In its annual Beach Report Card, Heal the Bay, a Santa Monica-based environmental group, gave 90 percent of California's 463 beaches grades of C, D or F. For a state renowned for its beaches - nearly 100 million locals and tourists visit each year to play on them - the low grades were particularly alarming.

Unusually high volumes of rain were blamed as the reason for the deteriorating conditions. Storm drain runoff resulted in the most damage, followed by sewage spills, according to the report. The study used data gathered by county health departments, local clean water groups and state testing at 346 locations.

"That tells us we're not doing our job of reducing storm water pollution," said Mark Gold, the executive director for the group. "California's efforts to protect public health at the beach have been woefully inadequate."

During the summer months, the coastlines can experience long dry spells. During such periods, the group graded 415 of the 463 monitored beaches at A or B. Only a total of 27 beaches received failing grades.