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Research about Illinois, Iowa, Minnesota, Wisconsin

Source-linked reports with geographic coverage including Illinois, Iowa, Minnesota, Wisconsin.

18 recordsLinked to original sources
USGS2025

Impacts of flowering rush (Butomus umbellatus L.) on macrophyte diversity and composition in the Upper Mississippi River

Flowering rush ( Butomus umbellatus L.), a perennial plant native to Eurasia, made a widespread appearance in the Upper Mississippi River in the United States in 2020, following extremely high river discharge during the previous year. Flowering rush expanded rapidly and was found at 1–10% of sites (n = 6,630 total sites) across a 400 km river reach within the first 4 years of invasion. Flowering rush invaded at least 12 of 31 wetland vegetation classes, including submersed aquatic, rooted-floating, deep marsh, and shallow marsh. Analysis of long-term macrophyte data and our targeted field study revealed that plant diversity declined with greater abundance of flowering rush over a 4-year early invasion period, suggesting that native species were displaced. Furthermore, species correlation plots showed a significant negative correlation (r < -0.1) between flowering rush and several native species, including wild celery, water stargrass, and wild rice. Non-metric multi-dimensional scaling (NMDS) ordination placed flowering rush near the center of the plot, which may indicate tolerance to a wide range of environmental conditions such as water depth, flow, and substrate. Centering on the NMDS plot also shows that flowering rush invades many types of vegetated aquatic land cover classes, which was also supported by our geographic information systems analysis of land cover invasion. These habitat associations and ecological impacts of the recent, widespread invasion of flowering rush in the Upper Mississippi River can help inform restoration and management actions during early invasion. Continuing long-term data collection can break limitations on modeling cause-effect relationships and provide insights to the future ecological trajectory of the macrophyte community to this non-native invasive species.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2025

Identifying recruitment sources across trophic levels in a large river food web

Assemblages are connected through the movement of physical and biological resources including recruits. Identifying recruitment sources for predators and their prey could help us understand how assemblages use connectivity across multiple trophic levels and whether predator and prey recruitment is coupled. Recruitment sources of organisms across multiple trophic levels can be quantified by trace element analysis of stomach contents. We used trace element analysis of otoliths to determine recruitment contributions from tributaries of predatory largemouth bass ( Micropterus salmoides ) and bowfin ( Amia calva ) and their consumed prey collected from Pools 4, 8, and 13 of the Upper Mississippi River. We used laser ablation inductively coupled mass spectrometry to quantify strontium:calcium of the core of each otolith and classified each fish to a natal origin (i.e., tributary or potential resident). We compared patterns of natal origin across study reaches, collection years, and species and with previously published origins of independently sampled prey fish. Predator and prey assemblages across all study reaches recruited from tributaries. More prey (44%) than predators (17%) recruited from tributaries. Of fishes originating from tributaries, individuals recruited from various rivers including the large Minnesota and Wisconsin Rivers and several small tributaries. Patterns in natal origin were similar among predators and prey families and among reaches, across sampling years, and between consumed prey and independently sampled prey. Tributaries consistently contributed recruits to both prey and predator fishes, leading to a coupling of predator and prey recruitment sources across space and time. Predators directly and indirectly used tributaries for recruitment and persistence through their own and their prey's recruitment. We further highlighted the utility of using consumed prey to simultaneously study the ecology of prey and predator assemblages, thereby reducing research sampling needs.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2025

Integrating data to assess occupancy patterns of an endangered bumble bee

There is growing interest in integrating community science data with structured monitoring data to estimate changes in distribution patterns of imperiled species, including pollinators. However, significant challenges remain in determining how unstructured community science data should be incorporated into formal analyses of species distributions. We developed a dynamic framework for combining community science and structured monitoring data of bumble bees to estimate changes in occupancy of rusty-patched bumble bees ( Bombus affinis ), a federally endangered species in the United States. We applied traditional metapopulation theory and accounted for imperfect detection to estimate site-specific extirpation risk and colonization rates across the known distribution of B. affinis in the Upper Midwest (USA). Despite a 144% increase in presence-only detections from 2017 to 2022, occupancy probabilities and the estimated number of occupied sites remained static or declined slightly across a 4-state region during this period. Our results provide preliminary evidence that the probability of local extirpation risk of B. affinis increased in response to drought, but that effect was tempered with a high number of neighboring patches occupied by B. affinis (i.e., rescue effect). Our framework can be used by managers to track population recovery goals for B. affinis and other bumble bees of conservation concern. In addition, our study highlights the importance of accounting for imperfect detection and addressing spatial sampling biases in bumble bee monitoring efforts, particularly those for which a portion of the monitoring data are generated from community science projects.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2024

