Minnesota Water Resources Conference - Poster Presentations

Amelia Olsen, University of Minnesota 
Agricultural Water Issues

Manoomin (Ojibwe), also known as Wild Rice, is a spiritually and culturally important plant species that grows in shallow lake beds and throughout the Great Lakes Region. Manoomin is under threat from climate change as well as the impacts of land use change. The Otter Tail River Watershed (OTRW) located in west-central Minnesota contains over 2,800 miles of streams and 1,300 lakes, including many ricing lakes. In the OTRW agriculture is the most abundant form of land use. The northernmost headwaters of the OTRW lie within the White Earth Band of Ojibwe Reservation. There is great concern surrounding the observed decline of Manoomin on reservation and on ceded territory. Agricultural runoff can lead to the accumulation of nutrient anions and pesticides in surface and groundwaters, posing a threat to Manoomin. In collaboration with tribal partners at White Earth, sampling of surface and groundwater was conducted throughout the OTRW. Nutrient anion and pesticide concentrations were analyzed to determine the presence of agricultural chemicals in the watershed. Early results showed near ubiquitous elevated concentrations of Atrazine and 2,4-D in surface waters, including our “control site” upstream of the majority of agriculture. Surface water concentrations of chloride and sulfate were elevated in the spring indicating a potential source of contamination from snowmelt or road salt, decreasing into the summer months. Notably, sulfate levels exceeded the 10 ppm Minnesota state limit for ricing lakes at two sites. Analysis of historical OTRW data from the MN DNR and the MPCA has shown nitrate and phosphorus levels elevated above EPA standards for drinking water and aquatic life in some surface and groundwaters, with higher concentrations seen in groundwater, particularly in the past two decades. Results from this work will allow a better understanding of how agricultural land use in the OTRW impacts water chemistry and, subsequently, Manoomin health.

Peter Bartot, Natural Resources Research Institute
Agricultural Water Issues, Contaminants of Emerging Concern, Lakes

The use of pesticides has increased substantially in recent years in both agricultural and residential settings. These pesticides are applied to crop fields, lawns and gardens, household surfaces, and even our pets. Many of the same chemicals used agriculturally can also be purchased without a license. This widespread use and availability creates a difficult-to-control scenario when it comes to preventing these chemicals from spreading throughout the environment. Some pesticides have also been shown to undergo atmospheric transport while they can also be transported within water bodies through rivers, streams, and currents. The objective of this study is to examine the spatial distribution of pesticides in Lake Superior and Lake Huron. We hypothesize that pesticide application method will affect the spatial distribution of pesticides. Specifically, we hypothesize that distributions of post-emergent pesticides (pesticides sprayed on plants post-germination) will be present in offshore sediments, reflecting reflect potential for atmospheric transport. In contrast, we expect preemergent pesticides (applied directly to soil prior to germination) will be present at elevated levels in near-shore sediments adjacent to tributaries, reflecting advective transport in streams. Surface sediment samples (60) were collected from Lake Superior and Lake Huron in 2021 and 2022, respectively. An analytical method was adapted for analysis of 38 pesticides by accelerated solvent extraction, extract clean-up via solid phase extraction, and analysis by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS). This presentation will focus on results from surface sediments for Lake Superior and Lake Huron. Future work will focus on extraction and analysis of pesticides in surface sediments from the remaining Great Lakes, with an anticipated project end date in 2026.

Tucker Burch, USDA-Agricultural Research Service
Agricultural Water Issues, Contamination/Remediation, Rivers, Streams, and Floodplains

Many recreational waterways can become contaminated by pathogens from humans, wildlife, and livestock. These pathogens cause acute gastrointestinal illness (AGI) when ingested during recreational water use, but prevailing levels of health risk for many sites and activities are unknown. We assessed risks posed to recreators during swimming and limited contact activities like kayaking and fishing for six sites on rivers in the Des Moines, Iowa metropolitan area. Water samples (n = 147) collected over two years were tested for a variety of waterborne pathogens, and AGI risk was estimated using quantitative microbial risk assessment (QMRA). Risk estimates varied from 1 to 83 AGI cases per 1,000 recreators depending on site and activity. Swimming risk for two sites exceeded USEPA’s 2012 acceptable risk benchmark of 36 AGI cases per 1,000 recreators. Risk estimates for other sites and limited contact activities were generally below the benchmark. Risk was examined relative to the presence of human, cow, pig, and bird feces using microbial source tracking to provide insights about the sources of elevated health risk; risk was highest when multiple fecal sources were present. Elevated concentrations of the fecal indicator E. coli did not always match periods of elevated AGI risk determined by QMRA. Work was completed in 2023, and final reports are currently under review. Results inform risk mitigation initiatives at the sites studied and provide context for understanding risk associated with similar activities and sites in Minnesota and other Midwest states.

