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Water Quality Monitoring

The Environmental Monitoring Division of OC Public Works/Environmental Resources implements monitoring programs to comply with municipal separate storm sewer system (MS4) permit requirements on behalf of the County, the Orange County Flood Control District, and the 34 cities of Orange County (Orange County Stormwater Program). Since Orange County is within the jurisdiction of two Regional Water Boards (Santa Ana and San Diego), there is a monitoring plan for each region of Orange County, as follows:

Santa Ana Region

MS4 Permit Monitoring Plan for the Santa Ana Region of Orange County
See the following links for maps of Santa Ana Region monitoring sites:    

San Diego Region

Transitional monitoring is currently being performed in the San Diego Region of Orange County, in conformance with the Regional MS4 Permit, as the Water Quality Improvement Plan (WQIP) is being developed. See the South OC WQIP page for more information.  

Monitoring Program Goals


While these programs satisfy MS4 permit requirements, the overall goal of the monitoring, assessment, and research efforts is to track progress toward solving existing problems, identify emerging issues that could become problems in the future, and support research and development that improves our understanding of key processes and advances the efficiency and effectiveness of monitoring methods. The approach is based on answering the following five assessment questions as detailed in the State of the Environment Reports prepared in 2013/14:

  1. Is there a problem?
  2. If so, what is its magnitude and extent?
  3. What are the sources of the problem?
  4. Are conditions getting better or worse?
  5. Are management actions working as intended?

Monitoring & Assessment Themes

The following three monitoring & assessment themes, also detailed in the State of the Environment Reports prepared in 2013/14, provide a foundation and framework for evolving the program to provide more effective information to support smarter stormwater management.   







Additional Programs

OC Watersheds is also a participating agency in the following efforts to examine emerging water quality issues and environmental concerns for Southern California at the regional scale:

  • Southern California Bight Studies – The Bight studies, coordinated by the Southern California Coastal Water Research Project (SCCWRP), utilize standardized sampling and analytical methods to produce a wide range of data from both impacted and reference areas.
  • Stormwater Monitoring Coalition (SMC) – The SMC often use exploratory data analysis methods to investigate new measurement methods, improve basic understanding, characterize problems, or provide one-time measurements of important parameters or processes.