The availability of spawning gravel is an essential part of the natural reproduction cycle for resident Rainbow Trout. Trout lay their eggs in nests made in the gravel. After Pine Flat Dam was completed in 1954, the natural recruitment of gravel suitable for spawning downstream of the dam was severely curtailed. Mill Creek, a large tributary, is currently the only significant source of spawning gravel for the Kings River, but it is usually heavily impacted by silt brought in by the creek during high flows.
To enhance the available spawning habitat, thereby encouraging natural trout reproduction downstream from Pine Flat Dam, large quantities of spawning gravel have been added in the river. The gravel sites include areas where gravel will either be transported downstream or areas where it will remain in-place and be available for trout spawning year round.