Lake Associations are an important part of Minnesota's lake management framework. They are informal government organizations often formed out of a need to address specific issues on a lake such as aquatic invasive species management, social norm adherence, or water quality issues. The demonstrated collective action of groups such as Lake Associations is known as social capital. The goal of our research is to evaluate whether the amount of social capital—as measured by collective action efforts and governance activities—of Lake Associations is correlated with water quality. We use the Minnesota Pollution Control Agency’s eutrophication index data which includes Secchi depth measurement, total phosphorus, and Chlorophyll-A data as a surrogate for water quality. The results of a survey, developed in collaboration with Minnesota Lakes and Rivers Advocates, addresses Lake Association organizational structure and collective action which are used to estimate social capital. Interactions between the estimated social capital of Lake Associations and water quality trends are evaluated, controlling for some biophysical factors (ecoregion, point sources) and governance factors of Lake Associations (tax levy status, recreation vs. residential). The results of this study will provide insight into the impact that Lake Associations have on their respective lakes and surrounding areas. Lake Associations can be a powerful tool for improving overall lake health; with the economic benefits that clean water and recreation provide it is in the public’s best interest to be invested in lake management practices.

Leah Gifford, SRF Consulting Group
Climate Change/Resiliency, Engineering Solutions and Applications

After several wet and flashy years, Nicollet County discovered an impressive 60-foot-deep scour hole below a 60” corrugated metal, 50-foot-deep, centerline culvert during routine inspections. This culvert was located along CSAH 23 (461st Avenue) about 4 miles south of the town of Nicollet, MN. Two roadside ditches that drained to the scour hole also had severe headcutting and cracks parallel to the road. The culvert drained to an unnamed stream that flowed approximately 2 miles along a wide ravine to the Minnesota River. The erosion was threatening the embankment of the road and had contributed more than 7,500 tons of sediment into the river system.

The design consisted of considering different stabilization techniques within an alternative analysis, with construction access and methods being a key factor in the steep terrain. Ultimately the design approach used various techniques including the protection of the existing pipe and road embankment, a series of storm sewer drop structures to dissipate energy on the downstream side of the existing culvert, and a new two stage inlet configuration on the upstream side for a more resilience design. The slopes were stabilized with a combination of gravel filled geocell, geogrid reinforcement, turf reinforcement mat (TRM), stable slopes, benches and french drains, and drop inlets along a riprap channel. Construction was completed in 2022.

A poster presentation would be a great way to showcase some of the stabilization techniques, before-and-after photos, and lessons learned.

Colin Livdahl, US Geological Survey
Climate Change/Resiliency, Groundwater, Hydrology

During prolonged periods of above-average precipitation, rising groundwater levels have the potential to cause damage to and interfere with underground infrastructure and building foundations. To understand the relations between precipitation and groundwater in the vicinity of Lake Nokomis, the US Geological Survey, in collaboration with the University of Minnesota, quantified four components of the groundwater budget; groundwater recharge, change in surficial aquifer storage, surficial groundwater discharge to Lake Nokomis, and groundwater discharge to underlying bedrock aquifers. Field data, geologic records, and empirical calculation methods are used to quantify groundwater budget components for the period April 2023 through April 2024. Groundwater recharge is calculated from eight continuous monitoring well hydrographs. Change in aquifer storage is calculated from monthly water level measurements from the same eight monitoring wells. Groundwater discharge to Lake Nokomis is calculated from a lake budget equation that accounts for evaporation, surface outflow, and changes in lake volume. Groundwater discharge to underlying bedrock aquifers is calculated according to Darcy methods using water level measurements in a nearby well nest. Data collection is complete, data analysis is underway. Preliminary results from water level analysis suggest that the lake may be losing water to the surficial aquifer along its northeast boundary. This study is a start toward understanding relations between precipitation, Lake Nokomis levels, and the groundwater levels that could have an impact on local underground infrastructure.

Ashley Petel, University of Minnesota
Climate Change/Resiliency, Wetlands

Ecological restoration is a tactic widely used by land managers. Challenges associated with effectively planning for restoration include anticipating how many resources—namely, time and money—are needed to carry out restoration projects. One can speculate how a site may recover with supportive restoration efforts by considering the inherent ecosystem resilience remaining within these sites. The amount of resilience determines how much human intervention is necessary to move the site from its current state to a desired state.

