Diverse situational factors (such as hydrogeological formations and agricultural cropping practices) and the lack of a clear federal mandate present a new challenge to the Environmental Protection Agency and state governments in implementing groundwater protection policy. An implementation regime framework is presented that calls on state and federal administrators to negotiate an informal working relationship that is appropriate for each state. This might include either the traditional implementation of a uniform federal mandate or a program tailored to specific state needs. The success of an implementation regime in achieving its policy objectives is based on the ability of the federal government to frame a clear and consistent message that will reduce state implementors ‘ concerns over federal government intrusion. A regime typology is presented depicting ideal regime types that may be used by the federal government in selecting an appropriate federal message.