To reduce the risk of saltwater contamination of water supply bores serving Richmond, the Tasman District Council has used emergency powers to construct a bund across the lower Waimea River.
The gravel bund will allow water to build up behind it, increasing the freshwater pressure to reduce the risk of incoming tides affecting salt levels in the bores.
Tasman District Council acting Engineering Services manager Dwayne Fletcher said king tides were expected this week.
“The tides combined with extremely low freshwater flows in the river put our water supply bores at significant risk, so the bund is needed to protect the water supplies for Richmond, Mapua and Hope, as well as other aquifer water users.”
The Council has used emergency powers under the Resource Management Act to build the bund, which was completed on Friday 15 February.
“We’re taking the lessons we learned in 2001, when two of our production bores had to be shut down permanently due to saltwater contamination, and taking additional measures to protect our water supplies,” Dwayne said.
The bund is temporary and its effects are being monitored weekly by the Council’s water resource scientists.
“Please don’t be tempted to drive over it,” Dwayne said. “We’ve already had reports of vehicles damaging the bund and leaking oil into the river – it’s not there to provide vehicle access across the river, it’s there to try to protect our water supplies through this drought.”