Oil Spills: Background and Governance

October 25, 2006 – June 22, 2023 RL33705

Oil Spills: Background and Governance
Updated June 22, 2023
Congressional Research Service
https://crsreports.congress.gov
RL33705

Oil Spills: Background and Governance

Summary
Oil is a primary source of energy in the United States. Domestic oil production has increased in
recent years, and vast quantities of oil continually enter the country via vessel or pipeline, moving
throughout the country to various destinations. With such widespread use and nonstop movement,
it is inevitable that some number of spills will occur.
Oil spills have raised environmental concerns for decades. Several major U.S. oil spills have had
lasting repercussions that transcended local environmental and economic effects: the 1969 well
blowout off the coast of Santa Barbara, CA; the 1989 Exxon Valdez oil spill in Prince William
Sound, AK; and the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. More recent spills
in various locations from other sources, including pipelines and rail transportation, have garnered
attention from policymakers. The impacts of an oil spill depend on the size of the spill, the rate of
the spill, the type of oil spilled, and the location of the spill. Depending on timing and location,
even a relatively minor spill can cause significant harm to individual organisms and entire
populations. Oil spills can cause impacts over a range of time scales, from days to years, or even
decades for certain spills.
Over the past two decades, the annual number and volume of oil spills have declined. However,
this trend was altered dramatically by the 2010 Deepwater Horizon oil spill in the Gulf of
Mexico. The incident led to a significant release of oil. According to estimates, the well released
168 million gallons of oil before it was contained almost three months later.
The governing framework for oil spills in the United States remains a combination of federal,
state, and international authorities. Within this framework, several federal agencies have the
authority to implement oil spill regulations. Agency responsibilities can be divided into two
categories: (1) oil spill response and cleanup and (2) oil spill prevention/preparedness.
Oil spill response authority is determined by the location of the spill: the U.S. Coast Guard has
response authority in the U.S. coastal zone, and the Environmental Protection Agency (EPA)
covers the inland zone. The Clean Water Act, as amended by the Oil Pollution Act (OPA) in 1990,
provides the federal authority to perform cleanup immediately using federal resources, monitor
the response efforts of the spiller, or direct the spiller’s cleanup activities. The lead federal
responder (either from Coast Guard or EPA) determines the level of cleanup required. Federal
responders have immediate access to funds in the Oil Spill Liability Trust Fund to support
cleanup activities. The trust fund is primarily financed by a per-barrel tax on domestic crude oil
and imported petroleum products. The fund’s balance is estimated to reach $9.7 billion at the end
of FY2024.
Parties responsible for an oil spill may be liable for cleanup costs, natural resource damages, and
specific economic damages, including personal property damage and lost profits or earning
capacity. OPA provided (1) limited defenses from liability—act of God, act of war, and act or
omission of certain third parties—and (2) conditional liability limits (or caps) for cleanup costs
and other damages.
Jurisdiction over oil spill prevention and preparedness duties is determined by the potential
sources (e.g., vessels, facilities, pipelines) of oil spills. A series of executive orders, coupled with
memoranda of understanding, have established the various agency responsibilities. For example,
EPA oversees onshore facilities, the Coast Guard oversees vessels, the Department of
Transportation oversees pipelines and rail transportation, and the Department of the Interior’s
Bureau of Ocean Energy Management oversees offshore facilities (e.g., oil platforms).
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Oil Spills: Background and Governance

Introduction
Oil remains a dominant source of energy in the United States, accounting for the largest
percentage of total U.S. consumption by source (approximately 36%) in 2021.1 The United States
has led the world in oil production since 2013.2 Oil use is widespread, providing fuel for the
transportation, industrial, and residential sectors. Vast quantities continually move throughout the
country to various destinations.3 With such widespread use and nonstop movement, it is
inevitable that some number of spills will occur.
This report provides background information regarding oil spills and identifies the legal
authorities and processes for oil spill prevention, response, liability, and compensation. The first
section highlights background issues, including oil spill statistics and potential environmental
impacts. The second section discusses the legal and regulatory framework that governs oil spill
prevention and response.
Background
Oil spills occur from a wide variety of sources.4 Some sources release relatively minor amounts
per individual release but, in aggregate, contribute a significant annual volume (e.g., recreational
vessels). Other sources, such as oil tankers or offshore oil wells, release oil on a less frequent
basis but have the potential to release a significant volume in one incident. These variances in
frequency and volume of oil releases create different environmental impacts as well as different
challenges for responders and policymakers.
Major oil well blowouts are relatively uncommon but have accounted for the largest unintentional
oil spills in world history. In 1979, the IXTOC I oil well blowout released an estimated 139
million gallons to 428 million gallons in Mexican Gulf Coast waters.5 By comparison, the largest
oil tanker spill in world history—the Atlantic Empress off the coast of Tobago in 1979—was
estimated at approximately 84 million gallons.6
Over the past few decades, two major U.S. oil spills have had lasting repercussions that
transcended local environmental and economic effects:
1. 2010 Deepwater Horizon Oil Spill. On April 20, 2010, an explosion occurred at
the Deepwater Horizon drilling platform in the Gulf of Mexico, resulting in 11
fatalities. The platform had been attached to the Macondo oil well approximately
5,000 feet below sea level. Two days later the platform sank into the Gulf, and

1 By comparison, natural gas accounted for 32%; coal accounted for 11%; and renewable energy accounted for 12%.
See Energy Information Administration (EIA), Monthly Energy Review, Primary Energy Consumption by Source,
Table 1.3, at https://www.eia.gov/totalenergy/data/monthly/.
2 EIA, International Data, total production of crude oil, natural gas plant liquids, and other liquids, at
https://www.eia.gov/international/data.
3 For more background, see CRS Report R46723, U.S. Energy in the 21st Century: A Primer, coordinated by Melissa
N. Diaz.
4 In this report, oil refers to crude oil and petroleum products, including gasoline and other fuels, unless stated
otherwise.
5 National Academies of Sciences, Engineering, and Medicine, Oil in the Sea IV: Inputs, Fates, and Effects, 2022
(hereinafter “Oil in the Sea IV, 2022”), p. 75, at https://nap.nationalacademies.org/catalog/26410/oil-in-the-sea-iv-
inputs-fates-and-effects.
6 For a list of the largest oil tanker spills, see International Tanker Owners Pollution Federation (ITOPF) website, at
http://www.itopf.com/.
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responders discovered that the well was releasing oil at a significant rate.
According to estimates, the well released more than 100 million gallons of oil
before it was contained 86 days later.7
2. 1989 Exxon Valdez Oil Spill. On March 24, 1989, the Exxon Valdez oil tanker
ran aground on Bligh Reef in Prince William Sound, AK, releasing
approximately 11 million gallons of crude oil.8 Cleanup efforts lasted for six
months in 1989 until the U.S. Coast Guard suspended operations due to weather
and climatic conditions. Cleanup efforts resumed during the warmer months of
1990 and 1991. The Exxon Valdez spill produced extensive consequences beyond
Alaska. According to the National Academies, the Exxon Valdez disaster caused
“fundamental changes in the way the U.S. public thought about oil, the oil
industry, and the transport of petroleum products by tankers.... ‘Big oil’ was
suddenly seen as a necessary evil, something to be feared and mistrusted.”9
Oil Spill Data: Recent Trends
No single agency or organization collects oil spill data from all of the major sources for all
locations. Although the National Response Center collects and provides details about a wide
spectrum of incidents, the spill volume data are often initial, unverified estimates, and drawing
lessons from these data may be difficult.
A national assessment of oil spill volume and frequency necessitates data collection from several
sources, including the U.S. Coast Guard and the Department of Transportation’s Pipeline and
Hazardous Materials Safety Administration (PHMSA). Combining the data from these sources
may be problematic, because (1) some incidents may be included in both sources of data; and (2)
the data collection processes and scopes may vary. Therefore, data from these sources are
presented separately below.
Coast Guard Data
Pursuant to the National Contingency Plan (discussed below), the Coast Guard’s oil spill response
jurisdiction is the “coastal zone,” defined in regulations to include
all United States waters subject to the tide, United States waters of the Great Lakes,
specified ports and harbors on inland rivers, waters of the contiguous zone, other waters of
the high seas subject to the NCP, and the land surface or land substrata, ground waters, and
ambient air proximal to those waters.10

7 BP and the federal government disputed the final spill volume. Spill volume is a central factor in assessing civil
penalties under the Clean Water Act. The parties agreed that responders recovered 34 million gallons (810,000 barrels)
at the wellhead before the oil could contact sea water. After accounting for this collection, the U.S. government
estimated the net discharge at 176 million gallons (4.2 million barrels). BP estimated a net discharge of 103 million
gallons (2.45 million barrels). In the context of Clean Water Act penalty calculations, a federal court concluded that
168 million gallons (4.0 million barrels) were released from the reservoir, resulting in a net discharge (after factoring in
the recovered oil) of 134 million gallons (3.19 million barrels). See U.S. District Court for the Eastern District of
Louisiana, Findings of Fact and Conclusions of Law, Oil Spill by the Oil Rig Deepwater Horizon in the Gulf of Mexico
on April 20, 2010, January 15, 2015, at http://www.laed.uscourts.gov/OilSpill/Orders/1152015FindingsPhaseTwo.pdf.
8 Note that the Exxon Valdez spill ranks only 35th for spill volume on the list of international tanker spills since 1967.
See International Tanker Owners Pollution Federation Limited, “Historical Data,” at http://www.itopf.com/stats.html.
9 See National Research Council (NRC), Oil in the Sea III: Inputs, Fates, and Effects, National Academies of Science,
February 2003, p. 11.
10 40 C.F.R. §300.5.
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Figure 1 illustrates the number of oil spill incidents and spill volume between 2002 and 2021
from data provided by the Coast Guard. The spill data include incidents from vessels, facilities,
and offshore pipelines. The 2010 Deepwater Horizon oil spill is not included in the figure,
because the magnitude of its spill volume—more than 100 million gallons—makes it difficult to
compare to annual spill volumes. The figure does include an estimate of oil released on the
surface (approximately 400,000 gallons) from the Deepwater Horizon mobile offshore drilling
unit.
The figure indicates that the number of incidents has decreased over time. Except for several
large incidents in 2005 and 2006 (and the Deepwater Horizon incident in 2010), the volume of
spilled oil has remained relatively consistent. In 2005, approximately 8 million gallons of oil were
released from Louisiana facilities damaged during Hurricane Katrina; in 2006, approximately 2
million gallons spilled from a refinery in Louisiana.11
Figure 1. Oil Spills from All Sources in U.S. Coast Guard’s Jurisdiction: 2002-2021
Does not include the volume from the 2010 uncontrolled Macondo well

