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Central OC Watershed Management Area

Please visit for the most up-to-date information on Integrated Regional Water Management (IRWM) efforts in North and Central Orange County.

Efforts to develop a combined Integrated Regional Water Management (IRWM) Plan for the North and Central OC Watershed Management Areas (The OC Plan) began in February 2017.  The OC Plan, completed in March 2018, is available upon request.

For more information about the North/Central WMAs, IRWM Plan (OC Plan), project submittal and selection processes, and opportunities for stakeholder involvement, please visit the

The Central Orange County (COC) Watershed Management Area (WMA) encompasses the Newport Bay Watershed with an area of approximately 154 square miles. Cities within the WMA include Irvine, Newport Beach, Tustin, and portions of Costa Mesa, Laguna Hills, Laguna Woods, Lake Forest, Orange, and Santa Ana. San Diego Creek and Santa Ana-Delhi Channel are the major inputs into the Newport Bay Watershed. The COC WMA includes three Critical Coastal Areas (CCAs), two Areas of Special Biological Significance(ASBS), nine miles of coastline, and a functioning estuary designated as a State Ecological Reserve. The entire area within the WMA drains to the CCAs and ASBS, which means conditions in the WMA significantly impact the coastal ecosystem. Water supplies are diverse including groundwater, desalted groundwater, recycled water, and imported water.

Integrated Regional Watershed Management Plan (IRWMP) Efforts

Phase I

In 2007, the County of Orange led the development of this IRWMP to meet Proposition 50 guidelines. 
Click link Phase I Central Orange County Integrated Regional and Coastal Watershed Management Plan

Phase II

The City of Newport Beach was awarded a planning grant to prepare an Integrated Regional Coastal Watershed Management Plan.
 Click link Phase II Integrated Regional and Coastal Watershed Management Plan

Central OC WMA

Phase III

In 2012, the County of Orange completed the third phase of the COC WMA IRWMP. This Phase III IRWMP was developed to meet proposition 84 guidelines and priorities. 

IRWM Plan can be accessed by Section:

Executive Summary, Table of Contents, Acronyms 

  1. Introduction 
  2. Governance 
  3. Regional Description 
  4. Objectives 
  5. Resource Management Strategies 
  6. Projects 
  7. Data Management 
  8. Finance 
  9. Technical Analysis 
  10. Coordination with Existing Local/Regional Plans 
  11. Stakeholder Involvement 
  12. Climate Change

    Appendix A-Projects