Animas River Research Articles

River Communities, Disaster Science, and the Politics of Water Safety: Understanding Water Quality Debates in the Aftermath of the Gold King Mine Spill

ABSTRACT After environmental disasters, scientific claims about environmental risk face a paradox. Impacted communities turn to scientific bodies for safety information, yet scientific findings are often challenged publicly in post-disaster debates. This study explores this paradox after the 2015 Gold King Mine spill in the Animas River, USA. We ask how a river is declared “safe” after such a disaster, by whom, and based on what metrics. We examine how scientific claims about water safety were debated in newspapers in three locations: Silverton and Durango, Colorado, and the Navajo Nation. Drawing on Cash et al.’s [Knowledge systems for sustainable development. Proceedings of the National Academy of Sciences, 100(14), 8086–8091. https://do.org/10.1073/pnas.1231332100] key features of science for public decision-making, we find that local debates hinged on issues of salience, credibility, and legitimacy, but these criteria varied in importance across locations. We also argue that these criteria do not sufficiently explain river safety debates. Attention to regulatory and scientific standards used to interpret river safety is necessary for understanding spill responses. Clean Water Act (CWA) standards sidelined public concerns about waterways that fell outside CWA benchmarks. This study highlights the importance of scrutinizing the standards used to deem environments “safe” when producing and communicating disaster science. Key policy highlights Scientific communication after an environmental disaster should be salient, credible, and legitimate. In addition, the scientific and regulatory standards used to deem post-disaster environments “safe” must be scrutinized and their limitations acknowledged. Acknowledging and addressing community-specific concerns and histories – especially those of indigenous communities – is vital in disaster-recovery communication.

Forest fire mobilization and uptake of metals by biota temporarily exacerbates impacts of legacy mining

While wildfires are a natural occurrence and ecosystems have evolved with fire, a changing climate is extending the wildfire season increasing the number, size and severity of fires in the western United States. In 2018, wildfire consumed 30% more area in the Western United States than the average ten years prior, and 76% more area than the average twenty years ago. These recent wildfires have impacted communities in the southwestern Rocky Mountains. In 2018, the 416 Fire, burned over 21,000 ha of public and private lands in southwestern Colorado. The 416 Fire is uniquely located in a legacy mine region in Colorado. The fire occurred in the Animas River watershed, which was already recovering from impacts of the Gold King Mine release of 2015. Three years of water quality monitoring after the 416 Fire have demonstrated elevated total and dissolved metal concentrations downstream of the burn area in Hermosa Creek and the Animas River. Following high-intensity rainstorm events, concentrations of metals such as aluminum, cadmium, iron, lead, manganese and zinc were significantly higher compared to pre-fire conditions in the burned watershed, and several metals often exceeded water quality standards for aquatic life. Macroinvertebrate monitoring in the Animas River and the main fire-impacted tributary indicate substantially altered insect communities. Macroinvertebrate tissue samples, with high concentrations of aluminum, iron, lead and nickel provide evidence that metals observed in the water column of fire-impacted streams were transferred to the benthic communities. In contrast, algae tissue from below the fire did not have elevated metals. High sediment volumes with absorbed metals from mineral rich and mined hillsides were transported to the streams and their aquatic ecosystems after the fire. Results from this study highlight the post-fire mobilization of naturally occurring metals to streams that already experience elevated metals from legacy mines, and will help in development of mitigation efforts in downstream communities.

Review: Gold Metal Waters: Gold Metal Waters: The Animas River and the Gold King Mine Spill

Review: Gold Metal Waters: Gold Metal Waters: The Animas River and the Gold King Mine Spill

Effects of hydrologic variability and remedial actions on first flush and metal loading from streams draining the Silverton caldera, 1992–2014

