The NSW Government has released its latest State of the Beaches report.

While grades are fairly strong — 84 per cent of beaches were rated good or very good — three popular beaches have been downgraded.

The report card monitors a selection of 250 beaches, estuarine sites, lakes/lagoons and ocean baths across the state.

Rose Bay Beach - a dog-friendly beach in central Sydney - has been downgraded to poor.

Rose Bay’s water quality was impacted by significant rainfall, including the wettest March in Sydney since 1975.

Two popular central coast beaches — Terrigal Beach and Avoca Beach — received a ‘poor’ rating for the third year in a row.

While water quality at these sites was deemed suitable for swimming in dry weather conditions, the report warns that contamination can still occur after low levels of rainfall.

Stormwater from significant rainfall events also impacting water quality at Malabar Beach, but its rating has remained the same.

Coogee Beach has received a ‘good’ grade after being stuck on the threshold between poor and good ratings for three years.

Bayview Baths was upgraded to good too, while South Cronulla Beach was upgraded from good to very good.

Overall, 98 per cent of the state's open ocean beaches were deemed to have ‘excellent’ water quality.

More than half of the 28 lake and lagoon swimming sites tested were rated either poor or very poor.

NSW Environment Minister Gabrielle Upton said it was good to see an improvement.

“It is so much better today than the bad old days of a generation ago where the quality of our water was much lower,” she said.

“It is because of this report, because of our baseline data [which gives] government and community the opportunity to address the issues.”

The State of the Beaches report is accessible here.