A popular swimming spot on the Northern Rivers has returned poor results after a recent microbial assessment.
Assessments are done regularly for a number of local swimming spots as part of the state government's Beachwatch monitoring program.
Water samples are collected and tested for bacteria, showing signs of faecal pollution, and whether it is safe for swimming.
Results are posted online every week.
The most recent result for the Evans River was two stars, which is deemed a "poor" result.
Richmond Valley Council monitors five swimming sites - Airforce Beach, Main Beach, Shark Bay, Elms Street Bridge North and the Evans River.
The three ocean beaches and Elms Street Bridge North are sampled weekly from October to March, but the Evans River is sampled weekly all through the year.
The river was the only location to return a two-star rating this week, with all other spots getting four stars, a "good" rating.
A total of 13 Ballina Shire swimming sites are also monitored as part of the Beachwatch program.
These include four spots at Lake Ainsworth at Lennox Head, five spots at Shaws Bay, Seven Mile Beach at Lennox Head, Shelly Beach and Lighthouse Beach at East Ballina, and The Serpentine at Ballina.
The three ocean beaches and The Serpentine are sampled weekly from November to February, and Lake Ainsworth and Shaws Bay are sampled weekly throughout the year.
The most recent results show all but one site returned four-star ratings.
Shaws Bay West had a "fair" three-star result.
According to the Beachwatch website, the monitoring program provides regular and reliable beach water quality information to help people decide when and where to swim.
"Our routine water quality monitoring measures the impact of pollution sources at swimming sites over time," the website states.
"This enables the effectiveness of stormwater and wastewater management to be assessed, and highlights areas where further work is needed."