The Future of Water Quality in Coeur d'Alene Lake (2022) / Chapter Skim
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9 Risks of Metals Contamination in Coeur d'Alene Lake
9 Risks of Metals Contamination in Coeur d'Alene Lake
Pages 259-302
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From page 259... ...
This was premised on the possibility that nutrient inputs to the Lake may be increasing, which might promote growth of algae and consequently lead to low oxygen conditions in the Lake that could promote release of sediment-bound metals. The remedy for the Bunker Hill Superfund site was based on removing sources of metals contamination and/or breaking exposure pathways linking metals to human and ecological receptors in the CDA Lake watershed.
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From page 260... ...
The following sections briefly summarize conclusions from the 2001 HHRA, the 2005 NRC study and the latest five-year review (EPA Region 10, 2021) as they might apply to human health exposure pathways relevant to CDA Lake.
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From page 261... ...
. EPA has not yet changed its national lead health risk policy; thus, the remediation action objective for the CDA basin remains at a mean BLL of 10 mg/dL (EPA Region 10, 2021)
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From page 262... ...
. Declines in average lead concentrations in domestic dust and soils in the CDA basin have been accompanied by a downward trajectory in blood lead levels of children ages 0–9.
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From page 263... ...
concluded that "97 percent of eligible parcels have been sampled and remediation is 93 percent complete" in the lower basin. Although property remediation is nearly complete in the watershed and overall community geometric mean soil lead concentrations and house dust lead concentrations are lower than the action levels, some pathways of exposure still pose risks (EPA Region 10, 2021)
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From page 264... ...
These include human exposure to contaminated lake water and lake sediments -- in particular, those whose work or recreation involves incidental exposure to suspended or bed sediments in the Lake, eating fish from the Lake, and other dietary exposure pathways related to subsistence lifestyles. TABLE 9-1 Number of Children Tested for Blood Lead Levels and Percent Exceedances of the 2012 CDC Reference Level of 5 mg/dL OU-3 Lower Basin Year Number of children 0–9 % > 5 mg/dL Number of children 0–9 % > 5 mg/dL 2015 94 6% 2 ND 2016 70 8% 8 38% 2017 105 22% 3 0% 2018 88 7% 5 0% 2019 84 7% 5 20% SOURCE: EPA Region 10 (2021)
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From page 265... ...
These include development of a shoreline-specific soil/sediment lead exposure level, updated evaluations of recreational exposures in common-use areas, better understanding of effects of flooding and flood control in lakeside recreational areas, and improved participation in blood lead testing. A thorough Lake-wide survey of lead concentrations in fine-grained fractions of shoreline soils and sediments could be a first step in determining whether and where further risk assessment would be of value, especially near areas of greatest recreational use.
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From page 266... ...
Routes of Exposure The Superfund remedy considers human exposure to arsenic in the CDA basin via a number of pathways that are the same as with lead, including ingestion of arsenic from contaminated soil and sediment in residential, commercial, and undeveloped areas; and inhalation of contaminated airborne dust generated at these locations. Ingestion of arsenic from drinking water wells is an exposure pathway less relevant to lead that has been explored in the CDA basin, as evidenced by the evaluation of private wells in OU-3 for arsenic contamination (EPA Region 10, 2021, Table 6-2)
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From page 267... ...
Water withdrawals from the Spokane Valley-Rathdrum Prairie Aquifer are anticipated to increase in the future as development in the region continues. As such, to the extent that in the future areas in and/or near the northern bays of CDA Lake could experience anoxic conditions and release of metals of significance to human health, such as arsenic, there exists a potential pathway for water quality in CDA Lake to impact water supplies outside the Lake area.
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From page 268... ...
and global (e.g., combustion) sources, but once present in a watershed, it presents a risk to aquatic food webs and humans who consume animals from those food webs.
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From page 269... ...
In a 2009 national study conducted by EPA, 48.8 percent of lakes in the United States exceeded the EPA's recommended tissue-based mercury water quality standard of 0.3 mg/kg wet weight.5 In all of Idaho there are 341 river miles and more than 143,000 acres of lake that are listed as being impaired by mercury. The detection of greater than 0.3 mg/kg of mercury in fish (four of 30 samples in the northern Lake, seven of 40 in the central Lake)
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From page 270... ...
Note that these results represent a search for all data in the USGS National Water Information System database with mercury-related parameter codes (any method, any media) for all subwatersheds within the CDA Lake watershed (17010301 -- North Fork CDA River, 17010302 -- South Fork CDA River, 17010303 -- mainstem CDA River and CDA Lake, and 17010304 -- St.
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From page 271... ...
Understanding the potential processes that may lead to HABs is key to predicting whether they might play a role in CDA Lake water quality in the future. One process involves production of reactive oxygen species (ROS)
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From page 272... ...
But occurrence of the conditions conducive to such blooms in protected localities, some littoral habitats of the Lake, or in the lateral lakes, could be enhanced by the presence of metal contamination. Monitoring such locations could provide an early warning about the beginnings of more-widespread conditions conducive to HAB formation.
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From page 273... ...
Similarly, an event of higher probability is an increase in FAB resulting in localized degradation of water quality in nearshore Lake regions most often used by humans. ECOLOGICAL HEALTH Although the greatest concern for the ecological health of lakes has traditionally been eutrophication driven by excess nutrients, in CDA Lake, the ecology is threatened by profound contamination with heavy metals, including arsenic, cadmium, lead, and zinc.
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From page 274... ...
. Loss of taxa from a community also can affect interactions among taxa and food webs, cascading into broader effects on the ecosystem.
