About

Joe Magner is a research professor in the Department of Bioproducts and Biosystems Engineering at the University of Minnesota. He holds a Ph.D. in Hydrology and Watershed Management from the University of Minnesota and a B.S. in Soil and Water Science from the University of Wisconsin, River Falls. Magner is a licensed professional hydrologist registered with the American Institute of Hydrology, a licensed professional soil scientist in Minnesota, and a licensed hydrologist in Wisconsin. With over 42 years of experience, he has served as an environmental scientist and educator, primarily with the Minnesota Pollution Control Agency, and has advised U.S. federal and local governments as well as officials in China, India, Azerbaijan, and South Africa. His teaching and research focus on water quality, hydrology, ecological engineering, and watershed management, exploring ecological connections between increased precipitation and groundwater. Magner has successfully advised more than 40 graduate students and has contributed to over 100 publications. He is also a co-author of the 4th edition of 'Hydrology and the Management of Watersheds' published by Wiley-Blackwell in 2013.

Research topics

• Computer Science
• Environmental science
• Geography
• Environmental resource management
• Ecology
• Engineering
• Water resource management
• Cartography
• Economics
• Environmental economics
• Remote sensing
• Business
• Agricultural engineering
• Civil engineering
• Geology

Selected publications

• Non-ideal continuously stirred bioreactor model for multi-media denitrifying processes

  Biosystems Engineering · 2025-04-04 · 1 citations

  articleOpen accessSenior author
  PublisherDOI

• A Streamlined Methodology for Identifying Point Source Inputs from Rural and Agricultural Sources

  Preprints.org · 2025-11-21

  preprintOpen accessSenior author

  Rural and agricultural runoff continues to pose a threat to water quality and human health despite a plethora of research identifying likely causes. Large livestock operations and leaking septic systems have proven to be significant sources of both nutrients and bacteria in the form of algal blooms and antibiotic-resistant Escherichia coli. Many times, these impacts are witnessed on a watershed scale. Implementing remedies are complicated by livestock operations defined as point source facilities under the USA Clean Water Act (CWA) but regulated as non-point source agricultural runoff. Additionally, the State of Michigan is the only state in the USA without a comprehensive rural septic system law. Pollutant assessment of watersheds involves a wide array of sampling parameters that focus primarily on impacts after-the-fact. Non-point source pollution, particularly in rural areas, lacks regulatory teeth; this watershed management approach is not sustainable as evidenced by continual degradation of our rural watersheds. This study lays out a streamlined methodology incorporating focused parameters that can infer pollutant pathways and processes. We illustrate the methodology using data collected in the Pine River watershed (central Michigan) where multiple pollutant inputs were defined as exceeding water quality standards in channels and reservoirs. The results of this work beg for better understanding of what should be defined as sustainable and unsustainable land use/watershed management. Using simplified field and laboratory techniques, it is possible for local communities, educational institutions, and regulatory agencies to identify likely pollutant sources violating water quality standards regardless of point or nonpoint designation.

  PublisherOA PDFDOI

• Optimizing water-efficient agriculture: evaluating the sustainability of soil management and irrigation synergies using fuzzy extent analysis

  Scientific Reports · 2025-08-11 · 7 citations

  articleOpen accessSenior author

  Sustainable agriculture demands the integration of optimized irrigation and soil tillage practices. Poor selection or mismatched combinations of these practices can lead to inefficient resource use, declining soil health, and reduced crop productivity. Despite extensive research on individual tillage and irrigation methods, limited studies explored their combined effects on multiple agricultural sustainability parameters. This gap underscores the need for a comprehensive assessment framework that can guide farmers and stakeholders in identifying optimal combinations for diverse agricultural objectives. This study employs a compounded fuzzy extent analysis to evaluate the cumulative impact of various soil tillage and irrigation methods on key agricultural parameters, including affordability, maximum yield, climate resilience, water usage, soil disruption, disease resistance, ease of operation, nutrient utilization, and crop diversification. The analysis compares individual practices and their combinations using comparative matrices to identify the most suitable options across all parameters. The fuzzy logic approach addresses data uncertainty by converting linguistic variables into triangular fuzzy numbers, enabling more accurate decision-making. The results indicate that Zero Tillage is the most effective tillage practice (score of 0.176), while Deficit Irrigation emerges as the most efficient irrigation method, scoring 0.144. The research suggests that integrating Zero-Tillage (ZT) with Deficit Irrigation (DI) is the most cost-effective agricultural practice. Additionally, combining No-Tillage (NT) with Surface Irrigation and Mulching (SIM) results in higher yields and improved water use efficiency. Furthermore, the synergy of No-Tillage (NT) and Drip Irrigation (DI) enhances crop resilience to climate change. These findings provide valuable insights for developing sustainable agricultural strategies that balance productivity, resource conservation, and environmental protection.