This project focuses on building a resilience-based site assessment tool for common ecosystem types found in Washington County: upland prairie, oak savanna, deciduous forest, and palustrine wetland. Creating this tool involved reviewing literature and examples, exploring passive and active restoration, facilitating discussions with restoration professionals, and conducting site visits. When building the tool, ecosystem characteristics that influence resilience, termed resilience indicators, were selected for each ecosystem type. These resilience indicators were assigned observable metrics to determine the level of resilience remaining in the system. The level of resilience corresponds with the degree of restoration intervention needed—natural, assisted, and reconstructive. Associated protocols were developed to guide restoration practitioners in collecting the data needed to determine the level of resilience left in a site, and therefore the degree of resources needed to restore it.

The tool enables restoration professionals to have a consistent process across people, time, and ecosystems. The systematic approach provides an objective way to assess potential restoration sites and predict the resources needed to restore them. Future work with this assessment tool includes testing and evaluating the tool’s validity and digitizing the process.

Amber McRae, Natural Resources Research Institute
Contamination/Remediation, Contaminants of Emerging Concern, Groundwater

Poly- and perfluoroalkyl substances (PFAS) for treatment of groundwater contaminated by aqueous film-forming foam (AFFF) due to the presence of various co-contaminants and a wide range of structurally diverse PFAS. Injectable particulate amendments consisting of colloidal activated carbon are an emerging in-situ treatment approach, but the impacts of biogeochemical conditions on long-term PFAS retention performance are poorly understood. To address these knowledge gaps, a series of batch sorption experiments were performed to evaluate the PFAS sorption and desorption behavior for two commercially available injectable particulate amendments. Sorption equilibration times were determined via preliminary kinetic batch sorption tests, and isotherms were determined with mixed and individual PFAS species in the presence and absence of humic acid. Desorption behavior was also assessed for a subset of isotherm batches with mixed PFAS to provide insight into long-term retention behavior. Preliminary results revealed slow PFAS sorption kinetics despite the small particle sizes of the colloidal amendments, with required equilibration times for some PFAS exceeding 30 days. Future work will involve laboratory column tests and development of simple modeling tools to predict long-term retention behavior.

Neda Amanat, Natural Resources Research Institute, University of Minnesota Duluth
Contamination/Remediation, Contaminants of Emerging Concern,Water Resource Sustainability

Over 1.3 billion tons of food waste (FW) are disposed of in the world annually. Methane emissions from food waste in landfills are an emerging concern, as methane is a potent greenhouse gas. Anaerobic digestion (AD) of food waste is a promising means of sustainably generating renewable energy and nutrient-rich fertilizer while preventing methane emissions in landfills. However, poly- and perfluoroalkyl substances (PFAS) have been widely detected in food and food-contact materials, and PFAS do not fully degrade during AD. Consequently, soil amendments derived from food waste could unintentionally spread PFAS to the environment. While thermal treatment processes such as hydrothermal treatment and pyrolysis have shown promise for destructive PFAS treatment, the effectiveness of these processes for PFAS treatment in food waste remain poorly understood. The overall goal of this study is to evaluate PFAS fate during food waste processing by sequential AD and thermal treatment. This presentation will focus on the phase distribution of PFAS in model food waste before and after dry and wet (i.e., co-digestion with municipal sludge) AD at the laboratory scale. Preliminary findings show that most PFAS partition substantially into the solid phase of the untreated food waste, while long-chain PFAS such as perfluorooctane sulfonic acid (PFOS) also partition into the oil phase. We hypothesize that breakdown of fatty acids during AD will cause long-chain PFAS to increasingly partition into the solid phase, such that subsequent treatment of the AD solids will be of interest. Future work will focus on PFAS fate during pyrolysis and hydrothermal treatment of digestate from dry and wet digestion, respectively.

Anne Nelson, Minnesota Department of Health
Drinking Water/Water Supply, Education and Citizen Involvement, Stakeholder & Community Engagement

Private well users in Minnesota have few protections against contaminants beyond how their well is constructed and sealed. They are responsible for inspecting their well, testing the water for contaminants, and treating their drinking water if they find unsafe levels of contaminants. Because of this, the Minnesota Department of Health (MDH) and its partners must rely on education and outreach to increase knowledge and change behaviors. One impactful audience that MDH focused its efforts on is real estate professionals. These professionals serve as a first point of contact and information for new home buyers who may not have experience with a private well.

As part of a Center for Disease Control and Prevention grant MDH created and launched a free, online training for real estate professionals in November 2023 called “Be a Well Savvy Real Estate Professional.” The course was created using Adobe Captivate and is hosted on the MDH Learning Center platform. Participants were able to access two free continuing education credits towards their real estate license for completion of the course. As of April 2024, 96 participants have completed the course, in their course evaluation over 50 percent of the participants indicated that they would like specific educational materials developed for their clients and updated online information. In response, MDH created a printable brochure called “Buying or Selling a Home with a Private Well” and updated web content to communicate information more clearly for real estate professionals. More work is ongoing to help increase knowledge of impactful audiences, including a focus on rental property owners and natural resource professionals.

