The first cases of water limit breaches by rural irrigators this summer are being investigated by Hawke's Bay Regional Council as river flows continue to lower.
The council's pollution response and enforcement team leader Wayne Wright said 18 consents had used more than 5 per cent of their allowable water volume during December.
"These range from a 100cu m additional to 1500cu m of water being taken on top of their consented limits. Each breach will be investigated and enforcement action will be taken if deemed appropriate.
"Every breach is dealt with on a case by case basis. There were three under 5 per cent and these will receive advice or warning letters."
The council said it would take a harder line on irrigators who used more than their quota of water this summer. It required all water users to install meters and Mr Wright said there were 85 consents which had not confirmed whether they had meters installed, affecting 75 consent holders.
"The only requirements in the regulations for meter installations is they must be +/-5 per cent accurate and suited to the water quality.
"No meters have been identified this year as not meeting the accuracy requirement as we are yet to find a viable way of testing the accuracy of meters in situ, this has been a nationwide issue. The approved installers have ensured that the meters being installed are appropriate for the water quality."
The council's "state of our environment" report for December said the temperature was near average with rain, river flows and soil moisture all "near to below normal".
The hottest daily temperature for December was 32.2C recorded at Bridge Pa, Hastings. The lowest daily temperature for the month was -2.7C recorded at Taharua north of Napier.
The Heretaunga Plains received 38 per cent of its normal December rainfall which was the lowest in the region, just below northern Hawke's Bay on 39 per cent. The Ruahine Ranges however recorded 105 per cent and the average for the Hawke's Bay region was 62 pre cent of normal December rainfall.
River flows were lower than usual in most areas after four months of below normal rainfall, with the Heretaunga Plains (33 per cent) and the Tukituki River (33 per cent) the lowest in the region.