AbstractThis study examined water quality in the upper Animas River watershed, a mined watershed that gained notoriety following the 2015 Gold King mine release of acid mine drainage to downstream communities. Water‐quality data were used to evaluate trends in metal concentrations and loads over a two‐decade period. Selected sites included three sites on tributary streams and one main‐stem site on the Animas River downstream from the tributary confluences. During the study period, metal concentrations and loads varied seasonally and annually because of hydrologic variability and remedial actions designed to ameliorate the effects of acid mine drainage. Water‐quality data were divided into two periods based on the timing of remedial activities in the watershed. The first period includes active water treatment, surface reclamation and installation of bulkheads in adits; the second period includes the decade following these activities. Water‐quality data were used to estimate annual and monthly zinc loads using the Adjusted Maximum Likelihood Method (using LOADEST software) and U.S. Geological Survey streamflow data. This study presents one of the first applications of LOADEST focused on metal loads. Monthly flow‐weighted concentrations were analysed using a Mann‐Kendall trend test to determine the direction, magnitude, and significance of temporal trends in zinc loading in any given month and using t‐test comparisons between the two periods. Zinc loads estimated for the Animas River below the tributaries indicate decreased zinc loading during the rising limb of the hydrograph in the second period, perhaps reflecting a reduction of snowmelt‐derived zinc load following surface reclamation activities. In contrast, base‐flow zinc loading increased at the main‐stem site, perhaps because of the cessation of water treatment in tributary streams. Flow weighting of monthly load estimates yielded increased statistical significance and enabled more nuanced differentiation between the effects of hydrologic variability and remedial activities on zinc loading.

Development of a Culturally Anchored Qualitative Approach to Conduct and Analyze Focus Group Narratives Collected in Diné (Navajo) Communities to Understand the Impacts of the Gold King Mine Spill of 2015.

The Gold King Mine Spill (Spill) occurred in August 2015 upstream from Silverton, Colorado and released three million gallons of contaminated water into the Animas River, a tributary to the San Juan River that flows across the Navajo Nation. Using principles of community-engaged research, the Gold King Mine Spill Diné Exposure Project co-developed a culturally anchored approach to conduct focus groups and analyze narratives collected in three Diné (Navajo) communities along the San Juan River within 9 months of the Spill. Focus group questions were designed to document the socio-cultural impacts of the Spill. This paper: (1) outlines the partnerships and approvals; (2) describes focus group design, training, data collection and analysis; and (3) reflects on the use of a culturally anchored approach in Indigenous, specifically Diné-centered research. Diné social and cultural etiquette and concepts of relationality were used to adapt standard (non-Indigenous) qualitative methods. Findings describe community perceptions of short-term impacts of the disaster, as well as past and present injustices, communication related to the Spill, and concerns of persistent threats to Diné lifeways. The culturally anchored approach was critical in fostering trust with Diné participants and aligned with the candor of the discussions.

Portable X-ray Fluorescence (PXRF) Analysis of Total Metal(loid)s and Sequential Extraction of Bioavailable Arsenic in Agricultural Soils of Animas Watershed

The Animas River provides irrigation water in northwestern New Mexico and the Navajo Nation. Concerns regarding the river water quality arose on August 5, 2015, when approximately 11.35 million liters of heavy metal contaminated water was accidentally released from the Gold King Mine into the Animas River. This study sought to determine the total concentrations of 7 heavy metal(loid)s (As, Pb, and Zn as metals of concern and Fe, Mn, Ca, and Cu as metals of interest) using portable X-ray fluorescence (PXRF) in two agricultural fields and compare these values to Environmental Protection Agency (EPA) regional screening levels (RSL). Total concentrations of 6 out of 7 metals were below the RSL; only As exceeded the soil screening value of 7.07 mg kg−1 at some locations in the agricultural fields. We also determined water-soluble (WS) and exchangeable fractions (Ex) of As that might be available for agricultural crop uptake using sequential extractions. The WS-As ranged from 0.014 to 0.074 mg kg−1 and Ex-As ranged from 0.135 to 0.248 mg kg−1 and thus were less than 1 and 3% of the total As concentration respectively (ranging from 5.62 to 14.79 mg kg−1) and not considered a threat for plant tissue accumulation. While the concentrations of As observed in the agricultural fields may have exceeded screening levels, the As was not apparently plant available and its risk to crops was determined to be low.

