Riverhead, N.Y. ? On New York’s Long Island, it’s used to prevent drownings. In Greece, it’s a tool to help solve a financial crisis. Municipalities update property assessment rolls and other government data with it. Some in law enforcement use it to supplement reconnaissance of crime suspects.

High-tech eyes in the sky — from satellite imagery to sophisticated aerial photography that maps entire communities — are being employed in creative new ways by government officials, a trend that civil libertarians and others fear are eroding privacy rights.

“As technology advances, we have to revisit questions about what is and what is not private information,” said Gregory Nojeim, senior counsel at the Washington, D.C.-based Center for Democracy and Technology.

Online services like Google and Bing give users very detailed images of practically any location on the planet. Though some images are months old, they make it possible for someone sitting in a living room in Brooklyn to look in on folks in Dublin or Prague, or even down the street in Flatbush.

Sean Walter, an attorney and first-term town supervisor in Riverhead, N.Y., insists he is a staunch defender of privacy rights and the Fourth Amendment, which protects against unreasonable search and seizure.

But Walter supported using Google Earth images to help identify about 250 Riverhead homes where residents failed to get building permits certifying their swimming pools complied with safety regulations. All but about 10 eventually came to town hall.

Walter said the focus was safety, not filling town coffers with permit money, which averaged about $150 depending on the size of the pool. A 4-foot fence is required, gates have to be self-closing and padlocked. All pools must have an alarm that sounds when sensors are activated indicating someone is in the pool.

“We have a town employee who is a personal friend of mine whose son was found face-down in a swimming pool,” Walter said. “He’s OK, but I don’t want to be the supervisor that attends the funeral of a child that drowns in a swimming pool.”

Lillie Coney, associate director of the Electronic Privacy Information Center in Washington, D.C., fears that while Walter’s focus was safety, other municipalities may use the images to check for other transgressions.

“It’s only a matter of time,” Coney said. “There are lots of ordinances where this can be used. In California, where they deal with brush fires, could a satellite image show if a homeowner has brush growing too close to his home? What if someone has junk cars on their lot in violation of ordinances?”

Riverhead resident Tony Villar said the town’s action “could be considered Big Brother looking down at you.”

“But at the same time … the government can listen to your telephone conversations in the name of terrorism,” he said.

Standing outside the Riverhead Public Library, Walter Casey of Flanders agreed. “I think it’s a great intrusion on people’s privacy; they should use it on the politicians’ backyards.”

The New York Civil Liberties Union’s Donna Lieberman said there are ways to enforce requirements “without this sort of engaging in Big Brother on high.”

In Greece, officials are struggling with a debt crisis and have sought to catch tax-evaders by using satellite photos to spot undeclared swimming pools — indicators of taxable wealth.

Google spokeswoman Kate Hurowitz said in a statement that Google Earth acquires its information from a broad range of commercial and public sources.

“The same information is available to anyone who buys it from these widely available public sources,” she said. “Google’s freely available technology has been used for a variety of purposes, ranging from travel planning to scientific research to emergency response, rescue and relief in natural disasters such as Hurricane Katrina and the Haiti earthquake.”

At least nine lawsuits seeking class-action status have been filed in the United States, contending that Google collected fragments of e-mails, Web-surfing data and other information from unencrypted wireless networks as it photographed neighborhoods for its “Street View” feature. Google is also facing investigations or inquiries in 38 states as well as in several countries, including Germany, Spain and Australia.