Newport Bay Watershed Programs & Projects

The Newport Bay Watershed is approximately 152 square-miles that includes portions of the cities of Costa Mesa, Irvine, Laguna Hills, Laguna Woods, Lake Forest, Newport Beach, Orange, Santa Ana and Tustin. The designation of “Newport Bay Watershed” refers to the hydrologic watershed that is defined by drainage and only minimally by jurisdictional boundaries.

Watershed Programs

Integrated Regional Watershed Management Program

The Newport Bay watershed is part of the Central Orange County Watershed Management Area (WMA). A local Central Orange County Watershed Management Area Integrated Regional Watershed Management Plan (IRWMP) was finalized in 2012. This Central Orange County WMA IRWMP was an effort to work cooperatively to develop planning water management strategies for the region.

Newport Bay Watershed Executive Committee

Total Maximum Daily Load (TMDL)

a TMDL sets a limit for the total amount of a particular pollutant that can be discharged to a waterbody, such that the pollutant loads from all sources will not impair the designated beneficial uses of the waterbody. The timeframe for compliance with TMDL targets varies, but may take many years. TMDLs will often include a compliance schedule, identifying interim and final targets. A TMDL is developed when a waterbody has been identified as impaired. Section 303(d) of the federal Clean Water Act requires states to establish a listing of all impaired waterbodies and to rank those waterbodies according to priority for TMDL development. This list, called the 303(d) List is updated every two years and is developed by the Regional and State Water Quality Control Boards and approved by EPA. Additional information can be found by clicking TMDL