Frequently Asked Questions
1. How do I know that it is safe to swim at my local beach?Over the past 40 years, the Health Care Agency and two local sanitation agencies (the Orange County Sanitation District and South Orange County Wastewater Authority) have been testing the coastal ocean, bay and harbor waters in Orange County for bacteria that indicate the possible presence of disease causing organisms. The results of the tests are reviewed by the Health Care Agency Environmental Health staff, and if the data indicates a contamination, warning or closure signs are posted at the beach depending on the extent and cause of the contamination. Signs are posted at the locations where the contamination was detected so that you will know where it is not recommended to swim. You may also call the Beach Closure and Posting Hotline at (714) 433-6400 or click on the "Beach Closures & Warnings" icon on the menu to find the latest status of a beach.
2. How are water samples taken?The Health Care Agency and the sanitation agencies routinely collect water samples at approximately 150 ocean, bay, harbor, storm drain, creek and river locations along the shoreline of Orange County. Water samples are collected in sterile bottles according to specific guidelines. Sampling staff typically collect samples in ankle deep water using a long pole with a sample bottle attached to the end to scoop up the water. The sample bottles are immediately capped and placed into an ice chest with "blue ice" for preservation. The time, date, weather conditions and location of collection are recorded on a log sheet. The samples are then transported to the laboratory for analyses.
3. How often are samples collected?The frequency of sample collection ranges from at least weekly to five times per week along the Orange County coastline, depending upon the requirements of the agency collecting the samples. When the results of testing indicate a contamination problem exists, the sampling frequency and locations around the original sample location may increase until the sample results are within standards and/or the source of the problem is determined.
4. What types of bacteria may be in the ocean, bay or harbor waters?Water samples are analyzed for indicator bacteria - total coliform, fecal coliform and enterococcus - which indicate possible pollution from numerous sources including fecal waste. They are called indicator bacteria because they are relatively easy to collect and analyze, and may indicate the presence of harmful viruses, bacteria or protozoa (also known as pathogens). Collecting and measuring the disease-causing organisms directly is difficult. Sources of indicator bacteria may be:
• Environmental - soils, decaying vegetation.
• Animal wastes - birds, dogs, cats or rabbits.
• Humans - sewage, kids with diapers, shedding from body.
• Storm water or urban runoff.
5. How are the water samples analyzed?Water samples are analyzed for indicator bacteria three ways. The results of each of these techniques are considered to be equivalent.
The membrane filtration technique uses extremely fine paper filters through which the water sample is passed. These filters are then placed on bacteriological growth media that contain food specific to the indicator bacteria (total coliforms, fecal coliforms and enterococci). If these bacteria are present, they will grow on the filter and form colonies. These colonies are counted and the number of the original bacteria present in the water sample calculated. Results for the membrane filtration technique are reported as the number of colony forming units (CFU) per 100 milliliters of water sample or CFU/100ml. All three of the agencies collecting and analyzing ocean and bay samples in Orange County (the Health Care Agency and the two local sanitation agencies - Orange County Sanitation District and South Orange County Wastewater Authority) use the membrane filtration method.
The multiple tube fermentation technique uses test tubes containing nutrient broth or food (media) specific to the indicator bacteria. These tubes are inoculated with several dilutions of the original water sample. The presence of indicator bacteria is evidenced by the production of carbon dioxide gas, a byproduct of bacterial respiration. After the positive tubes are tallied, a statistical technique is used to determine the concentration of bacteria in the sample. Results for this technique are reported as Most Probable Number (MPN) of bacteria per 100 milliliters of water sample or MPN/100 ml.
The defined substrate technology technique uses a multiple well tray test kit to detect the presence or absence of indicator bacteria. The detection of indictor bacteria is based on a color change of the media in the wells to yellow or show fluorescence. Results for this technique are reported as Most Probable Number (MPN) of bacteria per 100 milliliters of water sample or MPN/100 ml.
6. How are ocean and bay waters closed or warnings posted?The results of shoreline bacteriological testing are reviewed on a daily basis. The status of ocean and bay waters can include:
7. What are the State Ocean Water-Contact Sports Standards?The California Ocean Water-Contact Sports Standards are found in the California Code of Regulations - Title 17 and the California Health and Safety Code.
Single Sample Standards:
30-day geometric log mean standards of 5 weekly samples:
8. What harmful microorganisms may be found in polluted water and what illnesses do they cause?Polluted runoff and untreated sewage released into bathing waters may result in swimmer exposure to pathogenic bacteria, viruses and protozoans. These disease-causing organisms may be present at or near the site where the polluted discharges enter the water. The following table lists the types of organisms and the diseases (or symptoms) they may cause
9. What happens to the bacteria, viruses and protozoa in swimming waters?The levels of bacteria, viruses and protozoa decrease over time due to the following reasons:
• Die off due to sun (ultraviolet exposure), salt water or age;
• Predation by other organisms; and
10. What can I do to help improve water quality at the beach?Everyone can help improve water quality at the beach no matter where they live, work or play. Runoff from anywhere in the County eventually ends up at the beach and with the runoff, all the bacteria, litter, oil or grease it picks up along the way. Many of the storm drains lead to the beach, not to a treatment plant! Some easy things we can do to help include: