Summer in the city means long days, tall drinks and hopefully lots of  beach time. But how clean is that water you’re stepping into? After all, a big city like San Francisco is bound to have various pollutants in its bay runoff, like the 1.36 million gallons of trash reported in this Huffpo story.

Fortunately, there’s a way to find out the general cleanliness of your favorite surf spot. The NRDC has published a detailed report with maps of beach water quality across the US, with the Beach Action Value (BAV) developed by the EPA that includes individual beaches in the Bay Area. Details with map can be found here. California’s beach water quality is just above average, 11th out of 30 states.

But the good news is the general cleanliness of our beaches, particularly those on the ocean, where less than 10% of samples taken in 2013 exceeded the BAV safety threshold. For example, of the 55 samples taken at Ocean Beach at Lincoln Ave., only 2% exceeded BAV thresholds, while none of the 29 samples taken at Stinson Beach where over. Even beaches within the bay had decent marks. Crown Beach in Alameda had only 5% of its 42 samples over the BAV.

That said, conditions can change from day to day, especially after a rain when freshly polluted runoff goes directly into the bay. Some beaches like those in Alameda monitor the cleanliness of their water daily, so check in before jumping in, if you care about water purity. Great Whites? That’s another story. (For the record, there are upwards of 2,400 estimated to be swimming off the coast of California.)