Flooding and dam operations facilitate rapid upstream migrations of native and invasive fish species on a regulated large river

Dams commonly restrict fish movements in large rivers but can also help curtail the spread of invasive species, such as invasive bigheaded carps ( Hypophthalmichthys spp). To determine how dams in the upper Mississippi River (UMR) affect large-scale invasive and native fish migrations, we tracked American paddlefish ( Polyodon spathula ) and bigheaded carp across > 600 river km (rkm) and 16 navigation locks and dams (LD) of the UMR during 2 years with contrasting water levels. In 2022, a low-water year, both native paddlefish and invasive bigheaded carp had low passage rates (4% and 0.6% respectively) through LD15, a movement bottleneck being studied for invasive carp control. In contrast, flooding in 2023 led to open-river conditions across multiple dams simultaneously, allowing 53% of paddlefish and 46% of bigheaded carp detected in Pool 16 to move upstream through LD15. Bigheaded carp passed upstream through LD15 rapidly (μ = 32 rkm per day) a maximum of 381 rkm, whereas paddlefish moved an average of 9 upstream rkm per day (maximum of 337 rkm). Our results can inform managers examining trade-offs between actions that enhance native fish passage or deter movements of invasive species. This understanding is critical because current climate change models project increases in flooding events like that observed during 2023.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2023

Aquatic vegetation types identified during early and late phases of vegetation recovery in the Upper Mississippi River

Assemblage patterns and processes of aquatic vegetation in most large floodplain rivers are not well understood, particularly after plant recovery. Identifying vegetation types, which are recurring plant groupings based on species composition, diversity, and abundances, can describe plant assembly patterns and environmental drivers that aid conservation planning and management. We used a 22-year dataset ( n = 18,000 sampling plots) to identify aquatic vegetation types during an “early phase” and “late phase” of plant recovery at multiple spatial scales nested within a 500-km river reach of the Upper Mississippi River, USA. We hypothesized that vegetation types varied according to scale because of the stark environmental differences among riverine habitats and differing regional species pools along the river's latitudinal gradient, and that the late phase of recovery had developed several new vegetation types. We first used cluster analyses at multiple spatiotemporal scales to identify the number of vegetation types and their characteristics, such as indicator species, species compositions and abundances, and diversity index. Then we applied a multivariate regression to pinpoint environmental factors (such as hydrodynamics, system productivity, local habitat, and water quality) that structured those vegetation types. Clustering revealed that ~90% of plots irrespective of recovery phase were not classified into vegetation types, which indicated that most aquatic sampling plots are unique in species composition and unpredictable. However, impounded areas upriver from dams had matured five vegetation types: lotus ( Nelumbo lutea Willd.), submersed (a mix of 11 common submersed species), watercelery ( Vallisneria americana Michx.), arrowheads ( Sagittaria rigida Pursh and Sagittaria latifolia Willd.), and a diverse community (with high diversity indices and multiple life forms). The vegetation types were associated with three environmental gradients related to inundation depth and duration, system productivity, and water clarity. These five vegetation types are known to be of high ecological value to fish and wildlife and thus targets for restoration, for example, the watercelery community is principal forage for migrating canvasback ducks ( Aythya valisineria ) along the Mississippi River flyway. Our results provide insights on vegetation assembly during recovery and aid habitat conservation by providing quantitative, environmental targets for restoration.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2022

Addressing detection uncertainty in Bombus affinis (Hymenoptera: Apidae) surveys can improve inferences made from monitoring