Waverly Reibel, Minnesota Pollution Control Agency
Education and Citizen Involvement, Monitoring

For over 50 years, the Minnesota Pollution Control Agency has supported volunteers in collecting water clarity data through its Volunteer Water Monitoring Program. Volunteer-collected data is directly used in Minnesota’s formal water quality assessment process—a testament to the value the MPCA places on volunteers’ ability to accurately collect data. However, the real power of the program lies in the sheer magnitude of data collected by both short and long term volunteers over decades. These datasets are the driving force behind the program’s ability to conduct trend analyses on thousands of waterbodies across the state. Using the open-source statistical program R, the program annually updates lake and stream clarity trend results and shares them with the public and water resource practitioners alike. Through the Volunteer Water Monitoring Program, the MPCA broadens its understanding of water health in the state while directly supporting local water advocates interested in protecting Minnesota’s lakes and streams. In this poster, we will share information about the data volunteers collect, statistical analyses used to detect trends in water clarity, and how the MPCA uses and shares trend results in this ongoing project.

Lucy Rose, University of Minnesota
Green Infrastructure, Hydrology, Nutrients

Canopy interception alters throughfall nutrient concentrations relative to open precipitation, but interception processes are poorly understood in urban forests. We sampled weekly canopy throughfall chemistry under mature ash (Fraxinus sp.) and maple (Acer sp.) trees in St. Paul, MN during the 2022 and 2023 growing seasons. Throughfall [NO3-N] was highest in the early growing season and lowest in the late growing season, and mean throughfall [NO3-N] and [SRP] were 2.7 and 11.5 times higher, respectively, than open precipitation concentrations during the 2023 growing season. Preliminary nitrate isotope data (d15N and d18O) suggest primarily biological (e.g., microbial nitrification) rather than anthropogenic (e.g., vehicle exhaust) sources of throughfall nitrate, with biological contributions decreasing over time. Stormwater NO3-N and total phosphorus (TP) concentrations in proximal St. Paul sub-watersheds demonstrated similar temporal patterns to throughfall, with higher event [NO3-N] and [TP] in early growing season stormflow (mean NO3-N = 0.6826 +/- 1.4277 mg/L; mean TP = 0.9918 +/- 2.2868 mg/L) than in late growing season stormflow (mean NO3-N = 0.2540 +/- 0.2877 mg/L; mean TP = 0.3613 +/- 0.6343 mg/L). Our data highlight considerable local concentration variability, complicating comparisons across multiple domains of urban forestry and hydrology. Seasonal tree dynamics (e.g., canopy leaf, flower, and pollen status) correspond to tree-specific nutrient responses. For example, high throughfall nutrient enrichment can occur under one tree, while lower nutrient enrichment occurs in the immediately adjacent tree. This hyper-local variability highlights the influence of tree-level factors (e.g., rust pathogens, gall diseases, insect bycatch in throughfall samplers) on throughfall chemistry. Our results reinforce the need for multi-faceted sampling approaches and nuanced interpretation of above- and below-ground nutrient cycling processes in urban systems.

Mirae Guenther, University of Minnesota
Green Infrastructure, Nutrients, Stormwater

Concerns surrounding urban water management continue to grow with increasing urbanization and extreme weather events. Issues such as flooding, nutrient pollution, and declining water quality of recreational lakes cause concerns for public health, safety, and infrastructure protection. Amongst other variables, trees have demonstrated influence on stormwater quantity and quality and have high urban stormwater management potential.

Due to new development and redesign, resident preferences, or land use histories of urban areas, tree canopy cover and functional diversity can vary across a city and variably affect the efficiency of stormwater management. Compared to natural systems, urban areas have a multitude of contaminants and high variation in pollutant loads. The high density of impervious surfaces and diverse land uses in cities typically elevate contaminants in stormwater. Little is known about how variable extents of urban forests could affect nutrient concentrations in urban watersheds.

In this study, we examine if stormwater event scale dynamics of nitrogen and phosphorus species are sensitive to precipitation event characteristics, urban tree canopy cover, and other land use metrics in selected watersheds in Saint Paul, MN. Event flux of stormwater nutrients in all five study sub-watersheds were significantly influenced by seasonal variation and land use characteristics. Urban tree canopy cover stood out as an influential factor in models often with higher concentrations of nutrients during the leaf-on growing season than during leaf-off seasons. Data and place-based studies that focus on the specific, measurable effects of trees on urban water quality will support more resilient urban forest planning and management and further define the benefits and trade-offs of trees growing in urban watersheds.

