Occupying the west and northwest portions of the San Juan Creek watershed, the 25-square-mile (65 km²) Oso Creek watershed comprises about 18% of the 133-square-mile (340 km²) San Juan Creek watershed.
It includes parts of the cities of Mission Viejo, Laguna Niguel, and San Juan Capistrano.
Most of the watershed is used for residential, commercial, and agricultural purposes.
Oso Creek runs parallel to Trabuco Creek, while Salt Creek is to the southwest, Sulphur Creek to the west, and Aliso Creek to the northwest.

The southernmost portions of the San Joaquin Hills lie to the west and southwest of the Oso Creek watershed, and the Santa Ana Mountains border it to the north and northeast.
The drainage divide between Oso Creek and the Aliso Creek watershed is quite pronounced, connecting the San Joaquin Hills to the Santa Ana Mountains in a northeasterly direction.
Occupying the west and northwest portions of the San Juan Creek watershed, the 25-square-mile (65 km²) Oso Creek watershed comprises about 18% of the 133-square-mile (340 km²) San Juan Creek watershed. It includes parts of the cities of Mission Viejo, Laguna Niguel, and San Juan Capistrano. Most of the watershed is used for residential, commercial, and agricultural purposes. Oso Creek runs parallel to Trabuco Creek, while Salt Creek is to the southwest, Sulphur Creek to the west, and Aliso Creek to the northwest.
The southernmost portions of the San Joaquin Hills lie to the west and southwest of the Oso Creek watershed, and the Santa Ana Mountains border it to the north and northeast. The drainage divide between Oso Creek and the Aliso Creek watershed is quite pronounced, connecting the San Joaquin Hills to the Santa Ana Mountains in a northeasterly direction.
Oso Creek