Review of Grasse River Lake Sturgeon habitat use and possible post-Superfund remediation agency actions

The Grass River (hereafter Grasse River) historically served as a major source of fisheries production for the Saint Lawrence River (hereafter St. Lawrence River) basin, providing critical spawning habitat and support for other life history stages of numerous species including the culturally and ecologically significant Lake Sturgeon (Acipenser fulvescens). Decades of environmental degradation resulted in designation of the lower Grasse River as the Grasse River Superfund site and part of the St. Lawrence River Area of Concern (AOC) at Massena/Akwesasne. The primary problems were severe contamination of sediments and fish, with numerous environmental beneficial use impairments (BUIs) including losses and degradation of habitat and diminished animal populations that limited fisheries production and reduced ecosystem services provided by the Grasse River. Efforts to restore the lower Grasse River within the AOC were initiated in 2019 to remove or isolate contaminants, repair damaged habitats, and rebuild fish and wildlife populations. The purpose of this report is to 1) summarize the history and contemporary status of environmental conditions and fisheries in the Grasse River, with an emphasis on Lake Sturgeon; 2) summarize remediation and restoration activities and how they may affect fisheries habitat and populations; and 3) discuss potential options for continued habitat remediation in addition to currently proposed restoration actions.