Cleaning up the mess left by the oil industry on Alaska’s North Slope could cost anywhere from $2.7 billion to $6 billion, but oil companies have so far set aside just a fraction of that money and are not under any legal obligation to meet specific cleanup standards, the General Accounting Office announced yesterday. The report, which was requested by congressional Democrats opposed to additional oil drilling in the Arctic region, found that oil companies operating on federal land need only be bonded for about $500,000 each, and that cleanup standards imposed by the state of Alaska are “generally insufficient to ensure that any federal lands disturbed by oil industry activities will be restored.” State officials criticized the report as a partisan ploy and defended their regulations, saying the vagueness was deliberate and would allow specific standards to be established when the oil fields actually close, some 30 to 50 years in the future. There are more than 3,000 active wells in the North Slope, connected by a massive network of roads, drilling pads, production facilities, and pipelines, all of which will have to be removed when the industry leaves the area.