For the second year in a row, the Santa Monica Pier is home to the most polluted beach in Los Angeles County, according to environmental group Heal the Bay.

The beach is also seventh-dirtiest in the state, and it's one of two LA-area beaches to make Heal the Bay's annual "Beach Bummers" list of the most contaminated swimming spots on the California coastline.

But it's not all bad news. By and large, it's been an exemplary year for water quality at California beaches. In LA County, 91 percent of beaches received an A grade for water quality during the summer months, and more than half earned an A during wet weather, when stormwater runoff spills into and often contaminates nearby ocean water.

The ratings are based on the amount and type of bacteria found in samples collected at beaches throughout the year. From those samples, beaches get a zero-to-100 score, which is then translated to a letter grade.

The number of LA beaches that received A or B grades during summer months was up 6 percent over the area's five-year average, suggesting that swimmers last summer enjoyed some of the cleanest water in recent memory.

Unfortunately, the reason for this has little to do with environmental precautions or efforts to rid beaches of pollutants. In fact, more than 200,000 gallons of sewage spilled into the ocean in LA County over the past year, triggering four beach closures.

Instead, the above average cleanliness is mainly the result of below average rainfall. The current drought-like conditions may lead to enhanced fire risk, but they’ll also likely keep LA’s beaches clean.

Eight beaches in the county made Heal the Bay’s “Honor Roll,” meaning that they received nearly perfect marks throughout the year, regardless of weather conditions. Four of those beaches—El Matador, Escondido, Dan Blocker, and Las Tunas—are in Malibu. Three others—Bluff Cove, Abalone Cove, and Portuguese Bend Cove—are on the Palos Verdes Peninsula. El Segundo Beach at Grand Avenue took the final honor roll spot.

But not all beaches stayed clean in the dry weather. For the fifth year in a row, Santa Monica Pier was one of the most contaminated stretches of shoreline in the state. That’s in spite of significant efforts by local officials to clean up the water there. In recent years, the city has replaced an aging storm drain beneath the pier, created a stormwater diversion system, and added netting to repel birds. (Bird poop is a major contributor to ocean water contamination.)

According to Heal the Bay, the biggest contributor to the area’s unclean water may be the pier itself, which blocks sunlight and creates a friendly environment for bacteria to spread. Still, a new stormwater storage tank now under construction could help keep the water a bit cleaner in the future.

The only other Los Angeles beach included on the “beach bummers” list was the harbor side of Cabrillo Beach in San Pedro. That’s a bit of a setback for the beach, since two years ago it seemed on its way to a remarkable transformation after spending more than ten years as one of the state’s dirtiest beaches.