Feb 20, 2020

Average Concentration – Bacteria Oyster Farm Monitoring on One Site

The graph shows the geomean, a type of average, for each year’s fecal coliform data at one of the monitoring sites in the oyster growing area. The data must remain below the red line which is the regulatory standard indicating that waters are clean enough for shellfish to be safe for human consumption. The data shows a decrease beginning in 2016, which is when seasonal closures were instituted. Historically, bacteria readings have been elevated during the rainy winter months. Rather than trying to stay open during the time of year with typically poor water quality, CDPH worked with the farmers to establish seasonal closures. During these times of year, the farmers cannot bring to market oysters directly harvested from their leases. If oysters are harvested during this time and then treated in an onshore depuration facility, then they can be safely consumed.