The Mei Te Vai Ki Te Vai project management unit is preparing the full report of its environmental investigations, but we are now certain that groundwater in the Muri catchment is directly connected to water in Muri Lagoon.
Past environmental studies of the Muri Lagoon did not confirm the factors contributing to the lagoon’s water quality, so we decided to undertake further studies to close the remaining information gaps. The extent of connection between groundwater and the lagoon was one of these gaps.
We installed monitoring wells in Muri, conducted ground surveys on Muri beach, and tested water in the lagoon. What this showed was that groundwater, even at very deep levels below the ground, responds to the lagoon tide. There were also chemical indicators of groundwater far out into the lagoon. This proves that groundwater and water in the lagoon are mixing.
This means that toxic material dumped on the ground or in streams can make its way into groundwater and eventually into the lagoon. Examples of common products likely to cause issues are insecticides, weed killer, pharmaceuticals, paint and motor oil.
Improving sanitation infrastructure can help protect groundwater and the lagoon, and we are working towards this, but we also need to take a more conscious approach to choosing products we use on the land.