The Dam

The dam uses nature’s delivery system – rivers – to supply water from the upstream reservoir to the rivers downstream, and then to the aquifers that supply Waimea’s plains and bores.  

Rainfall is caught and stored, with the water’s release managed in times of need, to maintain sufficient flows in the Lee and Waimea rivers. 

Maintaining higher river flows and aquifer levels during droughts also protects the overall health of the river, which is essential for river plants and fish and eel species, and lowers the risk of coastal saltwater seeping into the aquifers and damaging potable water supply. 

Behind the dam, the 13 million m3 reservoir – gifted the name Te Kurawai o Pūhanga by Ngāti Koata in 2023 – spreads over 68 hectares within the Richmond Ranges, below Mt Rintoul. From the dam, the reservoir extends southeast approximately 4.5 kilometres up the Lee River and branches into Waterfall Creek and Flat Creek. The reservoir is large enough to maintain sufficient river flow and aquifer recharge to mitigate the impact of a drought greater than a 1:50-year event across much of the Waimea Plains. 

The flow from the dam supports 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, and benefit from the recharged aquifers. 

The dam provides three key benefits. Firstly, having a reliable water supply supports the urban population of the fast-growing Richmond and Waimea areas. Secondly, the irrigators of the Waimea Plains benefit from water security, driving our primary industry and supporting our wider region’s economy. And thirdly, the environment – higher river levels improves river health 

• Water security. The dam significantly reduces the risk of water shortages and gives the region confidence to grow and plan for the future, knowing a stable water supply is in place as the population grows. 

• Economic benefit. The Waimea Plains are among the South Island’s most fertile and productive lands and is considered a region of national strategic importance for New Zealand’s horticulture. Water security means continued growth in primary production, benefiting everyone in the region through jobs, exports, and a stronger economy. A reliable water supply underpins a wide network of industries – everything from food processing and packaging, fibre processing, transport, technology, research, and business services that support agriculture.  

• Healthy rivers. By releasing water strategically, the dam maintains a minimum flow of about 1,100 litres per second at the end of the Waimea River even during dry periods​. A higher base flow means improved river and wetland health – water stays cooler and cleaner, supporting fish populations and other aquatic life​. It also prevents saltwater intrusion into groundwater aquifers.