NEW HAVEN — A new environmental report says Long Island Sound's water quality is improving.

The Long Island Sound Report Card 2018 released Monday by environmental groups includes 10 years of data and an assessment of how water quality is trending in each region of the Sound. In most regions, the water quality improved.

The New Haven Register reports that the study grades areas based on oxygen levels, water clarity, the amount of phytoplankton in the water and levels of dissolved organic carbon.

Curt Johnson, president of Connecticut Fund for the Environment-Save the Sound, says the Sound's overall condition has improved dramatically since the late 1980s when a steady increase in population and poorly treated sewage led to harbors full of dying fish and shellfish, dirty beaches and waters almost devoid of oxygen.