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Browsing by Subject "Hydrology"

Now showing 1 - 17 of 17
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    Assessing Hydrologic Connectivity using Water Temperature, Wax Lake Delta, Louisiana
    (2018-09) Evans, Nicholas
    We take a reduced complexity approach to assessing the advective factors that contribute to the hydrologic connectivity between a primary distributary channel and interdistributary island on the Wax Lake Delta of coastal Louisiana. We deployed a relatively inexpensive, open-source data logging platform to collect high quality continuous water temperature, water depth, air temperature, and shortwave solar radiation from a portion of Wax Lake Delta from February 18 through May 19, 2015. We use this field data to create a reference model of predicted water temperature at the data logging locations at the site. Based on comparison of that model with the water temperature observations, we find that different regions of the island have differing degrees of hydrologic connectivity to the primary distributary channel.
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    Comparison of Evapotranspiration Estimation Methods and Implications for Water Balance Model Parameterization in the Midwestern United States
    (2019-12) Talbot, Michael
    Evapotranspiration is the second most dominant component of the global water cycle behind precipitation, yet it remains one of the most difficult to measure and model. The numerous methods that have been developed for estimating evapotranspiration (ET) rates using climatological data vary in both complexity and spatiotemporal robustness. While the Penman-Monteith method has continually been shown to compare better with observed ET rates across more geographies and timescales than any other method, its high data requirements remain a barrier to use in many areas, and it is often desirable or necessary to make use of an alternative method. Daily reference ET estimates from the Penman-Monteith method were compared to ET estimates from seven alternative methods, which were generated using 14 years of observed weather records at five locations across the Midwestern United States. Then, a one-dimensional water balance model, DRAINMOD, was run at 362 locations across the Midwest using 50 years of synthetic climate data and three distinct sets ET inputs: 1) reference ET from the Penman-Monteith method, 2) potential ET generated from the Penman-Monteith reference ET and location-specific crop coefficient curves, and 3) potential ET from the Thornthwaite method. Results suggest that the best alternative method to Penman-Monteith varies by location, application, and timescale of interest, and that the misapplication of ET estimates for water balance model parameterization could have a dramatic impact on the accuracy of model predictions.
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    Denitrification in Agricultural Surface Waters: Quantifying the Effect of Environmental Parameters and Hydrologic Connectivity on Nitrate Uptake and Microbial Communities
    (2017-10) Tomasek, Abigail
    The development of synthetic fertilizer has led to increases in crop yields and allowed for global population growth over the past century. However, this increase in available nitrogen has greatly altered the global nitrogen cycle, including increased nitrate loading to surface water and groundwater in the Midwestern United States, with negative effects on human health and aquatic ecosystems. Therefore, there is a need for effective management strategies and an understanding of the mechanisms for nitrate transport and uptake. Denitrification, the microbiological reduction of nitrate to nitrogen gas, can be viewed as a net sink for reactive nitrogen in aquatic systems. Small areas, termed hot spots, and short time periods, termed hot moments, frequently account for a large portion of denitrification. This research focuses on identifying the environmental parameters and hydrologic regimes that promote denitrification, along with determining how parameters, denitrification rates, and microbiological communities are related at multiple temporal and spatial scales. At the finest scale, a recirculating laboratory flume was used to determine the effect of turbulence and organic carbon on denitrification rates and the microbial community. An outdoor experimental stream and flow-through basin in the Outdoor StreamLab at the St. Anthony Falls Laboratory (SAFL) were used to determine the effect of short-term inundation and periodic inundation on denitrification. At the largest scale, water and sediment samples were collected over two years from a field site in an agricultural watershed in Southern Minnesota. The objectives of this research were to: (1) determine how turbulence and organic carbon affect denitrification, (2) investigate how inundation and hydrologic connectivity leads to the formation of denitrification hot spots and hot moments, (3) quantify and correlate the driving environmental parameters of microbial denitrification and the differences in these relationships for in-channel and riparian locations in an agricultural watershed, (4) develop and evaluate functional relationships between environmental parameters and denitrification rates, and (5) identify how denitrifying gene abundances, denitrification rates, and environmental parameters are related across a hydrologic gradient from channels to riparian areas.
