“This year, some people are again claiming that herbicide was used, pointing to ‘lines’ in satellite images as proof. But when you compare the 2020 spray pattern with the March 2026 image, the difference is obvious: Herbicide spraying produces straight, consistent, regular lines, while biocontrol impact causes patchy, irregular, uneven decline.
If a drone pilot produced lines as messy as those in the March 2026 image being circulated, we would seriously question their flying ability,” the CBC said.
“To be clear, the last time water hyacinth was legally sprayed with approved herbicides was before 2017. In 2019, the CBC introduced the inundative biocontrol programme at the dam. Since 2020, the hyacinth mats have collapsed every summer between January and March, including this year, due to the insects,” the CBC said.
“In December 2020, a private group funded a helicopter spray on the western side of the dam. The Department of Water and Sanitation (DWS) stopped the operation halfway, so the spray was never completed,” the CBC said.
“The ‘lines’ people are pointing to now are simply plants dying at different rates due to the insects. This varies naturally with insect numbers, their dispersal across the mat, and daily wind-driven movement of the plants. It is a biological system, not a chemical one.”
