Concurrent Session I, Track A: Stormwater Management Tools and Techniques

1112: West Riverside Energy Center: How Nature Based Solutions Supported Envision Platinum Verification

Michael Ryan, HDR Engineering, Inc.

To transition toward cleaner energy production, Alliant Energy embarked on the development of the most environmentally friendly, natural gas energy facility in the Midwest. The West Riverside Energy Center (WREC) provides power to more than 550, 000 homes. Located on a 90-acre site in Wisconsin, the WREC became the first Envision Platinum-verified project in the state by following the Institute for Sustainable Infrastructure’s framework for sustainability, resiliency, & equity in infrastructure.

The planning, design, and construction of the WREC leveraged Nature-Based Solutions to restore natural systems. The project restored 67 acres of natural environment through the conversion of agricultural cropland to native prairie grasses & wildflowers, creating new habitat and improving connectivity. In addition to the landscape restoration, the project was designed to mimic pre-development hydrologic conditions. Innovative techniques, including stormwater harvesting and re-use, stormwater pond retrofits, and treatment trains including rain gardens and bioswales helped the project achieve the Restorative designation for stormwater management, becoming the first ever Envision-certified project to reach this performance standard, in which stormwater management was not intended as the primary purpose of the project.

The WREC manages 170 acres of stormwater runoff through BMPs that include vegetated swales, a 1- acre infiltration basin with engineered subsurface media, 5, 000 gallon stormwater harvest and re-use cistern, and land use conversion. The project reduces stormwater flow rates by 20%, volume by 65, 000 CF annually, and TSS by 84%. The design achieved ISI’s Restorative designation for stormwater management by improving pre-developed hydrologic conditions and retaining or repurposing more than 100% of the pre-development infiltration capacity of the site. Successful planning, design, and construction of the WREC serves as a model for Nature-Based Solutions in the Midwest.

1087: Introducing A Tool for Assessing Phosphorus Retention in Stormwater Ponds

Author(s): Ben Janke, University of Minnesota; Poornima Natarajan, University of Minnesota; Vinicius Taguchi, North Carolina State University; Jacques Finlay, University of Minnesota; John Gulliver, University of Minnesota; William Herb, University of Minnesota

Description: Thousands of ponds are being used for stormwater management in Minnesota cities, providing runoff detention and removal of phosphorus (P) and other pollutants. Yet, as many of these ponds are now decades old, their treatment performance may be degraded from accumulating organic matter, phosphorus, and growth of aquatic and shoreline vegetation. Assessment of pond performance through comprehensive monitoring is expensive and not a practical option for most watershed managers, given the large number of ponds in many cities. Thus, there is a substantial need to assess the performance of ponds for P removal in a robust, straightforward, and inexpensive manner. Building on the results of several years of intensive data collection (e.g., water samples, water chemistry, sediment phosphorus release, aggregation and characterization of supporting datasets) through multiple research projects the results, we have developed a spreadsheet-based Pond Assessment Tool. This tool is designed to use readily-available spatial, water quality, and pond data to indicate risk and provide estimates of water column phosphorus concentration, sediment phosphate release, and anoxia in ponds treating stormwater. We will introduce the background data collection and analysis, including the development of risk indicators used by the Tool – landscape and water body characteristics (such as anoxia, duckweed cover, canopy cover, and land use) that were related to high phosphorus water concentrations and sediment release of dissolved phosphorus in our studied ponds. We will also discuss how the Tool can be used to prioritize monitoring or maintenance in ponds, improving pond phosphorus retention and the cost-effectiveness of stormwater management.

1105: Patterns in Stormwater Pond Sediment Chemistry in the Twin Cities Metropolitan Area