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    Estimation And Analysis Of Total Suspended Solid Yields From The Mica Creek Experimental Watershed, Idaho
    (2016-08) Elverson, Charlie
    Transport and concentration of Total Suspended Solids (TSS) in forested streams play an important role in ecosystem health, affecting the health of fish populations and playing a role in nutrient delivery to floodplains. Despite a long history of studying TSS yields, estimates of TSS yields remain uncertain. Multiple methods have been commonly used to estimate time-aggregated TSS yields from water samples. This study investigated the effects of contemporary timber harvest practices on TSS yields as well as the robustness of conclusions to different methods of TSS yield calculation. TSS yields were calculated using linear interpolation, flow-weighted averaging, and statistical regression. The study utilized a paired-watershed design, with 6 years of calibration data between the control watershed and 2 treatment watersheds. One watershed was clearcut across 50% of its area and allowed to recover for the remaining 12 years of the study period. The other treatment watershed had 50% of basal area removed across 50% of it's total area. After the thinning treatment, the watershed was allowed to recover for 9 years before being clearcut across 46% of the area which was originally thinned. The watershed was then allowed to recover for the remaining 3 years of the study. Harvest impacts on TSS yield varied between treatment watershed and season, with the most significant changes occurring during spring (March through June). Furthermore, the different methods of TSS yield estimation provided different conclusions about TSS yield trends as well as total yields, with statistical regression providing the most consistently defensible estimates.
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    Evaluating the Eco-Hydrochemical Response of Tropical Glacierized Mountainous Watersheds to Climate Change: A Case Study of the Volcán Chimborazo, Ecuador
    (2021-05) Saberi, Leila
    With global climate change, some of the highest rates of warming are occurring at high elevations in low latitudes, making tropical glacierized mountains some of the most vulnerable hydrological systems in the world. In the Andes, which hold 99% of all tropical glaciers, observations reveal that streamflow in many watersheds is already decreasing due to the retreat of glaciers. With the water security threat this presents to populations who rely on stream discharge from these glacierized mountains, understanding the hydrological impacts of climate change in these systems is critical. Recent studies have begun to investigate the response of streamflow to fast-retreating glaciers. However, many important knowledge gaps remain. For example, the contribution of meltwater to streamflow through subsurface flow has been largely overlooked, and this may be biasing estimates of how much groundwater may buffer glacier retreat. Further, in addition to causing glacier retreat, warming temperatures are also driving upslope vegetation migration, yet little is known about how this will further affect stream discharge in tropical glacierized watersheds. Finally, climate-driven changes in hydrology can alter solute weathering and transport on glacierized mountain slopes, but the effect on solute export from these watersheds has not been investigated, even though this could have implications for geochemical cycling and ecological function downstream in the Amazon Basin. Data sparsity in these remote, tropical glacierized mountainous watersheds, as well as unique characteristics such as their year-round glacier ablation and endemic páramo ecosystem, present major uncertainties associated with predicting hydrogeological, hydrochemical, and ecohydrological responses to climate change. We address these challenges by implementing a recently developed watershed model with reactive transport, BioRT-Flux-PIHM, for a sub-humid glacierized watershed on Volcán Chimborazo in the Ecuadorian Andes. BioRT-Flux-PIHM integrates multicomponent reactive transport with hydrological processes and land surface interactions, and thus has the potential to capture spatiotemporally distributed watershed surface and subsurface flows and pathways as well as hydrochemical processes. Implementing BioRT-Flux-PIHM with available field observations makes it possible extend sparse measurements over space and time, and to uncover unobserved processes. Our model results indicate that glacier melt contributes a broad range of 10-90\% of weekly discharge (~50% on average) over the course of one study year, mostly through fast surface runoff, but also through infiltration that increases groundwater flow by nearly 37%. Combined removal of glacier melt, upslope migration of vegetation, and a 4.5 °C increase in temperature results in substantial reduction of streamflow by 74% from current conditions, primarily due to an increase in evapotranspiration. Under this scenario, the model shows that near no-flow conditions can occur in the stream, which has crucial implications for local communities who rely on this water for irrigation. The model further predicted a unique relationship between the concentration (C) of weathering solutes in the stream and discharge (Q) that was mostly chemostatic (constant C with varying Q) because of large melt-supported groundwater inputs, but superimposed by melt event-driven dilution episodes. In a model scenario with no glacier melt, major ion concentrations, including Na+, Ca2+, and Mg2+, became higher and much more stable, but weathering rates decreased, which ultimately attenuated solute export by 23% compared to current-day estimates. We expect this reduction to be exacerbated by higher evapotranspiration and drier conditions with expanded vegetation. This work brings to light the importance of understanding interactions among warming temperatures, mineral weathering, subsurface meltwater flow, and vegetation changes to predict hydrological and hydrochemical processes in tropical watersheds with rapidly retreating glaciers.
