Under this permitting program, environmental impacts are to be avoided if possible, reduced and mitigated if necessary. Permits are limited to a maximum period of five years and use public notice and comment procedures. While the U.S. Army Corps of Engineers issues the permit, responsibility for enforcement is shared between the U.S. Army Corps of Engineers and the EPA. However, the scope of what constitutes a wetland and thus what falls under CWA command and control regulation has changed over time. Two recent Supreme Court decisions have impacted the definition of wetlands under the Clean Water Act:    Additional federal policy instruments include private-public sector collaborations such as educational efforts, conservation easement programs, land banking, and numerous voluntary programs. States government tools for addressing wetland protection, include but not limited to:  Local Wetland Protection  Local governments tools for addressing wetland protection, include but are not limited to: