Released by the NSW Office of Environment and Heritage, the annual report details water quality of beaches and other swimming locations around the state.

Grades are based on potential pollution sources and water quality measurements gathered over previous years through the Beachwatch program.

Cookies Beach, Caseys Beach, Malua Bay Beach, Broulee Beach and Narooma’s Main Beach all received the top “very good” rating, meaning they had excellent microbial water quality and very few potential sources of faecal pollution.

They were deemed suitable for swimming “almost all of the time” and had a less than one per cent risk of gastrointestinal illness and less than 0.3 per cent risk of acute fever and rash.

Surf Beach, Bengello Beach, Shelley Beach, Tuross Main Beach, Brou Beach and the Wagonga Inlet were rated “good”.

They were deemed to have good microbial water quality and the water was considered suitable for swimming most of the time.

However the report stated swimming should be avoided during, and for up to one day following, heavy rain at ocean beaches rated “good” and up to three days at estuarine sites.

Surf Beach, Shelley Beach and Wagonga Inlet were rated as having a moderate likelihood of faecal contamination, and the rest of the shire’s 11 monitored beaches “low”.

Surf Beach, Bengello Beach, Tuross Main Beach and Brou Beach each had a slightly higher risk of illness; between one and five per cent for gastrointestinal and between 0.3 per cent and 1.9 per cent for acute fever and rash.

The report states rainfall is the major driver of pollution to recreational waters, generating stormwater runoff and triggering discharges from wastewater treatment and transport systems.

In 2014-15, 96 per cent of the 139 monitored ocean beaches were graded as very good or good.

Five were poor; the Central Coast’s Terrigal, Avoca, Copacabana and Ocean beaches, and the boat harbour at the northern end of Bate Bay in Cronulla.

Seventy-seven per cent of the 71 monitored estuarine beaches were graded as very good or good, four fair, 11 poor and one – Foreshores Beach in Botany Bay – very poor.