A new report shows the water quality of many Northland rivers is getting better but there is still a long way to go, with Whangarei Falls having a high health-risk level for E.coli contamination.

The LAWA (Land, Air, Water Aotearoa) National River Water Quality Trends report released this week gives an analyses of water health at nearly 1500 river sites nationally, including 40 in Northland.

Water quality parameters monitored over a 10-year period showed more sites were improving than deteriorating.

The report shows results for E.coli bacteria, clarity, turbidity, nitrogen, ammoniacal nitrogen and phosphorus levels, with most sites rated among the worst or best 50 per cent or 25 per cent of sites overall.

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While the report indicates improvements or otherwise, the river sites do not get a pass or fail mark. In some cases there is no comparative data to show if rivers followed the improvement trend or not.

An example is Hatea River at Mair Park, which is in the lowland urban category. It rates in the worst 50 per cent of all measures except for total phosphorous levels, where it is in the better performing half. However, that snapshot is listed without history to show whether it is improving or not.

The other test spot on the Hatea River, the Whangarei (Otuihau) Falls, appears in the ''trends'' report with no data, and a reference it has been moved to LAWA's ''Can I swim here?'' site which concentrates on swimmable rivers.

The falls site fails miserably. Three years of summer monitoring data show a high health-risk level for E.coli contamination (6131 per 100ml), recommended as unsuitable for swimming.

The Waitangi River at Waimate North falls into the improvement trend although is still among the worst 25 per cent of similar national sites (rural).

But Northland Regional Council (NRC) is taking the results as a win in one of its key areas of concern, freshwater eco-management.

The report gives a promising picture of what can be achieved, NRC chairman Bill Shepherd said.

The NRC works with landowners, businesses, iwi and wider community to reduce run-off and pollution into waterways, manage river ecosystems, and maintain good water levels.

"It's important to remember all our individual solutions contribute to the bigger picture,'' Shepherd said.

The data the trends are based on comes from regular water quality monitoring by all regional and unitary councils, supplemented with Niwa information.

Colin Dall, NRC group manager of regulatory services, said the council regularly monitors more than 40 Northland river sites.

The latest report is based on data collected between 2007 and 2016, with data available on the LAWA website.

Federated Farmers said the report shows the hard work being done to improve freshwater quality is starting to pay off.

The report, following a similar 10-year analysis in 2015 by Niwa, helped identify where action is needed catchment by catchment, Federated Farmers spokesman Chris Allen said.

LAWA is a collaboration between New Zealand's 16 regional and unitary councils, Cawthron Institute, and Ministry for the Environment, supported by Massey University and the Tindall Foundation.