Source: Prepared by CRS; data from the Bureau of Transportation Statistics, “Petroleum Oil Spil s Impacting
Navigable U.S. Waterways” (which cites the Coast Guard Oil Spil Compendium and personal communications
with the Coast Guard as its data sources), at https://www.bts.gov/content/petroleum-oil-spil s-impacting-
navigable-us-waters.
Notes: Oil includes crude oil, fuel oils (heavy and intermediate), gasoline products, other petroleum oils, and
nonpetroleum oils. The Coast Guard states that its Oil Spil Compendium includes spil s that have been
“investigated” by the Coast Guard. Further, “this data is provided ‘as reported,’ with no interpretation or
filtering. For example, incidents that fall within the jurisdiction of other agencies, or that are not required to be
reported under existing Coast Guard regulations, may be included in the compendium.” For example, starting in
2007, the Coast Guard data did not include spil data from onshore pipelines.
The 2005 spil volume attributed to the “other” category was largely due to onshore spil s from tank farms
associated with Hurricane Katrina.
The spil volume from the 2010 uncontrol ed Macondo well is not included in the above figure; the magnitude of
its spil volume (estimated at more than 100 mil ion gallons) makes it difficult to compare to annual spil volumes.
The figure does include an estimate of oil released (approximately 400,000 gallons) from the Deepwater Horizon
mobile offshore dril ing unit.

11 U.S. Coast Guard, Oil Spill Compendium, Part II.
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Figure 2 compares the volume of spills over a longer time period from the same selected sources.
As Figure 2 illustrates, the annual oil spill volumes from all sources—particularly tankers and
barges—declined dramatically in the 1990s compared to previous decades. This historical decline
is likely related, at least in part, to the Oil Pollution Act of 1990 (OPA), which was enacted after
the 1989 Exxon Valdez oil spill.12 The 1990 act (discussed below) made comprehensive changes
to U.S. oil pollution law by expanding federal response authority and increasing spill liability.
The high costs associated with the Exxon Valdez spill,13 and the threat of broad liability imposed
by OPA (in some scenarios, unlimited liability), were likely significant drivers for the spill
volume decline seen in the 1990s.
Figure 2. Volume of Oil Spills by Source in the Coast Guard’s Jurisdiction: 1973-2021
Does not include the volume from 2010 uncontrolled Macondo well in the Gulf of Mexico

Source: Prepared by CRS; data from the USCG Oil Spil Compendium (available from the author) and Bureau of
Transportation Statistics, “Petroleum Oil Spil s Impacting Navigable U.S. Waterways” (which cites the Coast
Guard Oil Spil Compendium and personal communications with the Coast Guard as its data sources), at
https://www.bts.gov/content/petroleum-oil-spil s-impacting-navigable-us-waters.
Notes: Oil includes crude oil, fuel oils (heavy and intermediate), gasoline products, other petroleum oils, and
nonpetroleum oils. The Coast Guard states that its Oil Spil Compendium includes spil s that have been
“investigated” by the Coast Guard. Further, “this data is provided ‘as reported,’ with no interpretation or
filtering. For example, incidents that fall within the jurisdiction of other agencies, or that are not required to be

12 In addition, several substantial oil spills occurred in 1990, including the Mega Borg tanker that spilled over 4 million
gallons of oil in the Gulf of Mexico.
13 The Exxon Valdez spill tallied approximately $2 billion in cleanup costs and $1 billion in natural resource damages
(not including third-party claims)—in 1990 dollars. Punitive damage claims were litigated for more than 12 years,
eventually reaching the U.S. Supreme Court in 2008 (Exxon Shipping v. Baker, 128 S. Ct. 2605 (2008)). Plaintiffs were
eventually awarded approximately $500 million in punitive damages. An additional $500 million in interest on those
damages was subsequently awarded.
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reported under existing Coast Guard regulations, may be included in the compendium.” For example, starting in
2007, the Coast Guard data did not include spil data from onshore pipelines.
The 2005 spil volume attributed to the “other” category was largely due to onshore spil s from tank farms
associated with Hurricane Katrina.
The spil volume from the 2010 uncontrol ed Macondo well is not included in the above figure; the magnitude of
its spil volume (estimated at more than 100 mil ion gallons) makes it difficult to compare to annual spil volumes.
The figure does include an estimate of oil released (approximately 400,000 gallons) from the Deepwater Horizon
mobile offshore dril ing unit.
PHMSA Data
PHMSA collects oil spill data for pipelines and rail transportation—two modes of oil
transportation that have received attention in recent years. Figure 3 illustrates the number of oil
incidents and spill volume by mode of transportation between 2002 and 2022. The pipeline and
rail data illustrated in the figure include incidents that involve spills as small as one gallon.
As the figure indicates, spill volumes have fluctuated over time depending on the number and size
of major spills in particular years. For example, in 2020, one pipeline spill of gasoline accounted
for almost 2 million gallons;14 in 2022, a portion of the Keystone pipeline in Kansas released
almost 600,000 gallons.15
The number of spills from rail transportation increased between 2009 and 2014 largely due to the
increased transportation of crude oil by rail.16 Since that time, rail transportation has decreased,
but remains above pre-2010 levels.17 As with pipeline spill volume, the annual spill volumes from
rail transportation are a function of the number and size of major spills. For example, the
increased rail volume in 2013 is the result of two major incidents of over 450,000 gallons. The
increased rail volume in 2015 is the result of three major incidents of over 100,000 gallons.

14 In August 2020, a Colonial Pipeline discharged an estimated 2 million gallons of gasoline in Huntersville, NC. For
more information, see resources available at the North Carolina Department of Environmental Quality website, at
https://www.deq.nc.gov/about/divisions/waste-management/underground-storage-tanks-section/colonial-pipeline-spill-
information-huntersville-nc#Background-9200.
15 For more information, see EPA, “EPA and TC Oil Pipeline Operations Inc. Enter Into Agreement to Clean Up Oil
Discharge From Pipeline Rupture Near Washington, Kansas,” press release, January 9, 2023, at https://www.epa.gov/
newsreleases/epa-and-tc-oil-pipeline-operations-inc-enter-agreement-clean-oil-discharge-pipeline.
16 Based on data from Energy Information Administration, “Movements of Crude Oil and Selected Products by Rail,”
at https://www.eia.gov/dnav/pet/pet_move_railNA_a_EPC0_RAIL_mbbl_a.htm; for further details, see CRS Report
R43390, U.S. Rail Transportation of Crude Oil: Background and Issues for Congress, by John Frittelli et al.
17 For more details, see CRS In Focus IF10727, Rail Transportation of Crude Oil and the FAST Act: An Update, by
John Frittelli.
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Figure 3. Oil Spills from Pipeline and Rail Transportation: 2002-2022
Spill Volume and Number of Incidents

Source: Prepared by CRS; data from PHMSA; pipeline incident and volume data are from the “Pipeline Incident
Flagged Files,” at https://www.phmsa.dot.gov/data-and-statistics/pipeline/pipeline-incident-flagged-files; rail
incident and volume data are available in the “Hazmat Incident Report Search Tool,” at
https://www.phmsa.dot.gov/hazmat-program-management-data-and-statistics/data-operations/incident-statistics.
Notes: Oil includes crude oil and petroleum products, such as gasoline, diesel, and ethanol blends. The spil
volumes do not account for oil that may have been recovered after the incident.
One issue that has received attention in recent years is a comparison of oil spill frequency and
volume between pipeline and rail transportation.18 The two figures below provide a comparison
between pipeline and rail transportation, taking into account the volume of oil transported by each
mode. In contrast to previous figures in this report, the spill data in these figures include only
crude oil incidents, because the transport data (million gallons transported) from the Energy
Information Administration include only crude oil.
Figure 4 illustrates the number of oil spill incidents per barrel of oil transported. The figure
indicates that incidents from rail (per gallon transported) exceeded pipeline incidents from 2010
through 2015. Since 2016, pipeline incidents (per gallon transported) have exceeded rail
incidents.

18 The increase in rail incidents, including several large spills between 2010 and 2014, generated considerable interest
from policymakers. In addition, the part of the debate over the Keystone XL pipeline focused on this comparison. See
CRS Report R43390, U.S. Rail Transportation of Crude Oil: Background and Issues for Congress, by John Frittelli et
al.
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Figure 4. Pipeline vs. Rail Crude Oil Spill Incidents: 2010-2021
Spill Incidents per Million Gallons Transported

Source: Prepared by CRS; pipeline incident data are from the PHMSA “Pipeline Incident Flagged Files,” at
https://www.phmsa.dot.gov/data-and-statistics/pipeline/pipeline-incident-flagged-files; rail incident data are
available in the “Hazmat Incident Report Search Tool,” at https://www.phmsa.dot.gov/hazmat-program-
management-data-and-statistics/data-operations/incident-statistics; pipeline transport data from Energy
Information Administration, “Refinery Receipts of Crude Oil by Method of Transportation,” at
http://www.eia.gov; rail transportation data from EIA, “Movements of Crude Oil and Selected Products by Rail,”
at https://www.eia.gov/dnav/pet/pet_move_railNA_a_EPC0_RAIL_mbbl_a.htm. The pipeline and rail data include
all crude oil incidents in the PHMSA database.
Figure 5 compares the volume of oil spilled per volume of oil transported by mode of
transportation. The figure indicates that in 8 of the last 12 years, the volume of oil spilled by
pipeline (per gallon transported) exceeded that of rail transport. However, in several of the years
(e.g., 2013 and 2015) in which rail transport volume exceeded pipeline volume (per volume
transported), the differences between rail and pipeline volumes were more substantial. As
discussed above, these differences are due to a small number of relatively large spills from rail
that occurred in those years.
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Figure 5. Pipeline vs. Rail Crude Oil Spill Volume: 2010-2021
Spill Volume per Million Gallons Transported

