A couple of years ago Stamets partnered with Battelle, a major player in the bioremediation industry, on an experiment conducted on a site owned by the Washington State Department of Transportation in Bellingham. Diesel oil had contaminated the site, which the mycoremediation team inoculated with strains of oyster mycelia that Stamets had collected from old-growth forests in the Pacific Northwest. Two other bioremediation teams, one using bacteria, the other using engineered bacteria, were also given sections of the contaminated soil to test.

Lo and behold. After four weeks, oyster mushrooms up to 12 inches in diameter had formed on the mycoremediated soil. After eight weeks, 95 percent of the hydrocarbons had broken down, and the soil was deemed nontoxic and suitable for use in WSDOT highway landscaping. By contrast, neither of the bioremediated sites showed significant changes.