Sydney beaches water quality tanks

The State of the Beaches report says eleven beaches rank as having poor water quality - four more than in the past year.

Sydney's Coogee beach has failed a faecal bacteria and water quality test, a government report says. (AAP)

Popular Sydney beach Coogee has failed a faecal bacteria and water quality test, along with 10 other Sydney swimming spots, a government report says.

The 2015-16 State of the Beaches report showed a decline in water quality in Sydney beaches and an increased presence of a bacteria found in poo in the water.

The report points to increased rainfall as the main driver for the increases in contamination.

Coogee beach and nearby Malabar beach dropped from a good rating to poor after higher levels of faecal pollution and poorer microbial water quality.

Coogee was closed in April after raw sewerage leaked into the popular beach.

The report noted that the water quality was good during dry weather but recommended against swimming in the beaches for up to three days after rainfall.

For the fifth year running Sydney's most contaminated beach was Foreshore Beach in Botany Bay.

There was better news at the state level, with 83 per cent of all 248 monitored swimming spots showing good or very good water quality, the same rate as the previous year.

The report showed that more than 60 per cent of the state's monitored lakes and lagoons were rated as poor quality.

The Illawara and southern coast regions recorded near-perfect scores.