What is the burden of producing evidence under the doctrine of presumption?

When the foundational facts are established, a presumption affecting the burden of producing evidence obligates the trier of fact to assume the existence of the presumed fact unless and until evidence is introduced to support a finding of its nonexistence -- in which event the trier of fact determines the existence or nonexistence of the fact from the evidence and without regard to the presumption. ( 604.) Although the presumption disappears where, as here, it is met with contradictory evidence, inferences may nevertheless be drawn from the same circumstances that gave rise to the presumption in the first place. (Ibid. ["Nothing in this section shall be construed to prevent the drawing of any inference that may be appropriate"]; but see Bonzer v. City of Huntington Park (1993) 20 Cal.App.4th 1474, 1481.)