Molly Tilsen, University of Minnesota Twin Cities
Invasive Species

Many aquatic invasive species (AIS) are primarily spread through recreational boating pathways. Understanding these pathways is essential for developing effective prevention and resource allocation strategies. Boater networks have been used for risk assessment, optimization plans, and collaboration, but have been developed using outdated data, with limited spatial scale. We hypothesize that boater traffic patterns have changed and see significant value in new data sources to expand regional approaches. Our goal was to create a predictive network of boater movements to establish a current baseline for comparisons with commensurate networks to provide viability analysis for scaling to the regional level. To predict boater connectivity, we created a network using data from the Minnesota watercraft inspection program from 2018 to 2023 using XGBoost, a gradient boosting-based machine learning algorithm. We also created a parallel model using data from FishBrain, a mobile phone application popular with anglers. For each model, we predicted weighted, directional connectivity between 9,233 lakes. Network comparisons include model predictions and metrics that describe the connectivity and influence on the network, with expected model completion in June 2024. Preliminary comparison of the FishBrain and previous networks revealed overall spatial coverage alignment and model convergence on three of the ten most influential lakes. Our boater network includes increased granularity and modularity to provide support for evidence-based targeted AIS prevention. Our data-driven approach promotes collaboration between management, scientists, and stakeholders, and has the potential for scaled applications to provide prevention, prioritization, and innovation across regions with patchy data availability.

Ashlyn Cowgill, University of Minnesota
Nutrients, Rivers, Streams, and Floodplains

Phosphorus and sediment loading remain an ongoing issue in many agricultural watersheds despite rigorous efforts to reduce nutrient runoff. As of 2024, listed impaired waters for the state of Minnesota include 740 waterways impaired for nutrients and 455 waterways impaired for sediment (total suspended solids and turbidity). The ability of phosphorus to be transported in solution as well as bound to fine sediment makes it difficult to determine the transport mechanism and residence time of phosphorus and sediment contaminants in streams. The objective of this study is to identify areas and characteristics where sediment-bound phosphorus can accumulate in stream reaches and banks. To investigate the storage of sediment and sediment-associated phosphorus within midwestern agricultural watersheds and stream reaches, we will analyze publicly available datasets of suspended sediment concentrations, total phosphorus concentrations, stream discharge, and applied phosphorus in impacted waterways. Phosphorus and sediment inputs to the watershed will be compared to channel outputs with respect to landform characteristics to evaluate the locations of potential stores. Determining where legacy phosphorus stores are likely to develop will indicate if sediment and phosphorus loading is likely to continue increasing even if rates of current anthropogenic inputs begin to decline. This will help inform future watershed management practices aimed at decreasing overall sediment and phosphorus loads in waterways affected by agricultural practices.

Dillon Huss, University of Minnesota Duluth
Stormwater

Trout streams in northern Minnesota are stressed by the changing climates and land development, which result in warm and polluted stormwater runoff. Stormwater control measures (SCMs) such as bio-infiltration basins are designed to reduce the volume and remove the pollutants of stormwater runoff from impervious surfaces before discharge into local waterways. Bio-infiltration basins are also expected to attenuate thermal impacts to trout streams caused by overland flow during summers. Tischer Creek in Duluth, MN, is a trout stream that has been impaired by temperature, and the University of Minnesota Duluth (UMD) is a main contributor of stormwater runoff to the west branch of Tischer Creek. An outdoor stormwater laboratory was installed to assess the influence of SCMs on the UMD campus regarding Tischer Creek’s water temperature. A network of temperature sensors and flow measuring devices were installed from the inlet of the bio-infiltration basin to its outlet and the stream. Additionally, six temperature sensors were installed at different depths (10 cm, 20 cm, 30 cm, 40 cm, 48 cm, and 50 cm) within the bio-infiltration basin. Monitoring was performed in the Summer and Fall of 2019, and seven storm-runoff events were captured. The monitoring data showed that the temperature of effluent storm runoff varied as it passed through the bio-infiltration basin, influenced by the vertical gradient of soil temperature in the basin. The bio-infiltration basin attenuated thermal impacts during daytime storm events and stabilized the temperature during nighttime storms.