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    Ground Water/Surface Water Interaction in Nearshore Areas of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota, 2003–04
    (2006) Jones, Perry M
    This is a geologic and hydrological study of three lakes on the Grand Portage Reservation and is largely technical in scope. These three lakes have higher conductivity levels than other lakes in the Reservation. Public water comes from surficial water supplies, while ground water is used for private water sources such as wells, mainly within two miles from Lake Superior. Ground water is too saline to use for public water use. Results of the study show that water movement and quality in this geologically-fractured area are complex, and that lake sediment temperature monitoring may be the most reliable method for natural resources managers. Key findings from the report are extracted and reproduced below. “The availability of good quality water from lakes and wetlands on the Grand Portage Reservation in northeastern Minnesota is an important concern of the Grand Portage Band of Chippewa Indians. Development and changing land-use practices may affect the quality and quantity of water resources on the reservation. To effectively protect the water quality and quantity of the lakes and wetlands, an understand¬ing of exchanges between ground water and surface water on local and regional scales is needed. Numerous hydrologic studies have been done on the reservation, but none of these studies has focused on determining ground-water/surface-water interactions of lakes and wetlands. The U.S. Geological Survey (USGS), in cooperation with the Grand Portage Band of Chippewa Indians, conducted a study to assess ground-water/surface-water interactions in nearshore areas of three lakes, North, Teal, and Taylor Lakes on the Grand Portage Reservation in 2003 and 2004. These three lakes were selected on the basis of the rela¬tively high specific conductance values of water from these lakes compared to other lakes on the reservation. The high specific conductance values of the lake water may indicate that ground-water inflow is an important component of the water balance of the lakes. The objective of the study was to identify areas of ground-water inflow to the three lakes and surface-water outseepage to local aquifers through the assess¬ment of existing aerial photographs and water-quality data. Results from this study indicate that ground-water and surface-water interactions at the study lakes are complex, and the ability of the applied techniques to identify ground-water inflow and surface-water outseepage locations varied among the lakes. Measurement of lake-sediment temperatures proved to be a reliable and relatively inexpensive reconnaissance technique that lake managers may apply in complex settings to identify general areas of ground-water inflow and surface-water outseepage.”
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    Hydrogeologic Monitoring at University of Minnesota Outreach, Research and Educational Park (UMore Park), 2011
    (2012-01) Groten, Joel T.; Alexander, E. Calvin
    The mining of the gravel resource and subsequent development at the University of Minnesota Outreach, Research and Educational Park (UMore Park) may potentially impact the groundwater quality at, and around UMore Park. In order to provide a pre-mining baseline against which to monitor potential water quality changes, monitoring of water quality in selected monitoring wells began in 2009 (Anger and Alexander, 2010.) Anger and Alexander (2010) reviews the previous work defining the hydrogeology of the UMore Park site and installing the existing monitoring wells. This report updates and Anger and Alexander (2010) with monitoring data obtained through June 2011.
