A new report card was released Friday that lists Long Island’s cleanest water and its dirtiest on the North Shore.

According to the group Save the Sound, 200 swimming beaches in New York and Connecticut were deemed safe for swimming 93.3 percent of the time between 2016 and 2018 -- higher than the national average.

But the study also found a troubling trend for North Shore beaches. Periods of high rainfall have led to the temporary closure of a growing number of beaches along the Sound to swimming as untreated sewage, waste and fecal bacteria wash ashore.

MORE: View the Sound Health Explorer  

Tracy Brown, the director of Save the Sound, is pushing for towns to invest in “repairs and upgrades to aging sewers and installing improved septic technology.”

Save the Sound also says residents can help improve water quality by picking up beach litter.

Rep. Tom Suozzi said he would continue to push for federal money to protect and improve the Sound.