Basics
- Puget Sound Indicator Name
- Oil spills
- Progress Indicator
- Gallon (gallons)
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- Topics
- Oil Spills
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Laura Vary
- Contributing Partners
- Last Updated
- 04/21/2025 23:49:23
Map
Description
This indicator measures the volume of oil spilled from any source to the Puget Sound environment, including both spills to land and surface waters. Any amount of oil spilled causes environmental damage, therefore oil spills pose high-impact risks to natural, cultural, and economic resources. This indicator helps to assess how well the region is doing at preventing accidental oil spills and mitigating the impact of spills if they do occur.
Progress Indicator Chart
Figure 1. Gallons of oil spilled to the Puget Sound environment from 2018 through 2022 and 3-year rolling average of gallons of oil spilled. For example, the 2020 3-year rolling average is calculated by averaging gallons spilled across 2018 through 2020. Source: Department of Ecology’s Spills Prevention, Preparedness, and Response Program; data most recently accessed in 2023.
Puget Sound is a sensitive ecosystem that nourishes the health, economy, and quality of life of nearly 5.3 million residents. A healthy Puget Sound, with waters free of toxic chemicals, is essential to sustaining a vibrant ecosystem and economy, meeting our state’s obligations to Tribal nations’ treaties and sovereign rights, and supporting our need for connection to the natural world.
Washington is a major hub of international and domestic shipping and a major oil refining state [i]. Toxic spills from these industries into Puget Sound significantly threaten the function, resilience, and well-being of Puget Sound and its residents. Although Puget Sound has experienced relatively few major oil spills over the past several decades, a major oil spill would cause irreparable damage to Puget Sound’s valuable natural, cultural, and economic resources.
It is important to reduce the risk and potential harm of oil spills through strategies centering education, preparedness, and prevention. Preventing spills from happening in the first place is by far the most cost-effective and ecologically-sound approach. This indicator is one way to assess the region’s success in preparedness and prevention activities to ultimately reduce the volume of oil spilled to surface waters.
[i] Washington Department of Ecology (n.d.). Oil Spill Prevention in Washington. Oil Spill Prevention, Department of Ecology, Washington. https://ecology.wa.gov/Spills-Cleanup/Spills/Oil-spill-prevention.
Key Progress Indicator Results
From 2018 through 2022, oil spills are a persistent issue across the Puget Sound region. Regional performance in this indicator is getting worse when comparing the recent 3-year rolling average of oil spilled (2020 through 2022; 42,695 gallons spilled annually on average) to the baseline 3-year rolling average of oil spilled (2018 through 2020; 38,107 gallons spilled annually on average). However, this increase in average gallons of oil spilled annually (+4,588 gallons) is relatively small.
Oil spill volumes vary by year between 2018 through 2022.
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From 2018 through 2022, an average of 34,655 gallons were spilled each year.
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Volume of oil spilled hit a high in 2020 (69,132 gallons spilled).
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Three major* spills occurred in 2020 in Pierce, King, and Whatcom counties after accidents at a refinery (Pierce; 10,500 gallons spilled), marine terminal (King; 10,701 gallons spilled), and a train accident (Whatcom; 28,962 gallons spilled).
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*A major oil spill is an incident in which more than 10,000 gallons were spilled [i].
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The majority of spills during this period (99.8 percent) were less than 1,000 gallons in size.
[i] Department of Ecology (1997). Oil Spills in Washington State: A historical analysis. Washington State Department of Ecology, Olympia, WA, revised in 2007. https://apps.ecology.wa.gov/publications/documents/97252.pdf.
Methods
- Monitoring Program
Washington State Department of Ecology Spills Preparedness, Prevention, and Response Program (SPPR)
- Data Source
Washington State Department of Ecology Spills Program Integrated Information System (SPIIS)
This Progress Indicator tracks the total volume (gallons) of oil spilled from both regulated and non-regulated sources to the environment in the Puget Sound region.
When an oil spill occurs, responsible parties notify the WA Dept. of Ecology (Ecology) by calling the Washington Emergency Management Division. Ecology response personnel may then be dispatched to the location to determine spill volumes by a variety of means, including but not limited to visual estimation, investigative interviews, review of relevant records, and mass balance calculations [i]. Ecology distinguishes between spills from regulated sources, which are required to take certain actions related to spill preparedness or prevention (commercial cargo ships, for example), and all other non-regulated sources (recreational fishing vessels, for example).
