Both the federal and state governments have the authority to regulate activities to protect human health and the environment. In implementing the federal environmental statutes, the EPA typically sets the minimum standards that must be met by all the states. States
that have been authorised by the EPA to implement specific federal environmental programmes typically model their laws on federal statutes or may adopt them by reference. States may adhere closely to the federal regulatory standards or set their own, more restrictive standards,
or seek more stringent interpretations of existing federal law.