15 December 2010

The growing number of low flow irrigation bans on Hawke’s Bay’s rivers and streams may be later than usual for summer, but Hawke’s Bay Regional Council is concerned at how quickly rivers are dropping after the drier than normal November.

With other regions of the country experiencing drought conditions, the Regional Council is concerned that there may be an expectation to truck stock into Hawke’s Bay for pasturing.

“There is a cover of green in many parts of the region which may look OK, but soil moisture levels are dropping fast and there is no real growth now,” said Mike Adye, Group Manager Asset Management.

Thunderstorms brought rain in patches to the Heretaunga Plains area yesterday and up to 20-40mm of rain is forecast for the coming weekend which may be widespread and temporarily relieve soil moisture and river levels. The Council will continue to monitor the conditions and keep growers informed.

This pattern is similar to the start of summer in 2009, with a wet spring leading to a later than usual dry period. All catchments had below average rainfall for November, with only 40% of normal rainfall region-wide (ranging from 22% in the Ruahines to 62% in Northern Hawke’s Bay). Rainfall in December to date has been up to 38mm in the Waikaremoana and northern Hawke’s Bay areas and 5-10mm on the Plains. We’re ranging from 2% of normal December rainfall in the Kawekas to 18% in Northern Hawke’s Bay and around the 10-12% mark elsewhere.

Soil moisture levels dropped in November and are now down to 4.4% at Bridge Pa, 11.7% at Ongaonga and 15-20% elsewhere. Bridge Pa is lower than mid-Dec of the past 4 years and becoming one of the driest elsewhere. Soil temperatures seem about average, mostly around the 20oC mark.

Irrigators are reminded to double check their resource consents to ensure they are fully aware what their takes are, the monitoring sites these are linked to, and the low flow restriction that applies to their takes.

Irrigation bans now in force in Hawke’s Bay -
• Ngaruroro River (takes from Whanawhana monitoring site in upper reaches only)
• Maraekakaho Stream (takes linked to 350 litres / sec and 300 litres/sec minimum flow)
• Karewarewa Stream
• Mangateretere Stream (takes linked to 150l/s min flow)
• Makaretu Stream (takes linked to 1300l/s min flow)
• Waipawa River (takes linked to SH2 monitoring site for 4000l/s, 3700 l/s, 3600 l/s min flow)
• Tukituki River (Tapairu Road site 5000 l/s min flow).

Warnings are on the Maraekakaho Stream (250l/s limit), Te Waikaha, Mangateretere (100l/sec), Waipawa River (SH2 site for 3400l/s, 3000l/s) and Tukituki (Tapairu Road 3000 l/s).

Regional Councils set minimum flow levels on resource consents for irrigation water takes from rivers and streams so that a water flow can be maintained to protect stream life and habitats. Hawke’s Bay Regional Council staff monitor the levels closely from October and contact consent holders to alert them when river levels are approaching the low flow irrigation ban limits.

ENDS

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