Author(s): Joseph Bischoff, Barr Engineering

Description: Stormwater ponds are one of the most common stormwater practices in the Twin Cities Metropolitan Area (TCMA) designed to settle and remove phosphorus from watershed runoff. These stormwater ponds come in many shapes and sizes ranging from newly constructed ponds to existing wetlands excavated to improve particulate and phosphorus settling. Most traditional designs for stormwater ponds assume minimal anoxia over the sediments and that settled phosphorus is permanently removed from watershed loading to downstream waters. Recent studies challenged these assumptions demonstrating that even shallow stormwater ponds have long periods of anoxia and subsequent sediment phosphorus release reducing the effectiveness of the stormwater ponds. Many cities and watershed districts are now investigating sediment chemistry to describe current conditions and develop an understanding of the mechanisms that lead to sediment phosphorus release. As a result, patterns are emerging in sediment chemistry that may have implications for management actions aimed at sequestering phosphorus in the sediments. For example, labile organic phosphorus may play a larger role in sediment P release in stormwater ponds as compared to lakes, potentially increasing the importance of aerobic phosphorus release or minimizing the importance of redox sensitive P fractions. Understanding these patterns supports the investigation of methods to reduce or eliminate sediment P release by evaluating where selected practices will be successful. There are also significant data gaps in our understanding of sediment P pools and future research is needed to develop passive management techniques that support permanent phosphorus sequestration in stormwater ponds.

1104: Litter from Urban Street Trees Is a Significant Portion of N and P Loads to Stormwater Throughout The Year

Author(s): Erin Mittag, University of Minnesota, Dept of Ecology, Evolution, & Behavior; Sarah Hobbie, University of Minnesota; Jacques Finlay, University of Minnesota; Paula Kalinosky, Emmons & Olivier Resources, Inc.; Ben Janke, University of Minnesota; Rachel King, NA; Lawrence Baker, University of Minnesota;

Description: Street trees in urban environments can be important conduits for nutrients; they take up nitrogen (N) and phosphorus (P) from soils and deposit them onto streets in the form of litter. These nutrients can rapidly enter stormwater in dissolved and particulate forms, contributing to eutrophication of receiving waters. Our goal was to quantify the contribution of street trees to stormwater nutrient loads. Using data from high-frequency street sweeping programs in the Twin Cities Metro Area (TCMA), we modeled the relationship between percent canopy cover over streets and the mass of litter N and P swept in the spring, summer, and fall. We used these relationships to estimate loads of N and P from street trees to stormwater, then compared these estimates to observed nutrient outputs from 12 TCMA watersheds. Preliminary results suggest that street tree contributions to total stormwater N and P regularly exceed 40% annually and 20% across all seasons, with the greatest contributions in the fall. This work will conclude in summer 2023 by exploring additional watershed characteristics that mediate the relationships between trees and stormwater N and P. These findings provide support and guidance for street sweeping and street tree management as tools to address excess nutrients across the urban landscape.

Concurrent Session I, Track B: Agricultural Water Management

1007: Examining Chloride in an Agricultural Watershed Using a Mass Balance and Simple Hydrologic Model

Author(s): Alycia Overbo, University of Minnesota Water Resources Science Program; Sara Heger, University of Minnesota Water Resources Center; John Gulliver, University of Minnesota Department of Civil, Environmental, and Geo- Engineering

Description: Elevated chloride levels in lakes, rivers, streams, and groundwater are a concern in many northern states, particularly in urban areas where deicing salt can be a major source of chloride pollution. A growing body of research shows that in agricultural and mixed land-use watersheds, potash fertilizer, water softening, manure, wastewater discharge, and industries can also be important sources of chloride pollution. A chloride mass balance was conducted for Sand Creek Watershed, a chloride-impaired, agricultural watershed in southern Minnesota, with the intent of developing a simple chloride model to characterize chloride sources in a mixed land-use watershed. Annual chloride mass contributions were estimated for major point and nonpoint sources, including wastewater treatment plants, industry, deicing salt, potash fertilizer, livestock waste, and septic systems using various permitting data, monitoring data, land cover data, spatial data, and other records. The estimated annual chloride loading was used in conjunction with a simple hydrologic model to estimate annual and monthly loads and flow-weighted mean concentrations over a five-year study period. Results from the simple model indicate that deicing salt, agriculture, and wastewater were the greatest sources of chloride loading to Sand Creek Watershed over the study period. Elevated chloride levels were typically observed in low-flow periods when point sources had greater impact on stream concentrations. The presentation will discuss impacts of loading and timing of individual chloride sources in the watershed, as well as implications for chloride management.

