Surface carryover loads are loads that have been bypassed from upstream gutter inlets. Note that the term "upstream" in this case refers to the directionality of the gutter network, which does not necessarily correspond to the directionality of the subsurface piped network. In fact, carryover loads may even come from inlets that are part of a separate pipe network. Note that carryover loads are assumed to have the same time of concentration as the surface catchment load. The times of concentration from their original catchments are not considered.