Washington State Ferries says Klahowya will start using a five-percent-biodiesel fuel tomorrow; the largest-capacity ferry on the Fauntleroy-Vashon-Southworth run, Issaquah, is already using that mix. WSF says the biodiesel comes from tallow (beef fat), not vegetable oil. Side note: You can find out where Issaquah, Klahowya, and other WSF boats are, at any given time, by using the ferry system’s online Vessel Watch feature.