BP plc’s claims that the Gulf of Mexico (GOM) has returned to pre-Macondo well blowout condition are “inappropriate as well as premature” because the largest offshore spill in U.S. history still is being assessed, federal and state trustees overseeing the Natural Resource Damage Assessment (NRDA) said.

BP said Monday in a report about GOM cleanup efforts that scientific data and studies indicate that the Gulf has returned to its baseline conditions pre-Macondo. The well blowout happened in April 2010. Impacts from the four-month-long oil spill that followed “largely occurred in the spring and summer of 2010,” according to thereport, which was posted on BP’s website.

“The data and studies summarized in this report are encouraging and provide evidence that the most dire predictions made after the spill did not come to pass,” said BP’s Laura Folse, executive vice president for response and environmental restoration. “The Gulf is showing strong signs of environmental recovery, primarily due to its natural resilience and the unprecedented response and cleanup efforts.”

The report’s conclusions are based on “scientific studies that government agencies, academic institutions, BP and others conducted as part of the spill response, the ongoing NRDA process or through independent research,” the producer said. “While individual studies are helpful, they tell only part of the story.” The company’s report is a “wide-ranging compilation of reputable studies by respected researchers” that “provides a broader overview of the state of the Gulf environment.”

Among other things, the available data “does not indicate the spill caused any significant long-term population-level impact to species in the Gulf,” the report said. Data “do not reveal ongoing adverse impacts to bird populations linked to the spill beyond the initial, limited acute mortality in 2010. National Oceanic and Atmospheric Administration (NOAA) data show that fish populations are robust, and commercial landings generally have been consistent with pre-spill trends and ranges. Findings published by a group of researchers, including scientists working with the NRDA trustees, show the accident did not affect most deepwater coral communities.”

BP’s report also claims that the affected areas “are recovering faster than predicted. For example, in 2010 the U.S. Coast Guard documented 86 miles of marsh that were categorized as heavily oiled. And by early 2014, after the response effort as well as natural attenuation, just 0.7 miles remained heavily oiled and were recovering naturally.”

Trustees slammed the report because the assessment, five years old and still going strong, isn’t yet completed. Trustees represent Florida, Alabama, Mississippi, Louisiana and Texas, as well as NOAA, the U.S. Environmental Protection Agency, Department of Interior and Department of Defense (DOD). Some of the impacted area is DOD-owned.

“Citing scientific studies conducted by experts from around the Gulf, as well as this council, BP misinterprets and mis-applies data while ignoring published literature that doesn’t support its claims and attempts to obscure our role as caretakers of the critical resources damaged by the spill,” trustees said. “At over 100 million gallons of spilled oil, the Deepwater Horizon oil spill is more than 10 times the size of the Exxon Valdez.From decades of experience with oil spills, we know that the environmental effects of this spill are likely to last for generations.”

The trustees, working with scientific colleagues at several universities and institutions, “are engaged in a rigorous, scientific process of injury assessment and are still analyzing the data, conducting studies, and evaluating what happened. Our obligation under the Oil Pollution Act is to restore the public’s natural resources injured by the Deepwater Horizon spill to the condition they would have been in but for the spill and to compensate the public for the services of those natural resources that were injured or lost.”

In addition to assessing damage from the oil spill and undertaking early restoration efforts, a long-term plan is being developed with public involvement.

“The assessment is a thorough and time consuming process by which we evaluate the best scientific evidence available to ensure we understand the injuries caused by the spill, as well as the most appropriate means to restore those injuries and to compensate for the lost use of the Gulf’s resources while they are injured,” trustees said. “The restoration planning effort involves a great deal of public outreach to ensure we consider the public’s perspective when making restoration decisions.”

The NRDA, the largest U.S. environmental evaluation of its kind ever conducted, was set up for federal government, state agencies and BP to identify injuries to natural resources resulting from the Macondo well blowout. The assessment also is providing what trustees consider to be the best methods to restore injured resources and the amount of money that may be required.

To date, the NRDA has cost about $1.3 billion. BP has committed to pay $500 million over 10 years to support independent research through the GOM Research Initiative. In addition to those costs, BP has spent more than $28 billion on response, cleanup, early restoration and claims payments.