Several Hawke's Bay beaches and waterways feature on a national list showing which freshwater swimming spots are a health risk and should be avoided.
It includes Clive River at boat ramp, Lake Tutira, Puhokio Stream and Waipatiki Lagoon, which were given the worst possible ranking in the latest recreational water quality report from the Ministry for the Environment, released this week.
The ministry assessed 210 freshwater beaches nationwide and 248 coastal beaches used for recreation, based on monitoring data acquired over five consecutive summers.
The beaches were given one of five grades to describe their likely condition for recreation during summer, based on an assessment of potential sources of faecal contamination.
The grades ranged from very good - considered satisfactory for swimming at all times - to very poor - high risk of illness and should be avoided.
Fish and Game New Zealand's Hawke's Bay regional manager, Peter McIntosh, agreed the report was timely, given the public debate on the proposed Makaroro dam and the Tukituki Choices document, which outlines four options for the management of the Tukituki river catchment.
"Fish and Game is more concerned about freshwater areas rather than beaches but still wants safe areas for swimming, angling and food gathering," Mr McIntosh said.
"The report focuses on E. coli (a bacteria) but that is just one measure of water quality, there are lots of other loadings which add up to the bigger picture."
That included the nutrient "loadings" into rivers from extra farm production activities which could be enabled if the Makaroro Dam project went ahead.
"The proposed intensification as a result of the dam would also certainly result in more faecal matter coming off the land and going down the river. It's just a matter of how that is managed."
Hawke's Bay Regional Council, which is charged with looking after the region's rivers, said it was well aware of ongoing lower quality levels at Clive River and Tutira and understood that the other areas were slowly seeing improvement.
It was working with the Hawke's Bay District Health Board on the summer recreational water-quality programme to ensure people had access to good information about water quality before using swimming spots.
The health board's Medical Officer of Health, Nicholas Jones, said the areas named as very poor were not suitable for recreation "on an ongoing basis".
"There is work going on with the regional council towards improving the water over time. We are providing warning signs and advice on the (regional council) website but at the same time realise that's not going to stop people making a decision to use the water."
Dr Jones said Clive River was a particular issue because while it rated poorly it was popular with recreational users such as rowing crews and jet skiers.
"We are doing what we can to provide the best advice to people but we recognise people will go ahead and do that (use the river) anyway.
"For those who are, they can minimise the risk by making sure they don't swallow the water."
Senior Massey University ecology lecturer Mike Joy said the ministry's results weren't surprising. The clear difference between the good and the bad sites was whether they were upland or lowland: "When I look at the local sites I know of - swimming holes like Horseshoe Bend on the Tokomaru River - it comes straight out of native forest and there's a lovely swimming hole and it's beautiful and of course there's no e.coli, there's no problem with bacteria.
"If you look at any of the sites downstream, they fail because of all of the run-off from dairy farms and the effluent from the wastewater treatment plants."
The report highlighted the effects of uncontrolled intensification of dairy farming and a failure of freshwater protections, Dr Joy said.
Stronger legislation, fencing waterways off from cattle, and riparian planting was needed to help protect fresh water from more contamination, he said.
A new member's bill drafted by Green MP Catherine Delahunty aims to tighten controls on sustained pollution of waterways. It would close a loophole in the Resource Management Act that allows contaminating discharges with toxic effects and discolouration of waters under "exceptional circumstances".
Ms Delahunty said the existing phrase had no timeframe and her bill would limit its use to five years.
The most "legendary example" was the Tarawera River in the Bay of Plenty that inspired the name and purpose of her "Black Drain Bill", she said.
Of the 458 monitored beaches that were graded:
17 per cent of freshwater beaches and 18 per cent of coastal beaches were graded as "very good". Another 15 per cent of freshwater and 42 per cent of coastal beaches were graded as "good".
24 per cent of freshwater beaches and 25 per cent of coastal beaches were graded as "fair".
24 per cent of freshwater and 13 per cent of coastal beaches were graded as "poor".
21 per cent of recreational freshwater beaches and 3 per cent of coastal beaches used for recreation were graded as "very poor".