WHAKATANE District Council is preparing for possible salt water contamination of the water supply with king tides expected in the Bay of Plenty.
With the upriver emergency intake used once already this week, council public affairs manager Ross Boreham said the potential for water issues from king tides had increased.
“When salinity becomes an issue, it limits intake from the river and therefore the processing capacity of the treatment plant.
“The emergency intake, which is about a kilometre upstream, partially offsets that,” he said.
“With higher than usual spring tides due over the next week and a half, no rain in the forecast and the river flow steadily reducing, people in both communities will need to keep conserving as much water as possible if we are to avoid the introduction of formal restrictions,” he said.
Bay of Plenty Regional Council data services manager Glenn Ellery said rainfall in the region was between 25 percent and 85 percent of the long term monthly normal over January.
“At this point, February is following a similar trend. At a third of our way through the month, there has been little to no rainfall occurring across the majority of the regional council area, the exception being some minor localised rain activity at the periphery of the region,” he said.
“The extended period of hot weather is showing its effects in the Bay of Plenty, with lowering soil moisture levels and receding river levels.”
Though river levels have been receding, Mr Ellery said they were not yet at mean annual low flows.
“However, some of the smaller streams that are predominately fed by surface run-off, rather than ground water, are significantly lower due to the reduced soil moisture levels being experienced,” he said.
Mr Boreham said voluntary water conservation measures had helped maintain adequate storage in the reservoirs supplying Whakatane and Ohope but that could change.
“If demand does exceed our ability to supply, we will have to bring in formal water use restrictions,” he said.
“We haven’t needed to introduce formal restrictions in recent years because voluntarily water conservation has allowed us to maintain a safe level of storage.”
He said water usage in Whakatane and Ohope had steadily fallen since the council’s recent plea to the public for voluntary water conservation.
“We’re seeing a great response from the community,” he said. “That will need to continue though until we get some significant rain and the river flow increases. No sign of that in the long-range weather forecast at this stage.”
If further water restrictions were needed, Mr Boreham said it would be implemented in stages.
“In the first instance, that means people are only allowed to use hoses and sprinklers on alternate days. If the situation worsens, a complete ban on hoses and sprinklers would be introduced,” he said.