In 2019, the U.S. Geological Survey (USGS), in cooperation with the National Park Service, initiated a study using surrogate technology to predict real-time metallic-contaminant concentrations (MCCs) in the Clark Fork at two USGS streamgages that bracket Grant-Kohrs Ranch National Historic Site (GRKO) near Deer Lodge, Montana. Clark Fork at Deer Lodge(streamgage 12324200), Mont., about one mile upstream from GRKO, and Clark Fork above Little Blackfoot River near Garrison (streamgage 12324400), Mont., about 12 miles downstream from GRKO property were instrumented with turbidity and acoustic sensors for monitoring the Clark Fork during National Park Service Superfund remediation activities. Time-series data from backscatter signals from fixed-point turbidity and acoustic sensors were correlated with discrete MCC samples collected from the Clark Fork and were used as surrogates for estimating real-time cadmium, copper, iron, lead, manganese, zinc, and the metalloid trace element arsenic. A stepwise regression approach was used to develop statistical models to predict MCCs based on instantaneous values of turbidity and acoustic backscatter. Simple linear regression models using turbidity as the sole explanatory variable produced the best models with R-squared values exceeding 0.90 in 9 of 12 models. Nash-Sutcliffe Efficiency values were used to evaluate the effectiveness of predictive models to approximate measured MCCs, and model biases were calculated as an additional check on model accuracy. The R-LOADEST statistical package was used to compute annual and daily metallic-contaminant loads along with 95-percent prediction intervals. R-LOADEST loads were compared to time-series computed loads to evaluate the applicability of time-series data for calculating daily and annual metallic-contaminant loads. Results from annual load estimates indicated an increase in loads for all metallic contaminants between the two monitoring sites. These results provided real-time information to National Park Service management for evaluating variation in water quality during Superfund remediation, comparing MCC values relative to aquatic life standards, and will help quantify benefits from Superfund remediation activities.

In 2019, the U.S. Geological Survey (USGS), in cooperation with the National Park Service(NPS), initiated a study using surrogate technology to predict real-time metallic-contaminant concentrations (MCCs) in the Clark Fork at two USGS streamgages that bracket Grant-Kohrs Ranch National Historic Site (GRKO) near Deer Lodge, Montana. Clark Fork at Deer Lodge (streamgage 12324200), Mont., about one mile upstream from GRKO, and Clark Fork above Little Blackfoot River near Garrison (streamgage 12324400), Mont., about 12 miles downstream from GRKO property were instrumented with turbidity and acoustic sensors for monitoring the Clark Fork during NPS Superfund remediation activities. Time-series data from backscatter signals from fixed-point turbidity and acoustic sensors were correlated with discrete MCC samples collected from the Clark Fork and were used as surrogates for estimating real-time cadmium, copper, iron, lead, manganese, zinc, and the metalloid trace element arsenic. A stepwise regression approach was used to develop statistical models to predict MCCs based on instantaneous values of turbidity and acoustic backscatter. Simple linear regression (SLR) models using turbidity as the sole explanatory variable produced the best models with R-squared values exceeding 0.90 in 9 of 12 models. Nash-Sutcliffe Efficiency values were used to evaluate the effectiveness of predictive models to approximate measured MCCs, and model biases were calculated as an additional check on model accuracy. The R-LOADEST statistical package was used to compute annual and daily metallic-contaminant loads (MCLs) along with 95-percent prediction intervals. R-LOADEST loads were compared to time-series computed loads to evaluate the applicability of time-series data for calculating daily and annual MCLs. Results from annual load estimates indicated an increase in loads for all metallic contaminants between the two monitoring sites. These results provided real-time information to NPS management for evaluating variation in water quality during Superfund remediation, comparing MCC values relative to aquatic life standards, and will help quantify benefits from NPS remediation activities.