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    Hydrology and Water Quality of the Copper-Nickel Study Region, Northeastern Minnesota
    (1980) Siegel, Donald I; Ericson, Donald W
    This 35-year old hydrologic study documents conditions in the Cu-NU region of Minnesota’s Iron Range. It is primarily a technical report, but its main value is the baseline data provided, and that it contains a water budget for the area. It’s primary message for decision-makers is that “the introduction of trace metals from future mining to the ground-water system can be reduced if tailings basins and stockpiles are located on material of low permeability, such as till, peat, or bedrock." Key segments are extracted and reproduced below. Abstract: "Data were collected on the hydrology of the Copper-Nickel study region, to identify the location and nature of ground-water resources, determine the flow characteristics and general quality of the major streams, and determine the potential effects of mining copper and nickel on the hydrologic system. Ground-water investigations indicate that water generally occurs in local flow systems within surficial deposits and in fractures in the upper few hundred feet of bedrock. Availability of ground water is highly variable. Yields commonly range from only 1 to 5 gallons per minute from wells in surficial materials and bedrock, but can be as much as 1,000 gallons per minute from wells in the sand and gravel aquifer underlying the Embarrass River valley. Except over the mineralized zone, ground water in the surficial deposits is a mixed calcium magnesium bicarbonate type. Ground water over the mineralized zone generally has both a greater percentage of sulfate, compared to bicarbonate, and concentrations of copper and nickel greater than 5 micrograms per liter. "Surface-water investigations indicate that the average annual runoff from streams is about 10 inches. Plow characteristics of streams unregulated by industry are similar, with about 60 percent of the annual runoff occurring during snowmelt in April, May, and June. Flood peaks are reduced in the Kawishiwi River and other streams that have surface storage available in onchannel lakes and wetlands. These lakes and wetlands also trap part of the suspended-sediment load. Specific conductance in streams can exceed 250 micromhos per centimeter at 25° Celsius where mine dewatering supplements natural discharge. "Between 85 and 95 percent of the surface water used is for hydroelectric power generation at Winton and thermo-electric power generation at Colby Lakes. Mine dewatering accounts for about 95 percent of the ground-water used. Estimated ground-water discharge to projected copper-nickel mines ranges from less than 25 to about 2,000 gallons per minute, depending on the location and type of mining activity. The introduction of trace metals from future mining to the ground-water system can be reduced if tailings basins and stockpiles are located on material of low permeability, such as till, peat, or bedrock."
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    Impact of large-scale irrigation on a closed basin wetland: Water flow alterations and participatory irrigation management effects on the Sultan Marshes ecosystem in Turkey
    (2008-07) Celik, Filiz Dadaser
    This dissertation analyzes alterations in a closed-basin wetland system resulting from the construction of a large-scale irrigation project in its catchment. The study was conducted at the Sultan Marshes ecosystem (Develi Basin, Turkey), which has been severely degraded within the last 20 years due to diversion of its major water sources for agricultural irrigation. Spatial changes in the Sultan Marshes from 1980 to 2003 were analyzed using satellite remote sensing. Changes in the areal coverages of lakes, marshes, agricultural, and steppe areas determined by unsupervised classification of four Landsat images showed that both lakes and marshes became smaller after construction of the irrigation project. Steppe areas expanded onto wetlands. Significant portion of northern (Kepir) marshes were converted to agriculture. Hydrologic changes in the Sultan Marshes were analyzed statistically and used to develop a dynamic hydrologic model of the system. Water levels dropped more than one meter in the lakes and marshes from 1993 to 2003, and decreases were observed in ground-water levels and spring flows, although precipitation and evaporation rates remained mostly stable. Simulations with the hydrologic model showed that even if surface