When Heal the Bay released their annual “Beach Bummer” list of California’s most polluted beaches last month, there was at least one strange exception: Imperial Beach, San Diego, a beach that’s been closed because of dangerous bacteria levels 1,600 times in the past decade alone. Southern California readers saw the list, and wondered, probably aloud, but also in our comments section, “What about IB? How the hell do they compile this list anyway?”

Well, we wondered, too. Fortunately, Heal the Bay had read our story and contacted me to see if they could help clear up any confusion. I recently spoke with Ryan Searcy, Beach Water Quality Manager for Heal the Bay about how they decide which beaches make the dirty cut, and why the oft-filthy IB didn’t appear on the list.

First, some good news, which is often overshadowed by the bad, when it comes to pollution.

96 percent of beaches tested in CA this year scored an “A” or “B” in the letter grade-system used by Heal the Bay for last summer’s beach season. More than 30 beaches scored an A+ year-round, winter, summer, whatever, including 14 Orange County beaches. That’s impressive. Unfortunately, nearly half the beaches tested received “C” or worse grades during rainy periods. That’s impressive, too, in a bad way.

As far as why beaches like IB didn’t make the Bummer list, Searcy explained that, during dry periods, IB is actually a clean-water beach. In fact, it received a grade of A+ during dry periods last winter. When it rains, though, I wouldn’t approach that beach in a hazmat suit.

“I’m fully aware of how dirty IB can get. In wet weather, it is awful,” Searcy said. “But in dry periods, it’s actually pretty clean.”

To aid in eliminating confusion about when beaches are clean and when they have the potential to make you sick, Heal the Bay has partnered with Stanford and UCLA as well as the State Water Resources Control Board to build the Nowcast system—daily reports of beach cleanliness based on computer modeling. Normally, you’d have to wait for samples to be collected and tested before an announcement is made about the safety of a beach’s water. With Nowcast, historical data is combined with sophisticated weather and ocean movement patterns to actually predict bacteria levels at beaches.

Right now, 10 of California’s most popular beaches are in the Nowcast program, with, Heal the Bay hopes, many more to come this winter. Those beaches are:

Cowell Beach (Santa Cruz)

Arroyo Burro/ Hendry's (Santa Barbara)

East Beach (Santa Barbara)

Santa Monica Pier

Redondo Beach Pier

Long Beach City Beach (at 5th Place)

Belmont Pier (Long Beach)

Huntington Beach (at Brookhurst)

Doheny State Beach

Moonlight Beach (Encinitas)

Searcy explained that the idea is to eventually develop an easy-to-read report for beaches with either a clean “green” rating, or a red “dirty” rating, with reports generated by 10 AM daily.

Until then, the standard rule of waiting 72 hours after a rain applies, though 90% of us ignore that every winter. Keep an eye on Heal the Bay for any announcements this fall on when their new winter forecasting program is ready. It’ll be interesting to see how many days are considered dangerous that we would normally surf happily through.

[Featured Image: Imperial Beach. Photo by Ghiglia]