Hydrographical studies have been undertaken since 1971 by the Fisheries and Marine Service in the prime spawning areas of the Nanika and Morice Rivers. The purpose of the studies was to document the physical and hydraulic conditions under which spawning and incubation naturally occur and to determine the minimum flows necessary to sustain salmon in these two life stages. The studies were concentrated in the major sockeye spawning area of the Nanika River and the major chinook spawning area of the Morice River and are in each case representative of a substantial proportion of the total river spawning area within the system.