There is mounting concern over the source and genetic history of plants used in restoration projects. This is because genetic mixing between remnant native plants and introduced nonlocal plants can have positive or negative effects on population fitness. In the past, nonlocal beach grass, Ammophila breviligulata, from Michigan were planted near remnant native populations at Park Point in Duluth as a component of dune restoration. This publication reports on efforts to assess the potential impact of these historical plantings. The authors conclude that Michigan genotypes may outcompete or swamp threatened Minnesota genotypes as a result of vegetative and reproductive fitness advantages. If Michigan plants begin to dominate Park Point, there will be an overall loss of genetic diversity. The authors recommend that local genotypes be used for all future dune restoration projects at Park Point.