On the 107th day of the Deepwater Horizon disaster, the Macondo well became an apparently harmless hole in the seafloor, clogged with 13-pound-per-gallon gunk, and barely more of a threat to spew oil into the Gulf of Mexico than to start gushing lemonade.

The “static kill” had worked.

The well that tormented the nation has flatlined. Federal officials green-lighted the cementing of the well, already jammed with mud, late Wednesday. Federal waters are reopening gradually to fishing. The oil slick, the once-horrific expanse of red-orange mousse and silver sheen, has largely disappeared, federal scientists said Wednesday, even though the amount of oil left is more than four times that dumped by the Exxon Valdez.

The Obama administration breathed a sigh of relief, holding a midday news conference featuring top officials who claimed credit for guiding BP in getting the well under control.

Officials hastened to remind the public that Macondo won’t be incontrovertibly dead until a relief well drills into it near its base and plugs it with cement. But even the cautious retired Adm. Thad Allen, national incident coordinator, called the static kill a “fairly consequential” event and a “very significant step.”

About three-quarters of the nearly 5 million barrels of oil that escaped Macondo has evaporated, dissolved or been dispersed by chemicals, skimmed by boats, burned, weathered and, most importantly, devoured by the Gulf of Mexico’s permanent oil-eating microbial workforce, according to a study released Wednesday by the National Oceanic and Atmospheric Administration and Interior Department.

This should terminate, once and for all, the more apocalyptic scenarios for the demise of the gulf and the spread of oil to Atlantic shores.