More than 10 years after the Deepwater Horizon drilling rig explosion on the Gulf of Mexico, conservation groups continue to sound the alarm regarding its lasting effects.[i]

The BP-operated rig spilled an estimated 4.9 million barrels of oil, killing marine life and damaging the Gulf coast from Louisiana to Florida.[ii] A complaint filed on October 21 by conservation groups alleges that the federal government has violated the Endangered Species Act (ESA) and Administrative Procedure Act (APA).[iii] The National Marine Fisheries Service (NMFS), a federal agency tasked with protecting marine resources, is accused of issuing “an arbitrary and capricious programmatic biological opinion governing federally authorized oil and gas activities.”[iv]

The biological opinion itself was completed after a different federal lawsuit settlement required the federal government to complete new assessments of its oil and gas leasing and development program in the Gulf.[v] Prior to the new opinion, the government had been relying on outdated 2007 investigations.[vi]

Groups Allege Government Ignored 2010 Oil Spill Impacts on Marine Wildlife and Danger of Future Disasters

The Trump administration has sought to change the ESA in a way environmental groups say weaken the federal government’s ability to prevent extinctions, including attempts to narrow the definition of protected habitats.[vii]

As of 2018, BP paid around $63.4 billion, which included legal fees and clean-up costs encompassing marine life mitigation measures.[viii] The 2020 complaint alleges that despite massive costs and lasting damage, the new biological report doesn’t include Deepwater Horizon damage and mitigation.[ix] As federal oil and gas leasing continues in the region, the government allowed a 10 year delay in issuing the biological opinion.

The opinion fails to account for “post-Deepwater Horizon population or habitat changes when assessing the effects of the program on ESA-listed species and habitats,” according to the complaint.[x] Groups emphasize continued threats to endangered Bryde’s whales, sea turtles, and coral species in the region.[xi] The Bryde’s whale population in particular has fallen below 50.[xii] The complaint seeks declaratory and injunctive relief, requesting a “sufficiently protective biological opinion” be completed within six months.[xiii]

[i] Morgan Conley, Groups Say Gulf Of Mexico Analysis Ignored Deepwater Spill, Law360, (Oct. 21, 2020),

[ii] On Scene Coordinator Report Deepwater Horizon Oil Spill,  (Sept. 2011),

[iii] Complaint, Sierra Club et al. v. National Marine Fisheries Service et al., No. 8:20-cv-03060, (D.Md. Oct. 21, 2020),

[iv] Id. at 2.

[v] Carolina Bolado, Enviros Say Feds’ Deepwater Horizon Review Delay Unlawful, Law360, (Dec. 4, 2018),

[vi] Id. at 5.

[vii] Press Release, The Natural Resources Defense Council (NRDC), Trump Administration Proposes Expanding Extinction Plan: Regulations Will Weaken Endangered Species Act and Worsen Biodiversity Crisis, (July 21, 2020),,protecting%20imperiled%20wildlife%20from%20extinction.&text=%E2%80%9CThis%20weakening%20of%20the%20ESA,wildlife%20already%20struggling%20to%20survive

[viii] Ron Russo, BP Deepwater Horizon costs balloon to $65 billion, Reuters, (Jan. 16, 2018),

[ix] Id. at 3.

[x] Id. at 3; see Biological Opinion on the Federally Regulated Oil and Gas Program Activities in the Gulf of Mexico, NOAA Fisheries, (Mar. 12, 2020),

[xi] Id. at 1.

[xii] Id. at 1.

[xiii] Id. at 3.