  PublisherDOI

• Biochemical Processes within a Two-Stage Agricultural Drainage Ditch in Mower County, Mn: Methods for Estimating Nitrogen Removal Rates and Efficiencies

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Biochemical Processes within a Two-Stage Agricultural Drainage Ditch in Mower County, Mn: Methods for Estimating Nitrogen Removal Rates and Efficiencies

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Biochemical processes within a two-stage agricultural drainage ditch in Mower County, MN: Methods for estimating nitrogen removal rates and efficiencies

  Agricultural Water Management · 2025-07-28 · 1 citations

  articleOpen access

  Drainage ditch design has historically focused on providing adequate water conveyance. More recently, greater attention has been placed on alternative designs that assimilate excess nutrients. However, due to the hydrologic complexities, accurately calculating nutrient removal in these systems presents a challenge. In 2009, 1.89 km of a conventional drainage ditch in Mower County, MN, was converted to a two-stage design. The objective was to evaluate three different methods for calculating nitrogen removal in this system. Continuous data from the growing season of 2010 was used to produce average monthly removal efficiencies by comparing influent and effluent concentrations, which ranged from 19.5 % in May to 12.9 % in September. Three dates were used in 2013, 2011, and 2010 to produce mass-balance relationships for in-channel denitrification using isotopic tracers. Removal efficiencies were estimated at 21 % (2013), 32 % (2011), and ∼20 % (2010) using the mass-balance approach. Nitrous oxide production was measured from soil samples taken for one date in 2013 to estimate potential soil denitrification using the acetylene inhabitation assay, which varied greatly among habitat zones from 0.08 to 1.85 µg N 2 O-N g DW −1 g h −1 . Potential habitat-weighted soil denitrification ranged from 19 % to 42 % compared to 1–3 % estimated for a hypothetical conventional drainage ditch. Although denitrification rates and removal efficiencies are difficult to quantify, comparing the results from multiple dates using an array of methods can validate and add robustness to studies of two-stage ditch denitrification, providing further support for alternative drainage ditch designs as an effective method for addressing nutrient pollution to our natural waterways. • A conventional drainage ditch was converted to a two-stage design in MN, USA. • Three different methods were used to calculate nitrogen removal efficiencies. • Nitrogen removal efficiencies ranged between ∼13 and 42 %. • Removal efficiency for a conventional drainage ditch was estimated at 1 – 3 %. • All removal methods produced results similar to one another and the literature.

  PublisherDOI

• Impacts of Impervious Surfaces on Urban Stormwater Quality: Minneapolis Case Study Analysis

  JAWRA Journal of the American Water Resources Association · 2025-11-09 · 1 citations

  articleOpen accessSenior author

  ABSTRACT Urban stormwater runoff is a major concern for water quality. Impervious surfaces, especially in urban environments, can allow stormwater direct access to receiving waterbodies and make up nearly 90% of land cover in downtown Minneapolis, Minnesota. A study of stormwater runoff from impervious surfaces in downtown Minneapolis, Minnesota, USA, was conducted to understand the potential impacts of different types of impervious surfaces (i.e., streets, sidewalks, parking lots, and rooftops). A rainfall simulator delivered water to the street, sidewalk, and parking lot sites and the rooftop runoff characteristics were studied separately using automated samplers and rain gauges. ANOVA statistical analysis was used to determine whether stormwater runoff pollutant concentrations (chloride, total suspended solids, and total phosphorus) varied significantly within surface types, between surface types, and across seasons. Results showed that the first flush of runoff contained higher pollutant concentrations than the whole rain event, and water quality differences for all surfaces were relatively minor for the summer and fall seasons. In contrast, pollutant concentrations were significantly higher in the spring, particularly on streets. Among all surface types, streets exhibited the highest event‐mean concentrations (EMCs) for all pollutants. The study highlights the importance of surface‐specific stormwater management strategies and the need for tailored BMP design and policies to enhance the effectiveness of mitigating water quality impairments in urban environments.