In 2019, the U.S. Geological Survey (USGS), in cooperation with the National Park Service(NPS), initiated a study using surrogate technology to predict real-time metallic-contaminant concentrations (MCCs) in the Clark Fork at two USGS streamgages that bracket Grant-Kohrs Ranch National Historic Site (GRKO) near Deer Lodge, Montana. Clark Fork at Deer Lodge (streamgage 12324200), Mont., about one mile upstream from GRKO, and Clark Fork above Little Blackfoot River near Garrison (streamgage 12324400), Mont., about 12 miles downstream from GRKO property were instrumented with turbidity and acoustic sensors for monitoring the Clark Fork during NPS Superfund remediation activities. Time-series data from backscatter signals from fixed-point turbidity and acoustic sensors were correlated with discrete MCC samples collected from the Clark Fork and were used as surrogates for estimating real-time cadmium, copper, iron, lead, manganese, zinc, and the metalloid trace element arsenic. A stepwise regression approach was used to develop statistical models to predict MCCs based on instantaneous values of turbidity and acoustic backscatter. Simple linear regression (SLR) models using turbidity as the sole explanatory variable produced the best models with R-squared values exceeding 0.90 in 9 of 12 models. Nash-Sutcliffe Efficiency values were used to evaluate the effectiveness of predictive models to approximate measured MCCs, and model biases were calculated as an additional check on model accuracy. The R-LOADEST statistical package was used to compute annual and daily metallic-contaminant loads (MCLs) along with 95-percent prediction intervals. R-LOADEST loads were compared to time-series computed loads to evaluate the applicability of time-series data for calculating daily and annual MCLs. Results from annual load estimates indicated an increase in loads for all metallic contaminants between the two monitoring sites. These results provided real-time information to NPS management for evaluating variation in water quality during Superfund remediation, comparing MCC values relative to aquatic life standards, and will help quantify benefits from NPS remediation activities.

Legacy mine waste from the Clark Fork River in Western Montana has contributed 100 million tons of tailings into the watershed between 1880 and 1982 (E.D. Andrews, Longitudinal dispersion of metals in the Clark Fork River, Montana, Lewis Publishers, 1987). Tailings deposited along the floodplain, streambanks and river channel continue to contribute metal contaminated material into the river in the form of metal-enriched particulate matter or seston, comprising a mixture of organic and inorganic materials (J.N. Moore and S.N. Luoma, Hazardous wastes from large-scale metal extraction: A case study. Environmental Science and Technology, v.24:1278-1285, 1990). Metal enriched seston poses a dietary exposure risk to filter-feeding macroinvertebrates that entrap and ingest suspended materials as a primary food source. Suspended particulate material and dissolved and total recoverable water samples were collected along a metal contamination gradient in 2017 and 2018 in the Clark Fork River and analyzed for metal concentrations to include the highly toxic metals arsenic, cadmium, and copper. Concentrations of seston arsenic (As), cadmium (Cd), and copper (Cu) ranged from 20.7–242 ug As/g, 2.7–16.2 ug Cd/g, and 129–1260 ug Cu/g. Dissolved (filtered) stream water concentrations ranged from 3.5–21.7 ug As/L, 0.1–0.38 ug Cd/L, and 1.5–12.5 ug Cu/L. Total recoverable (unfiltered) water concentrations ranged from 2.7–22.8 ug As/L, 0.1–0.35 ug Cd/L, and 2.0–14.9 ug Cu/L. Data presented here represent metal concentrations in water and seston from a mining-impacted river and provide insight to potential exposure of toxic metals to resident filter-feeding aquatic invertebrates.

