Blenheim Sewage Treatment Plant

Please be advised that occasionally a green colour may be observed from the discharge at the Blenheim Sewage Treatment Plant.

This is due to algae that grows in the pond system. Algal growth in the pond system helps with the treatment process as algae contribute to oxygen production which is necessary for the breakdown of the sewage.

The presence of algae indicates a healthy pond system; it is not a reflection that the discharge is outside of acceptable parameters.

Council meets all resource consent conditions for this discharge and takes samples three times per month with analysis for up to 40 elements, including BOD, enterococci, suspended solids, nutrients, and a range of heavy metals.

Any discharge is not continuous, the flow from it only occurs an hour after high tide and ceases again an hour before low tide. There is no discharge on an incoming tide. This prevents the plume travelling an upstream and ensures it goes out to sea as quickly as possible.

Council is currently working on renewing the consent to operate this Wastewater Treatment Plant. Council will be speaking with stakeholders and the community while various options for the plant are assessed. Feedback received will help to shape the final renewal application which must be lodged by April 2025.

Reports showing compliance with the resource consent to operate the wastewater treatment ponds can be found on Council’s website.

Go to the Blenheim Sewage Treatment Plant Upgrade page

The latest reports show compliance has been met.