The U.S. Fish and Wildlife Service developed national guidelines to track species recovery of the endangered rusty patched bumble bee [ Bombus affinis Cresson (Hymenoptera: Apidae)] and to investigate changes in species occupancy across space and time. As with other native bee monitoring efforts, managers have specifically acknowledged the need to address species detection uncertainty and determine the sampling effort required to infer species absence within sites. We used single-season, single-species occupancy models fit to field data collected in four states to estimate imperfect detection of B. affinis and to determine the survey effort required to achieve high confidence of species detection. Our analysis revealed a precipitous, seasonal, decline in B. affinis detection probability throughout the July through September sampling window in 2021. We estimated that six, 30-min surveys conducted in early July are required to achieve a 95% cumulative detection probability, whereas >10 surveys would be required in early August to achieve the same level of confidence. Our analysis also showed B. affinis was less likely to be detected during hot and humid days and at patches of reduced habitat quality. Bombus affinis was frequently observed on Monarda fistulosa (Lamiales: Lamiaceae), followed by [ Pycnanthemum virginianum Rob. and Fernald (Lamiales: Lamiaceae)] , Eutrochium maculatum Lamont (Asterales: Asteraceae), and Veronicastrum virginicum Farw. (Lamiales: Plantaginaceae). Although our research is focused on B. affinis , it is relevant for monitoring other bumble bees of conservation concern, such as B. occidentalis Greene (Hymenoptera: Apidae) and B. terricola Kirby (Hymenoptera: Apidae) for which monitoring efforts have been recently initiated and occupancy is a variable of conservation interest.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2022

Annual summer submersed macrophyte standing stocks estimated from long-term monitoring data in the Upper Mississippi River

System-scale restoration efforts within the Upper Mississippi River National Wildlife and Fish Refuge have included annual monitoring of submersed aquatic vegetation (SAV) since 1998 in four representative reaches spanning ∼ 440 river kilometers. We developed predictive models relating monitoring data (site-scale SAV abundance indices) to diver-harvested SAV biomass, used the models to back-estimate annual standing stock biomass between 1998 and 2018, and compared biomass estimates with previous abundance measures. We modeled two morphologically distinct groups of SAV with differing sampling efficiencies and estimated each separately: the first category included only wild celery Vallisneria americana, which has long, unbranched leaves and dominates lotic environments, while the second category included 17 branched morphology species (e.g., hornwort Ceratophyllum demersum and Canadian water weed Elodea canadensis ) and dominates lentic environments. Wild celery accounted for approximately half of total estimated total biomass in the four reaches, combined branched species accounted for half, and invasive species (Eurasian watermilfoil Myriophyllum spicatum and curly-leaf pondweed Potamogeton crispus ), a fraction of the branched species, accounted for < 1.5%. Site-scale SAV estimates ranged from 0 to 535 g·m −2 (dry mass). We observed increases in biomass in most areas between 1998 and 2009 and substantial increases (e.g., from < 10 g·m −2 to ∼ 125 g·m −2 ) in wild celery in extensive impounded areas between 2002 and 2007. Analyses also indicate a transitional period in 2007–2010 during which changes in biomass trajectories were evident in all reaches and included the start of a 9-y, ∼ 70% decrease in wild celery biomass in the southernmost impounded area. Biomass estimates provided new insights and illustrated scales of change that were not previously apparent using traditional metrics. The ability to estimate biomass from Long Term Resource Monitoring data improves conservation efforts through better understanding of changes in habitat and food resources for biota, improved goal setting for restoration projects and improved quantification of SAV-mediated structural effects such as anchoring of sediments and feedbacks with water quality.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2022

Aquatic vegetation dynamics in the Upper Mississippi River over 2 decades spanning vegetation recovery