Source: Prepared by CRS; pipeline volume data are from the PHMSA “Pipeline Incident Flagged Files,” at
https://www.phmsa.dot.gov/data-and-statistics/pipeline/pipeline-incident-flagged-files; rail volume data are available
in the “Hazmat Incident Report Search Tool,” at https://www.phmsa.dot.gov/hazmat-program-management-data-
and-statistics/data-operations/incident-statistics; pipeline transport data from Energy Information Administration,
“Refinery Receipts of Crude Oil by Method of Transportation,” at http://www.eia.gov; rail transportation data
from EIA, “Movements of Crude Oil and Selected Products by Rail,” at https://www.eia.gov/dnav/pet/
pet_move_railNA_a_EPC0_RAIL_mbbl_a.htm. The pipeline and rail data include all crude oil incidents in the
PHMSA database.
Impacts of Oil Spills in Aquatic Environments
The impacts of an oil spill depend on the size of the spill, the rate of the spill, the type of oil
spilled, and the location of the spill. According to the National Academies of Sciences (NAS)
2022 Oil in the Sea report, the effects of oil on organisms are both complicated and complex.19
Oil may harm organisms through a range of mechanisms, including physical contact and
poisoning from ingestion or inhalation. The vulnerability to organisms varies widely, depending
on the species involved, the organism’s life stage, habitat, and pathways for exposure.20
Oil spills can cause impacts over a range of time scales, from days to years, or even decades for
certain spills. Impacts are typically divided into acute (short-term) and chronic (long-term)
effects. Depending on the toxicity and concentration of the spill, acute exposure to oil spills can
kill various organisms and cause the following debilitating (but not necessarily lethal) effects:21
• reduced reproduction,
• altered development,

19 Oil in the Sea IV, 2022, p. 266.
20 Oil in the Sea IV, 2022, p. 271.
21 These “sub-lethal” effects can occur at concentrations that are several orders of magnitude lower than concentrations
that cause death (Oil in the Sea IV, 2022, p. 263).
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• impaired feeding mechanisms, and
• decreased defense from disease.
Birds, marine mammals, bottom-dwelling and intertidal species, and organisms in their
developmental stages (e.g., fish eggs and larvae) are particularly vulnerable to oil spills.22 In
addition to the impacts to individual organisms, oil spills can lead to a disruption of the structure
and function of the ecosystem. Certain habitats—such as coral reefs, mangrove swamps, and salt
marshes—are especially vulnerable, because the physical structure of the habitats depends upon
living organisms.
Long-term, chronic exposure typically occurs from continuous oil releases—leaking pipelines,
offshore production discharges, and nonpoint sources (e.g., urban runoff). Although spills are
normally associated with acute impacts, some oil spills have also demonstrated chronic exposure
and effects.23 Chronic, comparatively low-level releases into the marine environment “can take a
significant toll on wildlife populations.”24 The 2022 NAS report found “increasing evidence
suggesting significant longer-term effects on multiple aquatic and shoreline species and
communities, including humans, than previously estimated.”25
Economic Costs of Oil Spills
The economic costs that can result from an oil spill can be broken into three categories: cleanup
expenses, natural resource damages, and the various economic losses incurred by the affected
community or individuals.
Cleanup Costs
The cleanup costs of an oil spill can vary greatly and are influenced by a mix of factors: location
characteristics, oil type, and oil volume.
Location
Location is generally considered the most important factor because it involves multiple variables.
Areas with less water movement, such as marshlands, will generally cost more to clean up than
open water. Some spill locations may have relatively robust populations of indigenous micro-
organisms that help degrade the oil naturally.26
Tourist destinations or sensitive habitats, such as coral reefs, will likely require more stringent
cleanup standards, thus increasing the costs. The political and social culture at the spill site plays
a part as well. A spill in a high-profile area may receive special attention.27 Major oil spills,
especially ones that affect shoreline ecosystems, are often met with extensive media coverage,
placing pressure on parties to take action. Coupled with this pressure, authorities (federal, state, or

22 Oil in the Sea IV, 2022, Chapter 6.
23 Oil in the Sea IV, 2022, p. 268.
24 Oil in the Sea IV, 2022, p. 300.
25 Oil in the Sea IV, 2022, p. 356.
26 Oil in the Sea IV, 2022, p 84; see also Terry Hazen et al., “Deep-Sea Plume Enriches Indigenous Oil-Degrading
Bacteria,” Science (online), August 24, 2010; Richard Camilli et al., “Tracking Hydrocarbon Plume Transport and
Biodegradation at Deepwater Horizon,” Science (online), August 19, 2010.
27 For example, the November 7, 2007, spill (53,000 gallons) from a container ship into the San Francisco Bay
generated considerable interest.
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local) at these locations may require extensive oil spill response requirements, which can
influence cleanup cost.
Oil Type
The more persistent and viscous oil types, such as heavy crude oil (e.g., crude oil derived from oil
sands) and intermediates known as bunker fuels, are generally more expensive to clean up.
Gasoline and other lighter refined products may require only minimal cleanup action. Typically,
these materials will evaporate or disperse relatively quickly, leaving only a small volume of
petroleum product in the environment.
Oil Volume
Compared with other factors, spill volume is less important. A major spill away from shore will
likely cost considerably less than a minor spill in a sensitive location. Certainly, the amount of oil
spilled affects cleanup costs, because, all things being equal, a larger spill will require a larger and
more expensive cleanup effort. However, the relationship between cleanup costs and spill volume
is not linear. Cleaning up a smaller spill is likely to cost more than a larger spill on a per-gallon
basis, due to what some have described as an “economy of scale factor.”28
Natural Resources Damages
This category of costs relates to the environmental impacts caused by an oil spill. Pursuant to
OPA, the party responsible for an oil spill is liable for any loss of natural resources (e.g., fish,
animals, plants, and their habitats) and the services provided by the resource (e.g., drinking water,
recreation).
When a spill occurs, natural resource trustees conduct a natural resource damage assessment to
determine the extent of the harm. Trustees may include officials from federal agencies designated
by the President, state agencies designated by the relevant governor, and representatives from
tribal and foreign governments.29 The various trustees assess damages to natural resources under
their respective jurisdictions.30 If multiple trustees are involved, they must select a lead
administrative trustee (LAT), who coordinates trustee activities and serves as a liaison between oil
spill responders. The LAT need not be from a federal agency; however, only a federal LAT can
submit a request to the Oil Spill Liability Trust Fund for the initial assessment funding.31
The Oil Pollution Act (OPA) of 1990 states that the measure of natural resource damages includes
• the cost of restoring, rehabilitating, replacing, or acquiring the equivalent of the
damaged natural resources;
• the diminution in value of those natural resources pending restoration; and
• the reasonable cost of assessing those damages.32

28 This is primarily due to the fact that a spill of any size (e.g., in a sensitive area) will require that equipment and
response experts be sent to the scene. See, for example, Catalyst Environmental Solutions et al., California Oil Spill
Response Cost Study, prepared for the California Department of Fish and Wildlife, 2019.
29 For more information, see NOAA’s Damage Assessment, Remediation, and Restoration Program at
https://darrp.noaa.gov/.
30 33 U.S.C. §2706(c). In some cases, trustees may share responsibility over the same resource.
31 33 U.S.C. §2712 and Executive Order (EO) 12777 (October 18, 1991).
32 33 U.S.C. §2706(d).
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Pursuant to OPA, NOAA developed regulations pertaining to natural resource damage
assessments in 1996.33 Natural resource damages may include both losses of direct use and
passive uses. Direct use value may derive from recreational (e.g., boating), commercial (e.g.,
fishing), or cultural or historical uses of the resource. In contrast, a passive-use value may derive
from preserving the resource for its own sake or for enjoyment by future generations.34
The damages are compensatory, not punitive. Collected damages cannot be placed into the
general Treasury revenues of the federal or state government, but must be used to restore or
replace lost resources.35 NOAA’s regulations focus on the costs of primary restoration (returning
the resource to its baseline condition) and compensatory restoration (addressing interim losses of
resources and their services).36
Other Economic Costs
Oil spills can generate costs other than response expenses or damages to natural resources. An oil
spill can disrupt business activity near the spill, particularly businesses and individuals that count
on the resources and reputation of the local environment. For example, the local fishing and
tourist industry may be affected. In some cases, a well-publicized oil spill can weaken local or
regional industries near the spill site, regardless of the actual threat to human health created by
the spill.
Local infrastructure and services can be disrupted by an oil spill. Port and harbor operations may
be interrupted, altering the flow of trade goods. Power plants that use cooling water systems may
need to temporarily cease operations. For example, the Salem Nuclear Plant—the second-largest
nuclear plant in the United States—was forced to halt activity due to a substantial oil spill (more
than 250,000 gallons) in the Delaware River in November 2004.
Oil Spill Governance
When the Exxon Valdez ran aground in March 1989, there were multiple federal statutes, state
statutes, and international conventions that dealt with oil discharges. The spill highlighted the
inadequacies of the existing coverage and generated public outrage.37 Following the spill,
Members of Congress faced great pressure to address these issues. (See the Appendix for further
information concerning these issues.) The end result was the Oil Pollution Act of 1990 (OPA)38—
the first comprehensive law to specifically address oil pollution to waterways and coastlines of
the United States.
The governing framework for oil spills in the United States remains a combination of federal,
state, and international authorities. Within this framework, several federal agencies have the

