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27 records · Page 2Linked to original sources
USGS2022

Sources and characteristics of dissolved organic carbon in the McKenzie River, Oregon, related to the formation of disinfection by-products in treated drinking water

Executive Summary This study characterized the concentration and quality of dissolved organic carbon (DOC) in the McKenzie River, a relatively undeveloped watershed in western Oregon, and its link to forming disinfection by-products (DBPs) in treated drinking water. The study aimed to identify the primary source(s) of DOC in source water for the Eugene Water & Electric Board’s (EWEB) conventional treatment plant on the McKenzie River near river mile 11, upstream of Hayden Bridge. The two classes of regulated compounds examined—trihalomethanes (THMs) and haloacetic acids (HAAs)—form when organic carbon in raw source water reacts with chlorine and (or) bromine during water treatment. The objectives of the study were to: characterize the amount and quality of DOC in the McKenzie River and select tributaries during storms; identify the most common types of carbon using UV-vis spectroscopy and other methods; evaluate optical properties for predicting DBP precursors in surface water; and identify land cover classes or vegetation types that may be important sources of organic carbon and DBP precursors in EWEB’s source water. Eleven storms were sampled synoptically in upstream-to-downstream fashion to provide a “snapshot” of water quality conditions at four sites on the McKenzie River from Frissell Bridge (6 miles downstream from Trail Bridge Reservoir) to the EWEB water treatment plant at Hayden Bridge and nine contributing tributaries. Storms included late summer and early autumn “first flush” events and late autumn, winter, and spring storms spanning a range in streamflows from 3,000 to 26,000 cubic feet per second as measured in the main stem McKenzie River at the EWEB water intake. Water samples were analyzed for DOC concentrations and optical properties (fluorescence and ultraviolet absorbance [UVA]) across a range of wavelengths to characterize the quantity and quality of dissolved organic matter (DOM) in the McKenzie River at the drinking water intake and upstream locations. Paired sets of source and finished water samples were collected at the EWEB treatment plant to identify DOC quality parameters in raw source water that might predict DBP concentrations in finished drinking water. DOC concentrations were relatively low in the McKenzie River (0.4–3 milligrams per liter [mg/L]; average 1.5 mg/L) but much higher in the tributaries. The highest DOC concentrations occurred during “first flush” storms in October 2012 and September 2013; the highest value (16 mg/L) was measured at the 52nd Street stormwater outfall. The average DOC concentration in the lower basin-tributaries was 3.8 mg/L; three middle basin tributaries—Quartz, Gate, and Haagen Creeks, which drain private forestland with less coniferous forest compared with other higher elevation tributaries— had slightly lower average DOC concentrations (2.8 mg/L). These middle-basin watersheds may be important sources of DOC and DBP precursors to the McKenzie River, even more so than the lower basin tributaries, depending on their flows (and loads). This is particularly true after the September 2020 Holiday Farm fire, which burned much of this area. DOC concentrations increased 68 percent in the McKenzie River between the uppermost reference site at Frissell Bridge and Vida; this includes drainage from Quartz Creek, Blue River Lake and Cougar Reservoir, which all contributed DOC to the main stem. In contrast, the lowermost tributaries draining most of the agricultural and urban land did not have a large effect on DOC in the McKenzie River despite their higher DOC concentrations because of their presumed relatively low streamflows and, consequently, DOC loads. Apart from the continuous flow monitors in the McKenzie River and some tributaries (Blue River and South Fork McKenzie River, and streamflow at Hayden Bridge and Vida, Camp Creek and some other locations), streamflow was not assessed during sample collection for this study. This lack of streamflow data precludes a detailed analysis of loads, which is discussed in the future studies section. All DBP concentrations in finished drinking water were less than EPA maximum contaminant levels (MCLs) of 0.080 mg/L for the four trihalomethanes (THM4) and 0.060 mg/L for five haloacetic acids (HAA5). During the 11 storm sampling events the maximum summed concentrations were about 0.040 mg/L for both THM4 and HAA5. Compliance monitoring samples, collected separately by EWEB, yielded some higher concentrations—0.046 mg/L THM4 and 0.047 HAA5—during the December 2012 storm. The corresponding benchmark quotient (BQ) values, which indicate how close a measured DBP concentration is to the MCL, were 0.58 and 0.78, respectively, for THM4 and HAA5. Compared with a similar 2007–08 McKenzie River study that did not target storm events, concentrations of THM4 and HAA5 in finished water were 68 percent and 33 percent higher, respectively, during the current study. Due to the high dilution rates in the McKenzie River main stem, many of the individual fluorescence excitation-emission measurements were low (<0.1 Raman units) and approached analytical detection limits. Parallel factor analysis (PARAFAC) resulted in a five-component model (C1–C5) that represents five unique organic fluorophores. Components C1, C2, and C3 represent DOM associated with soil-derived, humic-like, more degraded organic matter. In contrast, components C4 and C5 represent “fresher” DOM, derived from terrestrial and