Washington -LRB- CNN -RRB- -- A BP official says a gusher of oil pouring from its damaged Gulf of Mexico well could be shut off as early as next week . BP Managing Director Bo Dudley said Thursday night the company will pump fluids into the well this weekend in the beginning of a process that -- if successful -- could lead to the leak finally being closed off in a matter of days . `` If that option does n't work , we 've got a second and a third option we 'll do after that , '' Dudley said on CNN 's Larry King on Thursday . `` We 're hopeful that next week we 'll be able to shut it off . '' Earlier in the day , BP acknowledged that the underwater gusher is bigger than estimated to date , as new video showed a cloud of crude billowing around its undersea siphon . Company spokesman Mark Proegler said Thursday that the siphon is now drawing about 5,000 barrels -LRB- 210,000 gallons -RRB- per day up to a ship on the surface of the Gulf -- as much as government and company officials had estimated the spill was pouring into the Gulf every day for a month . Proegler declined to estimate how much more oil was escaping . BP America Chairman Lamar McKay said Wednesday that the figure used by the oil spill response team had a degree of `` uncertainty '' built into it . But figures by independent researchers have run up to many times higher : Steve Wereley , a professor of mechanical engineering at Purdue University , told CNN 's `` American Morning '' that the spill could be as big as 20,000 to 100,000 barrels a day . And members of Congress released video from the company that showed much more oil pouring out of the damaged well than the siphon was capturing . Rep. Ed Markey , who leads a House subcommittee investigating the disaster , told reporters , `` I think now we are beginning to understand that we can not trust BP . '' `` People do not trust the experts any longer , '' said Markey , D-Massachusetts . `` BP has lost all credibility . Now the decisions will have to be made by others , because it is clear that they have been hiding the actual consequences of this spill . '' Meanwhile , the Coast Guard announced the creation of a federal Flow Rate Technical Group to assess the actual flow rate from the well . Coast Guard Capt. Ron LaBrec said that Adm. Thad Allen would oversee the team , which will include members from the Coast Guard , the Minerals Management Service , the National Oceanic and Atmospheric Administration , the Department of Energy , the U.S. Geological Society and others from the science community and academia . The peer-reviewed team , which has already begun its work , is to determine the flow rate from the beginning of the incident to the present , LaBrec said . The Obama administration announced Thursday that it has ordered BP to release all data related to the massive spill , including environmental sampling analyses , internal investigation reports and details of the cleanup effort . In a letter to BP Group CEO Tony Hayward , Homeland Security Secretary Janet Napolitano and Environmental Protection Agency Administrator Lisa Jackson told BP to post that information on a website and update it daily . `` The public and the United States government are entitled to nothing less than complete transparency in this matter , '' they concluded . The spill began with an April 20 explosion and fire that sank the drill rig Deepwater Horizon two days later . Eleven workers were lost with the rig , which was owned by drilling contractor Transocean and hired by BP . The resulting slick now threatens the coastal marshes of southeastern Louisiana , where brown , syrupy oil made it past protective booms and into the wetlands near the mouth of the Mississippi River on Wednesday . Over the weekend , BP inserted a piece of pipe into the larger of the two leak points and began drawing oil from the undersea gusher , located about a mile underwater , up to a ship on the surface . It also has been laying booms out along barrier islands and spraying hundreds of thousands of gallons of chemical dispersants on the surface and near the sources of the leak . But that element of the response came under new fire as well on Thursday , as the EPA ordered BP to find a less toxic chemical to use to break up the oil . The EPA gave the company a day to pick a new substance and three days to start using it instead of the current dispersant , known as Corexit 9500 . The chemical has been rated more toxic and less effective than many others on the list of 18 EPA-approved dispersants , according to testimony at a congressional hearing Wednesday . `` Because of its use in unprecedented volumes and because much is unknown about the underwater use of dispersants , EPA wants to ensure BP is using the least toxic product authorized for use , '' the agency said in a statement announcing the order . `` We reserve the right to discontinue the use of this dispersant method if any negative impacts on the environment outweigh the benefits . '' Corexit 9500 includes petroleum distillates , propylene glycol and a proprietary organic sulfonic salt , and prolonged contact with it can cause eye or skin irritation , according to the manufacturer 's material data safety sheet . The document warns that `` repeated or prolonged exposure may irritate the respiratory tract . '' But BP says Corexit is biodegradable , has been approved by the EPA and the Coast Guard and is `` readily available in the quantities required '' by a response plan approved by the government before the spill . iReport : Track the spill ; Share stories `` It has been very effective in causing the oil to form into small , isolated droplets that remain suspended until they 're either eaten by naturally occurring microbes , evaporate , are picked up or dissolve , '' the company said . But it added , `` At the same time , we are conducting ongoing assessment of alternative or supplemental dispersant products . '' Meanwhile , BP is readying a new attempt to plug the leak for Sunday by injecting a large amount of heavy `` mud '' -- a fluid used as a lubricant and counterweight in drilling operations -- into the well bore . If that succeeds , the well will be cemented shut , officials have said . `` Everything is being done to make sure that happens , '' Interior Secretary Ken Salazar , whose department oversees offshore oil drilling , told CNN 's `` American Morning '' Thursday . `` We have the best scientists in the world who are overseeing what is going on . So , we are hopeful that it will happen soon . '' Salazar said BP , which leased the rig from Transocean , has tried many techniques to stop the leaking and the government will do all in its power to hold them accountable . `` They 're putting a lot of hope on that Sunday , '' he said . `` We 'll see if it happens . '' Salazar announced Wednesday that he was dividing the Interior Department 's Minerals Management Service , which regulates oil exploration , into three divisions . The agency has come under fire since long before the spill , and Salzar said it would be reorganized to separate what he called the conflicting duties of regulating oil companies and collecting royalties from them . `` We inherited here what was a legacy of an agency that essentially was rubber-stamping whatever it was that the oil and gas industry wanted , '' Salazar said . `` We have been on a reform agenda from Day One . '' CNN 's Ed Lavandera , Marylynn Ryan and Aaron Cooper contributed to this report .