APEX-MODFLOW: A New integrated model to simulate hydrological processes in watershed systems

APEX (Agricultural Policy/Environmental eXtender) is an oft-used agroecosystem model but has limited use in groundwater-driven watersheds due to a simplistic representation of groundwater processes. This paper presents the linkage of APEX and the groundwater flow model MODFLOW into a single modeling code. The mapping of recharge, groundwater head, and groundwater-surface water interactions are handled internally via subroutines. The APEX-MODFLOW model is applied to three watersheds in the United States for testing code accuracy and hydrologic state variables and fluxes: the Animas River Watershed, Colorado and New Mexico (3543 km2); the Price River Watershed, Utah (4886 km2); and the Middle Bosque River Watershed, Texas (470 km2). Whereas the hydrology of the Animas River and Price River watersheds is driven by snowmelt and spring runoff, the hydrology of the Middle Bosque River Watershed is driven by summer thunderstorms. The model can be used for scenario analysis in groundwater-driven watersheds.

Cover Image, Volume 50, Issue 3

On the cover: In situ and rapid heavy metal(loid) analysis using portable X‐ray fluorescence spectrometer in the agricultural soils of the Animas watershed, New Mexico (USA). See G. Jha et al., “Agricultural soils of the Animas River watershed after the Gold King Mine spill: An elemental spatiotemporal analysis via portable X‐ray fluorescence spectroscopy,” https://doi.org/10.1002/jeq2.20209. Photo by Gaurav Jha. image

Agricultural soils of the Animas River watershed after the Gold King Mine spill: An elemental spatiotemporal analysis via portable X-ray fluorescence spectroscopy.

In August 2015, 11.3 million L of heavy metal-contaminated water spilled into the Animas River from the Gold King Mine (Colorado, USA).National attention focused on water quality and agricultural production in areas affected by the spill. In response to local concerns, surface soil elemental concentrations were analyzed in three New Mexico agricultural fields to determine potential threats to agronomic production. Irrigated fields in the Animas watershed were scanned using portable X-ray fluorescence (PXRF) spectrometry to monitor the spatiotemporal variability of Pb, As, Cu, and Cr. A total of 175 locations were scanned using PXRF before and after the growing season for 3 yr. The geostatistical model with the lowest RMSE was chosen as the optimal model. The lowest RMSE for the elements ranged from to 0.10 to 0.44 m for As, from 0.50 to 0.98m for Cr, from 0.15 to 0.91m for Cu, and from 0.14 to 0.44m for Pb across the models selected. The spatial dependence between the measured values exhibited strong to moderate autocorrelation for all metals except for As, for which spatial dependence was strong to weak. Some areas in each field exceeded the New Mexico Environment Department soil screening limit of 7.07mg As kg-1 . All sampling locations were below the screening limit at last sampling time in 2019. Mixed models used for temporal analysis showed a significant decrease only in As below the screening value at the end of the study. Results indicate that the agricultural soils were below the soil screening guideline values.

Water-quality change following remediation using structural bulkheads in abandoned draining mines, upper Arkansas River and upper Animas River, Colorado USA

Water-quality effects after remediating abandoned draining mine tunnels using structural bulkheads were examined in two study areas in Colorado, USA. A bulkhead was installed in the Dinero mine tunnel in 2009 to improve water quality in Lake Fork Creek, a tributary to the upper Arkansas River. Although bulkhead installation improved pH, and manganese and zinc concentrations and loads at the Dinero mine tunnel, water-quality degradation was observed at the nearby Nelson tunnel. Only manganese concentrations improved in Lake Fork Creek downstream from the tunnel. To improve water quality in Cement Creek, a tributary of the Animas River, multiple bulkheads were installed in mine tunnels during 1996–2003 and a water treatment plant operated from 1989 to 2003 to treat drainage from several draining tunnels. After bulkhead installation and cessation of active water treatment (about 2003), water quality (pH and dissolved copper, manganese, and zinc concentrations) degraded at the mouth of Cement Creek. The patterns and timing were similar to post-bulkhead increased discharge and trace-metal loads at non-bulkheaded tunnels indicating the bulkheads might have been the cause. Pre-1989 water-quality data for Cement Creek are scarce, although limited historical data indicate possible, slight improvement in only manganese concentrations after bulkhead installation. Increased zinc loads in Lake Fork Creek and decreased pH through time in Cement Creek may indicate increased groundwater discharge to the streams after bulkhead installation. In these two study areas, bulkheads did not substantially improve downstream water quality.

