NEW ORLEANS -- This city is not even close to being done with cleaning up the mess created three years ago by Hurricane Katrina, the Government Accountability Office said Monday.

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Crews remove debris in Kenner after Katrina.

In an environmental assessment for the third Katrina anniversary, the GAO said there are about 6,100 homes that must still be demolished. That will prolong a cleanup that has been fraught with environmental problems.

The report to congressional leaders gave a snapshot of the problems, which have ranged from illegal dumping to disposal of hazardous materials in landfills not suited to take them.

"Nearly 3 years later, the New Orleans area still faces significant debris management issues and challenges," John B. Stephenson, the GAO's director for natural resources and environment, wrote in the report.

The GAO is Congress' investigative arm. It has been tracking the performance of government agencies since Katrina hit on Aug. 29, 2005.

The GAO said Katrina was expected to create 100 million cubic yards of debris -- more than twice what Hurricane Andrew generated in 1992. Before Katrina, Andrew was the biggest "recorded amount of disaster-related debris in U.S. history."

As of May 2008, the GAO said state regulators had taken enforcement action for 120 environmental violations.

At two landfills, regulators found that items like tires, medical waste and creosote telephone poles were dumped without authorization, the GAO said. Penalties may be levied against the landfill operators, the GAO said.

Other violations at landfills included not covering the trash with 12 inches of soil every two weeks, breaking discharge limits and not policing the sites well enough. Meanwhile, on at least seven occasions people have mishandled asbestos, the GAO said.

Another problem was the reopening of a municipal landfill called Gentilly. There have been persistent fears that contaminants may leach out because the landfill does not have a protective liner.

But state and federal officials said a vigorous effort to monitor the landfill has shown that it does not pose a risk of pollution or of sliding, the GAO said.

Sam Coleman, an Environmental Protection Agency official in Dallas overseeing Katrina work, said none of the landfills used to collect hurricane debris pose a risk.

"We feel that every effort has been made to make sure those landfills were managed with the best possible standards in mind," he said.

Meanwhile, dirty water from another landfill, the Chef Menteur dump, has accumulated in a nearby pit, the GAO said. The landfill was opened in April 2006 and then closed in August 2006 under pressure from environmentalists and residents of a nearby Vietnamese community.

The landfill owners want to pump the water out. But state officials have said the water must be treated first, the GAO

reported.

Monday's report also urged the EPA to outline its plans to improve the way it responds to future disasters. Last summer, the GAO asked the EPA to develop those plans, but the report said the EPA has not followed through.

Stephenson said the threat of more hurricanes this year makes it urgent for EPA to outline what it has done.

Coleman, the EPA official, said his agency has conducted "extensive planning meetings" with state officials. He said the agency was prepared for the next disaster and that the EPA would soon respond to the GAO's request.

(Copyright 2008 by The Associated Press. All Rights Reserved.)