aquatic plants, including algae and cyanobacteria that are common in the McKenzie River and its tributaries and reservoirs. The fluorescence data and PARAFAC modeling suggest that most of the DOC in the McKenzie River originated from terrestrial sources (primarily components C1 and C2). The largest increases in DOC in the main stem occurred in the reach upstream of Vida, from inflows by Quartz Creek, Blue River, South Fork McKenzie River, and other tributaries. Concentrations of DBPs in EWEB’s finished drinking water were positively correlated with DOC concentrations in raw source water (THM4, p <0.05; HAA5, p <0.01) for paired samples collected 12−24 hours apart. DOC concentrations were significantly positively correlated ( p <0.001) with laboratory-based fluorescent dissolved organic matter (fDOM) measurements, suggesting fDOM as a useful parameter for monitoring and predicting DOC concentration in surface water and DBP concentrations in finished water. Of all the PARAFAC components in surface water, C5 had the highest correlations with DBPs in finished water (rho = 0.77–0.84, p <0.01), followed by components C1 and C2 (rho = 0.75 and 0.71, respectively, p <0.01). This C5 carbon is associated with recently produced DOM, possibly from decomposed terrestrial and aquatic vegetation. Model loadings of these three components were considerably higher in the sampled tributaries relative to the main stem McKenzie River, with most of the observed increases in the main stem apparent at Vida. This points to Quartz Creek or other tributaries in the reach between Frissell Bridge and the sampling site near Vida (South Fork McKenzie and Blue Rivers) as potentially key contributors of DOM source material that leads to the production of DBPs in treated drinking water. A limited load analysis showed that the reservoirs contributed 8–37 percent of the instantaneous DOC loads observed at Vida at the time of sampling, which suggests other sources such as Quartz Creek and other streams in the reach between Frissell Bridge and Vida are more important. Random forest analyses identified PARAFAC components C1 and C5 and fluorescence peaks A, C, M, T and N as the best predictors for HAA5 concentrations in finished drinking water, explaining 62.5 percent of the variation. The best predictors for THM4 were C1, C4 + C5, and peaks T, A, and N, which explained 33 percent of the variation. Several land cover and vegetation classes were correlated with DOC concentration and other optical measurements. The percentage of evergreen forest in each of the subwatersheds sampled was negatively correlated ( p <0.001) with DOC concentration and many optical indicators of DOM quantity: UVA 254 , fDOM, and all of the fluorescence peaks. In contrast, mixed (deciduous) forest was positively correlated ( p <0.001) with DOC, fDOM, UVA 254 , and several fluorescence peaks, demonstrating the importance of deciduous leaf fall in generating DOC and DBP precursors. The high level of human activities in the middle and lower portion of the basin—including timber harvesting and road construction on private forestland, agricultural, rural, industrial, and urban development—have resulted in the greatest loss in native coniferous and mixed deciduous forests in the basin. DOC loading from these tributaries and reservoir releases, which contain DOC from terrestrial and aquatic productivity, both enrich the McKenzie River. Concentrations of DOC increased an average of 71 percent (range 30–120 percent) in the McKenzie River between Frissell Bridge, the upstream reference site, and Vida. PARAFAC components C1, C2, and C5—which were correlated with DBPs in finished water—increased, on average, 109–136 percent (range 20–250 percent) in this same Frissell-to-Vida reach. These increases occur from input of tributaries in the middle basin such as Quartz Creek and others, as noted above. Future monitoring, field, and lab studies can improve our understanding of seasonal and spatial sources of organic carbon contributing DBP precursors to the McKenzie River and allow detection of long-term trends resulting from the recent Holiday Farm Fire, which burned 173,393 acres of forestland, including riparian areas along the main stem, and numerous structures, homes, and outbuildings in September 2020. Future studies could examine DOC fluxes and flushing of carbon from the watershed, investigate the role of precipitation amount and intensity in mobilizing carbon and sediment, and evaluate impacts to aquatic communities and human health as part of a post-fire assessment. Other areas ripe for study include evaluating the impacts of potential temperature increases on carbon sequestration and decomposition in the burned and unburned forests and identifying practices that foster sequestration of carbon in forest soils. The use of fluorescence sensors such as fDOM to monitor the concentration and composition of raw water supplies may be improved for detection of specific DBP precursors, to provide continuous and real-time information to treatment plant operators. Future studies that monitor DOM amount and quality, and DBP Formation Potential (FP), particularly during storm events, paired with streamflow measurements, as suggested above, could help identify areas that contribute high DOC loads and thus help managers identify the key areas to focus restoration activities. Other studies could examine treatment options for currently regulated DBPs and potentially unregulated compounds, including advanced biological treatments for their removal. This study was a collaboration between the U.S. Geological Survey (USGS) and EWEB in Eugene, Oregon, with additional funding provided from USGS Cooperative Matching Funds Program.