Allegra Johnson McKee, US Geological Survey
Water Resource Sustainability

The importance of understanding and characterizing our nation’s water resources has increased in recent years, due to the impending scarcity of clean drinking water. The volume and sources of water associated with the bottled water industry are largely unknown. In 2023, the US Geological Survey developed a nationwide inventory of water bottling facilities with the goal of understanding potential hydrologic and socioeconomic impacts resulting from water bottling. During the development of the national inventory, a Great Lakes regional assessment was done in which selected facilities within the Great Lakes Basin were evaluated for completeness and accuracy. Of the 2,852 facilities in the Great Lakes region, almost 30% had an undetermined source of water. For these undetermined facilities, the facility locations, facility/owner names, business statuses, products manufactured, and water sources were checked using business websites, local news articles, Google Earth images, records from US Environmental Protection Agency’s Safe Drinking Water Information System and other contextual clues to improve the accuracy of the facility dataset. An additional 288 facilities were added to the Great Lakes inventory because of this detailed data checking process. This process improved the quality of data, identified missing data and concretized specific errors that can now be corrected and improved in future water-supply data compilations. All data collection efforts have some degree of error, and the Great Lakes regional assessment had the rare opportunity to pinpoint exactly where those errors came from and how they can be mitigated in future projects.

Ingrid Schneider, University of Minnesota - Twin Cities, Forest Resources Department
Education and Citizen Involvement, Equity and Environmental Justice, Stakeholder & Community Engagement

Inequitable access to and benefits derived from nature- and water-based recreation persist, despite a rapidly diversifying population. Among the consequences are disproportionate benefit attainment and weakened gateway community resilience (Flores et al., 2018; Xiao et al., 2021). Although the black and African American population is the fastest growing in Minnesota (MN State Demographer, 2023), they account for only a small portion of outdoor recreationists (MN DNR, 2017). However, the extent of the visitation inequity is unknown. Therefore, this study quantified the inequity index along Lake Superior’s North Shore, a water-based ‘recreational hub’ (McCreary et al., 2018, p. 124). Adopting Flores et al. (2018) inequity index, we calculated county and regional-level visitation inequity indices for available North Shore datasets that included race and ethnicity measures. Among these datasets, we calculated indices among three groups: all travelers, tourists, and locals. Values deviating from zero indicate either positive or negative indices where black, African American populations are over- or under-represented in visitor bases. County-level results indicate consistent positive indices for nature-based recreation entities in one of three counties and these patterns intensified when considering only local visitation. Similarly, at the North Shore region level, primarily negative indices resulted and these patterns persisted more intensely when considering only local visitors. As multiple North Shore recreation and tourism organizations strive for equitable access, these results underscore imperative and timely opportunities to improve service provision and benefit attainment. In addition, results provide a foundation for future research to understand nuanced constraints to water-based recreation.

Emily Berquist, Minnesota Department of Health
Drinking Water/Water Supply, Contamination/Remediation, Groundwater

Radium (Ra) is a naturally occurring radioactive element that occurs in parts of Minnesota groundwater. Testing for radium in private wells is not required nor is there much information about it relating to private wells. Drinking water with elevated radium over long periods of time can increase a person’s risk of cancer. The maximum contaminant level (MCL) for combined radium 226/228 is 5 pCi/L. This study determined:

1. If radium is detected in private wells and at what concentrations.
2. Can well construction and/or aquifer help determine the presence of radium?
3. Whether a public water supply well is a good indicator that private wells in the area may also have elevated radium.
4. Whether gross alpha is a good indicator for radium in drinking water.

This investigation selected five regions throughout Minnesota. Each study site is centered around public water supply wells that have combined radium 226/228 concentrations above 5 pCi/L. In round one, approximately 20 private wells were selected near a public water supply well in each study site, with similar aquifer and/or well depth as the public well. These private wells were initially sampled for gross alpha. If a private well had gross alpha above detection it was resampled for combined radium 226/228. There was a total of 97 wells sampled for gross alpha and 48 wells resampled for combined radium 226/228 in round two. Of the wells analyzed for gross alpha; 55% of wells had a detectable level. Ninety-two percent of those wells had combined radium 226/228 above detection and 25% above the MCL. Gross alpha did not have to be elevated above the MCL for combined radium 226/228 to be above 5 pCi/L.

The results show radium was detected in private wells and can be elevated above the MCL for combined radium 226/228. Public wells with radium 226/228 may be a good indicator that radium may occur in nearby private wells. Gross alpha may indicate the presence of radium and be a good screening tool for private well users.

