While the BP well was still gushing, the Obama administration issued an order that limited the spreading of controversial dispersant chemicals on the Gulf of Mexico's surface. Their use, officials said, should be restricted to "rare cases."

But in reality, federal documents show, the use of dispersants wasn't rare at all.

Despite the order -- and concerns about the environmental effects of the dispersants -- the Coast Guard granted requests to use them 74 times over 54 days, and to use them on the surface and deep underwater at the well site. The Coast Guard approved every request submitted by BP or local Coast Guard commanders in Houma, La., although in some cases it reduced the amount of the chemicals they could use, according to an analysis of the documents prepared by the office of Rep. Edward J. Markey (D-Mass.).

The documents indicate that "these exemptions are in no way a 'rare' occurrence, and have allowed surface application of the dispersant to occur virtually every day since the directive was issued," Markey wrote in a letter dated Aug. 1 to retired Coast Guard Adm. Thad W. Allen, the government's point man on the spill. Markey chairs the House Select Committee on Energy Independence and Global Warming.

Some of them dealt with separate dispersant applications on the same day. Markey said it appeared that the order "has become more of a meaningless paperwork exercise" than a real attempt to curb use of the dispersants.

In an interview Saturday, Allen defended the decisions to grant the waivers, saying that overall use of dispersants declined sharply after that May 26 order to limit their use. The total use of dispersants underwater and on the surface declined about 72 percent from its peak, according to the Environmental Protection Agency.

Allen said that on some days the amount of oil on the surface justified a "tactical" decision, by on-scene Coast Guard commanders, to spray some dispersants.

"There's a dynamic tension that goes on when you're managing an incident that has no precedent," Allen said. "You establish general rules and guidelines, but knowing that the people on scene have the information" means trusting them to make decisions, he said.

In the end, Allen said: "You can quibble on the semantics related to 'rare.' I like to focus on the effects we achieved" by dispersing the oil. Officials have said that, in the days since the gusher was stopped, thick sheets of oil have nearly disappeared from the gulf's surface.

EPA Administrator Lisa P. Jackson conceded that there had been "frustration in the field" from EPA officials about the waivers. But Jackson said it was partly alleviated June 22, nearly a month after the order was issued, when Coast Guard officials began giving the EPA a greater role in the discussions over whether to approve dispersant use.

"EPA may not have concurred with every single waiver," Jackson said. But, she said, the Coast Guard had the ultimate say: "The final decision-making rests with the federal on-scene coordinator. That's where the judgment, the ultimate decision-making ability, had to lie."

The dispersants -- variants of a Nalco product called Corexit -- break up the oil, acting like a detergent on kitchen grease. They are intended to keep the oil from reaching shore in large sheets and to make it easier for microbes to consume the oil underwater.