Waimea Community Dam Running Second Phase of Valve Testing: April 9 and 10, 2024

People are asked to be cautious and preferably stay away from the Lee, Wairoa and Waimea rivers during a second phase of valve tests on Tuesday 9 and Wednesday 10 April, as river levels will rise because of water being released from the Waimea Community Dam.  

A successful managed water release was completed on Thursday 4 and Friday 5 April as part of a testing programme of the two permanent large dispersing cone valves, designed to release water from the reservoir Te Kurawai o Pūhanga in dry periods. Water has already been flowing from the dam through a small dispersing valve since Saturday 2 March, 2024. 

Waimea Water Ltd (WWL) CEO Mike Scott said that the valve testing programme this month is one of the final elements to take place ahead of commissioning the dam. 

He said that each of the two large cone valves has the capacity to release a flow of 10 cumecs, which is about the same as a typical winter flow. 

“During the first testing phase five cumec of water was released on both Thursday 4 April in the afternoon and throughout Friday 5 April, resulting in river levels rising as it might in winter or during a rainfall,” he said. “The public can expect similar river rises on Tuesday and Wednesday next week and so we advise people to stay away from the rivers on these days.

People are advised that the extra flow will cross some beaches that have not been ‘flushed’ for some time, so it’s likely there will be debris and discolouration in the river. This should only last 3 – 4 hours at a time. While it is temporary, people should not enter the river while it is elevated and discoloured. 

People should also not sit or park close to the Lee, Wairoa and Waimea rivers while testing is happening, nor swim or wade, particularly small children. 

“Once the performance of these two dispersing valves is verified, the dam will be fully commissioned and operational,” Scott said. 

Public information about the testing and river level rises has been provided directly to downstream users via text, email or phone, including residents, colleges, Fish & Game. It has also been distributed via media, social media channels, Council’s Antenno alert system, and the WWL website. Posters have also been put up at key river swimming holes, and WWL personnel will be walking the river over the next three days.  

Above: examples of information posters at key river access points downstream of the dam.


How the dam works 

Water released from the Waimea Community Dam complements the natural system by supplementing low river flows to assist recharge of the Waimea aquifers. Assisted recharge of the aquifers maintain water levels for extraction and reduce the risk of saltwater intrusion from the coast. Maintaining higher river flows also improves river health.  

The flow from the dam will support both horticulture and the domestic water wells near Appleby that supply water to the combined Richmond / Nelson water network. Māpua, Ruby Bay, Brightwater and Wakefield also use bores in the Waimea Plains, benefitting from the recharged aquifers.  

The size of the reservoir mitigates the impact of a drought greater than a 1:50 year event.