Legacy mine waste from the Clark Fork River in Western Montana has contributed 100 million tons of tailings into the watershed between 1880 and 1982 (E.D. Andrews, Longitudinal dispersion of metals in the Clark Fork River, Montana, Lewis Publishers, 1987). Tailings deposited along the floodplain, streambanks and river channel continue to contribute metal contaminated material into the river in the form of metal-enriched particulate matter or seston, comprising a mixture of organic and inorganic materials (J.N. Moore and S.N. Luoma, Hazardous wastes from large-scale metal extraction: A case study. Environmental Science and Technology, v.24:1278-1285, 1990). Metal enriched seston poses a dietary exposure risk to filter-feeding macroinvertebrates that entrap and ingest suspended materials as a primary food source. Suspended particulate material and dissolved and total recoverable water samples were collected along a metal contamination gradient in 2017 and 2018 in the Clark Fork River and analyzed for metal concentrations to include the highly toxic metals arsenic, cadmium, and copper. Concentrations of seston arsenic (As), cadmium (Cd), and copper (Cu) ranged from 20.7–242 ug As/g, 2.7–16.2 ug Cd/g, and 129–1260 ug Cu/g. Dissolved (filtered) stream water concentrations ranged from 3.5–21.7 ug As/L, 0.1–0.38 ug Cd/L, and 1.5–12.5 ug Cu/L. Total recoverable (unfiltered) water concentrations ranged from 2.7–22.8 ug As/L, 0.1–0.35 ug Cd/L, and 2.0–14.9 ug Cu/L. Data presented here represent metal concentrations in water and seston from a mining-impacted river and provide insight to potential exposure of toxic metals to resident filter-feeding aquatic invertebrates.

Weighted Regression on Time, Discharge and Season (WRTDS) and WRTDS with Kalman filtering (WRTDS_K) models were developed for total and dissolved cadmium, zinc and lead; total phosphorus and nitrogen; and dissolved orthophosphate at twelve sites in the Spokane River watershed, northern Idaho, for water years 1990 to 2018. The data table contains the annual mean concentrations and annual total loads estimated by WRTDS_K, and the flow-normalized annual mean concentrations and flow-normalized annual total loads estimated by WRTDS for each modeled site and constituent.

Weighted Regression on Time, Discharge and Season (WRTDS) and WRTDS with Kalman filtering (WRTDS_K) models were developed for total and dissolved cadmium, zinc and lead; total phosphorus and nitrogen; and dissolved orthophosphate at twelve sites in the Spokane River watershed, northern Idaho, for water years 1990 to 2018. The data table contains the annual mean concentrations and annual total loads estimated by WRTDS_K, and the flow-normalized annual mean concentrations and flow-normalized annual total loads estimated by WRTDS for each modeled site and constituent.

The U.S. Geological Survey is monitoring metal concentrations in streambed sediment pre- and post-dam removal in the lower Klamath River basin. Concentrations of aluminum, arsenic, cadmium, cobalt, chromium, copper, iron, potassium, magnesium, manganese, nickel, lead, titanium, vanadium and zinc were sampled at 10 mainstem sites, four tributaries and two reservoirs. Mainstem and tributary collections occurred once annually in 2018, 2019, 2021, 2022 and 2024. Reservoir sediment samples (Copco and Iron Gate) were collected in 2020.

The U.S. Geological Survey is monitoring metal concentrations in streambed sediment pre- and post-dam removal in the lower Klamath River basin. Concentrations of aluminum, arsenic, cadmium, cobalt, chromium, copper, iron, potassium, magnesium, manganese, nickel, lead, titanium, vanadium and zinc were sampled at 10 mainstem sites, four tributaries and two reservoirs. Mainstem and tributary collections occurred once annually in 2018, 2019, 2021, 2022 and 2024. Reservoir sediment samples (Copco and Iron Gate) were collected in 2020.

The U.S. Geological Survey is monitoring metal concentrations in streambed sediment pre- and post-dam removal in the lower Klamath River basin. Concentrations of aluminum, arsenic, cadmium, cobalt, chromium, copper, iron, potassium, magnesium, manganese, nickel, lead, titanium, vanadium and zinc were sampled at 10 mainstem sites, four tributaries and two reservoirs. Mainstem and tributary collections occurred once annually in 2018, 2019, 2021 and 2022. Reservoir sediment samples (Copco and Iron Gate) were collected in 2020.