Southold Town Beach in Southold overlooks the Long Island Sound,...

Southold Town Beach in Southold overlooks the Long Island Sound, Thursday, Oct. 15, 2015. Credit: Randee Daddona

Now that the federal government has approved the dumping of some 20 million cubic yards of dredge spoils into the eastern end of Long Island Sound, it’s time for New York State to follow through on the promise it made:

Sue the feds.

That’s what Gov. Andrew M. Cuomo said in August the state would do if the Environmental Protection Agency gave its OK to this ill-advised plan. And that’s what the state says it will do as soon as it’s legally possible. Many Long Island elected officials from both parties at all levels of government are with him on this. And they’re right.

The Army Corps of Engineers has been dumping dredge spoils from Connecticut’s harbors and waterways into the Sound for decades, but permits for two of the four sites expire on Dec. 31. The Corps says the other two cannot handle the volume — a conclusion disputed by two New York agencies — so it’s opening a third site off Fishers Island, an area the feds themselves have designated as an essential fish habitat. It’s in Connecticut waters, but pollution travels, and the Sound is just as important to New York in terms of recreation and commerce.

Sediment is tested before it’s dumped, but there are no guarantees that any material in large volumes is totally clean; traces of pesticides, heavy metals and other toxins will likely be there, and small amounts add up. Even clean material consumes oxygen, blocks sunlight and kills organisms on the ocean floor.

The dumping should be phased out, and the Corps should move to alternatives already being used elsewhere. And if that takes a lawsuit, see you in court. — The editorial board