Onion Creek is a stream located in California, specifically in San Diego County. It is a tributary of the San Diego River and plays a role in the local watershed. The creek is characterized by its natural surroundings, including various plant and animal species that thrive in the area. The creek is part of the larger Cleveland National Forest, which offers recreational opportunities such as hiking and wildlife observation. Onion Creek contributes to the ecological health of the region and is an important feature for both the environment and local communities.