water continues to be used for irrigation, reductions in appropriations from ground water and springs would restore and protect water levels in the marshes. Agricultural and environmental changes in the Develi Basin were analyzed after the irrigation management was transferred from state to "irrigation associations" in 1994. The analyses showed that irrigated areas and water use in the Develi Basin showed significant fluctuations. The area allocated to production of high water-consuming plants increased. Water fee collection rates were lower than 100%. Although soil and water quality in the Develi Basin did not change significantly, ground-water levels, flow rates from springs and water levels in the Sultan Marshes all dropped. Four recommendations were developed that would help to resolve the conflict between agricultural and wetland water requirements: (1) a basin-wide approach water planning, (2) more realistic water pricing, (3) demand-based irrigation scheduling, and (4) rehabilitation of the irrigation system. Economic costs and benefits associated with water diversions from agriculture to the wetlands were estimated, and the optimum or economically-efficient amount of water diversion was determined. When only direct-use values of the wetland (reed cutting, animal grazing and ecotourism) were included, the annual optimum amount of water diversion to the wetlands was found to be 5.2 million m 3 yr -1 (165 L s -1 ) compared to about 62 million m 3 yr -1 (1,957 L s -1 ) used in irrigation. Diversion of 5.2 million m 3 yr -1 water would be sufficient to restore the conditions in the marshes. The analysis showed that economically-efficient restoration of water levels in the Sultan Marshes is feasible with moderate amounts of water diversion.
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    Interpretable Machine Learning to Improve Predictions of Fluvial Sediment Transport
    (2021-08) Lund, J.
    Fluvial sediment-transport contributes to many environmental concerns including flooding, nutrient loading, aquatic habitat degradation, reservoir sedimentation impacting dam operation, filling in of navigable waterways, and degrading of streams requiring costly restorations. However, there is a general lack of fluvial sediment-transport predictive power as it is difficult to comprehensively understand due to its complex process controlled by many factors such as hydrology, geology, land-use, and sediment supply. Field data can be used to better understand fluvial sediment-transport but is often limited due to it being expensive, technical, and labor intensive to collect. Minnesota provides a unique opportunity to study sediment-transport due to a complex glacial history that produced diverse landforms which combine with varying land uses and land covers to yield surface water conditions. Fortunately, Minnesota has a large sediment-transport dataset available with which to build and test a statewide predictive model in order to increase the knowledge of sediment-transport and help solve environmental concerns. XGBoost machine learning models were developed and trained to predict suspended-sediment concentration (SSC) and bedload transport rates at unsampled rivers and streams by using SSC samples collected from 56 sites and bedload samples collected from 43 sites by the U.S. Geological Survey from 2007-2019. Basin (full upstream area), catchment (nearby landscape), near-channel, and in-channel feature variables were compiled from available state and national datasets (NHDPlusV2, StreamCat, U.S. Stream Classification System, and StreamStats). The 2-year recurrence interval statistic for each site was used to normalize streamflow. The slope of the dimensionless hydrograph was calculated to teach the model the rate of rising or falling streamflow conditions before and after each sample was collected. Models for both bedload and SSC transport explained roughly 70% of the variance in the dataset. Shapley additive explanation values (SHAP) facilitated model interpretation and connected important model features to their roles with the sediment-transport process. Cumulative suspended sediment loads were calculated from model output and compared to in-situ surrogate loads from four sites in the study area to show model utility, and test model improvements. Results show that these models can inform sediment loads and stream-restoration activities across Minnesota by providing estimates of suspended-sediment concentrations and bedload rates where samples have not been collected.
