Bay of Plenty Regional Council is warning people not to swim or play in beach outfalls, stormwater drains or ponds following the region's long period of hot, dry weather.

Regional Council Water scientist Paul Scholes says because of the weather, many stormwater drains and ponds had had little or no flow leaving the water at risk of bacterial contamination.

People are being warned not to swim or play in beach outfalls, stormwater drains or ponds. File photo.

'The water is sitting stagnant, and the high temperatures we've been having increases bacteria and a build-up of other contaminants which could be a health risk to both people and pets.”

Water at Harrisons Cut outfall onto Papamoa Beach, where families often swim and paddle, is being regularly monitored for health risks.

Tauranga City Council has deepened the channel across the beach to allow better tidal flow up the drain to improve water flows.

Paul says people should not swim or paddle there.

'Stormwater may look clean, but it has washed off roofs and roads, and may be contaminated by ducks and other avian species. Swimming or paddling in stormwater ponds or near stormwater pipe outlets could make you sick.

'Pets should also be kept out of stormwater ponds and drains, as they too can be affected by water-borne bacteria.” Low flows and hot summer weather could also affect water quality in popular swimming spots.

The Regional Council monitors swimming water quality more than 80 popular coastal, river and lake recreation sites around the Bay of Plenty for bacteria and for toxin-forming algae.