Devin Edge, Natural Resources Research Institute
Contaminants of Emerging Concern, Lakes

Many legacy and emerging organic contaminants are resistant to environmental degradation and are known to accumulate in sediments. The overall objective of this project is to advance understanding of relationships between environmental distributions of persistent bioaccumulative toxic contaminants (PBTs) and overall ecosystem health in the Great Lakes, as part of the US EPA Great Lakes Sediment Surveillance Program. This presentation will focus on the spatial and temporal trends for legacy and emerging organic contaminants in Lake Superior and Lake Huron. 120 sediment samples (60 surface sediments across the two lakes and 60 samples from 3 sediment cores in Lake Superior) were collected during 2021–2022 surveys, and 138 legacy and emerging contaminants (including polychlorinated biphenyls, polybrominated diphenyl ethers, and novel halogenated flame retardants) were analyzed in the sediments via gas chromatography triple quadruple mass spectrometry (GC QQQ-MS) following a multistep extraction and clean-up procedure. Future work will involve analysis of contaminants in sediments of all five of the Great Lakes, with an anticipated end date in 2026. The findings of this project will provide important context for interpretation of historical sediment data in conjunction with data from more recent ecological surveys.

Phillip Taylor, Hydro International
Climate Change/Resiliency, Engineering Solutions and Applications, Innovative Technologies

Challenges of Stormwater Runoff Management

On-site management of stormwater runoff volume is often one of the most challenging and expensive aspects of stormwater design. Increased frequency and intensity of rainfall events are causing significant flooding, with associated costs in the billions of dollars for damages. Regulatory bodies are considering adjusting design storms to account for higher volumes. Combined with stricter regulations limiting discharge rates, these changes make designing detention systems very challenging.

Traditional outlet control structures typically rely on orifice plates and weirs to manage outflow. Modeling the relationship between inflow and outflow dictates the required detention volume and overall cycle time of the detention tank. As outlet design becomes more restrictive, detention tanks become larger and cycle times lengthen.

Since the design storm dictates the inflow, the outlet control structure becomes a complex design problem. This is often further complicated by the need for a minimum outlet size to prevent blockages and utility and site use conflicts.

Frequent storms can leave detention systems partially drained, causing them to bypass water that should be detained. This is a major failure point for many systems. Additionally, traditional orifice and weir outlet control structures tend to inflate the size and cost of detention systems.

Vortex flow control devices offer significant improvements in the inflow to outflow response, enabling the designer to make the detention system more robust, often smaller, and save their client significant money. This presentation will case study the use of vortex flow controls that have resulted in significantly better outlet design over traditional orifice plate and weir designs, resulting in significant cost saving, faster cycle times, with no increase in the design flow at the outlet.

Ben Humlie, Dakota County Facilities & Grounds
Aquatic Biota, Lakes, Watershed Management

Shallow lake management activities in Minnesota are often conducted by state or watershed district level governments. As urban populations grow, residents’ priorities change, and Earth’s climate becomes less predictable, local governments are increasingly called upon to take additional actions toward protecting and improving their area lakes and wetlands. Work being done by Dakota County and by the City of Eagan (located in Dakota County) includes watershed protection projects, invasive species control, herbicide applications, alum dosing, game fish stocking, goldfish and carp control, and public outreach and education projects. Our presentation gives a summary of these efforts, including results from the first year of Dakota County’s new carp barrier project, installed in spring 2024.

Adithya Ganapathiraju, University of Minnesota 
Wastewater

This study reports the effects of hydrogen extraction from the fermentation (first) stage of a two-stage anaerobic digestion system with the goal of reducing hydrogen inhibition, recovering a valuable product, and potentially improving the efficiency of the methanogenic (second) stage. The experimental setup consisted of two parallel fermentation reactors: one with headspace gas collection, and one with active gas extraction via a hollow fiber membrane. Both reactors were fed with a brewery or sterile synthetic wastewater in a series of experiments. The reactors contained encapsulated mixed cultures, prepared as described by Gutenberger et al. in 2024. An HRT of 8 hours and pH of 6.5 was maintained during the experiment. A side stream, hollow fiber membrane module was used to extract dissolved hydrogen in the trial reactor. In experiments fed brewery wastewater, cumulative hydrogen production over 37 days was 8 times higher in the reactor with active gas extraction. Chemical Oxygen Demand (COD) reduction percentage (15-25%) remained similar in both reactors, in line with that observed in experiments conducted by Chen et al. in 2022. Due to natural fermentation in the brewery wastewater, volatile fatty acids (VFA) were present in variable amounts in the influent, with no clear trends observed in VFA concentration between the influent and effluent. In experiments fed sterile synthetic wastewater, efficient gas extraction was again observed, but the total gas produced was the same for both reactors. The proficient capture of hydrogen produced biologically offers a supplementary benefit for industrial utilization, irrespective of the fermentation process's advantages. Ongoing research is focused on identifying optimal gas extraction operating parameters with expected completion in June 2024. The findings will be used to inform the operation of a pilot two-stage anaerobic treatment system, which will be implemented at a partner brewery in summer 2024.

