Canterbury struggling with water quality targets, good progress on irrigation

The Rakaia River in Canterbury.
KIRK HARGREAVES/STUFF

The Rakaia River in Canterbury.

Canterbury is behind on its regional water quality targets, but is making strong progress on irrigation goals.

Rising nitrate levels in drinking water are a particular concern, as are a declining number of river spots suitable for recreation like swimming and kayaking.

Environment Canterbury (ECan) hs released an update on the Canterbury Water Management Strategy (CWMS), which set a series of regional targets in 2009.

Part of the Central Plains Water irrigation scheme.
DEAN KOZANIC/STUFF

Part of the Central Plains Water irrigation scheme.

The strategy was largely directed by the Mayoral Forum, in response to declining water quality and conflict over water allocation. It is a joint agreement across all councils in the region and includes groups such as Ngai Tahu and the Canterbury District Health Board.

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Its latest update shows some water quality targets are well off the mark, while other targets – such as increasing irrigation and water infrastructure – are on track.

The report showed nitrate levels were increasing in about 25 per cent of monitored wells, and decreasing in about 4 per cent.

The target is to show "a demonstrable decrease in nitrate concentrations in shallow groundwater in priority areas" by 2020.

It was a poor result, said Canterbury medical officer of health Dr Alistair Humphrey.

"At this point in time, from a health perspective, it is absolutely disappointing to see that there is not much progress on nitrates, if any," he said.

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"Their [ECan's] own data still shows that nitrates leaching is continuing to climb. It will take a long time to turn around the increasing levels of nitrates in our ground water and surface water. I would like to see more of an emphasis on that."

He said there was a "strange and difficult problem" that the regional council had pledged to both increase irrigation and reduce nitrates.

The balance was leaning towards irrigation rather than protecting drinking water, Humphrey said.

"They announce with some glee that they have achieved irrigation targets but water quality targets are not being met.

"There needs to come a point as a community where we have to make a choice between increasing irrigation and driving up intensification or whether we want to truly commit to reducing nitrates and other contaminants in our ground and surface water."

ECan acting chairman Steve Lowndes said the nitrate issue was a concern.

"It is a source of great frustration that we can't clearly show progress," he said.

"It is not a good result."

He defended the broad rate of progress and said water quality issues took a long time to resolve, due in part to legacy issues.

"If we did it in a radical shift we would put communities out of action," he said.

"We spend most of our time talking about environmental effects. This is an incredibly many-headed best that we are wrestling with."

The report also showed continuing problems with water quality standards for recreation.

From 2015, at least 80 per cent of river bathing sites were supposed to be suitable for recreation. When the target was set, 70 per cent were suitable.

The most recent figure was 58 per cent.

There was also meant to be no further reduction in salmon spawning by 2015, but there "continues to be a significant downward trend in spawning numbers", the report said.

The region was on its way to achieving many other targets, the report showed.

Among them was strong progress in setting catchment level environment limits, which would limit further pollution.

Rules such as those under the recently completed Plan Change 5 would put stricter limits on farming practice, which ECan said would improve water quality.

It was also making "good progress" towards meeting irrigated land area and water reliability targets.

Over five years, the irrigated area in Canterbury increased from 425,000 hectares to 507,000ha. The target is 850,000ha by 2040.

Irrigation had become more efficient, with a substantial move from inefficient border dyke irrigation to more efficient spray systems.

Water reliability had increased through development of on-farm water storage, which had a combined capacity of about 39 million cubic metres.

It was also making "good progress" on its infrastructure targets, relating primarily to water storage and pipes for irrigation schemes.

 - Stuff

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