Oregon↗
USGS2021

Annotated bibliography of scientific research on Ventenata dubia published from 2010 to 2020

Integrating recent science into management decisions supports effective natural resource management and can lead to better resource outcomes. However, finding and accessing science information can be time consuming and costly. To assist in this process, the U.S. Geological Survey (USGS) is creating a series of annotated bibliographies on topics of management concern for western lands. Previously published reports introduced a methodology for preparing annotated bibliographies to facilitate the integration of recent, peer-reviewed science into resource management decisions. Therefore, relevant text from those efforts is reproduced here to frame the presentation. Invasive annual grasses are widely distributed throughout the western United States and threaten native ecosystems by altering fire regimes, replacing native plants, and altering grazing patterns, often with tremendous associated costs. One invasive annual grass, Ventenata dubia (hereafter, ventenata), was first introduced to the United States in the 1950s and has recently been identified as a management concern. Ventenata has a wide native geographic range, from Africa to northern Europe, and could thus potentially spread widely in the United States if left unmanaged. We compiled and summarized peer-reviewed journal articles, government reports, and data products on ventenata published between January 1, 2010, and August 27, 2020. We first conducted a systematic search of three reference databases and three government databases using the search phrase: “ventenata” OR “Ventenata dubia.” We refined the initial list of products by removing (1) duplicates, (2) products not written in English, (3) publications that were not focused in North America, (4) publications that were not published as research, data products, or scientific review articles in peer-reviewed journals or as formal technical reports, and (5) products for which ventenata was not a research focus or for which the study did not present new data or findings about ventenata. We summarized each product using a consistent structure (background, objectives, methods, location, findings, and implications) and identified the management topics (for example, species and population characteristics, habitat, control and management efforts) addressed by each product. We also noted which publications included new geospatial data. The review process for this annotated bibliography included an initial internal colleague review of each summary, requesting input on each summary from an author of the original publication, and a formal peer review. Our initial searches resulted in 505 total products, of which 29 met our criteria for inclusion. Nonnative invasive plants; weed management; behavior or demographics; dispersal, spread, vectors and pathways; site-scale habitat characteristics; survival; and weed management subtopic: herbicides were the management topics most commonly addressed. The online version of this annotated bibliography will be searchable by topic, location, and year; it will also include links to each original publication, where available. The studies compiled and summarized here may inform planning and management actions that seek to maintain and restore landscapes and control nonnative invasive species across the western United States.

