When nonpoint source pollution is stochastic and the damage function is convex, intuition might suggest it is more important to control a nonpoint pollution source than a point source. Earlier research has provided sufficient conditions such that the permit price for a unit of ex-ante expected emissions should be higher than the permit price for a unit of certain emissions. Herein we provide a set of necessary and sufficient conditions such that this is the case. An approach to testing for the validity of the condition set is available, and has been applied to a related problem.