In situations where the impact of facility operations on the local environment is highly influenced by the meteorological conditions, it may be impossible or economically prohibitive to operate the facility so as to meet the regulations all of the time for normal operating conditions. In such situations it is possible to manage facility operations based on the prediction of the conditions which lead to violation, curtailing operations or rescheduling operations in order to ensure that the operation remains in compliance. CEMC has designed and implemented supplementary control systems for a number of facilities, including Vale Inco and Thompson, Falconbridge in Sudbury, Algoma Ore, Noranda Horne and Gaspé, and Cominco Trail. We offer support of supplementary control systems by training operators, providing forecast and data products, and assisting in negotiations with regulatory agencies.