New Report Confirms: Major Offshore Oil Spills Are Inevitable If Drilling Expands

Authors: Tim Haifley & Katie Thompson 

June 1, 2026

A statistical analysis of 60 years of U.S. offshore spill data finds that major spills occur roughly every 1.5 years — and that increasing production will increase that risk proportionally.

38

major spills (>1000 bbl recorded since 1964

~1.5 yrs

average time between major spill events

$65B+

paid by BP in Deepwater Horizon claims alone

Save Our Shores has released a risk assessment of offshore crude oil production in U.S. waters, drawing on six decades of federal spill data to answer a critical question as the country debates expanding offshore drilling: not if another major spill will happen, but when.

The analysis, authored by biostatistician Tim Haifley and Save Our Shores Executive Director Katie Thompson, reviewed incident records from U.S. government agencies covering 1964 through 2023 encompassing platform and pipeline spills across Gulf and Pacific waters.

"Major spill incidents are not a question of "if" but rather "when" and "how large". If more oil is produced offshore, the spill hazard frequency can be expected to increase."

What the data shows

Between 1964 and 2023, there were 38 major spill incidents — defined as spills exceeding 1,000 barrels. Statistical analysis of these events finds a hazard rate of 0.63 major spills per year, or roughly one every 1.58 years. The 95% confidence interval places this at between 1.2 and 2.2 years between major events. Crucially, the data shows no downward trend in the frequency or scale of major spills over this period.

The Deepwater Horizon disaster in 2010 discharged an estimated 4.3 million barrels into the Gulf, and BP has paid out more than $65 billion in resulting claims. That disaster has become a benchmark for catastrophic offshore risk, but the report notes it is not an outlier. The Taylor Energy platform, sunk in Hurricane Ivan in 2004, has been continuously leaking from submerged wellheads for over 20 years; containment efforts as recently as 2019 were capturing only around 25 barrels per day, and total cumulative spillage is estimated in the millions of barrels.

A new threat: deepwater expansion

The report's release is timely. On March 13, 2026, the Interior Department approved a new BP deepwater exploration platform in the Gulf that will operate at 6,000 feet of water depth, substantially deeper than the Deepwater Horizon. The authors argue this decision, and any broader expansion of offshore leasing, directly increases the probability of another catastrophic event.

California's coastline has remained largely protected from these risks thanks to six national marine sanctuaries, the California Coastal Act, and sustained opposition from state officials and environmental advocates since a catastrophic 1969 spill off Santa Barbara. The report highlights that the Gulf of Mexico's far greater exposure to spill risk is directly linked to its greater drilling density, which should be a cautionary model for any proposed Pacific expansion.

Why this matters for coastal communities

Offshore oil spills don't just damage ecosystems. The report underscores lasting harms to coastal and ocean habitats, commercial and recreational fishing, tourism, and ocean recreation, as well as the long-term health consequences for cleanup workers. A study tracking workers who responded to the Deepwater Horizon spill found measurable health impacts still present seven years after the disaster.

Save Our Shores urges policymakers, federal agencies, and the public to treat offshore drilling expansion as a documented, statistically predictable source of harm to coastal economies and ecosystems. Oil spills are not a theoretical future risk, but a near- certainty given the historical record.

Read the complete risk assessment with data sources, methodology, and figures from Tim Haifley and Katie Thompson.