Macrophytes have recovered in rivers across the world, but long-term data and studies are lacking regarding community assembly and diversity changes coincident with macrophyte recovery. We investigated patterns of aquatic vegetation species composition and diversity in thousands of sites in the Upper Mississippi River, USA, spanning 21 y of monitoring and a period of vegetation recovery. We analyzed site-level compositional dissimilarity and environmental associations using non-metric multidimensional scaling, compared stability of lake-level assemblages over time with convex hulls, and assessed shared trends in assemblage dissimilarity at the pool scale using dynamic factor analysis. Site-level differences in aquatic vegetation assemblage structure were associated with water depth and substrate, and a gradient of species abundance and diversity was apparent. A common trend in assemblage dissimilarity over time and across contiguous floodplain lakes indicate that assemblage composition changed and diversity increased with considerable synchrony within the past 21 y. Shared trends across the 400-km study reach are indicative of 1 or more widespread, common drivers; however, neither hydrologic extremes nor turbidity explained vegetation assemblage patterns. Following several years of strong changes in composition and increased diversity, the vegetation assemblage displayed signs of increasing stability in some pools but not others. Further research is needed to identify drivers and mechanisms of aquatic vegetation assemblage expansion, assembly, and resilience, all of which will be applicable to the recovery of aquatic vegetation in floodplain systems worldwide.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2020

Breeding birds of the upper Mississippi River floodplain forest: One community in a changing forest, 1994 to 1997

Floodplain forest on the upper Mississippi River (UMR), a unique habitat in the Midwest that is important for many bird species, has been reduced and is undergoing continued reduction and changes in structure and species diversity because of river engineering and invasive species. Hydrological changes are causing tree diversity to decline favoring Acer saccharinum (silver maple) and Fraxinus pennsylvanica (green ash). Invasive Phalaris arundinacea (reed canary grass, Phalaris ) threatens tree regeneration, and recent Agrilus planipennis (emerald ash borer) arrival threatens to decimate the important ash component of the forest canopy. During the 1990s, virtually no information was available about breeding songbird species and abundances on the UMR floodplain forest from along many river miles and a broad range of forest situations (for example, mainland, island, edge, interior). From 1994 to 1997, we surveyed breeding birds and sampled vegetation at 391 random points on UMR floodplain forest along a latitudinal gradient from Red Wing, Minnesota, to Clinton, Iowa, to characterize bird assemblages and associations with gradients in forest structure at survey points (local scale) and land cover composition within a 200-meter radius of survey points (landscape scale). Eighty-six bird species were detected during the study, but 28 species comprised 90 percent of all detections. Species that are typically associated with woodland edge or are tolerant of fragmentation were the most common: Setophaga ruticilla (American Redstart), Troglodytes aedon (House Wren), Turdus migratorius (American Robin), Quiscalus quiscula (Common Grackle), and Vireo gilvus (Warbling Vireo). Species typically associated with large forest patches— Setophaga cerulea (Cerulean Warbler), Hylocichla mustelina (Wood Thrush), and Dryocopus pileatus (Pileated Woodpecker)—were rare. Principal components analyses consistently described local habitat gradients related to canopy cover and Phalaris presence and described landscape gradients related to forest area and areas of open land cover types. However, nonmetric multidimensional scaling revealed no pattern in bird assemblages. Canonical correspondence analyses with local habitat variables for each year revealed that bird assemblages were affected by canopy cover, the presence of Phalaris , and the number of tree species. Four bird species were consistently associated with Phalaris presence or negatively with canopy cover, and no species were associated with the number of tree species variable. Although landscape variables were significantly related to the bird assemblage in canonical correspondence analyses, no bird species were consistently related to any landscape variable. These results indicate that there is one assemblage of forest birds on the UMR composed mainly of edge-tolerant species. Species associated with lower canopy cover and Phalaris presence may be favored to increase in abundance as canopy cover opens as trees die and Phalaris becomes more prevalent.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2012

Patterns in species richness and assemblage structure of native mussels in the Upper Mississippi River

1. To evaluate patterns in mussel assemblages in the Upper Mississippi River (UMR), data from systematic surveys of mussels conducted in three large reaches (Navigation Pools 5, 6, and 18) from 2005&ndash;2007 were analysed. 2. Nonmetric multi-dimensional scaling analyses and permutation tests indicated that assemblages differed among reaches. The mussel assemblage in Pool 18 was substantially different from the assemblage in Pool 5 and moderately different from the assemblage in Pool 6, whereas assemblages in Pools 5 and 6 were similar. Assemblages in broadly defined, flowing aquatic habitats did not substantially differ. 3. The dissimilarity of Pool 18 was primarily the result of Pool 18 having higher abundances of three Quadrula species (Q. quadrula, Q. pustulosa, and Q. nodulata), and lower abundances of Amblema plicata and Fusconaia flava. 4. Rarefaction analyses showed that species richness and species density were higher in Pool 18 compared with the other two pools. 5. Large-scale patterns in mussel assemblages may be related to other longitudinal trends in the system including geomorphology, water quality, and abundances of fish species that serve as hosts for glochidial larvae. 6. The results suggest that management goals and actions in the UMR may need to account for important differences in mussel assemblages that occur among reaches.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2011