Reports and data from oil spill investigations are then captured in SPIIS. Ecology staff perform quarterly quality assurance reviews of data in SPIIS to ensure that correct attributes of the spill are documented (including volume of spill, location, source, activity, etc.). Values are cross-checked with the responder’s narrative, the initial spill report, internal logic and consistency, and additional response personnel narratives.
Ecology staff then compile, confirm quality, and share requested data from SPIIS to calculate this indicator with Partnership staff. The dataset includes the following attributes for each spill event: date, case ID, response type, county/district, city/town, water body, latitude, longitude, medium, incident type, source type, source, oil type, total spilled (gallons), total recovered (gallons), activity, and spill cause.
The data are then filtered to include only the Puget Sound region where the volume spilled is a known quantity. Data are not restricted to spills to water, as spills to soil or impervious surfaces still enter and potentially impact the Puget Sound ecosystem. Total gallons spilled are calculated by year and county. These data also underpin Ecology’s Spills Maps tool: a platform containing a series of maps that display reported oil spills to waters, oil transfers across WA state, locations of geographic response plans, restoration sites, pipeline locations, and other information.
Current reporting period: 2022
Current 3-year rolling average: 2020 through 2022
Baseline period: 2018
Baseline 3-year rolling average: 2018 through 2020
Each reporting period for this indicator is one calendar year. The indicator data are updated every two years with updated reports. The baseline period is 2018 because that is the first year in which Ecology staff conducted comprehensive quality assurance processes with these data. The Partnership evaluate trends over time by comparing the most recent regional 3-year rolling average volume of gallons spilled to the regional baseline 3-year rolling average volume of gallons spilled (2018 through 2020).
Limitations
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Not all spills are reported. This indicator only captures spill volumes from reported spills.
[i] Washington Department of Ecology (1994). Guidelines for Determining Oil Spill Volume in the Field: Terminology, ranges, estimates, and experts. Washington State Department of Ecology, Olympia, WA, https://apps.ecology.wa.gov/publications/documents/96250.pdf.
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- Critical Definitions
Oil: oil of any kind that is liquid at twenty-five degrees Celsius and one atmosphere of pressure and any fractionation thereof, including, but not limited to, crude oil, bitumen, synthetic crude oil, natural gas well condensate, petroleum, gasoline, fuel oil, diesel oil, biological oils and blends, oil sludge, oil refuse, and oil mixed with wastes other than dredged spoil. Oil does not include any substance listed in Table 302.4 of 40 C.F.R. Part 302 adopted August 14, 1989, under section 102(a) of the federal comprehensive environmental response, compensation, and liability act of 1980, as amended by P.L. 99-499 [i].
Regulated source: sources required to take specified actions related to spill preparedness and/or prevention. Regulated sources include all tank ships and barges, commercial cargo ships, passenger vessels greater than 300 gross tons, commercial facilities that transfer oil over water, railroads that carry oil in bulk, and oil pipelines [ii].
Major oil spill: a spill in which 10,000 or more gallons of oil are released into the environment [iii].
[i] Washington Revised Code § 90.56.010 (2024). https://app.leg.wa.gov/rcw/default.aspx?cite=90.56.010.
[ii] Washington Department of Ecology (n.d.) Operations Manual Requirements, Washington State Department of Ecology. https://ecology.wa.gov/regulations-permits/plans-policies/operations-manual-for-regulated-facilities.
[iii] Department of Ecology (1997). Oil Spills in Washington State: A historical analysis. Washington State Department of Ecology, Olympia, WA, revised in 2007, https://apps.ecology.wa.gov/publications/documents/97252.pdf.
Interpretation of Results
From 2018 through 2022, oil spills are a persistent issue across the Puget Sound region. Regional performance in this indicator, as measured by a 3-year rolling average, is getting worse (+4,588 gallons of oil spilled to the environment). We thus apply the "Getting Worse" designation though recognize that 4,588 gallons of oil is a relatively small increase in oil spilled.
