Waiapu rivers ‘unsafe’

Several rivers in the Waiapu catchment would be regarded as unsafe for swimming, Gisborne District Council’s environmental planning and regulations committee has been told.

The Waiapu, Poroporo, Ihungia and upper Mata rivers rated “D” for e. Coli levels of the National Policy Statement for Freshwater Management, environmental monitoring and science manager Lois Easton told the committee.

This was a concern because the rivers were widely used for swimming. Unrestricted stock access was thought to be the cause but faecal source tracking studies were recommended.

She was presenting a report on water quality and quantity issues with the Waiapu River and its sub-catchments.

The Ratahi Lagoon at Te Puia Springs showed elevated levels of nitrogen and phosphorus and was likely to be eutrophic (overly enriched with minerals and nutrients).

This was significant for water quality, with a risk of algal blooms.

There was also a significant trend of increasing e. Coli levels in the lagoon.

More comprehensive monitoring of the lagoon was recommended.

All the monitored sites were highly impacted by sediment, reflecting the extensive erosion issues in the catchment.

The levels were such that they represented high to extreme stress for the aquatic ecosystem health.

“Erosion is the issue of this catchment,” she said. “It has got the highest rates of erosion in New Zealand.”

That meant there were very high levels of suspended sediment, a tremendous amount of which went down these rivers.

But in terms of the health of the rivers, that was taken away by heavy rain.

The catchment had some of the best health of streams in the region, notably the headwater streams in the Raukumara Ranges.

Ms Easton said the report was intended to provide an update on water quality and quantity issues for the river in preparation for a catchment plan.

The Waiapu was the second largest catchment in the district, with an area of 1730 square kilometres and seven major tributaries, as well as the Waiapu River.

It was subject to a joint management agreement between Gisborne District Council and Te Runanganui o Ngati Porou.

There were only two consented water takes in the catchment and a large number of water resources existed; potentially 2000 litres per second in the Waiapu River and 500l/s in the Mata.

There were shallow groundwater aquifers under Tikitiki and Takamore, potentially 450l/s.

The Waiapu groundwater system is a potential source of groundwater thought to be as large and complex as that under the Poverty Bay Flats.

Several rivers in the Waiapu catchment would be regarded as unsafe for swimming, Gisborne District Council’s environmental planning and regulations committee has been told.

The Waiapu, Poroporo, Ihungia and upper Mata rivers rated “D” for e. Coli levels of the National Policy Statement for Freshwater Management, environmental monitoring and science manager Lois Easton told the committee.

This was a concern because the rivers were widely used for swimming. Unrestricted stock access was thought to be the cause but faecal source tracking studies were recommended.

She was presenting a report on water quality and quantity issues with the Waiapu River and its sub-catchments.

The Ratahi Lagoon at Te Puia Springs showed elevated levels of nitrogen and phosphorus and was likely to be eutrophic (overly enriched with minerals and nutrients).

This was significant for water quality, with a risk of algal blooms.

There was also a significant trend of increasing e. Coli levels in the lagoon.

More comprehensive monitoring of the lagoon was recommended.

All the monitored sites were highly impacted by sediment, reflecting the extensive erosion issues in the catchment.

The levels were such that they represented high to extreme stress for the aquatic ecosystem health.

“Erosion is the issue of this catchment,” she said. “It has got the highest rates of erosion in New Zealand.”

That meant there were very high levels of suspended sediment, a tremendous amount of which went down these rivers.

But in terms of the health of the rivers, that was taken away by heavy rain.

The catchment had some of the best health of streams in the region, notably the headwater streams in the Raukumara Ranges.

Ms Easton said the report was intended to provide an update on water quality and quantity issues for the river in preparation for a catchment plan.

The Waiapu was the second largest catchment in the district, with an area of 1730 square kilometres and seven major tributaries, as well as the Waiapu River.

It was subject to a joint management agreement between Gisborne District Council and Te Runanganui o Ngati Porou.

There were only two consented water takes in the catchment and a large number of water resources existed; potentially 2000 litres per second in the Waiapu River and 500l/s in the Mata.

There were shallow groundwater aquifers under Tikitiki and Takamore, potentially 450l/s.

The Waiapu groundwater system is a potential source of groundwater thought to be as large and complex as that under the Poverty Bay Flats.

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