Large-scale agriculture is reliant on the use of chemical pesticides and herbicides to control the onset of pests that would eat the crops and weeds that would out-compete them. However, these chemicals can cause harm to people and animals if they end up in the water supply. Agricultural fields are particularly prone to runoff, and so are likely to leak chemicals into the water. There was not enough data available to score this indicator in any region, but it is an important factor to consider in water quality and overall ecosystem health.

Pesticides are toxic to humans, animals, and plants. Photo by Andy Powell via Flickr CC BY.