This past winter brought much needed relief to SoCal after years of drought, but the heavy rains had a negative impact on the water quality at the beaches. Its a good reminder to wait three days to swim at SoCal beaches after a rains storm.

Fecal bacteria levels spiked after rain storms at beaches on the SoCal coast this winter, resulting in the poorest winter water quality in five years, according to Heal the Bay’s 2016-17 Beach Report Card.

Put bluntly, this means animal and human waste were washing into the ocean with runoff from rain storms. Exposure to these bacteria is a health hazard. A study in Los Angeles and Orange Counties found, for example, that the regional public health cost of gastrointestinal illnesses caused by recreating in polluted ocean waters was between $21 and $51 million each year.

A good rule of thumb is to wait three days to swim or otherwise have contact with ocean water during a rainstorm, and for a minimum of the three days after the rain stops. Whether its raining or not, Heal the Bay and public health agencies suggest you never swim closer than 100 yards from any flowing storm drain. As much as you may want to surf, kayak, swim…whatever your activity of choice, when dealing with fecal bacteria, patience is a virtue.

Another thing that’s important to note is that some beaches are generally cleaner than others, and that there are a few beaches with particularly bad water.

Heal the Bay’s recently release beach report card identified a number of beaches in Los Angeles, Orange County and San Diego as “Honor Roll Beaches” with generally outstanding water quality. These include Malibu’s El Matador Beach, ¬†Orange’ County’s Balboa Beach (home to the infamous Wedge surf break), and Encinita’s Swami Beach (another famous surf break).

Here’s a table from the report showing beaches that made the honor roll:Wait three days to swim

Other beaches, however, dubbed “Beach Bummers,” got poor grades for water quality. These included San Clemente Pier in Orange County, Santa Monica Pier in Los Angeles and La Jolla Cove in San Diego, which made its first appearance on the Beach Bummers list.

Here’s are the bummer beaches:

wait three days to swim

The cause of poor water quality at these beaches varies, and in some cases is unknown. Bacteria may thrive under piers, where they can hide from the sun, which might explain the high levels. A bump in seal and sea lion activity might help explain La Jolla Cove, as could the lack of water circulation due to the sheltered nature of a cove. Insufficient storm water management facilities is a major factor according to Heal the Bay.

With SoCal’s climate predicted to become even more of a “boom-and-bust” cycle, meaning droughts broken by deluges, rainy periods are likely to continue to result in hazardous beach water conditions. Until the state and California cities and counties invest in infrastructure to make better use of rain water and prevent beach pollution, the rule, one more time, is to wait three days to swim after a rain storm.