(CNN) -- The government's point man in charge of the response to the Gulf of Mexico oil spill said it is "impossible" to lead cleanup efforts without cooperation from BP.
Speaking from Washington's National Press Club Friday, retired U.S. Coast Guard Admiral Thad Allen said, "You can call it trust, you can call it cooperation, you can call it collaboration."
He referred to the Oil Pollution Act of 1990, a law that established the burden of payment on the "responsible party" -- in this case, BP.
"It is very hard for the public to understand that a responsible party that is clearly responsible for the event itself could somehow be cooperative in the response to the spill. But as a matter of fact, since 1990, that's exactly the way we've conducted oil spill response in this country."
"The very notion of cooperating with BP in this response has met with universal disapproval," he said, adding that he and others in the Coast Guard who have worked on previous oil spills have had to manage that "paradox" of the law's requirements.
"The current response model assumes the responsible party will work with the federal on-scene coordinator and local state entities to achieve unity of effort and effective spill response. It's been challenging at times to create that unity of effort given sometimes what appears to be the rejection of the notion [by] the general public," Allen said.
The admiral delivered the remarks after providing an update on the status of BP's ruptured well. If all goes as planned, the "bottom kill" operation to permanently plug the ruptured underwater well in the Gulf of Mexico could be completed by the week after Labor Day, he said.
Thursday, Allen authorized BP to replace the existing blowout preventer on the well with a new one. That removal will require close supervision by government scientists, BP engineers and joint investigation teams -- all of whom will want to examine the device closely to gain insight into what happened during the explosion on April 20 when the oil rig exploded, killing 11 workers, and later sank. The government estimates some 4.9 million barrels of oil subsequently gushed into the Gulf, 800,000 of which was captured by surface ships.
The well was capped July 15, stopping the flow of oil, and a "static kill" operation two weeks ago further plugged it with cement and mud from above. The "bottom kill" operation is believed to be a permanent fix, in which the well will be intercepted by a relief well and the ruptured well will be plugged from below.
Allen told reporters Friday that officials are in the midst of conducting an ambient pressure test to determine whether the pressure in the top of the well matches the pressure outside the well. That test is expected to be complete Saturday morning. If no anomalies are detected, BP will conduct a "fishing experiment" to try to pull out the drill pipe through the top of the well, Allen said. If both steps are successful, he will then have to issue another go-ahead to remove the existing blowout preventer and replace it with a new one.
When asked about studies issued earlier this week that appear to be at odds with conclusions the government arrived at two weeks ago stating that 74 percent of the oil released from BP's leaking well has been captured, removed or broken down, Allen said the results were "based on a set of assumptions." He said after accounting for the amount of oil burned, skimmed, dispersed and evaporated, the remaining number is what scientists believe remains in the Gulf.
The University of Georgia said in a release earlier in the week it estimates 70 to 79 percent of the oil that gushed from the well "has not been recovered and remains a threat to the ecosystem." But Allen and National Oceanic and Atmospheric Administration Administrator Jane Lubchenco have said the UGA study was based on a different set of parameters.
"As a simple sailor, I'd say let's calm down and look at the data," Allen said Friday.
Additionally, the Woods Hole Oceanographic Institution issued a study Thursday that detailed finding an oil plume from the Deepwater Horizon spill that was at least 22 miles long and more than 3,000 feet below the Gulf surface back in June. Allen said he discussed the study results with Lubchenco and that they had known about the plume.
"We knew at the time they had located it. We actually dispatched NOAA boats and have had NOAA boats out there looking for hydrocarbons in the water column in and around the well head" but that "locating these things in perpetuity and tracking them is an ephemeral task." It's extremely "difficult" to track hydrocarbons as they travel and break down, Allen said.
While 22 percent of the Gulf of Mexico's federal waters remain closed to fishing, the Louisiana Wildlife and Fisheries Commission opened all state inshore and offshore territorial waters to recreational angling, including charter boat angling Friday.
The LWFC also voted to submit a letter urging the FDA and NOAA to expedite the required testing to re-open commercial fishing areas previously closed due to confirmed reports of oil. Previous to the opening, approximately 862 square miles, or 11 percent of saltwater areas of the state, remained closed to all recreational fishing due to the impacts from the Deepwater Horizon oil spill.