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Hydrologic extremes, whether periods of drought or flooding, are occurring more frequently with greater severity and can have substantial economic impacts. Along with flooding, the timing and volume of streamflow also is changing across the United States. The focus of this report is to characterize a unique trend in mean annual streamflow occurring in eastern North and South ��ֱ����, hereafter referred to as the eastern ��ֱ����s, that is not being observed anywhere else in the conterminous United States.
Streamflow records for 1,853 U.S. Geological Survey stream gages obtained from the U.S. Geological Survey National Water Information System database with a continuous record of mean annual streamflow during water years 1960–2019 were included in this study. Using a Kendall tau statistical test, 573 stream gages had a statistically significant upward trend in mean annual streamflow and are primarily located in the Midwest and northeastern United States. Of the stream gages, 182 had a statistically significant downward trend and are located primarily in the western and southeastern States. Several sites had increases in streamflow between 100 and 500 percent. Most of the stream gages with the highest increases in mean annual streamflow are along the same rivers in the eastern ��ֱ����s, regardless of basin size.
A comparison of mean annual streamflow of the last decade (2010–19) to the first decade (1960–69) of the study period shows that the largest increases in annual streamflow volumes in the United States also are in the eastern ��ֱ����s. Among all 1,853 stream gages in the United States, the Sheyenne River near Warwick, North ��ֱ����, has the greatest percent change, with an increase of 486 percent. Several factors may be contributing to increasing trends in streamflow in the eastern ��ֱ����s and may include, in part, precipitation changes owing to climatic variation within the region, geologic makeup of the subsurface, and land-use changes. A better understanding of these research areas will help producers, resource managers, and infrastructure engineers to make more informed environmental and economic decisions. 

Presentation will provide an overview of water rights administration in South ��ֱ���� and the tools used to manage the state’s water resources. South ��ֱ���� water rights law follows the doctrine of prior appropriation (first in time – first in right) in the administration of the appropriation of the state’s water resources. Water within the state is the property of the people of the state, but the right to the use of water may be acquired.  All uses of water except domestic use require a water right to be obtained. The criteria for approval of a water permit are: 1) there must be a reasonable probability unappropriated water is available, 2) proposed diversion can be developed without unlawful impairment of existing domestic uses and water rights, 3) the proposed use must be a beneficial use and 4) be in the public interest within the regulatory authority of the Water Management Board. State law provides that water resources be put to beneficial use to the fullest extent of which they are capable, and that the waste or unreasonable use of water be prevented.  South ��ֱ���� has protections in law to prevent over appropriation to ensure water resources are maintained into perpetuity.  Most notably the “anti-groundwater mining” statute which does not allow average annual withdrawals to exceed recharge to our various aquifers. The Department of Agriculture and Natural Resources maintains an observation well network of about 1,600 wells to monitor water levels in over 100 aquifers, participates with the US Geological Survey to fund stream gaging stations, requires water use reporting for irrigation water rights and new water rights for non-irrigation uses, and participates with our SD Geological Survey on aquifer studies. 

Climate patterns in the Northern Great Plains can influence water availability, leading to notable changes in the surface area of regional lakes. Since the late-1990s, surface area expansion in Eastern South ��ֱ���� lakes has been linked to elevated mercury (Hg) concentration in fishes. Adult walleye Sander vitreus in many of these lakes can have Hg concentrations exceeding 3 ppm and these populations often exhibit limited natural reproduction. To evaluate the influence of methylmercury exposure on walleye reproduction, we compared seasonal reproductive characteristics between two walleye populations – one that exhibits low Hg concentration (Pelican Lake, mean =0.05 ppm ) and one that has high Hg concentration (Bitter Lake, mean Hg=1 ppm). Mean monthly concentrations of estradiol-17β and testosterone for both male and female walleye were suppressed in fish from Bitter lake (high Hg) compared to Pelican lake (low Hg). Gonadal development in male fish was significantly lower in Bitter Lake than in Pelican Lake. Moreover, eggs fertilized with sperm from males with high Hg concentrations had significantly lower fertilization success (30 %) than those from low Hg males (65%). Because methylmercury concentration in lakes with elevated fish Hg were within the range where fertilization success declined, waterborne Hg concentrations could negatively impact walleye reproduction.

Heavy rains over the Big Sioux, Vermillion and James River Basins in June of 2024 created a record flood event in southeast South ��ֱ����. Timing of flood crests on major rivers in the region determined how significant the flood impacts would be. Impacts included destruction of homes, broken wastewater force mains, erosion and inundation of ag land, flooded roads and highways, and damage to bridges. Preparation for and response to the flood included river forecasting, inundation mapping, discharge measurements, and water quality issues. The South ��ֱ���� Flood Information System, which is managed by DANR, was extremely useful in predicting flood impacts and used frequently by state and local officials during the flood event.

Per- and polyfluoroalkyl substances (PFAS) are recognized as a challenge for drinking water systems due to their widespread use and persistence in the environment. This presentation will provide a practical understanding of PFAS focusing on compliance with evolving regulations, how these chemicals could enter drinking water supplies, and the operational challenges involved in detecting and removing them. This presentation will equip audience members with an understanding of the state of PFAS in South ��ֱ����’s regulated drinking water systems, regulatory requirements that will be taken by public water systems, and plans the State currently is working on for the future.