Open-File Report↗
USGS2019

Fire risk in revegetated bunchgrass communities Infested with Bromus tectorum

In rangeland ecosystems, invasive annual grass replacement of native perennials is associated with higher fire risk. Large bunchgrasses are often seeded to reduce cover of annuals such as Bromus tectorum L. (cheatgrass), but there is limited information about how revegetation reduces fire risk over the long-term. For this research note, we conducted a pilot study to assess how community composition influences fire risk at 3 sites in Columbia National Wildlife Refuge in Washington, USA that were revegetated with large bunchgrasses 8 to 18 years prior to the study. At each revegetated site, five replicates with 10 plots each (plot size 10 × 10 m) were established. Fire risk was determined as the probability that a plot would completely burn following ignition at a randomly located point in each plot (i.e., if 8 of 10 plots burned fire risk was 80%). Pre-ignition, cover of bunchgrasses, cheatgrass, forbs, and surface cover characteristics were determined for each plot. Bunchgrasses successfully established to varying degrees among sites, but fire risk was still relatively high (around 73%) and did not significantly differ among sites cover. All sites had similar surface cover characteristics such as high total fuels cover (>80% at all sites) and low unvegetated gap cover (soil and soil cryptogams, <17%). Our pilot study suggests that even though revegetation may increase bunchgrass and decrease cheatgrass, fire risk remains high likely due to other surface cover characteristics. Future studies should aim to have larger variation in cover, grazing intensity, and weather conditions.

Washington↗
USGS2024

Colorado Delta riparian plant health improvement

The riparian corridor along Mexico’s arid Colorado River Delta is being affected by reduction in river flow and increases in heat, drought, human infrastructure, and disturbances. These disturbances can change riparian land cover by limiting water availability for riparian plant species, increasing fire intensity and frequency, and increasing soil and water salinities. In response to these forms of degradation, restoration efforts have begun to restore riparian habitats and native plant health, but vegetation greenness and corresponding plant water use continue to decline in unrestored reaches. Researchers from the U.S. Geological Survey (USGS) Southwest Biological Science Center are monitoring riparian plant health along the Colorado River Delta to support better ecohydrological decision-making. The researchers are helping a binational team to protect, restore, and maintain native vegetation within the 150-km long riparian corridor. Researchers are using Landsat 8 Operational Land Imager (OLI) data spanning 2014–2022 to measure greenness, a proxy for plant health, and actual evapotranspiration (ETa). Using an empirical model for ETa, evapotranspiration is estimated over each 16-day Landsat 8 OLI overpass period by considering the 8 days before and after the overpass date. In their paper, researchers noted an increase in vegetation greenness within the restoration sites over nine years, with an average increase of 41.3%, which may be partially due to targeted water deliveries at the restoration sites. Conversely, greenness in adjacent, unrestored control areas declined by 27.3%. The study showed a 22.1% increase in ETa in restored areas, compared to a 30.8% reduction in unrestored regions. Restored sites in one restored area experienced ETa increases up to 12.2%, whereas their unrestored counterparts showed a decline of 21.4%. These estimates of riparian greenness and water use may assist natural resource managers who are tasked with allocating water and managing habitats within similar riparian corridors.

Conference Paper↗
USGS2019

Sharp savanna-forest transitions in the Midwest followed environmental gradients but are absent from the modern landscape

Historically, closed eastern forests transitioned into open savannas and prairies in the US Midwest, but this transition is poorly understood. To investigate the eastern boundary of the prairie-forest ecotone, we conducted a case study of historic and modern vegetation patterns of the Yellow River watershed in northwest Indiana. Historic vegetation came from the Public Land Survey notes collected in the early 1800s, whereas modern vegetation came from the Forest Inventory Analysis and USGS National Land Cover Database. We mapped historical survey vegetation data using GIS to reconstruct the region’s past and current forest composition and structure. We also mapped climate, topography, and soil composition across the watershed to investigate the relationship between historic vegetation and environmental gradients. We found a sharp transition in the presettlement forest structure and composition, with dense deciduous forests in the eastern portion of our study area and open oak savannas in the west. The savanna ecosystem dominated in sandy well-drained soils and was at a slightly lower elevation than the adjacent closed forest. Modest environmental changes accompanied major vegetation changes in the past, which might suggest fire and hydrological patterns helped maintain the sharp ecotone. By contrast, the modern forest shows no difference in tree density and composition across the watershed, which is consistent with major land use and hydrology changes in the watershed since settlement. On the modern landscape, land that was historically closed forest now has higher agricultural productivity compared to land that was historically savanna, whereas the historic savanna currently supports more mesic forest. These results suggest the environmental gradient continues to subtly shape the landscape. Though land use change has largely removed the closed mixed hardwood forests and oak savannas from this area, a better understanding of the historic vegetation and the conditions that supported it can help inform land management and restoration, as well as reveal ecological processes that drive vegetation transitions.

