Some residents have noticed that Coronado has seen an increase in beach closures in recent weeks. San Diego County health officials have closed Coronado Beach three times since May 10. This follows the implementation of new, more sensitive seawater testing technology that provides faster results. San Diego County announced May 4 that it will soon begin using a DNA-based rapid seawater testing system.
The tests, it was reported, would lead to earlier warnings that bacteria levels had reached an unhealthy level. Coronado Beach closed May 10-13, May 18-26, and was recently closed June 4-6. The testing technology is used on more than 70 miles of shoreline that the county tests regularly. Samples are taken in the morning and results are provided the same afternoon. Previously, results were only available the next day after bacterial cultures had been allowed to grow in petri dishes.
Prior to each of the recent closures in Coronado, the county issued closures first for Imperial Beach and then Silver Strand due to sewage-contaminated runoff from the Tijuana River. Many factors affect the water quality at San Diego County beaches. One factor that affects South County beaches is the southern swell, which is more prevalent during the summer months and can carry sewage-contaminated water north across the international boundary. This sewage-contaminated water is the cause of the increased bacteria levels and recent closures. When the sample results show the water is safe for swimming, the closures will be lifted and the beach will be open.
The good news is that faster results mean closures are lifted sooner.