High weeds can conceal illegal activities, obscure dangerous debris, harbor rodents, serve as a breeding ground for mosquitoes. That's why Streets & Sanitation's Bureau of Street Operations is aggressive about keeping overgrown weeds from becoming a problem in our neighborhoods. Chicago residents should report instances of high weeds in their neighborhoods to 311. In most cases high weeds on vacant lots or in the public way will be cut. In a limited amount of instances where rough or uneven surfaces make traditional cutting difficult or dangerous, crews will use a common herbicide to remove the weeds. While the City feels that we have the necessary safeguards in place to use this spray option, residents with concerns can request a no spray option. You can learn more about this option by selecting the link below.