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From page 275... ...
Data on Ecological Risks from Metals in Coeur d'Alene Lake Understanding how the CDA Lake ecosystem will change in response to changes in metal and nutrient inputs and factors like climate change requires knowing the current status of the lake at each level of biological organization, described below using the available information. Exposure: Metal Concentrations The first step in an assessment of ecological health and future risks in CDA Lake is determination of exposure.
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From page 276... ...
Metal concentrations in surface sediments affect the food webs at the bottom of the Lake. Table 9-2 shows metal concentrations in surface sediments of the Lake.
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compared BLM calculations and DGT measurements to dissolved concentrations of cadmium, lead and zinc at seven mining sites in the South Fork of the CDA River and two locations with little contamination. DGT-labile lead was as low as 16 percent of dissolved lead concentrations.
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From page 278... ...
This means that benchmarks based upon total lead in water would overprotect from lead toxicity, all other things being equal. In contrast, nearly all the zinc and cadmium in the South Fork of the CDA River were present as potentially bioavailable free ion and inorganic complexes in most situations (Balistrieri and Blank, 2008; Smith et al., 2015)
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From page 279... ...
(2021) measured arsenic, cadmium, lead, and zinc concentrations in emergent and submergent aquatic macrophytes from three lateral lakes on the CDA River, a reference location in the St.
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9 They determined that incidentally ingested sediments composed ~ 22 percent of the food eaten by swans in the field. The food in the experiments contained 22 percent sediments from the CDA basin with different lead concentrations.
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From page 281... ...
accompanied lead bioaccumulation in ducks fed a diet contaminated with CDA sediments. Ducks and tundra swans that bioaccumulated lead from littoral sediments in the CDA basin had blood lead levels high enough to indicate lead poisoning and also showed depressed levels of d-aminolevulinic acid dehydratase (Blus et al., 1995, 1999; Henny et al., 2000; Spears et al., 2007)
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From page 282... ...
Blood lead from ducks from the Lake was correlated with concentrations of lead in sediments. Blood lead concentrations exceeding thresholds for "clinical poisoning" (> 5 mg/dL)
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From page 283... ...
. Although results from one particular study cannot be directly extrapolated to CDA Lake, they illustrate the complexity of the phytoplankton community responses that might be expected as zinc concentrations change in the Lake.
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From page 284... ...
. The ranges shown in Table 9-4 include criteria used in local studies to assess the meaning of sediment metal concentrations in the CDA basin (Maret et al., 200311)
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From page 285... ...
Their growth can lead to algal blooms and decreased water quality when nutrient inputs increase, frequently from anthropogenic sources (e.g., septic leachate, fertilizer runoff)
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From page 286... ...
Joe River, and two lateral lakes (Benewah Lake, Round Lake) for 2011–2020 (CDA Tribe and Avista Corporation, 2017, and courtesy of D
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From page 287... ...
Based on these data, it is problematic to infer patterns in the temporal dynamics of phytoplankton communities in CDA Lake except to note that since 2007 water quality conditions in terms of phytoplankton biomass and cyanobacteria dominance seem to have improved. Nevertheless, observation of high phytoplankton biomass with cyanobacteria dominance in 2008 indicates the possibility for the Lake to support blooms of potentially harmful cyanobacteria given suitable conditions.
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From page 288... ...
In CDA Lake, highly enriched concentrations of arsenic, cadmium, lead, and zinc are an additional potentially influential variable. Sediments from Lake locations north of C5 have metal concentrations that fall within the window or exceed the window predicting toxicity according to sediment quality criteria (EcoAnalysts, Inc., 2017; Table 9-4)
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From page 289... ...
Metal concentrations generally increased with depth, but there was no simple correlation between metal concen trations and any measure of community structure. Principal components and community similarity analyses were used to assess influences of roughly co-varying depth and metal concentration and showed a stronger relationship with depth than with metals (EcoAnalysts, Inc., 2017)
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From page 290... ...
Joe River (which was unaffected by mineral extraction activities) in CDA Lake (green bar)
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From page 291... ...
But it is nevertheless important to define expectations of ecological health or benefits from ecosystem services that would derive from reducing metal impacts. Is remediation complete when the EPA's National Ambient Water Quality Criteria (AWQC)
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From page 292... ...
to correct for local water quality conditions and calculated the appropriate range of benchmarks to be 18–27 mg Zn/L for CDA Lake. Thus, a single target concentration for cleanup is useful pragmatically, but it likely reflects jurisdictional interpretations of water quality and is not necessarily indicative of a threshold for ecological effects in a region.
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From page 293... ...
These studies evaluated dietary and dissolved metal bioavailability in concert with evaluation of effects on the community. Both were conducted under water quality conditions typical of streams in the CDA basin.
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From page 294... ...
These would include goals for the Lake ecosystem and ecosystem services and targets for metal concentrations below which such goals could be achieved. Different goals (e.g., compliance with state law vs.
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2017. Modernizing water quality criteria in the United States: A need to expand the definition of acceptable data.
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2016. Aquatic Life Ambient Water Quality Criteria Cadmium–2016.
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2006. A rationale for lowering the blood lead action level from 10 to 2 mg/dL.
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From page 298... ...
2016. The effects of ambient water quality and Eurasian watermilfoil on lakefront property values in the Coeur d'Alene area of northern Idaho, USA.
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2011. Ethical issues in using children's blood lead levels as a remedial action objective.
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2007. Blood lead concentrations in waterfowl utilizing Lake Coeur d'Alene, Idaho.
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2002. Fishes as integrators of benthic and pelagic food webs in lakes.
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