Temporal changes in spatial patterns of submersed macrophytes in two impounded reaches of the Upper Mississippi River, USA, 1998-2009

We examined temporal changes in spatial patterns of submersed aquatic macrophytes during a recent three-fold increase in macrophyte abundance and in response to the cumulative effects of management actions (island construction and water level management) and changes in regional environmental conditions (turbidity) in two navigation pools of the Upper Mississippi River, Pool 8 (managed) and Pool 13 (unmanaged). We used cross-correlograms to quantify changes in the degree and range of spatial correlation between submersed macrophytes and depth across the impounded portions of the two pools from 1998-2009. Along with increases in abundance, we observed gradual expansion of submersed macrophytes into deeper water in both pools. However, we detected no temporal change in spatial patterns in Pool 13, where the range of spatial correlation was ∼ 1500-2500 m in length in the downriver direction and ∼ 500-1000 m in length in the crossriver direction. We initially detected similar ranges of spatial correlation in Pool 8, but over time the range of correlation in the cross river direction increased from ∼ 500 m in 1998 to ∼ 2000 m by 2009. Thus, the expansion of submersed macrophytes into deeper water areas in Pool 8 appears to have occurred in the cross-river direction and led to increases in patch size and a more symmetrical patch configuration. Hence, very similar temporal changes in submersed macrophyte abundance corresponded with different diffusion dynamics and spatial patterns in the two pools. We hypothesize that management actions altered spatial patterns of depth, water flow and/or wind fetch and led to the differences in spatial patterns reported here.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2005

Modelling habitat associations with fingernail clam (Family: Sphaeriidae) counts at multiple spatial scales using hierarchical count models

1. Macroinvertebrate count data often exhibit nested or hierarchical structure. Examples include multiple measurements along each of a set of streams, and multiple synoptic measurements from each of a set of ponds. With data exhibiting hierarchical structure, outcomes at both sampling (e.g. within stream) and aggregated (e.g. stream) scales are often of interest. Unfortunately, methods for modelling hierarchical count data have received little attention in the ecological literature. 2. We demonstrate the use of hierarchical count models using fingernail clam (Family: Sphaeriidae) count data and habitat predictors derived from sampling and aggregated spatial scales. The sampling scale corresponded to that of a standard Ponar grab (0.052 m 2 ) and the aggregated scale to impounded and backwater regions within 38–197 km reaches of the Upper Mississippi River. Impounded and backwater regions were resampled annually for 10 years. Consequently, measurements on clams were nested within years. Counts were treated as negative binomial random variates, and means from each resampling event as random departures from the impounded and backwater region grand means. 3. Clam models were improved by the addition of covariates that varied at both the sampling and regional scales. Substrate composition varied at the sampling scale and was associated with model improvements, and reductions (for a given mean) in variance at the sampling scale. Inorganic suspended solids (ISS) levels, measured in the summer preceding sampling, also yielded model improvements and were associated with reductions in variances at the regional rather than sampling scales. ISS levels were negatively associated with mean clam counts. 4. Hierarchical models allow hierarchically structured data to be modelled without ignoring information specific to levels of the hierarchy. In addition, information at each hierarchical level may be modelled as functions of covariates that themselves vary by and within levels. As a result, hierarchical models provide researchers and resource managers with a method for modelling hierarchical data that explicitly recognises both the sampling design and the information contained in the corresponding data.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2004

Hydrologic and hydraulic factors affecting passage of paddlefish through dams in the Upper Mississippi River

