The unusual rainstorm over the weekend means lots of water washing through L.A. storm drains and down to the ocean, where the bacteria and pollution the storm water brings with it makes the water unsafe for swimming.
Currently, local health agencies use laboratory analyses of water samples collected at the beach to determine if it is safe for recreational use. Unfortunately, it takes 24-48 hours to collect the samples, transport them to the lab and analyze them. Meanwhile, water quality can change with environmental conditions and swimmers can be put at risk of illness.
This month, the nonprofit Heal the Bay rolled out a new tool that will predict water quality in real-time.
Heal the Bay’s “nowcasting” tool will allow visitors to some of Southern California’s most polluted beaches to access real-time beach water-quality data online before they hit – or don’t hit – the water. Created in conjunction with researchers from Stanford University, the tool uses statistical models to provide beach water-quality information similar to a daily weather forecast.
Working with researchers at UCLA and Stanford, Heal the Bay is overseeing a pilot program this summer that predicts good or poor water quality for the day at three beaches that have historically struggled with bacterial pollution: Doheny State Beach in Orange County, Santa Monica Beach at the Santa Monica Pier and Arroyo Burro Beach in Santa Barbara County.
The nowcasts are based on the results of predictive computer models that estimate fecal bacteria levels in the surf zone in real time, based on both water quality data (most recent samples and historic trends) and weather conditions (rain, wind and waves).
Early results have been promising, with researchers able to successfully predict three significant bacterial exceedances at Santa Monica Beach 24 hours before authorities posted warnings near the Pier.
Heal the Bay is now working with local government agencies to provide them nowcast data by 10 a.m. each day. By comparing these computer results to the state’s bacteria health standards, agencies can post warning notices in the morning if warranted, before most people arrive at the beach.
Swimmers at beaches riddled with bacterial pollution face a much higher risk of contracting illnesses such as stomach flu, ear infections, upper respiratory infections and skin rashes.
Ocean users can now visit www.beachreportcard.org to access the nowcasts at the three beaches. Sites are clearly marked as “good” or “poor,” depending on whether the model predicts bacterial levels will exceed state health standards.
If all continues to go well, the organization hopes to expand the nowcasting model statewide next summer.The nowcasting tool augments Heal the Bay’s Beach Report Card program, which provides A-to-F water quality grades to more than 400 beaches statewide based on weekly levels of monitored bacterial pollution.