The Swampscott harbor is in danger of being taken over by the protected eel grass.

"We are in danger of losing the harbor," Selectman Glenn Kessler told his colleagues.

He proposed that the board invite members of the Harbor Advisory Board to an upcoming Selectmen's meeting to show the extent of the problem with eel grass, which is part of a recent study.

"It is overwhelming," Kessler said. "It is shocking how invasive it is."

Unless the state marine authorities agree to allow Swampscott to remove the eel grass, as it has permitted Manchester by the Sea, then all of the dredging monies will go to transplanting the eel grass, Kessler said.

Eel grass is a protected species because it acts as nursery grounds for young fish, crustaceans and mollusks. It can also help prevent erosion and serve to clean polluted water.

The shallow harbor has been a boom to the eel grass that thrives on sunlight.

The proposed project is estimated to cost $500,000 to dredge the harbor to six feet. The state has agreed to contribute $400,000 to the project.

Some proponents are advocating that the harbor be dredged to eight feet, which would cost more.

Transplanting the eel grass would be very expensive, Kessler said.