Populations of paddlefish Polyodon spathula have been adversely affected by dams that can block their movements. Unlike high-head dams that preclude fish passage (unless they are equipped with fishways), the dams on the upper Mississippi River are typically low-head dams with bottom release gates that may allow fish passage under certain conditions. We evaluated the relation of dam head and river discharge to the passage of radio-tagged paddlefish through dams in the upper Mississippi River. Radio transmitters were surgically implanted into 71 paddlefish from Navigation Pools 5A and 8 of the upper Mississippi River and from two tributary rivers during fall 1994 through fall 1996. We tracked paddlefish through September 1997 and documented 53 passages through dams, 20 upstream and 33 downstream. Passages occurred mostly during spring (71%) but also occurred sporadically during summer and fall (29%). Spring passages varied among years in response to hydrologic conditions. We evaluated patterns in upstream and downstream passages with Cox proportional hazard regression models. Model results indicated that dam head height strongly affected the upstream passage of paddlefish but not the downstream passage. Several paddlefish, however, passed upstream through a dam during periods when the minimum head at the dam was substantial ( ≥1 m ). In these cases, we hypothesize that paddlefish moved upstream through the lock chamber.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2004

Feeding habitat characteristics of the Great Blue Heron and Great Egret nesting along the Upper Mississippi River, 1995-1998

The Great Blue Heron ( Ardea herodias ) and Great Egret ( Ardea alba ) nested in eight colonies along the Upper Mississippi River, USA, and individual birds were followed by airplane to feeding sites during the nesting seasons in 1995-1998. Both species used braided channel/backwater habitats for feeding more than expected, based on availability, and open pool and main navigation channel less than expected. Most individuals of both species fed <5 km from their breeding colony and avoided sites >10 km away. Habitat and distance need to be considered simultaneously when assessing habitat quality for herons and egrets. The Great Blue Heron flew farther to feeding sites during the care-of-young period than during incubation and the Great Egret showed the opposite pattern. The Great Blue Heron tended to feed solitarily; only 10% of the feeding flights ended at a location where another heron was already present. About one-third of Great Egret feeding flights ended at a location with another egret already present. Colony placement on the landscape seemed to be a function of the feeding radius of each colony.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS1995

Cadmium and mercury in sediment and burrowing mayfly nymphs (Hexagenia) in the upper Mississippi River, USA

Longitudinal patterns in the cadmium and mercury content of burrowing mayflies ( Hexagenia ) and surrounding sediments were examined along a 572-km reach of the upper Mississippi River. Surficial sediments and Hexagenia nymphs were sampled in 1989 at 12 sites extending from Pool 2 through Pool 16 and analyzed for total recoverable cadmium and total mercury. In sediment and nymphs, concentrations of both metals were highest in Pools 2, 3, and 4, which are just downstream from the Twin Cities (Minneapolis-St. Paul, Minnesota) metropolitan area, the primary anthropogenic source of metals to the studied reach of river. Concentrations of the two metals in sediments indicated a significant anthropogenic contribution, which was most pronounced for cadmium. The cadmium concentrations in surficial sediment varied less than 3-fold (range, 1.19–3.23 μg/g dry weight) among the 12 sites, whereas concentrations in Hexagenia varied almost 20-fold (range, 0.13–2.35 μg/g dry weight). Nymphs from Pools 2–4 had much greater concentrations of cadmium than nymphs from sites further downstream, even though the mean concentration of cadmium in sediment from Pools 2–4 (3.0 μg/g) was just twice that (1.6 μg/g) for the nine sites downstream. Mercury in sediments from the 12 sites ranged from 0.038 to 0.165 μg/g dry weight, averaging 0.14 μg/g in Pools 2–4 and 0.056 μg/g in the nine sites downstream. In nymphs, mercury concentrations ranged from 0.041 to 0.134 μg/g dry weight. The bioavailability of sediment-associated cadmium seemed greater in Pools 2, 3, and 4 than in the sites further downstream, based on the relative cadmium concentrations in Hexagenia nymphs and sediment. Moreover, it is concluded that the trapping of sediment and associated metals in Lake Pepin (a natural riverine lake in Pool 4) significantly reduces the exposure of the ecosystem further downstream to metals from the Twin Cities and other upstream anthropogenic sources.

Illinois, Iowa, Minnesota, Wisconsin↗