33 61 Federal Register 440 (January 5, 1996). See also NOAA, Injury Assessment Guidance Document for Natural
Resource Damage Assessment Under the Oil Pollution Act of 1990, 1996.
34 See 15 C.F.R. §990.30, definition of “value.”
35 33 U.S.C. §2706(f); William D. Brighton, Natural Resource Damages under the Comprehensive Environmental
Response, Compensation, and Liability Act, U.S. Department of Justice, Environment and Natural Resources Division,
2006.
36 William D. Brighton, Natural Resource Damages under the Comprehensive Environmental Response,
Compensation, and Liability Act, U.S. Department of Justice, Environment and Natural Resources Division, 2006.
37 A handful of other oil spills followed the Exxon Valdez in 1989 and 1990 (e.g., the Mega Borg spilled 5 million
gallons of oil in the Gulf of Mexico), further spurring congressional action.
38 P.L. 101-380, primarily codified at U.S.C. §2701 et seq.
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authority to implement oil spill regulations. The framework and primary federal funding process
used to respond to oil spills are described below.
Oil Pollution Act of 1990
With the enactment of OPA on August 18, 1990, Congress consolidated the existing federal oil
spill laws under one program (Appendix). The 1990 law expanded the existing liability
provisions within the Clean Water Act (CWA)39 and created new freestanding requirements
regarding oil spill prevention and response. Key OPA provisions are discussed below.
Spill Response Authority40
When responding to a spill, many considered the lines of responsibility under the pre-OPA regime
to be unclear,41 with too much reliance on spillers to perform proper cleanup.42 OPA strengthened
and clarified the federal government’s role in oil spill response and cleanup. OPA Section 4201
amended Section 311(c) of the CWA to provide the President (delegated to the U.S. Coast Guard
or EPA) with authority to perform cleanup immediately using federal resources,43 monitor the
response efforts of the spiller, or direct the spiller’s cleanup activities. The revised response
authorities addressed concerns “that precious time would be lost while waiting for the spiller to
marshall its cleanup forces.”44
The federal government—specifically the On-Scene Coordinator (OSC) for spills in the Coast
Guard’s jurisdiction—determines the level of cleanup required. Although the federal government
must consult with designated trustees of natural resources and the governor of the state affected
by the spill, the decision that cleanup is completed and can be ended rests with the federal
government. States may require further work, but without the support of federal funding.45
National Contingency Plan
The first National Oil and Hazardous Substances Pollution Contingency Plan (NCP) was
administratively prepared in 1968 after observing the British government’s response to a 37-
million-gallon oil tanker spill (Torrey Canyon) off the coast of England.46 The NCP contains the
federal government’s procedures for responding to oil spills and hazardous substance releases.47

39 The official statutory name is the Federal Water Pollution Control Act, P.L. 92-500, as amended, codified at 33
U.S.C. §1251 et seq.
40 For further details regarding response authorities for oil spills (and chemical spills), see CRS Report R43251, Oil and
Chemical Spills: Federal Emergency Response Framework, by David M. Bearden and Jonathan L. Ramseur.
41 See, for example, Cynthia Wilkinson et al., “Slick Work: An Analysis of the Oil Pollution Act of 1990,” Journal of
Energy, Natural Resources, and Environmental Law, vol. 12 (1992), p. 190.
42 See Benjamin Grumbles and Joan Manley, “The Oil Pollution Act of 1990: Legislation in the Wake of a Crisis,”
Natural Resources and Environment, vol. 10, no. 2 (1995), p. 38.
43 Leading up to the passage of OPA, parties referred to this approach as “federalizing” the spill.
44 U.S. Congress, House Committee on Merchant Marine and Fisheries, report accompanying H.R. 1465, Oil Pollution
Prevention, Removal, Liability, and Compensation Act of 1989, 1989, H.Rept. 101-242, Part 2, 101st Cong., 1st sess., p.
84.
45 OPA §1011.
46 See EPA “National Contingency Plan Overview” at http://www.epa.gov/emergencies/content/lawsregs/ncpover.htm.
47 The NCP is codified at 40 C.F.R. Part 300.
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OPA expanded the role and breadth of the NCP. The 1990 law established a multilayered planning
and response system to improve preparedness and response to spills in marine environments.48
Among other things, the act also required the President to establish procedures and standards (as
part of the NCP) for responding to worst-case oil spill scenarios.49
Tank Vessel and Facility Response Plans
As a component of the enhanced NCP, OPA amended the CWA to require that U.S. tank vessels,
offshore facilities, and certain onshore facilities50 prepare and submit oil spill response plans to
the relevant federal agency. In general, vessels and facilities are prohibited from handling,
storing, or transporting oil if they do not have a plan approved by (or submitted to) the
appropriate agency (discussed below).51
The plans should, among other things, identify how the owner or operator of a vessel or facility
would respond to a worst-case scenario spill. Congress did not intend for every vessel to have
onboard all the personnel and equipment needed to respond to a worst-case spill, but vessels must
have a plan and procedures to call upon—typically through a contractual relationship—the
necessary equipment and personnel for responding to a worst-case spill.52
In 2004, Congress enacted an amendment requiring nontank vessels (i.e., ships carrying oil for
their own fuel use) over 400 gross tons to prepare and submit a vessel response plan.53 Congress
reasoned that many nontank vessels have as much oil onboard as small tank vessels, thus
presenting a comparable risk from an oil spill. Moreover, the international standards for oil spill
prevention54 apply to tanker and nontanker vessels alike. Thus, the 2004 amendment brought the
U.S. law more in line with international provisions.
Double-Hull Design for Vessels
The issue of double hulls received considerable debate for many years prior to OPA, and it was
one of the stumbling blocks for unified oil spill legislation. Proponents maintained that double-
hull construction provides extra protection if a vessel becomes damaged.55 However, opponents
argued that a double-hulled vessel might cause stability problems if an accident occurred, thus
negating the benefits.56 Stakeholders also highlighted the impacts that a double-hull requirement

48 OPA §4202, amending §311(j) of the CWA.
49 OPA §4201(b), amending §311(d)(2)(J) of the CWA.
50 The response plan requirement is applicable only to an onshore facility that, because of its location, could reasonably
be expected to cause substantial harm to the environment by discharging into navigable waters, adjoining shorelines, or
the exclusive economic zone. CWA §311(j)(5)(iii).
51 OPA §4202, amending §311(j)(5)(E) of the CWA.
52 U.S. Congress, House Committee on Merchant Marine and Fisheries, report accompanying H.R. 1465, Oil Pollution
Prevention, Removal, Liability, and Compensation Act of 1989, 1989, H.Rept. 101-242, Part 2, 101st Cong., 1st sess., p.
87. OPA §4202, amending §311(j)(5)(C)(iii) of the CWA.
53 Amendments Relating to the Oil Pollution Act of 1990, Title VII of Coast Guard and Maritime Transportation Act of
2004 (P.L. 108-293), codified at 33 U.S.C. §1321.
54 Primarily the shipboard oil pollution emergency plans required by MARPOL 73/78, discussed later in this report.
55 A study from the National Academy of Sciences reached this conclusion in 1999. See National Research Council,
Double Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990, National Academies of Science, 1999,
p. 144.
56 Opponents maintained that if water entered the space between hulls, the ship could become unstable, hindering
salvage and possibly capsizing. Cynthia Wilkinson et al., “Slick Work: An Analysis of the Oil Pollution Act of 1990,”
Journal of Energy, Natural Resources, and Environmental Law, vol. 12 (1992), p. 196.
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would entail for the shipping industry (e.g., cost and time of retrofitting, ship availability).57 The
OPA requirements for double hulls reflected some of these concerns.
The act required new vessels carrying oil and operating in U.S. waters to have double hulls.58
However, OPA provided certain exceptions, depending on the size of the vessel (e.g., less than
5,000 gross tons)59 and its particular use (e.g., lightering).60 For older vessels, OPA established a
staggered retrofitting schedule, based on vessel age and size. As of January 2010, single-hull
vessels (with several exceptions, some of which expired in 2015) cannot operate in U.S. waters.
Liability Issues61
OPA unified the liability provisions of existing oil spill statutes, creating a freestanding liability
regime. Section 1002 states that responsible parties are liable for any discharge of oil (or threat of
discharge) from a vessel or facility62 to navigable waters, adjoining shorelines, or the exclusive
economic zone63 of the United States (i.e., 200 nautical miles beyond the shore).
Regarding the oil spill statutes prior to OPA, Congress recognized that “there is no
comprehensive legislation in place that promptly and adequately compensates those who suffer
other types of economic loss as a result of an oil pollution incident.”64 OPA broadened the scope
of damages (i.e., costs) for which an oil spiller would be liable. Under OPA, a responsible party is
liable for all cleanup costs incurred, not only by a government entity, but also by a private party.65
In addition to cleanup costs, OPA significantly increased the range of liable damages to include
the following:
• injury to natural resources,
• loss of personal property (and resultant economic losses),
• loss of subsistence uses of natural resources,
• lost revenues resulting from destruction of property or natural resource injury,
• lost profits and earning capacity resulting from property injury or natural
resource injury, and
• costs of providing extra public services during or after spill response.66

57 U.S. Congress, conference report accompanying H.R. 1465, Oil Pollution Act of 1990, H. Conf. Rept. 101-653, at
140-141 (1990).
58 OPA §4115, amending 46 U.S.C. §3703.
59 This exception applied to many inland barges.
60 Lightering is the process of transferring oil from a large vessel to a smaller vessel. This common practice occurs in
designated areas that are typically many miles away from shore.
61 For a discussion of liability issues raised by the 2010 Deepwater Horizon oil spill, see CRS Report R41679, Liability
and Compensation Issues Raised by the 2010 Gulf Oil Spill, by Jonathan L. Ramseur.
62 The definition of “facility” is broadly worded and includes pipelines and motor vehicles. OPA §1001.
63 Under the pre-OPA regime (primarily the CWA), a discharge 12 miles beyond shore had to affect the natural
resources before liability attached. Under OPA §1002, the discharge itself triggers liability. Cynthia Wilkinson et al.,
“Slick Work: An Analysis of the Oil Pollution Act of 1990,” Journal of Energy, Natural Resources, and Environmental
Law, vol. 12 (1992), p. 201.
64 U.S. Congress, House Committee on Merchant Marine and Fisheries, report accompanying H.R. 1465, Oil Pollution
Prevention, Removal, Liability, and Compensation Act of 1989, 1989, H.Rept. 101-242, Part 2, 101st Cong., 1st sess., p.
31.
65 OPA §1002(b)(1).
66 OPA §1002(b)(2).
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OPA provided limited defenses from liability: act of God, act of war, and act or omission of
certain third parties. These defenses are similar to those of the Superfund statute,67 established in
1980 for releases of hazardous substances (which does not include oil).
Except for certain behavior, including acts of gross negligence or willful misconduct,68 OPA set
liability limits (or caps) for cleanup costs and other damages. OPA requires the President to issue
regulations to adjust the liability limits at least every three years to take into account impacts of
inflation over time.69 The statute directs the President to use the consumer price index (CPI) to
account for these impacts. Administrations subsequent to the enactment of OPA in 1990 did not
adjust the liability limits until Congress amended OPA in 2006: The Coast Guard and Maritime
Transportation Act of 2006 adjusted the liability limits for vessels in statute.70 Subsequent limits
were adjusted through agency rulemakings.
For purposes of liability limits, OPA divides potential sources of oil spills into four general
categories. The liability limits differ by category, and in some cases, the scope of liability varies.
The categories and their scopes of liability are as follows:
• Tank Vessels. Liability limit includes both removal costs and natural resource
and economic damages. The limit is based on vessel size measured in gross
tonnage.
• All Other Vessels. Liability limit includes both removal costs and natural
resource and economic damages. The limit is based on vessel size measured in
gross tonnage. The limits are lower than those for tank vessels.
• Offshore Facilities (Not Including Deepwater Ports). Liability limit applies
only to damages (natural resource and economic damages). Liability for removal
costs is not limited.
• Onshore Facilities and Deepwater Ports. Liability limit includes both removal
costs and natural resource and economic damages.
Table 1 identifies the liability limit for each of the oil spill source categories listed above as
enacted in OPA. The table includes adjustments made in the Coast Guard and Maritime
Transportation Act of 2006, which modified only the limits for vessels, and subsequent
adjustments made through agency regulations.