Heavy metal content of produce grown in San Juan County (New Mexico, USA)

The Animas River Watershed has long received discharges of naturally occurring acid rock drainage; however, on August 5, 2015, three million gallons flowed into the agricultural region of Farmington, New Mexico and the Navajo Nation. Consumers and growers in the region were fearful that produce might absorb heavy metals from contaminated irrigation water originating from these rivers. Samples were collected from the region including corn (n = 30), pumpkin (n = 10), squash (n = 10), and cucumber (n = 10) then processed and tested using inductively coupled plasma-optical emission spectrometry (ICP-OES) for concentrations of nine metals of interest. These include toxic metals: Al, As, and Pb, which were compared to the World Health Organization limits, 18.29 mg d−1, 0.192 mg d−1, and 0.05 mg kg−1, respectively and essential metals: Cr, Fe, Mn, Zn, Ca, and Cu whose levels were compared to the National Academies’ dietary references for tolerable upper intake levels. Results indicate that produce grown in the region contained significantly less metal than the allowable limits, except for Pb in two corn samples. This research is the first attempt to monitor and analyze heavy metal absorption of produce in the area.

Effects of the Gold King Mine Spill on Metal Cycling through River and Riparian Biota

The 2015 Gold King Mine (GKM) spill into the Animas River, Colorado, USA, is an opportunity to evaluate acute mine discharge into a chronically metal-rich system. We measured metals, C and N isotopes in soil, water, sediment, plants, periphyton, invertebrates and fish to determine metal cycling between trophic levels in areas affected by the spill and chronic mine drainage from the Bonita Peak mining district during the past ~100 years. Soil and sediment metal levels were higher in sampling sites downstream of the mining district compared to a reference site without similar upstream mining activity. Plants at spill- and-mine-affected sites had higher metal concentrations: Pb in willow, Cd in cottonwood leaves, and Zn in all vegetation. Periphyton from spill-affected sites had higher concentrations of Fe, Zn, Cd and Pb than the reference site. Aquatic invertebrates in spill-affected areas had higher concentrations of metals compared with the reference that varied temporally. Diet reconstruction via δ15N and δ13C was most parsimonious for flannelmouth and blue suckers, but these fish did not show elevated metal levels in the spill-affected sites. Brown trout showed higher liver Zn, As and Cd in the spill-affected sites. In spite of mine drainage treatment implemented in response to the GKM spill, which has nearly eliminated dissolved metals leaving the Bonita Peak mining district, downstream GKM areas still exhibit higher metal levels across ecosystem components three-years following the spill; our results suggest that internal cycling via plant uptake, detritus-consuming aquatic invertebrates and bottom-feeding fish contribute to metal persistence in this area.

Unexpected Prevalence of eae-Positive Escherichia coli in the Animas River, Durango, Colorado.

Since 2014, biology students at Fort Lewis College have studied the water quality of the Animas River in Durango, Colorado. Environmental microbiology and molecular biology techniques have been employed to study Escherichia coli isolates from the river and to define characteristics of the bacteria related to public health. E. coli was found in the river, as well as in culverts and tributary creeks that drain into the river within the Durango city limits. Concentrations of E. coli in the river occasionally exceeded the US EPA guideline of 126 CFU per 100 mL for recreational water use. Many of the E. coli isolates were able to be grown at 45 °C, an indication of mammalian origin. Unexpectedly, 8% of the isolates contained the intimin (eae) gene, a virulence gene characteristic of two pathotypes of E. coli, the enterohemorrhagic and enteropathogenic E. coli. Several isolates tested were resistant to multiple antibiotics commonly used in animal and human medicine. Further study is warranted to determine the source of these bacteria entering the Animas River, and to further characterize the possible disease potential of multi-antibiotic resistant and virulence gene-containing isolates found in a semi-rural/urban setting.

