Sockeye salmon returning to the rivers are bright to dark red on their backs and sides with pale green heads. Most sockeye spawn in or near lakes with the juveniles using the lakes for rearing. Nooksack sockeye are a distinct run that spawns in the upper reaches of both the North and South forks and then rears for up to two years in the river instead of a lake. Sockeye migrate into the river beginning in April and spawn from August through early November.