Good Practices for In-situ Burning of Marshes Based on Two Decades of Responses in Louisiana

Spills that result in oiled marshes provide unique challenges for responders because intensive removal methods can cause additional harm and slow overall recovery of the habitat. These issues are of particular concern for spills that affect the marsh interior, where access is limited, often resulting in extensive damage from foot and vessel traffic. In Louisiana, extensive marshes are crossed by numerous pipelines and oil wells, and spills can result in heavy oiling of interior habitats in remote locations. Thus, in-situ burning (ISB) is often considered as the best response option. Monitoring of in-situ burns in marshes has provided the scientific basis for evaluating the conditions under which a burn can speed recovery. The lessons learned from multiple burns in Louisiana over the period 2000–2019 include: the burned area can be much greater than oiled area, so the potential for a larger burn should be explicitly considered and planned for; a water layer over the marsh soil is preferred but not required under all conditions; water-saturated soils are required; ISB can be used weeks post-spill to remove oil, but it will not prevent vegetation mortality from oil exposure prior to the burn; oil that penetrates into the substrates or is released below the marsh surface may persist after burning; select ISB as an option early, to prevent damage from foot traffic, etc.; vegetative recovery usually occurs within 1–2 growing seasons; burning can result in a change in dominant plant species; and ISB is very appropriate for small spills in the marsh interior where access for manual removal can cause extensive damage.