Geology topics

Jonathan I. Shikany

Publications and source records attributed to Jonathan I. Shikany.

3 recordsLinked to original sources

USGS2026

Tapwater contaminant mixtures and cumulative risk screening on the Crow (Apsáalooke) Reservation

Introduction: Water insecurity is a challenge for the Apsáalooke (Crow) Tribal Nation in south-central Montana, United States. Both private-well and public-supply tapwater (TW) are vulnerable to a range of contaminants, posing potential risks to community health and well-being. Ongoing community concerns about unrecognized inorganic, organic, and microbial contaminants underscore the need for continued comprehensive monitoring and improved water management strategies. Materials and methods: TW samples were collected from 26 private-well and 12 public-supply participant locations, selected and recruited by the Crow Water Quality Project. A total of 35 inorganic, 450 organic, and three microbial analytes were assessed in these samples. Public-Supply Maximum Contaminant Levels and Health benchmark-based screening levels were used to evaluate contaminant concentrations. Results: Sixty-one organic and 34 inorganic contaminants were detected. Screening levels were frequently exceeded, particularly due to multiple inorganic contaminants in private TW and both chlorine-based disinfection byproducts (DBPs) and inorganics in public TW. These findings highlight gaps in current source-water protection and water treatment practices. Conclusions: After reporting results to participants, anonymized data were shared at community events to inform risk management decisions. The study underscores the importance of broad monitoring and analysis throughout the upper Missouri River basin and across the United States to address Tribal concerns over water insecurity and mitigate potential unrecognized TW contaminant risks, particularly to vulnerable subpopulations.

Montana↗

USGS2026

Detection of Naegleria fowleri in thermally impacted recreational waters of western United States national parks

Naegleria fowleri is a thermophilic free-living amoeba (FLA) and the causative agent of primary amoebic meningoencephalitis, posing public health risks in warm freshwater environments. This multiyear, multiagency study surveyed 40 thermally impacted recreational waters across five western United States national parks and recreation areas–Yellowstone National Park, Grand Teton National Park, Olympic National Park, Newberry National Volcanic Monument, and Lake Mead National Recreation Area–to assess N. fowleri presence, concentration, and associated environmental conditions. A total of 185 water samples were analyzed by qPCR and Sanger sequencing, revealing widespread detection of N. fowleri in 34% of samples with positive detections from Lake Mead, Yellowstone, and Grand Teton hot springs and thermally impacted waters, with concentrations ranging from 4.9 to 115.7 cells/L. Multiple codetections of N. fowleri with nonpathogenic species including Naegleria australiensis were identified, suggesting they may inhabit similar ecological niches in the natural systems in contrast to engineered systems. These findings indicate that N. fowleri is present in thermally impacted areas across the western United States and underscore the use of enhanced monitoring, public awareness, and risk management strategies in thermally influenced recreational waters.

Arizona, Nevada, Oregon, Washington, Wyoming↗

USGS2026

Per- and polyfluoroalkyl substances (PFAS) and other contaminants of concern in tribal waters of Montana

We assessed potential exposures to a broad suite of contaminants (inorganic, organic and microbial) in culturally important surface waters from three watersheds in a northern plains Native American community (Apsáalooke [Crow Tribe of Montana]) in south-central Montana, United States, with water insecurity concerns. Inorganic (37), organic (435) and microbial (3) constituents were assessed in 12 surface water sites from the Pryor Creek ( n = 2), Bighorn River ( n = 2) and Little Bighorn River ( n = 8) valleys. Twenty-six organics, 33 inorganics and Escherichia coli were detected. Despite relatively low concentrations in surface waters within the Crow Reservation, mixture toxicity indicated prevalent chronic ecological effects and human-health secondary contact (recreation) effects at multiple sites. Further, to address Tribal concerns over the prevalence and corresponding risks of per- and polyfluoroalkyl substances (PFAS), we sampled water, sediment, biofilms and fish at a limited number of locations in the Little Bighorn River. Results indicated that PFAS were prevalent in fish tissues, including whole blood and filets, and to a lesser extent in biofilms, despite few detections in water and sediment samples. This is the first attempt to document environmental PFAS contamination within the reservation and the potential human-health concerns for the general population from consumption of recreational/subsistence fish. Overall, this effort provided preliminary information on the contaminant mixtures present and their potential health implications, which can support the protection of community health and culturally meaningful resources across the Crow Reservation.

Montana↗