Application of lagged correlations between solar cycles and hydrosphere components towards sub-decadal forecasts of streamflows in the Western USA

ABSTRACTTrade winds localized within the Western Equatorial Pacific express lagged and statistically significant correlations to sunspot numbers as well as to streamflow in rivers of the Southern Rocky Mountains. Both correlation sets were integrated in a linear regression analysis to produce relatively accurate sub-decadal streamflow forecasts for an annual and a 5-year average. In comparison to the autocorrelation technique, the prototyped method yielded the highest correlations, the highest goodness-of-fit scores, and the lowest root mean squared errors, for both the 5-year average and the annual average assignments. Of all of the cases examined, the highest Kolmogorov-Smirnov test scores between observation and prediction were found for the single solar-based forecast 5 years in advance for the 60-month average streamflow of the Animas River in New Mexico.

Removal and Breakthrough of Lead, Cadmium, and Zinc in Permeable Reactive Concrete

Heavy metal contamination of surface and ground waters from anthropogenic sources presents a significant risk to human health and the environment. Leaching of metals such as lead, cadmium, and zinc from historic mining residuals has led to extensive groundwater contamination, for example, the elevated concentrations found at the Oronogo-Duenweg Superfund site in Joplin, Missouri, United States. Excessive wastewater buildup and storage at historic mines have also caused the release of metal toxicants into river systems, as was the case in the catastrophic 2015 Gold King mine spill into the Animas River in Western Colorado. Prevention of metals contamination and the reclamation of contaminated water for human and agricultural use are compelling reasons to improve heavy metal remediation technologies. Permeable reactive concrete (PRC) is a novel, cementitious material that demonstrates substantial removal capacity for heavy metals from aqueous solutions at the bench scale. This study investigated breakthrough testing of PRC using a synthetic groundwater solution of lead, cadmium, and zinc at concentrations similar to reported values for the Oronogo-Duenweg site of ∼0.4 mg/L for lead and cadmium and 45 mg/L for zinc. Breakthrough testing elucidates removal mechanisms and reaction rates, but has never before been performed on PRC. Removal mechanisms documented in this study were precipitation of the hydroxide metals, complexation, and sorption of metals into the hydrated cement paste or metal precipitates. Demonstrated removal became more permanent over time, with total testing time around 260 days without breakthrough. Column breakthrough testing timeframes exceeded initial bench scale isotherm estimates by a factor of 20. Cost estimates for PRCs are ∼1/6th to 1/12th the cost of comparable technologies for similar site applications. PRC has been shown in this study to perform equal to, or greater than, comparable technologies and could significantly reduce remediation costs for other contamination sites.

Assessing the Dietary Bioavailability of Metals Associated with Natural Particles: Extending the Use of the Reverse Labeling Approach to Zinc.

We extend the use of a novel tracing technique to quantify the bioavailability of zinc (Zn) associated with natural particles using snails enriched with a less common Zn stable isotope. Lymnaea stagnalis is a model species that has relatively fast Zn uptake rates from the dissolved phase, enabling their rapid enrichment in 67Zn during the initial phase of labeling. Isotopically enriched snails were subsequently exposed to algae mixed with increasing amounts of metal-rich particles collected from two acid mine drainage impacted rivers. Zinc bioavailability from the natural particles was inferred from calculations of 66Zn assimilation into the snail's soft tissues. Zinc assimilation efficiency (AE) varied from 28% for the Animas River particles to 45% for the Snake River particles, indicating that particle-bound, or sorbed Zn, was bioavailable from acid mine drainage wastes. The relative binding strength of Zn sorption to the natural particles was inversely related to Zn bioavailability; a finding that would not have been possible without using the reverse labeling approach. Differences in the chemical composition of the particles suggest that their geochemical properties may influence the extent of Zn bioavailability.

Anoxia stimulates microbially catalyzed metal release from Animas River sediments.

