	Introduction

The estimated 4.1 million barrels of oil released during the 2010 Deepwater Horizon oil spill is considered to be the largest accidental marine oil spill in the history of the petroleum industry and will have an impact on the natural resources of the Gulf region for the foreseeable future. Under the Oil Pollution Act of 1990 (OPA), federal, state, tribal, and foreign governments may seek compensation for the costs of restoring damaged natural resources from the parties responsible through the Natural Resource Damage Assessment (NRDA) process. In particular, this report describes the statutory requirements of OPA, the NRDA process under the implementing regulations, and developments in the Gulf of Mexico. Liability

Pursuant to OPA, the parties responsible for causing the oil spill are responsible for damages to natural resources. Moreover, OPA specifically allows states to impose additional liability for oil spills and/or requirements for removal activities. And the third allows for recovery of the reasonable costs incurred in "assessing those damages." For offshore facilities, a responsible party's liability for economic damages is limited to $75 million, but there is no cap on removal costs. Trustees

The governmental entities with jurisdiction over resources—federal, state, tribal, and foreign—are the Trustees throughout the NRDA process. Under OPA, the function of the Trustees is to assess natural resource damages, as well as to "develop and implement a plan for the restoration, rehabilitation, replacement, or acquisition of the equivalent, of the natural resources under their trusteeship." Once money is recovered by a Trustee under OPA, including to cover the costs of assessing the damages, it is deposited in a special trust account in order "to reimburse or pay costs by the trustee ... with respect to the damaged natural resource." Money for the Trustees' immediate assessment of the natural resource damage may come from the OS Trust Fund until the responsible parties are identified and provide reimbursement to the Fund. The OS Trust Fund could also be used if the responsible parties are not known, insolvent, or refuse to give money for assessment before they are found responsible by a court. Under the OPA regulations, the Trustees are required to invite the responsible parties to participate in the NRDA process "as soon as practicable" but not later than the delivery of a Notice of Intent to Conduct Restoration Planning. The Trustees will also evaluate harm resulting from the response actions, such as the in situ burning, the use of dispersants, or vehicle damage to shores and marshes. The NRDA process in the Gulf is currently in the Restoration Planning Phase. Significantly, the RESTORE Act establishes in the Treasury the Gulf Coast Restoration Trust Fund, which is available to restore the Gulf Coast region. Also of importance, the RESTORE Act requires an additional 30% of the Gulf Coast Restoration Trust Fund to be disbursed to the five Gulf Coast states using a formula that weighs the mileage of oiled shoreline, the distance from the affected shoreline to the Deepwater Horizon drilling unit, and the population of coastal counties.
The 2010 Deepwater Horizon oil spill leaked an estimated 4.1 million barrels of oil into the Gulf of Mexico, damaging the waters, shores, and marshes, and the fish and wildlife that live there. The Oil Pollution Act (OPA) allows state, federal, tribal, and federal governments to recover damages to natural resources in the public trust from the parties responsible for the oil spill. Under the public trust doctrine, natural resources are managed by the states for the benefit of all citizens, except where a statute vests such management in the federal government.
In particular, OPA authorizes Trustees (representatives of federal, state, and local government entities with jurisdiction over the natural resources in question) to assess the damages to natural resources resulting from a spill, and to develop a plan for the restoration, rehabilitation, replacement or acquisition of the equivalent, of the natural resources. The types of damages that are recoverable include the cost of replacing or restoring the lost resource, the lost value of those resources if or until they are recovered, and any costs incurred in assessing the harm. OPA caps liability for offshore drilling units at $75 million for economic damages, but does not limit liability for the costs of containing and removing the oil.
The process established by OPA for assessing the damages to natural resources is known as Natural Resources Damage Assessment (NRDA). In the three steps of the NRDA process, the Trustees are required to solicit the participation of the responsible parties and design a restoration plan. This plan is then paid for or implemented by the responsible parties. If the responsible parties refuse to pay or reach an agreement with the Trustees, the Trustees can sue the responsible party for those damages under OPA. In the alternative, the Trustees may seek compensation from the Oil Spill Liability Trust Fund, but there is a cap of $500 million from the Fund for natural resources damages. The federal government may then seek restitution from the responsible parties for the sums taken from that Fund.
The Trustees are not required to adhere to the NRDA process set forth in the OPA regulations. However, they are accorded a rebuttable presumption in court for any determination or assessment of damages conducted pursuant to the regulations. Of course, the Trustees and the responsible parties are permitted to enter into settlement agreements at any point throughout the NRDA process.
The NRDA process in the Gulf is in the Restoration Planning Phase. The caps on the Oil Spill Liability Trust Fund and on OPA liability have captured Congress's attention, as has Gulf restoration. In 2012, President Obama signed the RESTORE Act, which establishes from Clean Water Act penalties the Gulf Coast Restoration Trust Fund, which is available for restoration activities in the Gulf Coast region.