The zebra mussel (Dreissena polymorpha), an invasive species originating from Eurasia, is likely to increasingly become a significant ecological and economic concern in South ��ֱ����'s freshwater systems. Since its initial detection in the state, the zebra mussel population has rapidly expanded, colonizing several major water bodies including the Missouri River. This invasion threatens native aquatic biodiversity, disrupts local ecosystems, and imposes costly damages to water infrastructure. Our study provides an initial analysis of the current known distribution across the state and highlights some of the significant economic and ecological impacts. We provide an update on our laboratory’s efforts to understand this species and its potential for spread across the state. We also highlight the monitoring and management strategies of zebra mussels in other states and the urgent need for coordinated efforts to mitigate further spread and reduce their ecological footprint.

An updated perspective on planning, development, and construction of a $100 million water transmission project. Topics will include evaluating future water needs, funding development, procurement strategies, and a discussion of lessons learned for other major transmission projects on the horizon. 

Recognizing South ��ֱ����’s arid climate and vulnerability to drought, groundwater availability, as well as the critical importance of water quality and quantity, ��ֱ���� Mainstem was conceptualized. This project is not just an infrastructure plan but a commitment to the state’s future, ensuring South ��ֱ���� continues to attract top-level businesses, industries, investors, and individuals. The genesis of ��ֱ���� Mainstem is a testament to the pragmatic approach of South ��ֱ����ns, who understand that such ambitious projects require substantial time, investment, and collaboration at local, state, and federal levels.

This presentation illuminates an innovative drainage project approach, emphasizing a paradigm shift to balance landowner and environmental needs. Integrating large wetland and storage practices, this mitigation process simultaneously addresses landowner requirements and promotes environmental stewardship. National Agricultural Drainage Expert, Chuck Brandel, PE, will lead the discussion on challenges that currently hinder drainage project implementation in Minnesota such as opposition from environmental groups, public perception, complex granting processes, and stringent cost/benefit criteria, excluding water quality as a benefit. Illustrating ISG's successfully funded and implemented water quality projects, the presenter will highlight the critical need for additional funding to scale these solutions, potentially reducing flooding and improving water quality. This session explores collaboration strategies and presenting opportunities for partnerships with environmentally committed farmers and firms. By showcasing real-world examples and fostering attendee feedback in overcoming barriers, the presenter will inspire support and investment in sustainable drainage projects for tangible, widespread benefits.

An overview of the Seasonal Riparian Area Management Program (SRAM) and its impacts on water quality in the Big Sioux River Watershed. What 4 years of water quality sampling has indicated from real-time data at strategic locations along Skunk Creek early in the development of the SRAM program. Declining E. coli concentrations in stretches of Skunk Creek have shown success of the management to achieve the levels needed to support designated beneficial uses. In conclusion, grazing livestock can still be carried out in riparian zones with minimal management and improve water quality

Building upon stakeholder interviews, SDSU School of Design and SDSU Extension have developed a statewide survey to assess our behaviors and values regarding water. This presentation will describe the survey, hypotheses, and preliminary findings.

Stormwater runoff is one of the most common forms of non-point source pollution. The presence of Escherichia coli (E. coli) in stormwater runoff indicates potential fecal contamination which has been linked to increased risk of waterborne illness during recreational exposures. A new filtration technology using recycled steel byproducts has been developed to remove E. coli from stormwater. This project installed a pilot scale filter using steel byproducts at a stormwater site in the City of Sioux Falls. The filter media consisted of 70% steel slag and 30% steel chips. The removal of E. coli of this pilot scale filter at multiple storm events was determined. The results showed that the steel byproduct filter removed an average of 35-60% of the E. coli under various flow conditions. Similar removal efficiencies were also observed for phosphate, another important stormwater contaminant. The results of this pilot scale study demonstrated that steel byproduct filtration is a highly effective technology for E. coli removal from stormwater under real world treatment conditions.

Water deficit and water excess are two challenges facing farmers and communities in the Upper Midwest of the United States. Excess moisture leads to crop loss at the field scale as well as flooding at the watershed scale. Deficit moisture conditions lead to crop loss or reduced crop productivity as well as potential water shortages for communities. Conservation agriculture and soil health advocates have pointed to improved capture and storage of precipitation as a way to mitigate both extreme conditions. While past research has documented improvements in parameters such as organic matter and water holding capacity, the extent to which these changes affect water volume and peak flow at the watershed scale has been less rigorously studied.

The Roadmap to Water Resilience project, in southeast South ��ֱ����, combined field measurements with social science and economics to model watershed-scale impacts of field-scale conservation implementation. Results from local social science surveys were incorporated into the modeling to develop realistic implementation scenarios. Incentive payments, as part of these scenarios, were then applied to each implementation scenario to understand the potential cost that would be incurred for a downstream entity to support conservation implementation as a way to reduce flooding. Policy implications include expected outcomes from payment for ecosystem services models and improved resilience to weather extremes at the field scale. This approach could be used to understand the impact of likely scenarios of conservation implementation for other ecosystem services.
 

In this presentation, we will talk about the past and current trends in climate, weather, and water resources in South ��ֱ����. The data will be obtained from USGS, NOAA, and other state and federal agencies. The presentation outputs will be a time series analysis indicating how the climate and weather impact the water resources (quantity) in South ��ֱ���� and what it means for SD Water Resources Sustainability and Security.