They also need gravel and rocks to spawn. Fine sediment is lethal to steelhead. It clogs the spaces between the rocks and gravel, buries the eggs, and prevents oxygen and flowing water from reaching the eggs. Sediment can also damage the gills of adult steelhead. Steelhead and salmon also require large woody debris and deep pools in the river, which provide refuge from predators and resting places during storms.
Deep pools give steelhead cool water when shallow areas warm up in the summer.
Life History Steelhead have a summer run and a winter run. Summer run steelhead migrate into freshwater from the ocean between May and October. Winter run fish migrate from November to April. Steelhead typically spawn in the spring, though this may range from January to June. They prefer streams in the highest reaches of the watershed, on steep slopes, and streambeds with large gravel and rock.