Indiana↗
USGS2024

Annotated bibliography of scientific research on Taeniatherum caput-medusae published from January 2010 to January 2022

Integrating recent scientific knowledge into management decisions supports effective natural resource management and can lead to better resource outcomes. However, finding and accessing scientific knowledge can be time consuming and costly. To assist in this process, the U.S. Geological Survey is creating a series of annotated bibliographies on topics of management concern for western lands. Previously published reports introduced a methodology for preparing annotated bibliographies to facilitate the integration of recent, peer-reviewed science into resource management decisions. Therefore, relevant text from those efforts is reproduced here to frame the presentation. Invasive annual grasses are widely distributed throughout the western United States and threaten native ecosystems by altering fire regimes, replacing native plants, and altering grazing patterns, often with tremendous associated costs. One invasive annual grass, Taeniatherum caput-medusae (hereafter, medusahead), was first documented in the United States in 1887 and has been identified as a species of management concern. Medusahead’s life history traits allow it to quickly and effectively dominate native plant communities, and it has already taken over millions of acres in western North America. Although medusahead can spread widely and disrupt ecosystem function, it has been studied less than other western invasive grass species. We compiled and summarized peer-reviewed journal articles, data products, and formal technical reports (such as U.S. Department of Agriculture Forest Service General Technical Reports and U.S. Geological Survey Open-File Reports) on medusahead, published between January 2010 and January 2022. We first performed a systematic search of three reference databases and three government databases using the search phrase “medusahead” OR “medusa head” OR “ Taeniatherum caput-medusae ” OR “ Taeniatherum caputmedusae ” OR “ Taeniatherum asperum .” We refined the initial list of products by removing (1) duplicates, (2) products not written in English, (3) publications that were not focused on North America, (4) publications that were not published as research, data products, or scientific review articles in peer-reviewed journals or as formal technical reports, and (5) products for which medusahead was not a research focus, or the study did not present new data or findings about medusahead. We summarized each product using a consistent structure (background, objectives, methods, location, findings, and implications) and identified the management topics (for example, species and population characteristics; habitat; and control and management efforts) addressed by each product. We also noted which publications included new geospatial data. The review process for this annotated bibliography included an initial internal colleague review of each summary, requesting input on each summary from an author of the original publication, and a formal peer review. Our initial searches resulted in 4,245 total products, of which 211 met our criteria for inclusion. The most commonly addressed management topics addressed in products summarized in the annotated bibliography were as follows: nonnative invasive plants, weed management, site-scale habitat characteristics, habitat restoration or reclamation, and cultural management of weeds. All published bibliographies, including the online version of this bibliography, are available at the Science for Resource Managers ( https://apps.usgs.gov/science-for-resource-managers ). This database is searchable by topic, location, and year and includes links to each original publication. The studies compiled and summarized here may inform planning and management actions that seek to maintain and restore sagebrush landscapes and associated native species across the western United States.

Open-File Report↗
USGS2016

Climate change and future fire regimes: Examples from California

Climate and weather have long been noted as playing key roles in wildfire activity, and global warming is expected to exacerbate fire impacts on natural and urban ecosystems. Predicting future fire regimes requires an understanding of how temperature and precipitation interact to control fire activity. Inevitably this requires historical analyses that relate annual burning to climate variation. Fuel structure plays a critical role in determining which climatic parameters are most influential on fire activity, and here, by focusing on the diversity of ecosystems in California, we illustrate some principles that need to be recognized in predicting future fire regimes. Spatial scale of analysis is important in that large heterogeneous landscapes may not fully capture accurate relationships between climate and fires. Within climatically homogeneous subregions, montane forested landscapes show strong relationships between annual fluctuations in temperature and precipitation with area burned; however, this is strongly seasonal dependent; e.g., winter temperatures have very little or no effect but spring and summer temperatures are critical. Climate models that predict future seasonal temperature changes are needed to improve fire regime projections. Climate does not appear to be a major determinant of fire activity on all landscapes. Lower elevations and lower latitudes show little or no increase in fire activity with hotter and drier conditions. On these landscapes climate is not usually limiting to fires but these vegetation types are ignition-limited. Moreover, because they are closely juxtaposed with human habitations, fire regimes are more strongly controlled by other direct anthropogenic impacts. Predicting future fire regimes is not rocket science; it is far more complicated than that. Climate change is not relevant to some landscapes, but where climate is relevant, the relationship will change due to direct climate effects on vegetation trajectories, as well as by feedback processes of fire effects on vegetation distribution, plus policy changes in how we manage ecosystems.