1008: Agricultural Drainage Projects: Why They Happen and Solutions That Protect Water Downstream

Author(s): Chuck Brandel, ISG; Jacob Rischmiller, ISG

Description: Many of Minnesota’s stormwater drainage systems are over 100 years old and in disrepair. As a result, landowners across the state face costly flooding and erosion issues and are requesting that systems be replaced. Guiding the development of efficient systems that reduce these issues is the Minnesota Statute Chapter 103E.

This chapter builds a framework for the petition and design of drainage systems and identifies important environmental considerations that should be accounted for in design. Prior to the petition process, there are many system solution options that landowners, drainage authorities, and engineers are considering and implementing. Of growing popularity are wetlands, storage ponds, and other Best Management Practices (BMPs) that can be implemented in rural watersheds to offset potential negative hydraulic and environmental changes.

In this presentation, ISG Vice President and Civil Engineer Chuck Brandel will discuss why agricultural drainage projects happen and describe modern considerations that go into moving forward with these projects, such as Chapter 103E considerations, cost-benefit analysis, and capacity. Chuck will provide an overview of current industry approaches to modeling drainage systems solutions using InfoWorks ICM software. This overview will highlight current trends for modeling overland flow, storage, tile size, and other considerations using BMPs that reduce downstream impacts while developing cost effective solutions for landowners.

1001: Does Soil Health Management Influence Water Infiltration

Author(s): Limeimei Xu, UMN Bioproducts/Biosystems Engineering; Leslie Ludtke, UMN, Bioproducts/Biosystems Engineering; Joe Magner, UMN, Bioproducts/Biosystems Engineering; Holly Dolliver, UMN, Bioproducts/Biosystems Engineering

Description: To protect and improve local soil resources, knowledge was developed to promote local sustainable soil health management more effectively. The main purpose of this study is to determine if local soil health management practice is having a positive impact on soil infiltration rates. To achieve the goal, four major land resources areas in Minnesota were chosen, and each of them was treated with three (undisturbed, soil health, and conventional) management practices. By looking at the infiltration measurements, specific management practice with other soil property related factors including soil moisture, soil type, bulk density at these land resources areas, data from a regional perspective were analyzed to see 1. If there are any area differences in infiltration rates under three management practices, and if soil health management practice has a positive impact on infiltration rates. 2. If the infiltration rate of the soil health management practice can do a regression by specific management practice, soil moisture, soil type and bulk density, plus how these different factors can affect infiltration rate. The study will be completed by summer 2023, the infiltration rates of areas are expected to have a great variability under three management practices that may be due to different soil types in different areas. Based on the regression model being developed, at least specific management practice plays an important role to determine infiltration rate of soil health management practice.

1003: Assessing the Effects of Agricultural Management Systems on Soil Architecture and Soil Moisture in Southern Minnesota

Author(s): Bailey Tangen, UMN; Anna Cates, UMN; Jeff Vetsch, UMN; Emily Krekelberg, UMN; Bill Lazarus, UMN; Gregg Johnson, UMN

Description: Soil health management systems that reduce disturbance are touted to improve soil hydraulic functions. Here, we investigated the response of soil volumetric water content to rainfall and aggregates under different agricultural management systems. Rainfall can cause physical slaking of aggregates, which can cause the loss of surface pores, reducing hydraulic functions. Soil health management systems have been shown to be correlated with increases in stable aggregates and soil pores but it’s not clear if this pore increase moves water more quickly into the soil profile following a rain in fine-textured soils in southern MN. Mechanisms aside, structural stability is of avid interest to farmers in temperate regions, where soil health farmers often claim they can get into the field earlier after a rain due to improved soil structure. During 2021 and 2022, we collected data from 5 replicated tillage/cover crop treatments at Southern Research and Outreach Center in Waseca, MN and 3 on-farm pairs representing conventional and soil health systems in southern Minnesota on clay loams and silt loam soils. We monitored moisture content and soil aggregate distribution 24 hours before, 24 hours following and 3 days following several rain events. In years with low rainfall, soil health and conventional treatments had little difference in the response to rainfall, though soil health treatments had significantly greater aggregate stability across growing seasons. While soil health systems had greater water capture at depth, there were few differences between treatments in terms of short-term changes to soil physical properties. Data was collected at these sites, including potentially mineralizable carbon, permanganate oxidizable carbon, infiltration data, and pore distribution. Using these metrics, we hope to link soil health indicators to meaningful soil functions, finishing the analysis in Fall 2023.