The Gold King Mine spill in August 2015 released 11 million liters of metal-rich mine waste to the Animas River watershed, an area that has been previously exposed to historical mining activity spanning more than a century. Although adsorption onto fluvial sediments was responsible for rapid immobilization of a significant fraction of the spill-associated metals, patterns of longer-term mobility are poorly constrained. Metals associated with river sediments collected downstream of the Gold King Mine in August 2015 exhibited distinct presence and abundance patterns linked to location and mineralogy. Simulating riverbed burial and development of anoxic conditions, sediment microcosm experiments amended with Animas River dissolved organic carbon revealed the release of specific metal pools coupled to microbial Fe- and SO42--reduction. Results suggest that future sedimentation and burial of riverbed materials may drive longer-term changes in patterns of metal remobilization linked to anaerobic microbial metabolism, potentially driving decreases in downstream water quality. Such patterns emphasize the need for long-term water monitoring efforts in metal-impacted watersheds.

Post Gold King Mine Spill Investigation of Metal Stability in Water and Sediments of the Animas River Watershed.

We applied spectroscopy, microscopy, diffraction, and aqueous chemistry methods to investigate the persistence of metals in water and sediments from the Animas River 13 days after the Gold King Mine spill (August 5, 2015). The Upper Animas River watershed, located in San Juan Colorado, is heavily mineralized and impacted by acid mine drainage, with low pH water and elevated metal concentrations in sediments (108.4 ± 1.8 mg kg-1 Pb, 32.4 ± 0.5 mg kg-1 Cu, 729.6 ± 5.7 mg kg-1 Zn, and 51 314.6 ± 295.4 mg kg-1 Fe). Phosphate and nitrogen species were detected in water and sediment samples from Farmington, New Mexico, an intensive agricultural area downstream from the Animas River, while metal concentrations were low compared to those observed upstream. Solid-phase analyses of sediments suggest that Pb, Cu, and Zn are associated with metal-bearing jarosite and other minerals (e.g., clays, Fe-(oxy)hydroxides). The solubility of jarosite at near-neutral pH and biogeochemical processes occurring downstream could affect the stability of metal-bearing minerals in river sediments. This study contributes relevant information about the association of metal mixtures in a heavy mineralized semiarid region, providing a foundation to better understand long-term metal release in a public and agricultural water supply.

Data-driven modeling of background and mine-related acidity and metals in river basins

A novel application of self-organizing map (SOM) and multivariate statistical techniques is used to model the nonlinear interaction among basin mineral-resources, mining activity, and surface-water quality. First, the SOM is trained using sparse measurements from 228 sample sites in the Animas River Basin, Colorado. The model performance is validated by comparing stochastic predictions of basin-alteration assemblages and mining activity at 104 independent sites. The SOM correctly predicts (>98%) the predominant type of basin hydrothermal alteration and presence (or absence) of mining activity. Second, application of the Davies–Bouldin criteria to k-means clustering of SOM neurons identified ten unique environmental groups. Median statistics of these groups define a nonlinear water-quality response along the spatiotemporal hydrothermal alteration-mining gradient. These results reveal that it is possible to differentiate among the continuum between inputs of background and mine-related acidity and metals, and it provides a basis for future research and empirical model development.

CHACOAN AND POST-CHACO OCCUPATIONS IN THE MIDDLE SAN JUAN REGION: CHANGES IN SETTLEMENT AND POPULATION

The Middle San Juan region occupies a critical location between Chaco Canyon to the south and Mesa Verde to the north. Site-settlement analysis and demographic reconstruction reveal continuous occupation across the Pueblo II–III transition and steady population growth for 200 years prior to regional depopulation in the late A.D. 1200s. These findings challenge previous research which postulated two distinct occupations: Chacoan domination during the Pueblo II period, followed by abandonment and subsequent immigration from Mesa Verde comprising reoccupation during the Pueblo III period. Our research indicates that late Pueblo II Chacoan colonization at Salmon Pueblo (along the San Juan River) and Aztec Ruins (on the Animas River) occurred abruptly in areas with little previous settlement. In contrast, much smaller Chacoan outliers were built within dense, extant communities in the La Plata Valley and lower San Juan River between A.D. 1075 and 1125. Instead of abandonment coinciding with the region-wide drought during the mid-1100s, we argue that demographic trends and other archaeological evidence indicate sustained population growth coinciding with changes in social identity during the post-Chaco era. Depopulation did not occur until the late thirteenth century when a similar process affected the entire Four Corners area.