Newport Bay Watershed

  • The TMDLs page describes on-going regulatory programs within the Newport Bay watershed.


  • The designation of “Newport Bay Watershed” refers to the hydrologic watershed that is defined by drainage and only minimally by jurisdictional boundaries. The Newport Bay Watershed drains approximately 152.02 square miles to the Pacific Ocean within southern Orange County, California. The watershed encompasses all waters draining to Newport Bay. This watershed has been divided into the following four subwatersheds:
  • Lower Bay includes all stormwater drains and natural creeks;
  • Upper Bay begins at the Hwy 1 bridge and extends across the bay including all drains to the bay as well as Big Canyon Wash, Costa Mesa Channel, and the Santa Isabella Channel;
  • Santa Ana Delhi Channel and its tributaries that empty into the far northwestern end of the Upper Newport Bay; and
  • San Diego Creek/Peters Canyon Wash and its tributaries that collectively drain into the northeastern end of Upper Newport Bay. San Diego Creek/Peters Canyon Wash is the largest subwatershed within the Newport Bay Watershed with San Diego Creek accounting for approximately 77% of the freshwater flow into the Newport Bay.

    For more information about this watershed please contact OC Watersheds

Watershed and City Boundary Map

Additional information about the Newport Coastal Streams Watershed such as land use, drainage and elevations can be accesed by clicking the link below