From 2018 through 2022, King county saw the highest total volume of oil spilled (53,295 gallons spilled between 2018-2022) with Pierce county tracking close behind (49,903 gallons spilled between 2018-2022). The remaining Puget Sound counties saw fewer gallons spilled than Pierce and King counties during this period.
Figure 2. Gallons of oil spilled to Puget Sound surface waters from 2018 through 2022, by county. Source: Department of Ecology’s Spills Prevention, Preparedness, and Response Program; data most recently accessed in 2023.
Additionally, oil spills incurred a total of $282,537 in assessed damages to the ecosystem from 2018 through 2022. These costs were calculated through the Natural Resource Damage Assessment process, which is the standardized process to appraise oil spill damages. These damages are deposited in the state Coastal Protection Fund which supports clean up and restoration work after a spill event.
Figure 3. Financial damages, cumulative financial damages, and number of cases requiring Natural Resource Damage Assessments from 2018 through 2022. Financial damages are calculated through the Natural Resource Damage Assessment process. Source: Department of Ecology’s Spills Prevention, Preparedness, and Response (SPPR) Program; data most recently accessed in 2023.
It is important to consider the larger context of the oil industry in Washington State to understand and evaluate trends in this indicator over time.
Vessel traffic and oil transport across the Puget Sound region is significant.
- Puget Sound is home to five oil refineries which direct roughly 20 billion gallons of oil into and out of Washington State each year [i, ii].
- The average annual amount of oil spilled in or near Puget Sound from 2018-2022 (34,655 gallons) is roughly 0.00017 percent of the estimated amount of oil transported around Washington State each year (20 billion gallons).
- Vessel traffic is monitored by the Department of Ecology in annual reports [iii].
- In 2022, there were 2,076 cargo and passenger vessel transits and 681 tank ships and articulated tug barge transits to Puget Sound ports.
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- From 2018 through 2022, there were an average of 2,006 cargo and passenger vessel transits and 668 tank ships and articulated tug barge transits to Puget Sound ports each year.
Figure 4. The number of entering transits into Puget Sound by vessel categories from 2009 to 2023. Source: Department of Ecology’s Vessel Entries and Transits for Washington Waters report, 2023. Note: “Entering transits” refer to the passage of a vessel from sea or Canada into Puget Sound ports; the trip back is not counted.
The number of spill incidents has remained relatively steady.
- Between 2018 and 2022, there were 9,045 individual spill incidents.
- The number of spill incidents varied each year, from a low of 1,604 in 2019 to a high of 1,949 in 2022. On average, there were 1,809 spill incidents annually over the baseline period.
Figure 5. Gallons of oil spilled to Puget Sound surface waters (blue columns) and the number of spill incidents (orange line) from 2018 through 2022. Source: Department of Ecology’s SPPR Program; data most recently accessed in 2023.
From 2018 through 2022, most incidents spilled a relatively small amount of oil to the environment.
- The vast majority of spill events (9,028 events or 99.8 percent of all spills) between 2018 through 2022 resulted in less than 1,000 gallons of oil entering the environment per event.
- Furthermore, 95 percent (8,603 events) of all spill events between 2018 through 2022 resulted in less than 42 gallons (1 barrel) of oil entering the environment.
From 2018 to 2022, 204 spill incidents (2.25 percent of all spill incidents) and 66,634 gallons spilled (38 percent of all oil spilled) were attributed to regulated sources.
Figure 6. The number of oil spill incidents attributed to regulated (top-most section of column, blue) or non-regulated/unknown (bottom-most section of column, yellow) in Puget Sound from 2018 through 2022. Source: Department of Ecology’s SPPR Program; data most recently accessed in 2023.
The high percentage of non-regulated sources and the significant frequency of small spills suggest that incidents are often the result of accidental spills from recreational activities [iv]. This further underscores the value of oil spill regulations, prevention, and the work of spill preparedness, prevention, and response partners. Continued action in spill prevention, response activities, and the education of recreators can help the region move towards Department of Ecology’s zero gallons spilled target. The Department of Ecology is committed to working with reporters of spills to clean up the area and neighboring natural resources. A spiller’s failure to report a spill may result in severe penalties.