Concurrent Session I, Track C: Assessing Contaminants in Minnesota Surface Waters

1005: Evaluation of Neonicotinoids in Minnesota Surface Water

Author(s): David Tollefson, Minnesota Department of Agriculture; Matt Ribikawskis, Minnesota Department of Agriculture; Bill VanRyswyk, Minnesota Department of Agriculture

Description: Neonicotinoid insecticides (neonics) are soluble in water and highly mobile in the environment. Neonics are used as a seed treatment for many agricultural crops across Minnesota and applied as a broad-spectrum insecticide in both agricultural and developed urban areas. The total amount of neonics used as a seed treatment is estimated to be far greater than other uses in Minnesota.

The Minnesota Department of Agriculture (MDA) began to analyze for neonics in water samples in 2010. Detections have occurred in rivers and streams, agricultural drainage tile, urban wetlands, rain, and groundwater. Three neonics are annually detected in Minnesota rivers and streams including clothianidin, imidacloprid, and thiamethoxam. From 2019 through 2022 detection frequencies in agricultural regions, excluding central Minnesota where detections in groundwater are more frequent, were generally consistent for clothianidin (16-49%), imidacloprid (18-33%) and thiamethoxam (0-12%). Imidacloprid was also detected in 44% of samples collected from urban streams for the same period. Detections of clothianidin and imidacloprid over the USEPA aquatic life benchmark occur annually in Minnesota rivers and streams.

Results will be presented that indicate increased neonic detection frequencies and higher concentrations during, and soon after, crop planting each year (May through July) suggesting neonic use as a seed treatment is a likely source. Imidacloprid detections in urban streams were less variable, with detection frequency increasing through the summer months. The water quality detection patterns are generally consistent with neonic use in agricultural and developed urban watersheds.

1014: The Minneapolis Pathogen Toolbox

Author(s): Shahram Missaghi, City of Minneapolis; Rachael Crabb, Minneapolis Park and Recreation Board; Allison Hansen, CDM Smith; Jodi Polzin, CDM Smith

Description: The Minneapolis Pathogen Toolbox provides procedures and resources to identify, investigate, analyze, and ultimately mitigate the sources of pathogens in urban aquatic environments. The elevated levels of Escherichia coli (E. coli), a ubiquitous pathogenic bacterium, in waterbodies is an impairment for recreation. Stormwater runoff carries bacteria to downstream creeks, rivers, and lakes. There is a potential risk to the environment, and human health in water contaminated with pathogenic bacteria. To minimize the risk of illness, beaches routinely close when E. coli bacteria levels exceed state standards, which impacts the quality of life that people enjoy. There is a need to establish a rapid, efficient, and dependable management scheme to detect, identify, and treat elevated bacteria in stormwater, creeks, rivers, and lakes. This is the purpose of the MN Pathogen Toolbox. The toolbox was one of the outcomes of the MN Pathogen Task Force, which was organized to provide guidance and support on the Regulatory, Monitoring, and Implementation challenges of managing bacteria in stormwater. CDM Smith was hired to create the toolbox structure and content. The toolbox was developed with a focus on providing resources for an MS4 water resource manager in an urban area. The resulting ten graphically rich and attractive tools provide detailed information on pathogen sources, monitoring, testing, modeling, BMPs, as well as literature and guidance on which tool to use for specific circumstances. The City of Minneapolis and the Minneapolis Parks and Recreation Board have long been actively working to meet the challenges of bacteria in stormwater and recreational water and are eager to share this toolbox with the stormwater community for a clean water.