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    Karst Hydrogeologic Investigation of Trout Brook, Dakota County, Minnesota
    (2013-02) Groten, Joel T.; Alexander, E. Calvin
    Trout Brook in the Miesville Ravine County Park of Dakota County is the trout stream with the highest nitrate concentration in the karst region of southeastern Minnesota. Water quality data from 1985 and 1995 (Spong, 1995) and from 2001, 2002, 2006 and 2010 by the Dakota County Soil and Water Conservation District (SWCD) (2010) document an increasing level of nitrate in Trout Brook. A karst hydrogeologic investigation was designed to measure nitrate levels at sampling points along the stream and to increase our understanding of the source and movement of nitrates throughout the length of Trout Brook. Eighteen springs and seeps have been located in the Main Branch and tributaries of Trout Brook. A previously unreported flowing section and stream sieve, Weber Sieve, were found above what had been thought to be the head of perennial flow in the East Branch of Trout Brook. Two new sinkholes developed after the 14-15 June 2012 flood in a field northeast of the East Branch of Trout Brook. This investigation included regular monitoring of major anions in the streams and springs, synoptic stream flow measurements, a dye trace of a sinking stream in the Trout Brook drainage, and continuous temperature monitoring at two springs. The initial assumption was that the majority of the baseflow of Trout Brook was from discrete springs. However, synoptic baseflow and nitrate measurements show that only 30-40 percent of the total flow in Trout Brook is from discrete springs, and the rest appears to be from distributed groundwater discharge directly into the stream. Both the discrete springs and the distributed recharge occur along reaches of Trout Brook that drain the significant high transmissivity zone near the bottom of the regionally important Shakopee aquifer. Dye traces have confirmed flow-paths from Weber Sieve to LeDuc and Bridgestone Springs and have begun to define springsheds for these head water springs. The temperatures of two springs were monitored for 7.5 months. The observed small, seasonal temperature fluctuations at the springs seem to be due to the air temperature while storms that result in flooding and surface runoff cause larger, short-term temperature fluctuations. Nitrate concentrations and chloride/bromide ratios decreased systematically from the upstream springs to the downstream springs. The nitrate concentrations have been increasing at four springs from 1985 to 2012 and at two surface sampling points from 2001 to 2012. The nitrate concentration of another surface sampling point increased from 2001 to 2006 but decreased from 2006 to 2012. Snowmelt and rainfall runoff was sampled on 2 March 2012 and showed no detectable nitrate in the runoff from a watershed with no row-crop agriculture, but elevated nitrate was detected in an adjacent watershed with row-crop agriculture. All of these trends illustrate the dominance of agricultural sources of nitrate in Trout Brook.
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    Manoomin (wild rice) and environmental change at a significant river system of the Lac du Flambeau Band of Lake Superior Chippewa
    (2021-01) Waheed, Alexander
    Wild rice, an annual aquatic grass that grows across the Great Lakes region, has dietary, cultural, medicinal, and spiritual significance to the sovereign Tribes of the region, but its abundance has been declining despite its legal protection under treaties. While certain factors (both environmental and societal) have been demonstrated to impact wild rice health and growth, there is no single answer to explain this broad regional loss. Ongoing work between researchers at the University of Minnesota and tribal partners - including natural resource stewards, Tribal leaders, elders, rice chiefs, and community members - has yielded a multidimensional approach that seeks to capture the various forces influencing wild rice. The collaborative emphasis has been an integral part of the methods, and a significant result in its own right. In this study, hydrologic, geochemical, nutrient, sediment, and vegetation parameters are assessed to examine their impact on the growth of wild rice at two riverine subsites on the Lac du Flambeau reservation in northern Wisconsin: one subsite with abundant wild rice and a second subsite with sparse wild rice. To broaden the inferences that could be made from this localized, intensive study, a large statewide dataset from a previous study by Myrbo et al. (2017a) was reanalyzed to develop multiple lines of evidence for the influence of these factors. Based on this multidimensional approach, the emerging data and observations suggest highly flocculent sediments and related nutrient deficiencies may be driving forces behind the loss of wild rice in this study system and have implications for wild rice health in the wider region.
