Submerged wreckage from the October storm, including pieces of houses, parts of docks, hot tubs, refrigerators and boats, also can create eyesores and public health hazards as it washes up against the shore.
Crews are patrolling beaches, searching marshlands and surveying under water.
"Every time we seem to get a handle on debris, more seems to be found," said Gilbert Anderson, Suffolk's public works commissioner. "It's a real mess out there."
Shoreline cleanup in New York is the responsibility of property owners -- individuals, villages, towns, counties and the state. Some towns, including Hempstead and Brookhaven, have assigned parks department workers and bay constables to monitor their waters through the summer, remove what debris they can and document the rest for future cleanups.
Babylon Town crews have pulled many items out of canals and creeks, and identified others, including 11 submerged boats. They plan to use underwater photography and sonar to ensure the water is clear of debris. Daily beach patrols in summer will supplement the effort.
"The debris fields were tremendous," said Brian Zitani, waterways managing supervisor in Babylon's Department of Environmental Protection. "We're pretty confident we have about 95 percent of the material collected or identified."
Statewide, the Department of Environmental Conservation, Division of Homeland Security and Emergency Services, and Office of Parks, Recreation and Historic Preservation have surveyed the shoreline from air, sea and land to identify hazards, according to Gov. Andrew M. Cuomo's office.
The DEC will clean up debris on its properties, including marshlands, agency spokeswoman Emily DeSantis said. The agency also is monitoring problems elsewhere and is prepared to work with federal and local governments to make sure cleanup needs are addressed, the governor's office said.
"Governor Cuomo has made it a priority to make sure Long Island's beaches are cleaned up, its boating areas are open and its infrastructure repaired in time for the summer tourism season," spokesman Richard Azzopardi said.
Assemb. Joseph Saladino (R-Massapequa) said he hopes boaters, volunteer groups and divers will help document and clean up the debris, but if a danger emerges, he'll seek assistance from the governor.
In New Jersey, state officials took control of cleaning up the shoreline and this month issued three debris-removal contracts.
Sandy debris that floated out with the tide may return to shore as winds change with the seasons, said R. Lawrence Swanson, an associate dean at Stony Brook's School of Marine and Atmospheric Sciences.
Winds commonly come out of the south or southwest in the spring, pushing debris north and northeast, he said. "If we have persistent winds, we could see a lot of it," Swanson said.
That was the case in 1988 when winds pushed medical waste and other debris onto Long Island beaches, causing sporadic closures along 100 miles of coastline, including at least three days at Jones Beach.
"People just stayed away," Swanson said. "I think local communities need to be vigilant" about the effect of debris.
Storm wreckage can block shipping channels, hurt fishing areas and create prime mosquito breeding sites. Nails, bits of boardwalk and household items could injure swimmers. "You really need to get that stuff out," Ragonase said.
No large floating debris fields associated with Sandy have been discovered, said Jason Rolfe, a regional coordinator with the NOAA Marine Debris Program, which is working with state, federal and local groups to assess the debris and develop plans to manage it.
The agency believes most of the debris sank or was pushed into marshes, he said.
Long Island boating groups are advising people to take it slow on the water. "It's going to be very treacherous out there," said Rob Weltner, president of Operation Splash in Freeport.
Suffolk County's Division of Vector Control -- responsible for mosquito control -- is monitoring wetlands for Sandy wreckage and has had crews helping remove debris in Mastic Beach, Lindenhurst, Bay Shore and West Babylon. When they see something that may block water flow and create mosquito breeding areas, they remove the items, which have included refrigerators and docks, Anderson said.
Islip Town's $53,000 contract with a Brookhaven engineering firm to assess conditions at 15 sites from Bayport to West Islip includes using underwater cameras to make sure recreational boating areas are free from debris, town spokeswoman Inez Birbiglia said.
In Long Beach, a Staten Island firm conducted a sonar search for debris before the city hosted the Feb. 3 polar bear plunge. The firm checked the water from the beach to 300 feet out into the Atlantic between New York and Laurelton avenues, public works Commissioner Jim LaCarrubba said.
"We were very happy to find they had nothing," he said.
The city, which plans a more comprehensive sonar check in late March or April, will also rely on daily beach monitoring and the surfing community to report any new debris that washes up.
They still haven't found a lifeguard station that floated out to sea in the storm.
With Joan Gralla