Dye test in Wellesley will turn Nith River pink temporarily
Posted Sep 8, 2026 12:16:22 PM.
Your eyes won’t be deceiving you if you notice a pink hue in the Nith River in Wellesley this week.
The Region of Waterloo says it needs to conduct a dye test to gather information for future planning in the township.
The colourful dye will be added into the Nith River at the Wellesley Wastewater Treatment Plant (WWTP) between 8 a.m. and 4 p.m. on Wednesday, Sept. 9.
The region says the pink dye is safe and environmentally friendly, and the tests are a common way to monitor how treated water is dispersed and how long it takes to travel downstream.
“The dye dilutes quickly as it moves downstream, doesn’t reduce dissolved oxygen levels in the river, and is safe for people, pets, livestock, aquatic life, and other wildlife,” read a notice shared by both the Region of Waterloo and Township of Wellesley on social media.
The pink hue will be most visible near the WWTP along Gerber Rd. while the testing is carried out.
It’s all part of efforts to develop the Wellesley Water and Wastewater Master Plan, which will look ahead to the next 30 years to accommodate growing needs as the township’s population is projected to grow.
