Two days after bacteria levels at a section of Baker Beach hit their second-highest level in more than three years, the pollution was found to have washed away and no-swimming signs were removed.
No-swimming signs were posted near the mouth of Lobos Creek Wednesday after high counts of E. Coli and enterococcus were detected.
Both types of bacteria cause human illnesses but the source of the pollution remains a mystery.
Levels of enterococcus recorded in water samples taken from the site on Tuesday were lower than just one other weekly recording taken since the start of 2007, city monitoring data shows.
The next samples are scheduled to be taken Tuesday.