1093: Piloting an Enhanced E. Coli Source Assessment on Five Impaired Lake Superior Beaches

Author(s): Kaity Taylor, MPCA; Lindsey Krumrie, MPCA; Tim Beaster, South St. Louis SWCD; Cindy Hakala, MDH; Tom Estabrooks, MPCA

Description: An enhanced E. coli source assessment was conducted in 2019 and 2020 by Minnesota Pollution Control Agency (MPCA), Minnesota Department of Heath’s Lake Superior Beach Monitoring Program and South St. Louis SWCD in support of the Duluth Area Beaches 2022 Total Maximum Daily Load (TMDL). Sources of E. coli are widespread and often intermittent ranging from untreated wastewater to seagulls and geese to dogs. Understanding the different source contributions of E. coli and their potential risk to human health is important to overall TMDL implementation practice selection and prioritization. A detailed, multi-step source assessment was conducted to better identify the source contributions to impaired beaches. Steps included:

1. A Planning Level Source Assessment to identify the “first-cut” of potential sources of pathogens and areas influencing beach water quality

2. Field Data Collection to obtain water quality data and observe beach conditions 3. Laboratory Analysis, including microbial source tracking to confirm potential sources with DNA biomarkers

Results helped target E. coli sources for TMDL implementation and developed beach-specific implementation activities. Results also prompted further action on Leif Erikson Beach and Chester Creek, both of which had high levels of human derived genetic markers, by the city of Duluth and the MPCA.

Unexpected project delays due to shipping issues provided key lessons in risk management and proper planning. Project leads also learned important lessons about clear messaging as assessment results were presented internally at the MPCA, across state lines to Wisconsin partners, to local stakeholders, and to the public. This presentation will highlight project design and implementation, discuss results and share lessons learned.

1039: Antibiotics in Minnesota Surface Water: Results from Ten Years of Monitoring

Author(s): Mark Ferrey, Minnesota Pollution Control Agency

Description: Thirty-two antibiotics were monitored in Minnesota’s rivers, lakes, and streams in five large probabilistic studies from 2012 to 2022. Fifty sampling locations were randomly selected across Minnesota for each study in cooperation with the National Aquatic Resource Study. Nineteen antibiotics were detected at least once, including eight sulfa drugs and trimethoprim, five fluoroquinolones, and five macrolides. Tetracyclines and penicillins have never been detected in surface water. The most frequently detected antibiotic was carbadox with 40 total detections, followed by sulfamethoxazole, erythromycin, and sulfamethazine, with 26, 15, and 8 total detections, respectively. Sulfamethazine was found at the highest concentration of 134 ng/L, while most antibiotics were detected at less than 50 ng/L. 95th percentiles were calculated for all antibiotics detected in any one of the five studies and ranged from 70 ng/L for carbadox in 2012 to 0.4 ng/L for sulfadimethoxine in 2022. Even at very low concentration, antibiotics in surface water may be contributing to the problem of antibiotic resistant bacteria. However, the number of antibiotic detections and concentrations appear to be decreasing since 2014, perhaps due to the overall decrease in antibiotic prescriptions and the increasing use of pharmaceutical drop-off locations across the state.

Concurrent Session I, Track D: Tools and Planning for a Changing Climate

1023: Climate-Ready Stormwater Ponds in Hennepin County: A Proactive Future Conditions Study

Author(s): Kris Guentzel, Hennepin County; Chris McLinn, Hennepin County; Della Schall Young, Young Environmental Consulting Group

Description: By 2050, climate predictions point to hotter and wetter conditions, creating the risk of surface flooding from larger rainfall events and undersized stormwater infrastructure. Hennepin County is leading proactive climate action planning through a study of current and prospective conditions. This project studied stormwater ponds and other existing infrastructure on three County-owned properties to:

  • Identify design conditions
  • Establish the current function and capacity
  • Evaluate improvements to ensure environmental benefits
  • Enhance resilience in the face of future climate conditions
  • Help the County make progress toward goals in its Climate Action Plan

In many cases, local stormwater infrastructure is not expected to withstand future storm frequency and intensity. The project team evaluated the ponds’ ability to meet design and regulatory objectives now and in the future by reviewing as-built data, collecting field surveys, assessing water quantity and quality, developing models, and assessing maintenance options.

Our project looked at future scenarios, using climate projection estimates from Headwaters Economics, the National Oceanic and Atmospheric Administration (NOAA), and the US Environmental Protection Agency to study a greater range of design events. The project sought to understand what additional infrastructure was needed to achieve ‘resiliency’ on these sites, defined as the ability to retain and treat the anticipated net increase in stormwater. We assessed a suite of best management practices (BMPs) and will consider the most effective ones for future funding.

