On July 14, 1991, a Southern Pacific train derailed on a stretch of track known as the Cantara Loop while crossing the upper Sacramento River near Mount Shasta, just north of Dunsmuir, California. Approximately 19,000 gallons of metam sodium, a chemical typically used as a soil fumigant and herbicide, spilled into the Sacramento River. When metam sodium is released into the environment, it forms both liquid and gas compounds that are highly toxic to people, plants, and animals. Residents of the town of Dunsmuir were forced to evacuate. Contaminated water killed fish, other aquatic organisms, and plants. It also seeped into the soil, entering the shallow ground water aquifers surrounding the river banks. Terrestrial wildlife were affected not only by the contamination of their water supply, but also by the gases in the air. In total, air, water, soil, plants, and animals along a 36-mile stretch of the Sacramento River were exposed to metam sodium. 

The U.S. Fish and Wildlife Service, the California Department of Fish and Game (CDFG), and other trustees, conducted a Natural Resource Damage Assessment to determine the effects of the spill on fish and wildlife resources. As a result of this assessment, a $38 million settlement was reached with the responsible parties. A portion of this settlement money was earmarked as compensation for the injured natural resources. These funds are allocated annually through a grant program overseen by the Cantara Trustee Council. Funds are provided for projects involving natural resource acquisition and protection, resource restoration and enhancement, resource recovery monitoring, and public outreach.