Snohomish County in western Washington State began converting its vehicle fleet to use a blend of biodiesel and petroleum diesel in 2005. As prices for biodiesel rose due to increased demand for this cleaner-burning fuel, Snohomish County looked to its farmers to grow this fuel locally. Suitable seed crops that can be crushed to extract oil for use as biodiesel feedstock include canola, mustard, and camelina. The residue, or mash, has high value as an animal feed. County farmers began with 52 acres of canola and mustard crops in 2006, increasing to 250 acres and 356 tons in 2008. In 2009, this number decreased to about 150 acres and 300 tons due to increased price for mustard seed.