New Orleans ? The state Health Department cleared the way Monday for people to begin to return to the New Orleans neighborhood that faced Hurricane Katrina’s worst fury, saying tap water in part of the Lower Ninth Ward is safe.

“Our displaced residents in some of the hardest-hit areas are now able to return to their homes and begin to rebuild their lives,” Mayor Ray Nagin said Monday in a statement.

The area encompasses the 10 blocks or so closest to the Mississippi River, where the ground is higher. In other parts of the neighborhood, people still must boil water before using it to drink, prepare food or bathe, Nagin noted. Officials said they do not know when they’ll be able to open those areas.

About 30 to 50 trailers provided by the Federal Emergency Management Agency have been set up on lots where the city has certified that power and safe water were available, said Darryll J. Madden, an agency spokesman. Lack of power and water has kept FEMA from filling 350 other requests in the neighborhood.