxicity Standards

July 29, 2010 — Aquatic organisms are exposed to effluent from wastewater treatment facilities as a test for effluent toxicity. This indicator is the percentage of facilities in CT passing these tests. Read More

Contaminant Trends in Mussel Watch Sites

July 28, 2010 — Mussels tend to stay in one location and feed by filtering particles out of the surrounding water. They can accumulate local contaminants such as metals and PCBs in their tissues. Measuring levels of contaminants in their tissue is a good indicator of local contamination. Read More

Frequency of hypoxia

Frequency of Hypoxia

July 28, 2010 — This map illustrates the frequency of occurrence of hypoxia in LIS bottom waters over the last two decades. It indicates what areas of Long Island Sound experience hypoxic conditions most often, and which are rarely affected. Read More

Sediment Quality Index

July 27, 2010 — This index indicates the extent and severity of contaminants such as PCBs, hydrocarbons, metals, and pesticides in seafloor sediments throughout Long Island Sound. Read More

Heavy Metals in Sediment

July 26, 2010 — Sediment cores were sampled near Norwalk Harbor to determine the historic trends of toxic contamination in the seafloor sediment of the Sound. The cores give a record of metal contamination from the pre-colonial period to the post-industrial era. Read More

LIS Point Source Nitrogen-Trade Equalized Loads

July 26, 2010 — This measure indicates the management effort to reduce nitrogen from wastewater treatment plants in order to meet state and federal water quality standards. Read More

Chlorophyll a Concentration

July 25, 2010 — Chlorophyll a is the green pigment in plants, and the concentration in surface water is an indicator of the amount of microscopic plants (called phytoplankton). This indicator is intended to characterize the spring phytoplankton bloom conditions in the western Sound each year. Read More

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