Studies of vegetation death and accelerated marsh erosion following Deepwater Horizon oil spill have shown that both of these impacts (or “injuries,” when assessing natural resource damages) can be related to the percent of oiling on the stems of marsh vegetation. Spatial quantification of these injuries thus relies on estimates of how many kilometers of shoreline fell into each of the four stem oiling categories on which these injury determinations were based (0–10%, 10–50%, 50–90%, 90–100%). The total length of the Louisiana coastline under mainland herbaceous marsh that was oiled was estimated to be 1,161 km, with 29% (334 km) falling into the two upper classes of stem oiling (i.e. &gt; 50% stem oiling).