Completed in late 2022, the project informs short-term planning for maintenance and long-term planning for site enhancements to reduce impervious surfaces, add green space, and build stormwater resiliency. This project shows how a Climate Action Plan can be implemented in both daily work and long-term planning to bring practical enhancements and ensure resilience.

1004: Potential Hydrologic Impacts from Trends in Intense Rainfall and Antecedent Moisture in Minnesota Watersheds Since 1950

Author(s): Jason Ulrich, Science Museum of Minnesota, St. Croix Watershed Research Station

Description: Increased occurrences and magnitudes of intense rain events have been a growing focus of climate research in Minnesota. From a water resources management perspective, the importance of these intense rainfall trends lies in their potential to increase the frequency/magnitude of flood flows at relevant watershed scales. This study explores watershed-scale trends in climate data-derived metrics associated with both intense rainfall events (>= 90th percentile 1- and 3-day events) and pre-event antecedent moisture from 1950-2021. Non-parametric trends analyses reveal annual statistically significant, spatially coherent trends in these metrics are present over much of southern Minnesota’s watersheds; elsewhere in the state, trends are less prominent. Most pronounced monthly increases are occurring in October, April, and May. The study further explores how intense rainfall and antecedent moisture (pre-event rainfall and baseflow) have directly influenced flood flows in select watersheds in southern Minnesota using a hybrid data-driven/modeling approach.

1083: Surface Water and Ocean Topography (SWOT) Satellite and Minnesota Applications

Author(s): Katy Thompson, Stantec; Jamil Ibrahim, Stantec

Description: At the end of 2022, NASA’s Jet Propulsion Laboratory (JPL) and its partners launched the new earth-observing satellites, SWOT, with the specific mission to conduct the first global survey of the Earth’s surface waters (lakes, wetlands, reservoirs, rivers), to detect new ocean features, and enable data applications. For the purposes of this presentation, we will focus on SWOT’s mission to create a global inventory of all terrestrial waterbodies and SWOT’s hydrologic applications, as part of its Early Adopter program.

As the SWOT satellite pass over the globe, it collects detailed measurements of water levels, day or night, regardless of cloud cover, with a 75-mile wide swath; this allows overlapping measurements over most of the globe every 11 days. Our objective is to leverage our existing remote sensing capabilities and machine-learning technologies to quickly and efficiently measure and monitor changes in freshwater bodies and rivers. The SWOT data will be particularly useful in Minnesota to validate lake and wetland water balance analyses and modeling, monitor flood events and quantify evaporation losses, assess water quality and sediment management projects, and provide hydrologic information for ungaged or remote watersheds. We will present the results of SWOT’s first mission year and applications in Minnesota.

1035: Rice Creek Climate Change Floodplain Resiliency

Author(s): Bret Zimmerman, Houston Engineering, Inc.; Kendra Sommerfeld, Rice Creek Watershed District

Description: The Rice Creek Watershed District recently completed a study to assess how vulnerable its communities are to increased rainfall depths and intensities due to climate change. The study was partially funded through an MPCA grant for climate adaptation planning projects. The project team used the district-wide hydrologic and hydraulic model to simulate estimated future conditions rainfall events, map the estimated future conditions rainfall floodplain, and identify capital improvement projects that would reduce the risk to increasingly vulnerable areas. The study identified a conceptual design for a number of capital improvement storage projects to reduce flood damages.

By looking at future conditions rainfall events, the District is taking a proactive approach to reduce flood damage rather than reacting to address flooding concerns after a damaging event. As part of the study, the District facilitated two planning meetings to engage community members and leaders in climate adaptation and resilience planning. This presentation will address the identified risks and vulnerable areas related to future conditions rainfall events, highlight the importance of engaging community members throughout the planning process, and present the capital improvement projects identified in the study.

Concurrent Session I, Track E: Special Session

The Changing Mindset of Work: How Values and Opportunities Shape a Digital-Ready Workforce

Tracy Fallon, Jeffrey Stamp, University of Minnesota

Does this digital-ready workforce have the skills needed to meet the industry's needs? Are there ways that industry needs to accommodate a digital transformation? A panel will discuss results from surveys sent this summer to hiring managers, students, and recent graduates on the changing face of our work and the workforce. The breakout session will center on how we define our values and opportunities to benefit that workforce and our customers.