67 §107(b) of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, commonly
known as Superfund), P.L. 96-510.
68 In addition, liability limits are unavailable if the violation of a federal safety, construction, or operating requirement
proximately caused the spill. Spillers must also report the incident and cooperate with response officials to take
advantage of the liability caps. OPA §1004(c).
69 OPA §1004(d)(4).
70 P.L. 109-241.
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Table 1. Oil Spill Liability Limits by Source of Potential Spill
Coast Guard and Maritime

Transportation Act of
Oil Pollution Act of 1990
2006
Current Limits
Tank Vessels
For vessels greater than 3,000
Single-hul s (including a single-
Single-hul s (including a
and Barges
gross tons:
hul vessel fitted with double
single-hul vessel fitted with
- the greater of $1,200 per
sides only or double bottom
double sides only or double
gross ton or $10 mil ion
only)
bottom only)
For vessels less than or equal
For vessels greater than 3,000
For vessels greater than
to 3,000 gross tons:
gross tons:
3,000 gross tons:
- the greater of $1,200 per
the greater of $3,000 per
- the greater of $4,000 per
gross ton or $2 mil ion
gross ton or $22 mil ion
gross ton or $29.6 mil ion
For vessels less than or equal
For vessels less than or
to 3,000 gross tons:
equal to 3,000 gross tons:
- the greater of $3,000 per
- the greater of $4,000 per
gross ton or $6 mil ion
gross ton or $8.1 mil ion
Double-hul s
Double-hul s
For vessels greater than 3,000
For vessels greater than
gross tons:
3,000 gross tons:
- the greater of $1,900 per
- the greater of $2,500 per
gross ton or $16 mil ion
gross ton or $21.5 mil ion
For vessels less than or equal
For vessels less than or
to 3,000 gross tons:
equal to 3,000 gross tons:
- the greater of $1,900 per
- the greater of $2,500 per
gross ton or $4 mil ion
gross ton or $5.4 mil iona
Nontank
The greater of $600 per gross
The greater of $950 per gross
The greater of $1,300 per
Vessels
ton or $500,000
ton or $800,000
gross ton or $1.1 mil iona
Offshore
$75 mil ion
No change; same as OPA
$167.8 mil ionb
Facilities
In contrast to other sources,
In contrast to other
this limit applies only to the
sources, this limit applies
sum of natural resource
only to the sum of natural
damages and covered
resource damages and
economic damages; removal
covered economic damages;
costs are not limited.
removal costs are not limited.
Onshore
$350 mil ion
No change; same as OPA
$725.7 mil iona
Facilities
The President may decrease
(includes
limit through regulations, but
pipelines and
this authority has not been
railroads)
exercised.
Deepwater
$350 mil ion
No change; same as 1995
$110 mil ion for the LOOPf
Ports: Louisiana
The Secretary (of the
regulatory change
Offshore Oil
department in which the
Port (LOOP)c
Coast Guard operates) may
adjust this limit to not less
than $50 mil ion.d
In 1995, the Department of
Transportation set the liability
limit for the LOOP at $62
mil ion.e
Source: Prepared by CRS.
a. The Coast Guard made regulatory adjustments to the liability limits pursuant to the consumer price index
provision (OPA §1004) in 2009, 2015, 2019, and 2022. See (1) U.S. Coast Guard, “Consumer Price Index
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Adjustments of Oil Pol ution Act of 1990 Limits of Liability—Vessels and Deepwater Ports,” 74 Federal
Register 31357, July 1, 2009; and (2) U.S. Coast Guard, “Consumer Price Index Adjustments of Oil Pol ution
Act of 1990 Limits of Liability—Vessels, Deepwater Ports and Onshore Facilities,” 80 Federal Register 72342,
November 19, 2015; and (3) U.S. Coast Guard, “Consumer Price Index Adjustments of Oil Pol ution Act of
1990 Limits of Liability—Vessels, Deepwater Ports and Onshore Facilities,” 84 Federal Register 39970,
August 13, 2019; and (4) U.S. Coast Guard, “Consumer Price Index Adjustments of Oil Pol ution Act of
1990 Limits of Liability—Vessels, Deepwater Ports and Onshore Facilities,” 87 Federal Register 78860,
December 23 2022. The limits are codified in 33 C.F.R. §138.230.
b. The Bureau of Ocean Energy Management (BOEM) made regulatory adjustments to the liability limits
pursuant to the consumer price index provision (OPA §1004) in 2014. See BOEM, “Consumer Price Index
Adjustments of 1990 Limit of Liability for Offshore Facilities,” 79 Federal Register 73832, December 12, 2014;
BOEM, “Oil Spil Financial Responsibility Adjustment of the Limit of Liability for Offshore Facilities,” 83
Federal Register 2540, January 18, 2018; BOEM, “Oil Spil Financial Responsibility Adjustment of the Limit of
Liability for Offshore Facilities,” 88 Federal Register 22910, April 14, 2023. The limits are codified in 30 C.F.R.
§553.703.
c. LOOP is the only deepwater port for oil operating in U.S. coastal waters. As of the date of this report, the
Sea Port Oil Terminal (SPOT) is in the process of receiving a license to operate as an oil export terminal.
Three other deepwater ports are in operation that accept liquefied natural gas. See U.S. Department of
Transportation, Maritime Administration, “Approved Applications and Operational Facilities,” at
https://www.marad.dot.gov/ports/office-of-deepwater-ports-and-offshore-activities/approved-applications-
and-operational-facilities/.
d. The Homeland Security Act of 2002 (P.L. 107-296) transferred the Coast Guard from the Department of
Transportation to the Department of Homeland Security.
e. Department of Transportation, “Limit of Liability for Deepwater Ports,” 60 Federal Register 39849, August 4,
1995.
f.
The Coast Guard made regulatory adjustments to the liability limits pursuant to the consumer price index
provision (OPA §1004) in 2009, 2015, 2019, and 2022. See (1) U.S. Coast Guard, “Consumer Price Index
Adjustments of Oil Pol ution Act of 1990 Limits of Liability—Vessels and Deepwater Ports,” 74 Federal
Register 31357, July 1, 2009; and (2) U.S. Coast Guard, “Consumer Price Index Adjustments of Oil Pol ution
Act of 1990 Limits of Liability—Vessels, Deepwater Ports and Onshore Facilities,” 80 Federal Register 72342,
November 19, 2015; and (3) U.S. Coast Guard, “Consumer Price Index Adjustments of Oil Pol ution Act of
1990 Limits of Liability—Vessels, Deepwater Ports and Onshore Facilities,” 84 Federal Register 39970,
August 13, 2019; and (4) U.S. Coast Guard, “Consumer Price Index Adjustments of Oil Pol ution Act of
1990 Limits of Liability—Vessels, Deepwater Ports and Onshore Facilities,” 87 Federal Register 78860,
December 23 2022. The limits are codified in 33 C.F.R. §138.230. This rulemaking adjusted the limit for
deepwater ports, other than LOOP, to $725.7 mil ion. As noted above, LOOP is the only deepwater port
that accepts shipments of oil.
Oil Spill Liability Trust Fund
Prior to OPA, some considered federal funding for oil spill response to be inadequate,71 and
damages recovery was difficult for private parties.72 To help address these issues, Congress
supplemented OPA’s expanded range of covered damages with the Oil Spill Liability Trust Fund
(OSLTF).
Pursuant to Executive Order (EO) 12777, the Coast Guard created the National Pollution Funds
Center (NPFC) to manage the trust fund in 1991. The fund may be used for several purposes:
• prompt payment of costs for responding to and removing oil spills;
• payment of the costs incurred by the federal and state trustees of natural
resources for assessing the injuries to natural resources caused by an oil spill, and

71 Cynthia Wilkinson et al., “Slick Work: An Analysis of the Oil Pollution Act of 1990,” Journal of Energy, Natural
Resources, and Environmental Law, vol. 12 (1992), p. 188.
72 U.S. Congress, House Committee on Merchant Marine and Fisheries, report accompanying H.R. 1465, Oil Pollution
Prevention, Removal, Liability, and Compensation Act of 1989, 1989, H.Rept. 101-242, Part 2, 101st Cong., 1st sess., p.
35.
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developing and implementing the plans to restore or replace the injured natural
resources;
• payment of parties’ claims for uncompensated removal costs, and for
uncompensated damages (e.g., financial losses of fishermen, hotels, and
beachfront businesses);
• payment for the net loss of government revenue, and for increased public
services by a state or its political subdivisions; and
• payment of federal administrative and operational costs, including research and
development, and $25 million per year for the Coast Guard’s operating expenses.
Although Congress created the OSLTF in 1986,73 Congress did not authorize its use or provide its
funding until after the Exxon Valdez incident. In 1990, OPA provided the statutory authorization
necessary to put the fund in motion. Through OPA, Congress transferred balances from other
federal liability funds74 into the OSLTF. In complementary legislation, Congress imposed a 5-
cent-per-barrel tax on the oil industry to support the fund.75 Collection of this fee ceased on
December 31, 1994, due to a sunset provision in the law. However, in April 2006, the tax resumed
as required by the Energy Policy Act of 2005 (P.L. 109-58). In addition, the Emergency Economic
Stabilization Act of 2008 (P.L. 110-343) increased the tax rate to 8 cents through 2016. In 2017,
the rate increased to 9 cents. The tax is scheduled to terminate at the end of 2025.76
Figure 6 illustrates the receipts, expenditures, and end-of-year balances for the OSLTF. As the
figure indicates, the fund’s balance has increased each year since 2006, when the per-barrel tax
was reinstated. The figure also illustrates that revenue supporting the fund has generally
surpassed fund expenditures. For example, between FY2013 and FY2022, the annual average
revenue supporting the fund was $841 million, most of which came from the per-barrel tax ($463
million). Average annual expenditures from the fund during this period were $208 million. As a
result, the fund’s balance has continued to increase. At the end of FY2024, the projected balance
is $9.7 billion.

