Background
Arrowstone Park, located in the Upper Clark Fork River sub-basin in Deer Lodge, MT, was heavily contaminated with mine waste sediments during the catastrophic flood of 1908. During initial cleanup in the late 1990s under the federal Superfund process, contaminated materials were capped rather than removed—a “waste-in-place” strategy intended to prevent exposure. Over time, however, human-driven erosion and natural processes have exposed buried contaminants, including arsenic and lead. These conditions have left local residents unknowingly vulnerable to contamination exposure at Arrowstone, Deer Lodge’s most frequented greenspace and only in-town river access point. Clark Fork Coalition has been working with Powell County and the City of Deer Lodge to advocate for timely contaminant removal, and to fund and implement a post-remedial restoration and redesign of Arrowstone Park based on community needs. The aim of this collaborative project is to improve opportunities for health, wellness, and quality of life for residents of one of the state’s most disadvantaged neighborhoods through improved access to and connection with the Clark Fork River.
In early 2025, the Montana Department of Environmental Quality (DEQ) determined that additional cleanup is needed at Arrowstone after detecting elevated arsenic levels in soils and riverbank areas. Additional remediation will take place in 2027. This renewed scrutiny underscores both the environmental and human health urgency of the project. Clark Fork Coalition and our partners cannot physically remove contamination or fund its removal, but we can watchdog and pressure state and federal agencies to complete remedial actions in a complete and timely fashion, something we have done successfully for decades. Beyond remediation, there is no public funding for rebuilding Arrowstone Park amenities and restoring the river-floodplain connection in a way that fits the needs of the Deer Lodge Community, one of the most disadvantaged in Western MT. Residents have voiced strong interest in ensuring that the Arrowstone Park cleanup process includes transparent communication and long-term protection of human and environmental health.
Latest Update: Spring 2026
In the spring of 2026, the Montana Department of Environmental Quality began sampling in the park in order to fill in data gaps. This sampling effort will cover many areas of the park that have not been adequately sampled during prior efforts, including areas that outside of the channel migration zone that has been used to define cleanup boundaries in other areas along the Clark Fork River. Samples will characterize the amount of contamination on the surface, as well as the depth profile of contaminants. As of June 2026, the threshold levels for arsenic or other contaminants that will be used to determine the cleanup extent have not been released.
The Clark Fork Coalition is working with Powell County and the City of Deer Lodge and other project partners to fund the design and development of a community-centric restoration and reconstruction of Arrowstone Park in a way that directly address inequities in access to healthy outdoor environments, including the Clark Fork River.