Trace metal and nutrient loads from groundwater seepage into the South Fork Coeur d’Alene River near Smelterville, northern Idaho, 2017

Abstract

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Trace metal and phosphorus loading from groundwater seepage into South Fork Coeur d’Alene River after remediation at the Bunker Hill Superfund Site, northern Idaho, 2022

“…This report describes results of the 2022 seepage study, specifically focusing on groundwater loading of dissolved zinc, dissolved cadmium, and total phosphorus to the South Fork Coeur d'Alene River. Results of the 2022 seepage study are compared to results of the 2017 USGS seepage study (Zinsser, 2019) to quantify changes in groundwater loading to the South Fork Coeur d'Alene River for dissolved zinc, dissolved cadmium, total phosphorus, and ambient water-quality-criteria (AWQC) ratios, and to describe general water quality pre-and post-remediation via the GWCS within the CIA.…”

“…[Short site names are used for brevity throughout this report, and data can be found on the National Water Information System web interface (U.S. Geological Survey, 2023) using the site numbers provided in this table. Abbreviations: Ave, Avenue; CTP, Central Treatment Plant; SF, south fork; R, river; ID, Idaho; Crk, creek; abv, above; SFCDR, South Fork Coeur d'Alene River; --, no Numerous seepage studies near the CIA have characterized groundwater loading of metals and phosphorus into the Kellogg-to-Smelterville reach of the South Fork Coeur d'Alene River (Barton, 2002;CH2M Hill, 2009;Zinsser, 2019). In this study area, "seepage study" has been used to describe investigations of groundwater discharge to surface water and surface-water recharge of groundwater that occurs in the South Fork Coeur d'Alene River (Barton, 2002;CH2M Hill, 2009;Zinsser, 2019).…”

“…Abbreviations: Ave, Avenue; CTP, Central Treatment Plant; SF, south fork; R, river; ID, Idaho; Crk, creek; abv, above; SFCDR, South Fork Coeur d'Alene River; --, no Numerous seepage studies near the CIA have characterized groundwater loading of metals and phosphorus into the Kellogg-to-Smelterville reach of the South Fork Coeur d'Alene River (Barton, 2002;CH2M Hill, 2009;Zinsser, 2019). In this study area, "seepage study" has been used to describe investigations of groundwater discharge to surface water and surface-water recharge of groundwater that occurs in the South Fork Coeur d'Alene River (Barton, 2002;CH2M Hill, 2009;Zinsser, 2019). Groundwater loading refers to the mass per unit time of a constituent entering the South Fork Coeur d'Alene River from groundwater that discharges to the river.…”

Trends in concentration, loads, and sources of trace metals and nutrients in the Spokane River Watershed, northern Idaho, water years 1990–2018

“…Moreover, surface water and groundwater readily exchange in multiple areas of the Bunker Hill Superfund Site; for example, areas with bedrock constrictions force groundwater into rivers, and areas with bedrock expansions and a bigger alluvial aquifer promote surface water infiltration into groundwater. Such exchanges occur throughout the SFCDR watershed and have been specifically studied in Canyon Creek, the SFCDR near Osburn, and the SFCDR near Smelterville (Barton, 2002;CH2MHILL, 2009a-b;Zinsser, 2019). Secondary sources of metals therefore include soils, sediment, floodplain deposits, groundwater, and surface water that occur throughout the CDR watershed.…”

“…First, as described here, the trends for metal concentrations and loads differ substantially from those for total phosphorus and orthophosphate, which indicates that governing processes for each differ. Second, while there is one identified source of phosphorus associated with mining activities (the phosphoric acid wastes in the Central Impoundment Area), loading from this source has been explicitly estimated (CH2M, 2018;Zinsser, 2019) and represents only a small fraction of the phosphorus present in the CDR system. On average, the modeled phosphorus loading from Central Impoundment Area groundwater to the SFCDR was about 6.5 metric tons per year in WYs 2009-14 (CH2M, 2018), whereas the average annual total phosphorus load in CDR at Harrison over the same time period was about 80 metric tons .…”