With help from the drought, SoCal's beaches get top marks

As California gets thirstier, the water at most local beaches keeps getting cleaner.

Santa Monica-based environmental group Heal the Bay released its annual Beach Report Card on Wednesday, showing continued improvement in the health of Southern California’s beaches, in part due to the drought and corresponding decline in surface runoff.

The Beach Report Card assigns letter grades to beaches to show how risky it is to surf and swim offshore, based on the previous year's weekly bacteria testing.

During 2014's dry summer, 94 percent of Los Angeles County beaches received high marks of "A" or "B," a slight uptick over last year.

"Water quality during the summer dry period — so that's between April and October — was excellent," says Heal the Bay's James Alamillo, who coauthored the report.

California's worst drought on record has kept most local beaches sparkling for two reasons, Alamillo says. First, the lack of rain means all the oil, garbage and toxic grime that builds up on city streets has fewer chances to wash out into the ocean. A second, smaller effect is that people have changed their behaviors to conserve water, reducing daily surface runoff from overwatering lawns and washing cars.

California's 10 dirtiest beaches based on dry-weather water sampling

1. Cowell Beach, Santa Cruz County
2. Mother's Beach, Marina Del Rey, Los Angeles County
3. Clam Beach County Park, Humboldt County
4. Aquatic Park, San Mateo County
5. Mission Bay, San Diego County
6. Santa Monica Municipal Pier, Los Angeles County
7. Candlestick Point, San Francisco County
8. Stillwater Cove, Monterey County
9. Cabrillo Beach, harborside, Los Angeles County
10. Huntington Beach at Brookhurst, Orange County

In the meantime, of course, all that grime builds up on the pavement.

On rainy days in 2014, nearly half of the 92 Los Angeles County beaches monitored received a letter grade of "F" — far worse than 2013's wet-weather days.

Alamillo says beaches' poor performance during rain is an argument for what is known as low-impact development: urban planning with the goal of managing stormwater runoff. Incrementally, he says, Southern California is realizing the need for it and capturing more rain.

"We're enacting policies and changing land use planning to make our cities less hard, so to speak — with less asphalt, concrete, pavement — and starting to treat our landscape to be more soft and more absorbing — spongelike," he says.

The worst beaches of Southern California — "beach bummers," as Heal the Bay calls them — were Mother's Beach in Marina Del Rey, Mission Bay Park in San Diego, Huntington State Beach and the Santa Monica Pier.

The environmental group uses bacteria pollution data collected by public agencies to assign its letter grades, in a process endorsed by the State Water Resources Control Board.

"Nowcasting" water quality

Heal the Bay is also working with Stanford University researchers to develop a predictive model for water quality that makes its own annual and weekly beach reports sound obsolete. It’s still in the pilot testing phase, and it’s known as “Water Quality Nowcast.”

Right now county health departments regularly monitor beaches for bacteria levels, but it can take up to a day and a half between when samples are collected and when test results are in.

By then, if the water quality is poor, plenty of swimmers might have developed rashes, upper respiratory infections and gastrointestinal issues. At the moment the beach managers post a water quality warning or close the beach, currents might have shifted, and the water quality might have completely changed.

But using historical data, statistical models and a few current conditions — e.g. solar radiation, windspeed, tides, water flow — scientists say preliminary data show they can predict current bacteria levels just as accurately as physical tests.

“We will know before 10 a.m. whether or not the beach should be posted,” says Heal the Bay’s James Alamillo, “which is infinitely faster than waiting for any actual bacterial testing.”

Two years into the development phase, the new predictive model has been just as accurate as the slow way of physical testing.

"We found that the models were doing much better than using the previous measurements. So, overall, the models were able to protect public health, because they were able to give an early warning of a posting decision that was missed by the sampling," says Alexandria Boehm, part of the Stanford team developing the statistical models. "It's definitely better."

“Nowcast” is still in its pilot stage at three beaches: Santa Monica Beach, Orange County’s Doheny State Beach and Santa Barbara’s Arroyo Burro Beach. Researchers expect to make predictive modeling available to the public for those beaches by July 6 on Heal the Bay's Beach Report Card site.