Geoscience Canada↗
USGS2008

Archive of digitized analog boomer seismic reflection data collected from Lake Pontchartrain, Louisiana, to Mobile Bay, Alabama, during cruises onboard the R/V ERDA-1, June and August 1992

In June and August of 1992, the U.S. Geological Survey (USGS) conducted geophysical surveys to investigate the shallow geologic framework from Lake Pontchartrain, Louisiana, to Mobile Bay, Alabama. This work was conducted onboard the Argonne National Laboratory's R/V ERDA-1 as part of the Mississippi/Alabama Pollution Project. This report is part of a series to digitally archive the legacy analog data collected from the Mississippi-Alabama SHelf (MASH). The MASH data rescue project is a cooperative effort by the USGS and the Minerals Management Service (MMS). A standardized naming convention was established to allow for better management of scanned trackline images within the MASH data rescue project. Each cruise received a unique field activity ID based on the year the data were collected, the first two digits of the survey vessel name, and the number of cruises made (to date) by that vessel that year (i.e. 92ER2 represents the second cruise made by the R/V ERDA-1 in 1992.) The new field activity IDs 92ER2 and 92ER4 presented in this report were originally referred to as ERDA 92-2 and ERDA 92-4 at the USGS in St. Petersburg, FL, and 92010 and 92037 at the USGS in Woods Hole, MA. A table showing the naming convention lineage for cruise IDs in the MASH data rescue series is included as a PDF. This report serves as an archive of high resolution scanned Tagged Image File Format (TIFF) and Graphics Interchange Format (GIF) images of the original boomer paper records, navigation files, trackline maps, Geographic Information System (GIS) files, cruise logs, and formal Federal Geographic Data Committee (FGDC) metadata for cruises 92ER2 and 92ER4. The boomer system uses an acoustic energy source called a plate, which consists of capacitors charged to a high voltage and discharged through a transducer in the water. The source is towed on a sled, at sea level, and when discharged emits a short acoustic pulse, or shot, which propagates through the water and sediment column. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), detected by the hydrophone receiver, and the amplitude of the reflected energy is recorded by an Edward P. Curley Lab (EPC) thermal plotter. This process is repeated at timed intervals (for example, 0.5 s) and recorded for specific intervals of time (for example, 100 ms). The timed intervals are also referred to as the shot interval or fire rate. On analog records, the recorded interval is referred to as the sweep, which is the amount of time the recorder stylus takes to sweep from the top of the record to the bottom of the record, thereby recording the amplitude of the reflected energy of one shot. In this way, consecutive recorded shots produce a two-dimensional (2-D) vertical image of the shallow geologic structure beneath the ship track. Many of the geophysical data collected by the USGS prior to the late 1990s were recorded in analog format and stored as paper copies. Scientists onboard made hand-written annotations onto these records to note latitude and longitude, time, line number, course heading, and geographic points of reference. Each paper roll typically contained numerous survey lines and could reach more than 90 ft in length. All rolls are stored at the USGS FISC-St. Petersburg, FL. To preserve the integrity of these records and improve accessibility, analog holdings were converted to digital files.

Alabama, Louisiana, Mississippi↗
USGS2021

Borehole analysis, single-well aquifer testing, and water quality for the Burnpit well, Mount Rushmore National Memorial, South Dakota

