The DHB, Hawke's Bay Regional Council and Napier City Council decided to leave the pond at a cautionary status because levels could fluctuate after heavy rain, Dr Jones said.
"On balance we believe the chances of illness from swimming, sailing or kayaking at Pandora are low, providing people avoid using it for three days after rainfall."
Dr Jones said several factors had most likely contributed to the contamination including bird droppings, and high numbers of people using the pond over hot summer days resulting in reports of human excrement, such as dirty nappies.
Another contributing factor was heavy rainfall-related stormwater discharges under the jurisdiction of the city council, which is still under investigation.
Early this month raw sewage was believed to have been discharged into Napier Marina's inner harbour after a sewer-system blockage in Meeanee Quay. The amount of sewage that entered the waterway is unknown, but it was enough to exceed acceptable limits.
The regional council is continuing testing into possible contributing factors of the contamination.
Senior coastal quality scientist Anna Madarasz-Smith said more test results were expected within the next month, which may help shed some more light on the issue.
"Some avian, or bird contamination has been found but that would be expected in an estuary such as Ahuriri and HBRC certainly doesn't have the full picture yet," she said.
Dr Jones said because the regional council's annual monitoring season had now concluded people needed to always check fresh waterways before swimming in them and to avoid them after heavy rain.
"A quick test that people can do on the spot to check the water is clear is to see whether their feet are visible when knee-deep in the water. It is also a good idea to check one of the weather websites for local rainfall information over the last few days," he said.
-Visit hbrc.govt.nz or lawa.org.nz/ for water quality information.