73 Omnibus Budget Reconciliation Act of 1986 (P.L. 99-509).
74 The CWA §311(k) revolving fund; the Deepwater Port Liability Fund; the Trans-Alaska Pipeline Liability Fund; and
the Offshore Oil Pollution Compensation Fund.
75 Omnibus Budget Reconciliation Act of 1989 (P.L. 101-239). Other revenue sources for the fund include interest on
the fund, cost recovery from the parties responsible for the spills, and any fines or civil penalties collected.
76 See 26 U.S.C. §4611 (as amended by P.L. 116-260).
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Figure 6. Oil Spill Liability Trust Fund
Receipts, Expenditures, and End-of-Year Balances

Source: Prepared by CRS; data from annual Office of Management and Budget, Budget of the United States
Government, Appendices.
Notes: The initial gap between the end-of-year balance (line) and the receipts-expenditures bars is due to the
FY1991 starting balance of $358 mil ion. The relative increases in “other receipts” in 1995 and 2000 are due to
transfers from the Trans-Alaska pipeline fund of $119 mil ion and $182 mil ion, respectively. The increases in
expenditures and “other receipts” between 2010 and 2013 are related to the 2010 Deepwater Horizon oil spil .
Financial Responsibility
To preserve the trust fund and ensure that responsible parties can be held accountable for oil spill
cleanup and damages, OPA requires that vessels and offshore facilities maintain evidence of
financial responsibility (e.g., insurance). The Coast Guard’s National Pollution Funds Center
(NPFC) implements the financial responsibility provisions for vessels; the Bureau of Ocean
Energy Management implements this requirement for offshore facilities.
The current levels of financial responsibility are related to the current liability limits for various
sources (e.g., vessels, offshore facilities) of potential oil spills. The liability limits differ by
potential source. In the case of vessels, whose liability limits are a single dollar amount
encompassing both removal costs and other damages, the financial responsibility levels are
directly tied to the corresponding liability caps (identified above). Current law requires
responsible parties for vessels to demonstrate the “maximum amount of liability to which the
responsible party could be subjected under [the liability limits in OPA Section 1004; 33 U.S.C.
2704].”
Because the scope of the liability limit for offshore facilities is different than that for vessels, the
corresponding financial responsibility limit provisions differ. Responsible parties for offshore
facilities in federal waters must demonstrate $35 million financial responsibility, unless the
President determines a greater amount (not to exceed $150 million) is justified (33 U.S.C.
2716(c)). The federal regulations that are authorized by this statutory provision (30 C.F.R. Part
553) base the financial responsibility amount—between $35 million and $150 million—on a
facility’s worst-case discharge volume (as defined in 30 C.F.R. §553.14). For example, a facility
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with a worst-case discharge volume over 105,000 barrels77—the highest level of worst-case
discharge listed in the regulations—must maintain $150 million in financial responsibility.
Other Federal Laws
Although OPA is the primary domestic legislation for oil spills, other federal laws contain
provisions that relate to oil spills. Many of these provisions were in place before OPA. The
following list is not all-inclusive, but it highlights the main requirements authorized by laws other
than OPA.
Clean Water Act
The Clean Water Act (CWA) was the primary federal statute governing oil spills prior to OPA,
and many provisions continue to apply. A key provision is found in Section 311(b)(3), which
prohibits the discharge of oil or hazardous substances into U.S. navigable waters. In addition, the
CWA contains various penalty provisions for noncompliance, including violations of the
discharge prohibition of Section 311(b).
Pursuant to statutory requirements in the CWA,78 the EPA crafted regulations79 for spill
prevention control and countermeasure (SPCC) plans in 1973. SPCC plans address the
“procedures, methods, and equipment and other requirements for equipment to prevent
discharges.”80 Unlike other oil spill preparedness provisions, SPCC plans focus more on
prevention than on response activities, requiring, for example, secondary containment (e.g., dikes,
berms) for oil-storage equipment.
The agency offered several regulatory amendments after the 1973 rulemaking. Following the
passage of the Oil Pollution Act of 1990 (OPA),81 the agency proposed substantial changes and
clarifications that were not made final until July 2002. For reasons beyond the scope of this
report, EPA extended the 2002 rule’s compliance date on multiple occasions and made further
amendments to the 2002 rule. For most types of facilities subject to SPCC requirements, the
deadline for complying with the changes made in 2002 was November 10, 2011.82 However, a
subsequent EPA rulemaking extended this compliance date for farms to May 10, 2013.83
Notwithstanding these deadlines, the 2002 final rule and subsequent revisions did not alter the
requirement for owners or operators of facilities, including farms, to maintain and continue

77 As a comparison, the explosion of the Deepwater Horizon offshore drilling rig on April 20, 2010, which took place
41 miles southeast of the Louisiana coast, resulted in a release of 168 million gallons from the oil reservoir. See
footnote 7 for more details.
78 Section 311(j)(1) of the 1972 CWA called for regulations to prevent the discharge of oil from vessels, onshore
facilities, and offshore facilities. Executive Order 11735 (August 3, 1973) granted EPA the authority to regulate
nontransportation-related onshore and offshore facilities.
79 U.S. EPA, “Oil Pollution Prevention: Non-Transportation Related Onshore and Offshore Facilities,” Federal
Register, vol. 38, no. 237 (December 11, 1973), pp. 34164-34170.
80 CWA §311(j)(1)(C).
81 P.L. 101-380, primarily codified at U.S.C. §2701 et seq.
82 EPA, “Oil Pollution Prevention; Spill Prevention, Control, and Countermeasure (SPCC) Rule-Compliance Date
Amendment,” 75 Federal Register 63903, October 14, 2010.
83 EPA, “Oil Pollution Prevention; Spill Prevention, Control, and Countermeasure (SPCC) Rule-Compliance Date
Amendment for Farms,” 76 Federal Register 72120, November 22, 2011.
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implementing their SPCC plans in accordance with the SPCC regulations that have been in effect
since 1974.84
The EPA’s SPCC plans apply only to nontransportation, onshore facilities that exceed a certain oil
storage capacity and that, in the event of a spill, can be reasonably expected, because of their
location, to produce an oil discharge that would reach navigable waters or adjoining shorelines of
the United States.85 The CWA defines “navigable waters” as “waters of the United States,
including the territorial seas,” but the statute does not define “waters of the United States”
(WOTUS).86 This term is relevant in many CWA regulatory programs, including the SPCC
requirements. Congress’s intent as to the meaning of WOTUS has been debated and litigated for
more than four decades.87
Outer Continental Shelf Lands Act
The primary federal law governing oil development and operations in waters in federal
jurisdiction is the Outer Continental Shelf Lands Act (OCSLA) of 1953 and its subsequent
amendments (43 U.S.C. §§1331-1356). The OCSLA provided the foundation for regulations (30
C.F.R. Parts 250 and 550) that are implemented by the Bureau of Ocean Energy Management
(BOEM) and the Bureau of Safety and Environmental Enforcement (BSEE).88 Sections of these
regulations address oil spill prevention and response issues by requiring that various equipment
and procedures be in place at offshore facilities.89
Pipeline Statutes
The U.S. pipeline network is extensive: The Pipeline and Hazardous Materials Safety
Administration estimates that there are approximately 150,000 miles of crude oil and petroleum
product pipelines in the United States.90 Moreover, U.S. inland pipelines are concentrated in
coastal areas, particularly in the Gulf states, and these pipelines may have an impact on coastal
waters if spills reach waterways that empty into coastal waters.
Several laws govern oil pipelines. The Hazardous Liquid Pipeline Act of 1979 (P.L. 96-129)
granted authority to the Department of Transportation (DOT) to regulate various issues regarding
oil spills from pipelines. On December 29, 2006, the President signed the Pipeline Safety
Improvement Act of 2006 (P.L. 109-468) to improve pipeline safety and security practices, and to
reauthorize the federal Office of Pipeline Safety.91 The Office of Pipeline Safety (OPS), which is

84 For further information on the SPCC regulations, see CRS Report R44536, Spill Prevention, Control, and
Countermeasure (SPCC) Regulations: Background and Issues for Congress, by Jonathan L. Ramseur.
85 See 40 C.F.R. §112.1.
86 33 U.S.C. §1362(7).
87 For more information, see CRS Report R47408, Waters of the United States (WOTUS): Frequently Asked Questions
About the Scope of the Clean Water Act, by Kate R. Bowers and Laura Gatz.
88 These agencies replaced the former Minerals Management Service (MMS). On May 19, 2010, the Secretary of the
Department of the Interior (DOI) replaced the MMS with the Bureau of Ocean Energy Management, Regulation, and
Enforcement (BOEMRE). On October 1, 2011, DOI divided BOEMRE into three separate entities: the Bureau of
Ocean Energy Management (BOEM), the Bureau of Safety and Environmental Enforcement (BSEE), and the Office of
Natural Resources Revenue (ONRR).
89 For more information, see CRS Report RL33404, Offshore Oil and Gas Development: Legal Framework, by Adam
Vann.
90 See PHMSA, “Annual Report Mileage for Hazardous Liquid or Carbon Dioxide Systems,” accessed June 2023, at
https://www.phmsa.dot.gov/data-and-statistics/pipeline/annual-report-mileage-hazardous-liquid-or-carbon-dioxide-
systems.
91 See 49 U.S.C. §60101 et seq.
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part of the DOT, implements provisions concerning pipeline design, construction, operation and
maintenance, and spill response planning.92

Vessel Statutes
Several federal laws directly or indirectly deal with oil pollution from vessels.93 Laws concerning
navigation reduce the possibilities of vessel collision or hull breach by objects in the waterways.94
Other laws call for particular vessel design standards. For example, the Ports and Waterways
Safety Act of 1972,95 amended by the Port and Tanker Safety Act of 1978,96 called for specific
construction and equipment design requirements for oil tankers. (As noted, OPA subsequently
amended this statute in 1990 to establish a phased-in schedule for double-hulled tankers.)
Congress enacted the 1970s legislation to coincide with international initiatives. In fact, many of
the federal laws concerning vessel standards and pollution control procedures were written to
implement international conventions, discussed below.
Federal Agencies’ Responsibilities
The United States shares jurisdiction over its coastal waters with the coastal states. The 1953
Submerged Lands Act (SLA) gave coastal states jurisdiction over the submerged lands, waters,
and natural resources (e.g., oil deposits) located, in most cases, within 3 nautical miles off the
coastline.97 The waters, seabed, and natural resources beyond the states’ waters are exclusively
federal, and extend to the edge of the exclusive economic zone (200 nautical miles from shore).
However, the federal government maintains the authority to regulate commerce, navigation,
national defense, power production, and international affairs within state waters.
The oil spill legal framework involves implementation by multiple federal agencies. Agency
responsibilities can be divided into two categories: (1) oil spill response and cleanup and (2) oil
spill prevention/preparedness.
Response
As mentioned above, the National Oil and Hazardous Substances Pollution Contingency Plan
(NCP) contains the federal government’s framework and operative requirements for responding
to an oil spill (and releases of hazardous substances). Although first developed through
administrative processes in 1968, subsequent laws have amended the NCP, including the Clean
Water Act in 1972; the Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA or Superfund) in 1980; and the Oil Pollution Act (OPA) in 1990. Oil spill response

92 For further information on pipeline governance, see CRS Report R44201, DOT’s Federal Pipeline Safety Program:
Background and Issues for Congress, by Paul W. Parfomak.
93 For a comprehensive list of federal maritime legislation see U.S. Coast Guard, Marine Safety Manual, Volume I,
2017, starting on page 2-13, at https://www.dco.uscg.mil/Our-Organization/Assistant-Commandant-for-Prevention-
Policy-CG-5P/Inspections-Compliance-CG-5PC-/Commercial-Vessel-Compliance/Marine-Safety-Manual/.
94 For example, the Rivers and Harbors Act of 1899, as amended (33 U.S.C. §401 et seq.), and the International
Regulations for Preventing Collisions at Sea, as amended (33 U.S.C. §1601 et seq.).
95 P.L. 92-340, 33 U.S.C. §1221 et seq.
96 P.L. 95-474, codified at 33 U.S.C. §§1221-1232 and 46 U.S.C. §§3701-3718.
97 Most state waters extend 3 nautical miles (1 nautical mile = 6,076 feet, or 1.15 miles) from shore. Louisiana waters
extend 3 imperial nautical miles (1 imperial nautical mile = 6,080 feet). Texas and Gulf Coast of Florida waters extend
3 marine leagues (equating to 9 nautical miles). See the MMS, OCS, website (“Definitions and Jurisdictions”) at
http://www.mms.gov/incidents/pollution.htm. See also CRS Report RL33404, Offshore Oil and Gas Development:
Legal Framework, by Adam Vann.
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actions required under the regulations of the NCP are binding and enforceable, per these
enforcement authorities.
The NCP establishes the National Response System (NRS), a multitiered and coordinated
national response strategy for addressing oil spills and releases of hazardous substances. The NCP
provisions specific to oil spill response are codified in 40 C.F.R. Part 300, Subpart D. Key
components of the NRS include the following:
• National Response Team (NRT). Composed of representatives from the federal
departments and agencies assigned roles in responding to oil spills. The U.S.
Coast Guard chairs the NRT when a response is being mounted to a spill in a
coastal region.
• Regional Response Teams (RRTs). Composed of regional representatives of
each NRT member agency, state governments, and local governments. The Coast
Guard leads the relevant RRT during responses to oil spills in coastal waters.
• Area Committees (ACs). Composed of qualified personnel from federal, state,
and local agencies. The primary function of each AC is to prepare an Area
Contingency Plan (ACP) for its designated area.
• On-Scene Coordinator (OSC). Directs the response efforts and coordinates all
other efforts at the scene.
Oil spill response authority is determined by the location of the spill: the Coast Guard has
response authority in the coastal zone, and the EPA covers the inland zone.98 The OSC has the
ultimate authority to ensure that an oil spill is effectively removed and actions are taken to
prevent further discharge from the source. The OSC is broadly empowered to direct and
coordinate all response and recovery activities of federal, state, local, and private entities
(including the responsible party), and will draw on resources available through the appropriate
ACPs and RRTs.
Although the OSC must consult with designated trustees of natural resources and the governor of
the state affected by the spill, the OSC has the authority and responsibility to determine when
removal (i.e., cleanup) is complete.
Other agencies, particularly those on the NRT and relevant RRT, may play a role in response
activities. As the chair of the NRT (and vice-chair during oil spills in the coastal zone), EPA may
provide response support. For example, during the Deepwater Horizon spill response, EPA
conducted air and water sampling and provided environmental monitoring support, particularly
regarding the use of dispersants.
In addition, NOAA provides scientific analysis and consultation during oil spill response
activities.99 Assistance can include oil spill tracking, cleanup alternatives, and knowledge of at-
risk natural resources. Moreover, NOAA experts begin to collect data to assess natural resource
damages during response operations.

98 The terms inland zone and coastal zone are defined in the National Contingency Plan (40 C.F.R. §300.5). The coastal
zone covers all waters subject to the tide, the Great Lakes, and all seaward waters (extending 200 nautical miles beyond
shore). The inland zone covers all other U.S. waters. Spills in inland waters can potentially affect coastal waters and
ecosystems, particularly if the spill occurs in water systems near the coast. In fact, a fine line may separate specific
inland and coastal waters (e.g., consider the nexus between a bay and a river).
99 For more information see NOAA’s Office of Response and Restoration website, at
http://response.restoration.noaa.gov/index.php.
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Prevention and Preparedness
Regarding oil spill prevention and preparedness duties, jurisdiction is determined by the potential
sources (e.g., vessels, facilities, pipelines) of oil spills. A series of executive orders (EOs),
coupled with memoranda of understanding (MOU), have established the various agency
responsibilities.100 Table 2 identifies the agencies responsible for implementing prevention and
preparedness regulations for the potential sources of oil spills.
Table 2. Federal Agency Jurisdiction for Oil Spill Prevention
and Preparedness Duties, by Source
Potential Source of Oil Spill

Responsible Agency
Vessels
Coast Guard
Onshore, nontransportation facilities
Environmental Protection Agency
Onshore, transportation facilities
Coast Guard and Department of Transportation
Deepwater ports0
Coast Guard and Department of Transportation
Offshore facilities (oil/gas extraction)
Department of the Interior’s Bureau of Ocean Energy
Management
Offshore pipelines directly associated with oil extraction
Department of the Interior’s Bureau of Ocean Energy
activities (i.e., “production lines”)b
Management
Offshore pipelines not directly associated with oil
Department of Transportation’s Office of Pipeline Safety
extraction activities (i.e., “transmission lines”)
Inland pipelines
Department of Transportation’s Office of Pipeline Safety
Source: Prepared by CRS.
a. There is only one operating deepwater port for oil in U.S. coastal waters: the Louisiana Offshore Oil Port
(LOOP). As of the date of this report, the Sea Port Oil Terminal (SPOT) is in the process of receiving a
license to operate as an oil export terminal. Three other deepwater ports are in operation that accept
liquefied natural gas. See U.S. Department of Transportation, Maritime Administration, “Approved
Applications and Operational Facilities,” at https://www.marad.dot.gov/ports/office-of-deepwater-ports-and-
offshore-activities/approved-applications-and-operational-facilities/.
b. For further discussion on federal pipeline jurisdiction, see National Research Council, Improving the Safety of
Marine Pipelines, National Academy of Sciences, 1994, pp. 86-89.
Prevention responsibilities include, among other things, assessing whether facilities or vessels
have the necessary equipment in place. As discussed above, vessels may be required to have
double hulls; facilities may need secondary containment.
Preparedness duties involve oversight tasks, such as evaluating facility and vessel response plans.
Preparedness responsibilities also include developing and maintaining contingency plans at
various levels: area, regional, and national. Personnel training is a vital component of sustaining
readiness. NOAA oil spill experts help train responders in government service and private
business.

100 Executive Order (EO) 12777 (October 18, 1991) delegates authorities pursuant to the Oil Pollution Act of 1990.
This order was amended by EO 13286 (March 5, 2003), which reorganized duties in response to the creation of the
Department of Homeland Security.
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In addition, OPA requires agencies to conduct internal examinations to test preparedness.101 As
part of this requirement, the Coast Guard conducts Spills of National Significance (SONS)
exercises to analyze the Coast Guard’s ability to respond to a major oil spill.
International Conventions
The relationship between international and domestic law can be complex. For example, a “self-
executing” agreement taking the form of a treaty, signed by the Executive and ratified with the
advice and consent of the Senate, stands on equal footing with federal statute. On the other hand,
if an international agreement is not self-executing, implementing legislation may be necessary for
the agreement’s provisions to be given domestic legal effect, including to provide U.S. agencies
with the domestic legal authority necessary to carry out functions contemplated under the
agreement.102
International conventions have played an important role in developing consistent standards for
oil-carrying vessels from different nations. A primary player in this regard is the International
Maritime Organization (IMO), a body of the United Nations, which sets international maritime
vessel safety and marine pollution standards. The Coast Guard represents the United States at
IMO meetings.
Multiple international conventions concern vessels and their impact on the marine environment.
Described below are two selected conventions that contain provisions that are particularly
relevant to oil pollution in coastal waters.
MARPOL 73/78
The IMO implements the 1973 International Convention for the Prevention of Pollution from
Ships, as modified by the Protocol of 1978 (MARPOL 73/78).103 Vessels whose nations are
signatories to MARPOL are subject to its requirements, regardless of where they sail, and
member nations are responsible for the vessels registered under their flag.
MARPOL 73/78 includes six annexes, each covering a different pollution type. Annex I
(Prevention of Pollution by Oil) entered into force in 1983 and established requirements for
controlling oil discharges to sea.104 Annex I requires vessels to have equipment that minimizes oil
discharge, such as oil-water separators, and shipboard oil pollution emergency plans (SOPEPs).
Although the SOPEP applicability is similar to that of the vessel response plan (VRP) required by
OPA, the purpose of the SOPEP is somewhat different.105 A SOPEP is intended to provide
guidance to the vessel’s officers regarding proper onboard emergency procedures when an oil
spill occurs, whereas the VRP is more focused on responding to the spill itself.106