Mount Rushmore National Memorial (hereafter referred to as “the memorial”), in western South Dakota, is maintained by the National Park Service (NPS) and includes 1,278 acres of land in the east-central part of the Black Hills. An ongoing challenge for NPS managers at the memorial is providing water from sustainable and reliable sources for operations, staff, and the increasing number of visitors. In 2020, the U.S. Geological Survey (USGS) and NPS completed a hydrological study of the Burnpit well (well 5), a 580-foot-deep open hole groundwater well completed in metamorphic (crystalline) rock at the memorial. The purpose of this study was to estimate the geological and hydraulic properties of the aquifer supplying the well and to determine the water quality of the groundwater from the well. The study provides NPS staff and managers background information for assessing future uses for the well. Methods for data collection and analysis for the study included borehole and video camera analysis in 2020, aquifer testing by the NPS in 2009 and the USGS in 2020, and water-quality sampling in 2020. Borehole camera video generally matched the lithology recorded in the well log. Fractures recorded in the well log and observed with the borehole camera, including more than 20 less prominent fractures and rough sidewall areas, indicated a fractured aquifer. The fractures are the primary conduits for groundwater flow through the rock and into the well. Transmissivity was estimated for the upper and lower water-level drawdown zones at the Burnpit well with data from the NPS and USGS using the Theis and Cooper-Jacob methods. Transmissivity for the NPS test using the Theis method was 9.0 and 11 feet squared per day (ft 2 /d) for the upper and lower drawdown zones, respectively. Using the Cooper-Jacob method, the transmissivity was 22 and 14 ft 2 /d for the upper and lower drawdown zones of the aquifer, respectively. Transmissivity estimates from data from the USGS test were similar. The Theis method, applied to the upper and lower drawdown zones of the aquifer, produced transmissivity estimates of 7.7 and 10 ft 2 /d, and the Cooper-Jacob method produced estimates of 9.7 and 12 ft 2 /d, respectively. Storativity (specific yield) estimated using the Theis method for the NPS aquifer-test data was 0.85 and 0.92 for the upper and lower drawdown zones of the aquifer, respectively. The Cooper-Jacob method applied to the NPS aquifer-test data produced storativity estimates of 0.11 and 0.50 for the upper and lower drawdown zones, respectively. The Theis method applied to the USGS aquifer-test data estimated storativity values of 0.77 and 1.0 for the upper and lower drawdown zones, respectively. The Cooper-Jacob method estimated storativity of 0.50 and 0.60 for the upper and lower drawdown zones of the USGS aquifer test, respectively. The estimated storativity values from the NPS and USGS aquifer tests for the upper and lower drawdown zones were higher than expected for limestones and schists. The hypothetical equilibrium drawdown for the Burnpit well was estimated after the NPS test in 2009 at no more, and possibly less, than 35 gallons per minute. The NPS noted that the sustainable yield likely was overestimated because the water level did not stabilize during the NPS aquifer test. The specific capacity for the NPS aquifer test in 2009 was 0.16 gallon per minute per foot ([gal/min]/ft) of drawdown at 3 hours, and the specific capacity for the USGS aquifer test in 2020 was 0.13 (gal/min)/ft of drawdown at 3 hours. The rate of water-level recovery after pumping ceased was 0.017 and 0.013 (gal/min)/ft for the NPS and USGS aquifer tests, respectively. The water-level recovery rate was nearly an order of magnitude less than the specific capacity estimated during pumping, indicating that water levels in the Burnpit well may not recover quickly enough during pumping to provide for a continuous source of water. Water-quality samples were collected at the Burnpit well on June 24 and July 23, 2020, and analyzed for field-measured properties, major ions, metals, nutrients, and perchlorate. Iron, zinc, and lithium concentrations for unfiltered samples in the well were at least three times greater than the mean filtered sample concentrations reported for crystalline aquifers in the Black Hills. Manganese concentrations were less than the mean concentration for crystalline aquifers but exceeded the U.S. Environmental Protection Agency (EPA) secondary drinking-water standards. The iron concentration from the June 24 sample was about 11 times greater than the EPA secondary drinking-water standards and mean concentrations from crystalline aquifers in the Black Hills. Arsenic concentrations in Burnpit well samples collected in 2020 were greater than the EPA primary drinking-water standard and the mean concentration for crystalline aquifers in the Black Hills. Arsenic occurs naturally in the rock of crystalline aquifers, and concentrations from samples in the Black Hills commonly exceed the EPA primary drinking-water standard of 10 micrograms per liter. High concentrations of arsenic, iron, and manganese metals in the Burnpit well make groundwater from the well in its natural state unusable as a drinking-water source, and water treatment would be necessary to reduce the trace element concentrations to less than the EPA primary and secondary drinking-water standards. However, if the memorial has immediate nonpotable water requirements, such as for construction and fire suppression, groundwater from the Burnpit well could provide water without causing additional stress to current (2021) drinking-water sources.

South Dakota↗