When barriers are involved in a river, the Great Lakes Fishery Commission completes an investigation of the entire watershed to determine any sea lamprey spread. The size and complexity of the Grand River and its tributaries present significant challenges and costs associated with conducting Sea Lamprey Control Program activities in the watershed. Investigative field work will take place prior to and during the construction of the AHS. Following construction, an increased level of barrier performance monitoring will commence including trapping of adult sea lampreys, eDNA sampling, and larval assessment. Like most major sea lamprey producing streams, including the Grand River, the monitoring phase is expected to continue in perpetuity. If sea lampreys are found above the AHS, the Great Lakes Fishery Commission is prepared to undertake mitigation measures that include shoring up dams upstream of Grand Rapids (e.g., the Ada Dam, the Weber Dam) to ensure sea lamprey blockage, deployment of portable electric barriers and traps to prevent sea lamprey migration into critical habitat, and lampricide applications to remove sea lamprey larvae from the river and its tributaries.