101 As required by OPA §4202(a), which amended CWA §311(j)(7), codified in 33 U.S.C. §1321(j)(7).
102 If a treaty is considered “self-executing,” domestic legislation implementing the treaty is not necessary. For more
details on these issues, see CRS Report RL32528, International Law and Agreements: Their Effect upon U.S. Law, by
Stephen P. Mulligan.
103 For convention texts and other materials, see http://www.imo.org.
104 The phrase “entry into force” signifies that the requisite number of nations have ratified the convention or annex,
thus making the agreed-upon requirements binding for all participating nations. For more discussion of the procedures
of international conventions, see the IMO website at http://www.imo.org.
105 All vessels of any type over 400 gross tons traveling over international waters must have a SOPEP approved by their
flag state. See USCG VRP/SOPEP “FAQs” at http://www.uscg.mil/vrp.
106 USCG, 1997, Marine Safety Manual, Marine Environment Protection, Volume IX, pp. 4-24.
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The United States implements Annex I through the Act to Prevent Pollution from Ships
(APPS).107 APPS applies to all U.S.-flagged ships, irrespective of location, and to all foreign-
flagged vessels in U.S. waters or at ports under U.S. jurisdiction. The Coast Guard issues and
enforces regulations necessary to carry out the APPS provisions. The Coast Guard inspection
program is a key component of its oil spill prevention effort.
Intervention Convention
The 1967 Torrey Canyon spill off the coast of Great Britain was one of the first major spills to
receive worldwide attention.108 The incident raised many questions regarding oil spill response,
particularly when dealing with vessels from other nations. For example, the incident prompted
debate over responses allowable if a nation’s waters and environment are threatened by a spill
from another nation’s vessel. The 1969 International Convention Relating to Intervention on the
High Seas in Cases of Oil Pollution Casualties (the Intervention Convention) sought to address
these issues.
To implement this convention in the United States, Congress passed the Intervention on the High
Seas Act of 1974.109 Under this act, if the Coast Guard determines there to be a “grave and
imminent danger to the coastline or related interests of the United States from pollution or threat
of pollution of the sea by convention oil [i.e., as defined in the convention],” the Coast Guard can
take action to “prevent, mitigate, or eliminate that danger.”
State Laws
As mentioned above, multiple states had oil spill liability laws before the passage of OPA in
1990. During the 15 years prior to OPA’s passage, the issue of whether or not to preempt state
liability laws was perhaps the primary obstacle to enacting unified oil spill legislation. Proponents
of preemption argued that differing state laws—particularly the various levels of liability—
frustrate the shipping industry and were contrary to the goal of comprehensive federal legislation.
Preemption opponents maintained that states should be allowed (as with most other federal
environmental statutes) to set stiffer standards regarding liability, compensation, and cleanup.110
In the aftermath of the Exxon Valdez spill, the scales tipped to the side of antipreemption.
According to OPA Section 1018 (referred to as a “savings clause”), the act will not preempt any
state from imposing “additional liability or requirements” with respect to the discharge of oil or
related response activity (e.g., cleanup standards). A 2003 study identified 16 states that impose
unlimited liability for oil spills.111
There was some concern that the language of OPA’s savings clause would allow states to regulate
matters typically reserved for the federal government, such as oil tanker construction. To address
this issue, the conference report stated that the savings clause would not disturb a 1978 Supreme
Court decision that dealt with the intersection of federal and state authority to regulate the

107 P.L. 96-478, 33 U.S.C. §1901 et seq.
108 The Torrey Canyon, a Liberian-flagged tanker, spilled approximately 35 million gallons of crude oil.
109 P.L. 93-248, 33 U.S.C. §1471 et seq.
110 One argument against preemption was that existing requirements under particular state laws would be diminished or
negated entirely. See Benjamin Grumbles and Joan Manley, “The Oil Pollution Act of 1990: Legislation in the Wake of
a Crisis,” Natural Resources and Environment, vol. 10, no. 2 (1995), p. 38.
111 Dagmar Etkin, A Worldwide Review of Marine Oil Spill Fines and Penalties, 2003, at http://www.environmental-
research.com/erc_papers/ERC_paper_10.pdf. See also CRS Congressional Distribution Memorandum, “Oil Spill
Liability in the Gulf States,” July 2, 2010 (on file with author; available to congressional clients upon request).
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shipping industry.112 In that case, the Court determined that a Washington State law was
preempted. The state law had attempted to govern oil tanker design, size, and movement in Puget
Sound.113
Regardless of the clarification in the conference report, the line between federal and state
jurisdiction (i.e., the extent of federal preemption) has been tested periodically. In 2000, the
Supreme Court struck down (as preempted) a Washington State rule calling for various personnel
requirements, such as training, on oil tankers.114 Similarly, in March 2010, a federal district court
in Massachusetts ruled against a state law—finding it preempted—that would affect tanker
design, personnel qualifications, and navigation.115

112 U.S. Congress, conference report accompanying H.R. 1465, Oil Pollution Act of 1990, H. Conf. Rept. 101-653, at
122 (1990).
113 Ray v. Atlantic Richfield, 435 U.S. 151 (1978).
114 United States v. Locke, 529 U.S. 89 (2000).
115 United States v. Massachusetts, 2010 Westlaw 1345018 (D. Mass. March 31, 2010).
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Appendix. Federal Authorities Before and After the
Exxon Valdez Spill
The following list highlights the primary federal authorities that were in effect when the Exxon
Valdez spill occurred in 1989:
• Clean Water Act (1972). The Clean Water Act (CWA) represented the broadest
authority for addressing oil spills at the time of the Exxon Valdez spill. Section
311 of the CWA established requirements for oil spill reporting, response, and
liability. The act also created a fund (311 Fund), maintained by federal
appropriations, that could be used for cleanup and natural resource restoration.
• Deepwater Port Act (1974).116 This statute addressed oil spills and liability
issues at deepwater oil ports. The act also set up the Deepwater Port Fund to
provide for prompt cleanup and to compensate damages above liability limits.
The fund was financed by a per-gallon tax on oil transferred at a deepwater port.
• Trans-Alaska Pipeline Authorization Act (1973).117 This act covered oil spills
and liability relating to the Trans-Alaska Pipeline System (TAPS). Although the
pipeline is constructed over land, spills from it could reach coastal waters via
inland rivers. The act created a trust fund, financed through a lessee fee, that
could be used to respond to spills and damages from the pipeline.
• Outer Continental Shelf Lands Act Amendments (1978).118 This act
established an oil spill liability structure and rules for oil extraction facilities in
federal offshore waters. With this legislation, Congress created the Offshore
Pollution Fund, financed by a per-gallon fee on produced oil, that could be used
for oil spill cleanup and damages.
• National Oil and Hazardous Substances Pollution Contingency Plan (NCP).
The first NCP was administratively prepared in 1968 after observing the British
government’s response to a 37-million-gallon oil tanker spill (Torrey Canyon) off
the coast of England.119 The NCP contains the federal government’s procedures
for responding to oil spills and hazardous substance releases.120
After the Exxon Valdez spill, many observers121 described the above legal collection as an
ineffective patchwork. Arguably, each law had perceived shortcomings (discussed below in the
context of post-Exxon Valdez legislation), and none provided comprehensive oil spill coverage.

116 P.L. 93-627, codified at 33 U.S.C. §1501 et seq.
117 P.L. 93-153, codified at 43 U.S.C. §1651 et seq.
118 P.L. 95-372, codified at 43 U.S.C. §1801 et seq.
119 See EPA “National Contingency Plan Overview” at http://www.epa.gov/emergencies/content/lawsregs/ncpover.htm.
120 The NCP is codified at 40 C.F.R. Part 300.
121 See, for example, U.S. Congress, House Committee on Merchant Marine and Fisheries, report accompanying H.R.
1465, Oil Pollution Prevention, Removal, Liability, and Compensation Act of 1989, 1989, H.Rept. 101-242, Part 2,
101st Cong., 1st sess., p. 32.
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For more than 15 years prior to the Exxon Valdez incident, Congress made attempts to enact a
unified oil pollution law. Several contentious issues produced deadlocks, hindering the passage of
legislation. One of the central points of debate, state preemption, dealt with whether a federal oil
spill law should limit a state’s ability to impose stricter requirements, particularly unlimited
liability. Other liability questions also generated debate. For example, if an oil spill occurred,
should the owner of the cargo (i.e., oil) be held liable, as was the ship owner/operator? Another
point of contention was whether oil-carrying vessels should be required to have double hulls.
Although proponents argued that a second hull would help prevent oil spills, the shipping
industry raised concern that implementing such a mandate would disrupt oil transportation and
potentially affect the national economy. A final issue involved the interaction between domestic
legislation (federal and state) and international measures. Some were concerned that if the United
States became a party to certain international agreements under consideration in the 1980s,122 the
international standards would preempt federal and state laws, especially those establishing
liability limits. Proponents argued that these concerns were overstated and stressed that joining
the international agreements was especially important for the United States because of the
international nature of oil transportation and associated pollution.

Author Information

Jonathan L. Ramseur

Specialist in Environmental Policy

Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan
shared staff to congressional committees and Members of Congress. It operates solely at the behest of and
under the direction of Congress. Information in a CRS Report should not be relied upon for purposes other
than public understanding of information that has been provided by CRS to Members of Congress in
connection with CRS’s institutional role. CRS Reports, as a work of the United States Government, are not
subject to copyright protection in the United States. Any CRS Report may be reproduced and distributed in
its entirety without permission from CRS. However, as a CRS Report may include copyrighted images or
material from a third party, you may need to obtain the permission of the copyright holder if you wish to
copy or otherwise use copyrighted material.

122 The two agreements under consideration were the 1984 Protocols to the International Convention on Civil Liability
for Oil Pollution Damage and the Protocols to the International Fund for Compensation for Oil Pollution Damages.
Congressional Research Service
RL33705 · VERSION 36 · UPDATED
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