  PublisherDOI

• A Monitoring and Modeling Approach to Quantifying the Effectiveness of Best Management Practices in a Small Agricultural Watershed

  2024-01-01

  articleOpen access1st authorCorresponding

  Conventional agricultural practices produce nonpoint source water pollution. The implementation of Best Management Practices (BMPs) in a watershed plays a vital role in improving water quality. Assessing the effectiveness of BMPs requires both monitoring and modelling. A nonpoint source management water policy change was introduced in Minnesota to monitor and model small watersheds for 16 years to determine the effectiveness of BMPs. Monitoring small watersheds alone has not shown water quality improvement; there has been a lack of observable improvement in water quality due to the fragmentation of landscape BMPs and lag time. Dobbins Creek was selected as a sentinel watershed to track water quality for a period longer than a few years to account for lag time. Dobbins Creek is a small agricultural watershed located in the headwaters of the Cedar River. This is an important large watershed that contributes to Gulf of Mexico hypoxia. A monitoring and modelling program were implemented in 2016 that included the analysis of sediment and nutrients at strategic locations in the watershed. We demonstrate how to show an exceedance of water quality standards primarily during stormflow before major BMP implementation. Over time we anticipate water quality changes with land use changes and financial incentives, but the proper approach must be designed and financially supported to be truly effective

  PublisherOA PDFDOI

• Biochemical Processes within a Two-Stage Agricultural Drainage Ditch in Mower County, Mn: Methods for Estimating Nitrogen Removal Rates and Efficiencies

  SSRN Electronic Journal · 2024-01-01

  preprintOpen access
  PublisherDOI

• The Evaluation of a Novel Denitrifying Woodchip Bioreactor: Fairmont, MN, USA

  Nitrogen · 2024-02-21

  articleOpen accessSenior author

  The risk of nitrate contamination became a reality for Fairmont in Minnesota, when water rich in NO3-N exceeded the drinking water standard of 10 mg/L. This was unexpected because this city draws its municipal water from a chain of lakes that are fed primarily by shallow groundwater under row-crop land use. Spring soil thaw drives cold water into a subsurface pipe where almost no NO3-N reduction occurs. This paper focuses on NO3-N reduction before the water enters the lakes and no other nitrogen management practices in the watershed. A novel denitrifying bioreactor was constructed behind a sediment forebay, which then flowed into a chamber covered by a greenhouse before entering a woodchip bioreactor. In 2022 and 2023, water depth, dissolved oxygen, and temperature were measured at several locations in the bioreactor, and continuous NO3-N was measured at the entry and exit of the bioreactor. The results showed better performance at a low water depth with lower dissolved oxygen and higher water temperature. The greenhouse raised the inlet temperature in 2022 but did not in 2023. The forebay and the greenhouse may have impeded the denitrification process due to the high dissolved oxygen concentrations in the influent and the stratification of dissolved oxygen caused by algae in the bioreactor.

  PublisherOA PDFDOI

Frequent coauthors

• Srinivas Rallapalli

  University of Minnesota

  17 shared

• John L. Nieber

  University of Minnesota

  15 shared

• Kate Brooks

  14 shared

• Bruce Wilson

  12 shared

• Judy C. Helgen

  11 shared

• Brenda DeZiel

  ID-FISH Technology (United States)

  10 shared

• George W. Lucier

  National Institutes of Health

  9 shared

• James G. Burkhart

  University of Montana

  9 shared

Education

• Hydrology & Watershed Management, Forest Resources

  University of Minnesota System

  2006

Awards & honors

• Registered Professional Hydrogeologist, American Institute o…
• Licensed Geoscientist (Soils), State of Minnesota (1998)
• Licensed Hydrologist, State of Wisconsin (1999)