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    Mixed-Silver Maple Forests Of The Upper Mississippi River Floodplain: Variations In Composition, Structure, And Growth Along Environmental Gradients
    (2020-05) Nielsen, Daniel
    Floodplain forests of the Upper Mississippi River are characterized by complex interactions between biota and the physical environment, specifically aspects of hydrology. The role of environmental variation in overstory composition, structure, and growth is not well documented. Goals of this study were to 1) characterize current stand conditions along gradients of inundation and relative elevation, and 2) describe growth patterns of silver maple (Acer saccharinum L.) trees, and their relationship to hydrological patterns. Patterns of forest composition and structure were more similar for plots comprising similar environmental conditions than plots within a stand, suggesting that current methods of stand delineation do not capture the full extent of within-stand environmental variation. I found evidence that growth patterns of silver maple had positive relationships to hydrology at a plot-level and a stand-level. These results suggest that forest managers may need to “rethink” how they summarize stand condition and develop silvicultural prescriptions.
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    Mixing of the Seneca and Blue Lake waste water treatment plant effluents with the Minnesota River
    (1984-11) Stefan, Heinz G.; Farrell, Gerard J.; Riley, Michael J.; Lindquist, Katherine F.; Horsch, George M.
    Eight field surveys, forty five laboratory experiments, and several types of analyses have produced information to understand and predict the mixing of the Seneca and Blue Lake WWTP effluents with the Minnesota River to a reasonable degree. Both discharges are from submerged pipes, 7 ft and 6.5 ft in diameter, respectively. The mean annual discharge rates are at present on the order of 23 to 25 cfs and at velocities on the order of .6 to .8 fps.
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    Neonicotinoid and Fipronil Insecticides in Minnesota: A Statewide Survey into the Occurrence, Detection, and Removal of Neonicotinoids and Fiproles in Minnesota Surface Waters ,Groundwater, and Engineered Treatment Systems.
    (2023-10) Goedjen, Grant
    Neonicotinoids and fiproles have been used extensively in Minnesota agriculture for the last three decades. Their high mobility in water and longevity in aquatic systems makes them key candidates for transport in surface runoff and groundwater to contaminate Minnesota surface and groundwater systems. Four large field studies of (1) Minnesota groundwater and natural springs, (2) Minnesota surface waters, (3) stormwater and precipitation at stormwater-impacted Saint Paul Lake, and (4) wastewater, drinking water, and compost treatment systems were conducted over three years (2019-2022) to evaluate the state of neonicotinoids and insecticides in Minnesota’s natural waters and the current capacity for removal by existing treatment processes. Shallow unconfined groundwater and natural springs were more susceptible to contamination than deeper groundwater. Clothianidin (41% of springs, 14% of wells) was the most common insecticide detected followed by thiamethoxam (31% of springs, 12% of wells), imidacloprid (22% of springs, 10% of wells), thiacloprid (19% of springs, 2% of wells), acetamiprid (12% of springs, 14% of wells), and fipronil (19% of spring, 1% of wells). Groundwater depth also appeared to limit groundwater contamination to shallow systems with detections increasing with increasing urban land use and watershed imperviousness. Tritium/groundwater age, dissolved oxygen (DO), and total nitrite plus nitrate (total oxidized nitrogen), all correlated to noenicitinoid occurrence. Clothianidin (31% lakes, 60% rivers), thiamethoxam (19% lakes, 44% rivers), imidacloprid (65% lakes, 85% rivers), acetamiprid (29% lakes, 35% rivers), thiacloprid (15% lakes, 13% rivers), and fipronil (32% lakes, 30% rivers) were all detected in surface water lakes and rivers. Thiamethoxam and clothianidin has an association with agricultural watersheds while acetamiprid, thiacloprid, and fipronil were associated with urban watersheds. Increasing watershed catchment size and imperviousness increased the likelihood of contamination but the previous year’s application rates were the largest determining factor in the risk of insecticide contamination. All five neonicotinoid and fipronil were detected in stormwater (6% - 49%) and snow melt (13% - 29%). Stormwater and snow melt concentrations spiked with the “spring flush” during the early spring and summer months. Imidacloprid (17% rain, 47% snow), acetamiprid (6% rain, 33% snow), and clothianidin (44% rain, 39% snow), were all detected in direct rainfall and snowfall samples. Most of the contamination in stormwater (>76% stormwater, >67% snowmelt) was picked up as water moves through the watershed with correlated strongly correlations to application rates and soil and lipophilicity. Neonicotinoids and fipronil were present in drinking water, wastewater, and compost material provided by a commercial composting center. Current wastewater biological treatment technologies did not result in a significant reduction in concentrations. Biologically-activated carbon filtration with and without pre-oxidation provided a substantial reduction in concentrations (86% - 100% removal). Pre-oxidation did generate oxidized transformation products (<3.5% yield) but all transformation products were removed by downstream filtration. Compost was capable of degrading fipronil in both residential and commercial composting operations while clothianidin and acetamiprid were degradable in commercial composting systems and acetamiprid, clothianidin, imidacloprid, fipronil were partially degradable in residential composters. Runoff produced from rainfall at the composting facility with substantial neonicotinoid and fipronil concentrations.
