The first leg of a multiphase project to dredge and restore the marshlands along the Town of Islip’s south shore was completed Thursday, officials said.

Suffolk County Executive Steve Bellone, standing next to the marsh at Champlin Creek on South Bay Avenue in Islip hamlet on Friday, said about 7,000 cubic yards of mud had been dredged and placed in a upland area in the East Islip marina, and another 7,000 cubic yards of sand was dredged and pumped into the adjacent marshland.

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The dredging has widened a canal from 50 feet to 100 feet and will aid in controlling the nitrogen pollution that destroys coastal vegetation, Bellone said.

“This project is not only important because of our role in making sure we can maintain the navigability of our waterways, which relates to our economy and tourism and quality of life, this project is also serving a dual purpose: It’s helping to restore our coastal vegetation, which is, after superstorm Sandy, critically important to protecting our communities from extreme weather events,” Bellone said.

The $500,000 dredging project was funded by the county as part of its capital projects, a county spokeswoman said. The U.S. Fish and Wildlife Service, along with the Seatuck Environmental Association, will soon begin an $11 million project to restore the area to a more natural habitat, funded by Congress’ Disaster Relief Appropriations Act from 2013.

Construction work on the next stages is set to go through the end of March and continue in November, breaking over the summer months as to not disturb the marsh’s growing season, said Michelle Potter, refuge manager for the Long Island National Wildlife Refuge Complex.