Rivers at near minimum levels

Dave Stewart.
Dave Stewart.
A close watch is being kept on Otago rivers as they drop steadily and little relief from rain is in sight.

The Otago Regional Council announced yesterday it was monitoring the rivers as they dropped nearly to minimum flow levels, especially in North Otago and the headwaters of the Taieri River.

Others with flows below normal for the time of year also included the lower Taieri, Manuherikia and Shotover rivers.

A lack of rain and increasing domestic demand for water also meant the Dunedin City Council was keeping a closer eye on its water supply.

Regional council environmental monitoring and operations director Jeff Donaldson said while rain was expected over the next few days, the predicted amounts were unlikely to reduce pressure on river levels.

''A reasonable spell of dry weather still has the potential to quickly reduce many rivers to minimum flow levels. Most other rivers throughout the region are in steady decline.''

The situation meant farmers needed to continue to manage their irrigation efficiently, and plan ahead in case the need for rationing arose, he said.

Hydrologist Dave Stewart said rivers in the North Otago and Central Otago areas had received little rain in the past few months because of the mostly westerly weather patterns.

''The wind in November quickly dried things out, too.''

The rain predicted for next week might bring a thunderstorm or a heavy shower, but it would raise river levels for only a day or so, he said.

''We need widespread rain that is not too heavy, so it will soak into the ground.''

In contrast, South Otago farmers would be enjoying the warmer weather after their recent soaking. However, flows in their rivers were also starting to drop.

If the fine weather continued it would not be long before the lower Taieri would also be joining the ranks of minimum flow contenders, he said.

The dry conditions had come earlier this year but it was not unheard of.

''Sometimes when we get an early dry spell, the rains return in late January or February to lift us out but this year has been so unusual ...

''A weak El Nino would only compound the situation as it produced more rain in the west and a drier east and would mean the coast from Dunedin south would also start to dry out.

Dunedin City Council water operations team leader Gerard McCombie said conditions were starting to ''tighten up'' with its water supply systems at Deep Stream, Deep Creek and the Waikouaiti River.

''Sufficient water is coming in to meet demand. We could do with a little bit of rain to lift flows.''

Demand on the water plant at Mt Grand and from Mosgiel's bores had also increased in the past four days as the weather warmed and the winds dried things out, Mr McCombie said.

It was timely to remind people not to waste water when watering their gardens by leaving sprinklers on for longer than necessary or by watering pavement verges.

rebecca.fox@odt.co.nz

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