Swimming at Bondi Beach is a safe bet, but 16 Sydney swimming spots have been graded susceptible to faecal pollution.

New figures show one in six areas sampled in the greater Sydney area had enough enterococci bacteria to be graded fair to very poor.

Most poor results were in lakes, lagoons and estuarine beaches due to issues with flushing contaminants out after heavy rainfall or sewerage problems.

Coogee recovered from a sewerage issue last year to scrape back into the good rating, while only three ocean beaches in the state – Terrigal and Avoca on the central coast and Malabar in Sydney – were rated poor and not always suitable for swimming.

Six estuarine beaches in Sydney, including Rose Bay and Riverview’s Tambourine Bay, recorded poor ratings.

Foreshores Beach at Botany Bay remains the only beach in NSW to be assessed as “very poor” because of a high risk of sewage overflows.

Enterococci, the preferred indicator of disease-causing pollutants in marine waters, is a bacteria in faeces and is rarely present in unpolluted waters.

The State of the Beaches report on Monday showed 16.5 per cent of Sydney swimming sites failed to reach a good rating in 2016/17 – up from 14 per cent in 2015/16.

Bondi’s enterococci reading to June 2017 increased by half to 95 units per 100mL, still well below the good rating threshold of 200 units.

Environment Minister Gabrielle Upton says Coogee is a good example of the impact the report can have on government working to improve water quality.

“We had local council come together with the environment department and community groups and they’ve identified where the issues are and how they can best attack it,” she told reporters at Bondi Beach on Monday.

Prolonged wet weather and storm activity was blamed for Central Sydney’s worst gradings in four years.

Elsewhere in NSW, all ocean beaches in Wollongong and Newcastle were assessed good or higher while Lake Macquarie’s lagoon beaches endured mixed results.

Daily water quality forecasts are available on the NSW government’s Beachwatch website.

The website warns that following heavy rain, swimming should be avoided for at least a day at ocean beaches and for up to three days in other areas.

-AAP