Water quality at San Diego County beaches continues to improve, with one beach in Oceanside rated as one of the highest in the state, according to a report released Thursday by environmental group Heal the Bay.
For the second year in a row, no area beaches were on the list of "Beach Bummers," the 10 most polluted shorelines in the state, in the group's 22nd annual Beach Report Card.
St. Malo Beach, in southern Oceanside just north of the Buena Vista Lagoon opening, was given an A-plus for water quality during dry conditions, and an A during periods of wet weather.
The beach near the mouth of the Tijuana River received the lowest marks countywide.
Heal the Bay's report card assigns A-to-F letter grades to more than 650 beaches up and down the coast, based on water pollution levels during the dry- weather period from April to October 2011. More than 300 areas of shoreline are tested year-round.
The report said 93 percent of the water quality monitoring stations in San Diego County received an A during dry weather in both summer and winter. During wet weather, 77 percent of the locations tested earned A or B grades, compared with a five-year average of 68 percent.
Statewide, 64 percent of the beaches were given As or Bs for water quality when it was rainy.
In IB, water quality depends on the flow of the Tijuana River.Summer Dry (April-Oct) Winter Dry (Nov-Mar) Wet Weather Year Round Carnation Avenue B A+ F Imperial Beach Pier C A F South end of Seacoast Drive B A+ F 3/4 mile north of Tijuana River A+ A+ F Tijuana River Mouth C F F Border Field State Park A C D Border fence A A F
The lowest-rated beaches in the county were:
- the San Luis Rey River outlet in Oceanside, which got a D for winter dry weather water quality and an F for wet weather;
- the foot of Avenida de la Playa in La Jolla, a D for wet weather quality;
- the mouth of the Tijuana River, a C in dry weather and an F when raining.
All beaches from Imperial Beach south received F grades during wet conditions because of runoff from the Tijuana River.
The report card cites the Tijuana River Bacterial Source Identification Study which found:
Wet weather monitoring designed to assess flows and FIB (fecal indicator bacteria) loads from the U.S. and Mexican portions of the watershed indicated that the majority of the bacterial load during storm events originates from the Mexican side of the border.
The study also found:
Rogue flows originating from Mexico during dry weather conditions have been identified as a source of bacteria to the Tijuana River as well as sources on the U.S. side of the border, such as storm drain effluent.
The rest of the beaches in San Diego County received mostly A-pluses and As.
Despite improvements, Los Angeles County has the highest number of beaches with poor water quality of any county in the state, according to the report.
Eleven beaches in Los Angeles County received F grades, up from nine last year.