On 28 November 2000, the M/T Westchester spilled 1,925 tonnes of Nigerian crude oil into the Mississippi River. An estimated 50 percent of the spilled oil was recovered during the response. Several factors contributed to this extraordinary recovery rate: deployment of booms within hours in locations where large volumes of oil were diverted out of the river and into sheltered holding areas for later recovery; the wind blew consistently from one direction piling the oil against one bank; the oil quickly emulsified thus spreading on the water surface was limited; the ambient air temperature was often below the oil's pour point so the oil formed thick accumulations that adhered to the shoreline; and the river levees provided good access to the shoreline in places. The spilled oil contaminated 35 kilometers of one bank of the river and sheens extended as far as 70 kilometers downriver of the release site. Oiled shoreline habitats included 22.5 km of riprap, 2.9 km of sand flats, 3.4 km of mud flats, and 5.4 km (1.38 acres) of freshwater marshes and sloughs. The shoreline assessment process supported operations in evaluating cleanup methods and developing operationally oriented cleanup endpoints.

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