If an oil spill has occurred, report it immediately by calling 1-800-258-5990 (24/7 Washington Emergency Management Division line).
Though oil spills are a persistent issue, responders also recover spilled oil from the environment.
- Across all incidents from 2018 through 2022, an average of 49 percent of the volume spilled was recovered each year.
- While 2020 saw the greatest volume of oil spilled between 2018 through 2022, it also saw the greatest volume recovered at 58 percent.
Figure 7. The volume of oil spilled and the volume recovered in Puget Sound from 2018 through 2022. Source: Department of Ecology’s SPPR Program; data last accessed in 2023.
Despite the occurrence of oil spills, Washington State has one of the lowest spill rates in the nation; this reflects the strength of legislation and spill response programs that protect natural resources [v]. The Department of Ecology’s SPPR program is dedicated to effective spill prevention, preparedness, and response, through public engagement, external partnerships, oversight of oil transportation, and diligent and coordinated preparedness and response strategies. For more information on activities the Department of Ecology is enacting to achieve a vision of a zero oil spills state, please review the Spill Prevention, Preparedness, and Response Program strategic plan (2024).
[i] Washington Conservation Action (2025). Ensure Safe Transport of Oil Already Traveling in Our Region. Washington Conservation Action, Seattle, Washington. https://waconservationaction.org/our-work/areas-of-work/fossil-fuels-old/safe-transport-of-existing-oil/.
[ii] Washington Department of Ecology (n.d.). Oil Transportation Data and Studies. Oil Transportation in Washington, Department of Ecology, Washington. https://ecology.wa.gov/Spills-Cleanup/Spills/Oil-spill-prevention/Oil-transportation-in-Washington.
[iii] Washington Department of Ecology (2024). VEAT 2023: Vessel entries and transits for Washington waters, 30th Edition. Spill Prevention, Preparedness, & Response Program, Department of Ecology, Washington. https://apps.ecology.wa.gov/publications/documents/2408005.pdf.
[iv] Washington Sea Grant (2024). Small Spills Aren’t Slick. Washington Sea Grant, University of Washington. https://wsg.washington.edu/community-outreach/boating/small-spills-arent-slick/
[v] Department of Ecology (1997). Oil Spills in Washington State: A historical analysis. Washington State Department of Ecology, Olympia, WA, revised in 2007, https://apps.ecology.wa.gov/publications/documents/97252.pdf.
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Washington has a very robust system of programs to prevent oil spills and respond effectively when they do occur. With vessel traffic projected to increase, new types of oil being transported across our region, and the precarious state of our Puget Sound ecosystem, understanding how oil spills occur and how they can be prevented is imperative [i].
Progress in this indicator is affected by:
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Compliance with preventative regulations on large commercial ships, oil-handling facilities, and oil transfers,
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Effective geographic response planning for inland and marine areas in Washington as well as oil spill drills and exercises with regulated industries,
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Adoption of best available technology, safe operating practices, and spill response equipment and training,
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Rapid reporting of any oil spills when they do occur,
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Effective and proactive risk assessments, with policies implemented that can lower the risk of spills,
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Education of recreational boaters on best practices to prevent oil spills and to report spills that do occur, and
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Political and funding climates that support oil spill prevention, preparedness, and response programs.
[i] Washington Conservation Action (2025). Ensure Safe Transport of Oil Already Traveling in Our Region. Washington Conservation Action, Seattle, Washington. https://waconservationaction.org/our-work/areas-of-work/fossil-fuels-old/safe-transport-of-existing-oil/.
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Additional Information:
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Vessel Entries and Transits for Washington Waters, Department of Ecology Spills Program
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Spills Program Resources for Local Emergency Planning Committees, Department of Ecology Spills Program
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Focus Sheet on Small Oil Spill Readiness, Department of Ecology Spills Program
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Focus Sheet on Spill Response Assistance, Department of Ecology Spills Program
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Fact Sheet on Reporting Oil Spills, Department of Ecology Spills Program
Datasets
No datasets uploaded.
Reporting Guidance
- Reporting Instructions
Subcategories
| Name | |
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| Volume Spilled |
3-year Rolling Average, Gallons
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