Central OC Watershed Management Area

The COC WMA encompasses the entire Newport Bay Watershed and the northern portion of the adjacent Newport Coastal Streams Watershed that lies within the jurisdiction of the Santa Ana Regional Water Board. This region 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 planning area, located approximately 40 miles south of Los Angeles and 70 miles north of San Diego, is highly urbanized, with a current estimated population of 705,000 residents expected to reach 787,000 by 2030. There are currently five Total Maximum Daily Loads (TMDLs) in the watershed, with more pending. 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.

The COC WMA encompasses an area of approximately 154 square miles with overland flows draining toward the Pacific Coast into Newport Bay. Major cities within the watershed include Irvine, Newport Beach, Tustin, and portions of Costa Mesa, Laguna Hills, Laguna Woods, Lake Forest, Orange, and Santa Ana. The principal watercourse of the Newport Bay watershed is San Diego Creek, with a drainage area that covers approximately 122 square miles of the Newport Bay Watershed. The main tributary to San Diego Creek is Peters Canyon Wash; smaller tributaries include Serrano Creek, Borrego Canyon Wash, Agua Chinon Wash, Bee Canyon Wash, Sand Canyon Wash, and Bonita Canyon Creek. The Santa Ana-Delhi Channel subwatershed covers approximately 17 square miles. The channel is an artificial drainage that conveys water from the city of Santa Ana into Upper Newport Bay. The San Diego Creek and Santa Ana-Delhi Channel are the major inputs into Upper Newport Bay. The San Diego Creek Watershed generates roughly 80-percent and the Santa Ana Delhi Channel generates about 15-percent of the discharges into Upper Newport Bay, with the balance from other small tributaries.

Central OC Watershed Management Area Integrated Regional Water Management Plan Efforts

Phase I

The County of Orange led the first Integrated Regional Water Management effort for the COC WMA which culminated in the production of the Phase I Central Orange County IRWM Plan (IRWMP). The Phase I IRWMP was undertaken to provide a bridge between existing and developing watershed planning efforts, allowing for more effective collaboration and greater opportunity to leverage agency resources across jurisdictions. It had a strong emphasis on the sensitive coastal resources, Areas of Special Biological Significance and Critical Coastal Areas (CCAs) that are located within the Central Orange County WMA. The Phase I IRWMP was also developed to meet Proposition 50 priorities. The Phase I IRWMP was integral to subsequent watershed planning efforts led by the City of Newport Beach. In January 2006, the City of Newport Beach was awarded a planning grant by the State Water Board through Proposition 40 for preparation of an Integrated Coastal Watershed Management Plan (ICWMP) to address ASBS and CCA issues along Newport Coast. Much of the material in the ICWMP was used during the preparation of the Phase I Central Orange County IRWMP.

Phase II

In May 2006, the City of Newport Beach was awarded a planning grant by the California Department of Water Resources through Proposition 50 for the preparation of an IRWMP for the Newport Bay Watershed including data collection, analysis, and formulation of policy and guidelines. Though building on some new elements, this Phase II effort incorporated the Phase I Central Orange County IRWMP.

Central OC WMA

Phase III

The County of Orange has completed the third phase of the Central Orange County IRWMP. Phase III is a compilation and revision of the first two IRWMPs; the information contained in the Phase I and Phase II plans helped to form the basis of the Phase III plan. In addition to the COC IRWMP efforts, stakeholders will participate in applying for Proposition 84 grant funding with other Santa Ana River Watershed funding area partners with the Santa Ana Watershed Project Authority (SAWPA).