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    Water Resources of the Fond du Lac Indian Reservation, East-Central Minnesota
    (1989) Ruhl, James F; Fond du Lac Indian Reservation Business Committee
    This interesting report presents the findings of a hydrologic study of the Fond du Lac Indian Reservation. The study is the outcome of a 1978 Federal mandate to the Bureau of Indian Affairs to review Indian water-rights claims in reservations throughout the United States. The Fond du Lac Indian Reservation study, done by the U. S. Geological Survey in cooperation with the Fond du Lac Indian Reservation Business Committee, is the first of the these studies undertaken in Minnesota under the Federal mandate. The report notes that ground water resources derive from three aquafers, and that surface waters derive from wetlands and surficial waters within the St. Louis River watershed. Except for a small number of well-water samples, water quality was found to be within EPA limits for pollutants and was determined to be safe for human and animal consumption. A few wells had elevated levels of lead and manganese; four principal streams contained E. coli and Streptococcus.
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    Wetlands of Cook Inlet Basin, Alaska: Classification and Contributions to Stream Flow
    (2017-04) Gracz, Michael
    Wetlands face threats from global change, even as protections have been institutionalized to conserve the amenities they provide. These institutional protections frequently rely on a wetland classification system to guide conservation. In the Cook Inlet Basin of Alaska, USA (CIB), for example, best wetland assessment practices require the use of a classification system to ensure the conservation of the most valuable amenities. However, the systems used widely in the USA outside of Alaska, where peatlands are not common, inadequately describe the diversity of peatlands on the glaciated landscape of the CIB. Here I present a new Cook Inlet Classification system (CIC) organized around the hydrogeologic settings of wetlands in the CIB. The variables most strongly correlated with ecological differences within major geomorphic classes were used to construct a system supported by ample field data. The CIC produced greater within-class similarity than other widely-used systems, likely due to the overriding importance of the seasonal variability of water levels in CIB peatlands. The CIC has been mapped over an area of 7600 km2 and has guided wetland functional assessments in the CIB, and may be adaptable to any region supporting peatlands on glacial landforms. The harmful effects of a warming climate on aquatic resources may be partially ameliorated by discharge of shallow groundwater from peatlands to streams. This potential benefit of peatlands was investigated in the CIB using end-member mixing analysis (EMMA) and a sensitivity analysis of a water budget to quantify the contribution from extensive peatlands formed over glacial lake deposits to stream flow during the dry-season. Although peatlands in this hydrogeologic setting are common globally, the discharge from them is challenging to quantify. A spatially distributed sampling protocol at a single point-in-time produced a reliable EMMA showing that over half of stream flow on a day during the summer dry period originated near the surface of peatlands. This finding is being used to establish the value of peatlands for buffering increases in stream temperature, which have exceeded tolerances of commercially important fishes in the CIB. The analysis also suggests that differences in hydrogeologic setting influence shallow groundwater hydrology in peatlands.