Xiating Chen, University of Minnesota Twin Cities, St. Anthony Falls Laboratory
Climate Change/Resiliency, Green Infrastructure

Urban trees are valuable components of green infrastructure, offering benefits such as reducing stormwater runoff and alleviating urban heat island effects. However, trees’ performance as GI depends on their health and their surrounding environments. In an ongoing study that began in summer 2022, we have been monitoring the canopy health, transpiration, and surrounding microclimates of 18 ash trees (Fraxinus sp.) across four urban parks in St. Paul. All of these trees received Emerald Ash Borer (EAB) treatments, presenting a unique opportunity to evaluate trees’ functions under drought and pest stress, and how best to maintain them.

Our results in the 2023 growing season show that transpiration (i) varies across trees and parks, (ii) declines over the growing season, and (iii) can be further reduced by droughts and deteriorating canopy conditions. Canopy conditions, often related to EAB treatment efficacy, also correlated with the daily transpiration volumes, with healthier trees exhibiting fuller canopies and more transpiration. Notably, trees with healthier canopy recover their transpiration more quickly after hotter days. These results show that although trees may reduce their water transport and cooling abilities during extreme weather conditions, they can still function well as GI once they recover, if their health is maintained.

Using our results, I aim to discuss the implications of urban forestry management on water resources. Quantifying urban trees’ water needs and their functions under climate stress will provide valuable guidelines for integrating municipal forestry and water resources management, and help optimize the positive impacts of urban trees on the environment and the communities they serve.

Rick Besancon, Burns & McDonnell Engineering Company, Inc.
Climate Change/Resiliency, Flood Protection, Rivers, Streams, and Floodplains

MUD Platte South Resiliency Evaluation

The Metropolitan Utilities District (MUD) supplies water and natural gas to the City of Omaha and surrounding areas. MUD has three water plants that serve Omaha: Florence Plant, Platte West, and Platte South. Florence is the oldest plant dating back to the 1800s and is a surface water intake, Platte South the 1960s, relying on a well field, and Platte West 2000s, also a well field. Platte West was designed to take the load off the other two plants while they were rehabilitated.

MUD is currently evaluating options to update Platte South based on age and production. As part of the evaluation, MUD was concerned about the Plant’s proximity to the Platte River, and the potential for climate change altering flood events. This is particularly prescient based on the 2019 flood due to a bomb cyclone and snow melt and the resulting damage.

Burns & McDonnell modeled the Platte River using HEC-RAS and the current regulatory model. MUD asked that the 2019 flood event be included in the modeling as it is an historic flood, therefore it was added. Burns & McDonnell personnel then researched current climatological data and research to attempt to evaluate the potential effects. Research from across the country was evaluated as well as Nebraska and Platte River specific research.

The research was tabulated and evaluated, and the results appeared to focus on a 30% increase in flood flow. This data was then modeled to produce flood elevations. The results were plotted on topographic mapping to provide the client with an estimated impact to their well field and plant. The results were used to inform the client about improvements and flood protection necessary to long-term efficacy.

Rick Besancon, Burns & McDonnell Engineering Company, Inc.
Rivers, Streams, and Floodplains, Stormwater, Wetlands

Burns & McDonnell partnered with Marine Corps Air Station (MCAS) Camp Pendleton and the U.S. Fish and Wildlife Service (USFWS) to plan and construct the Moosa Creek Riparian Restoration Project, which restored an out-of-use golf course, creating a protected natural riparian habitat. The work supported overall environmental and flight safety improvements at MCAS Camp Pendleton.

The project entailed regrading the project site to manage storm flows and flood flows in the Moosa Creek floodplain, while balancing the ability to restore vegetation. Five bridges were removed from Moosa Creek, reducing restrictions and improving conveyance. Storm sewer systems from adjacent streets and neighborhoods were removed, daylighted, and replaced with natural channels. The project was used as floodplain reconnection to improve overall conveyance, reduce flood elevations, and provide hydrology to the plantings.

The modeling was challenging because the area is considered a high sedimentation area and the existing regulatory model elevations varied from surveyed elevations by as much as seven feet. Burns & McDonnell obtained a Letter of Map Revision (LOMR) to produce a model that matched the current site conditions. The site was then modeled to verify the water surface elevations did not increase more than one foot.

The project site experienced a 100-year flooding event in January of 2023. The event inundated the site and produced erosion and some damage but overall, the site remained intact. In August 2023, hurricane Hillary made landfall at the project site. Due to the previous repairs, the project site was unharmed.

The restoration of the approximately 67-acre site benefits two bird species listed under the Endangered Species Act. The project improved an existing flood plain, creating a mosaic of natural habitats for multiple species. It also extended the habitat corridor of adjacent water bodies, reduced flood elevations, and improved local water quality and ecosystem.