Search USGS⌕ Search

SEARCH · Search USGS

Results for “River Systems”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
USGS2008

Flood trends and river engineering on the Mississippi River system

Along >4000 km of the Mississippi River system, we document that climate, land-use change, and river engineering have contributed to statistically significant increases in flooding over the past 100-150 years. Trends were tested using a database of >8 million hydrological measurements. A geospatial database of historical engineering construction was used to quantify the response of flood levels to each unit of engineering infrastructure. Significant climate- and/or land use-driven increases in flow were detected, but the largest and most pervasive contributors to increased flooding on the Mississippi River system were wing dikes and related navigational structures, followed by progressive levee construction. In the area of the 2008 Upper Mississippi flood, for example, about 2 m of the flood crest is linked to navigational and flood-control engineering. Systemwide, large increases in flood levels were documented at locations and at times of wing-dike and levee construction. Copyright 2008 by the American Geophysical Union.

Geophysical Research Letters↗
USGS2017

The Upper Mississippi River System—Topobathy

The Upper Mississippi River System (UMRS), the navigable part of the Upper Mississippi and Illinois Rivers, is a diverse ecosystem that contains river channels, tributaries, shallow-water wetlands, backwater lakes, and flood-plain forests. Approximately 10,000 years of geologic and hydrographic history exist within the UMRS. Because it maintains crucial wildlife and fish habitats, the dynamic ecosystems of the Upper Mississippi River Basin and its tributaries are contingent on the adjacent flood plains and water-level fluctuations of the Mississippi River. Separate data for flood-plain elevation (lidar) and riverbed elevation (bathymetry) were collected on the UMRS by the U.S. Army Corps of Engineers’ (USACE) Upper Mississippi River Restoration (UMRR) Program. Using the two elevation datasets, the U.S. Geological Survey (USGS) Upper Midwest Environmental Sciences Center (UMESC) developed a systemic topobathy dataset.

Illinois, Iowa, Minnesota, Missouri, Wisconsin↗
USGS2009

Prioritizing removal of dams for passage of diadromous fishes on a major river system

Native diadromous fishes have been extirpated from much of the Susquehanna River system for nearly a century. Recent restoration efforts have focused on removal of dams, but there are hundreds of dams and presently there is no biologically based system to assist in prioritizing their removal. We present a new method that uses existing habitat suitability index models (HSI) for American shad Alosa sapidissima, alewife A. pseudoharengus, blueback herring A. aestivalis, and American eel Anguilla rostrata to prioritize the removal of non-hydropower dams within the Susquehanna River system. We ranked HSI scores for each of the four species, association between a landscape-scale factor and HSIs, length of river opened by removing a dam, and distance from the mouth at Chesapeake Bay for each dam and then calculated a mean rank prioritization for dam removal by averaging the ranks for the seven criteria. This prioritization method is resistant to outliers, is not strongly affected by somewhat arbitrary decisions on metrics included in the analysis, and provides a biologically based prioritization for dam removal that can be easily amended to include other metrics or adapted to other river systems and that complements other social and economic considerations that must be included in decisions to remove dams.

River Research and Applications↗
USGS2018

Indicators of ecosystem structure and function for the Upper Mississippi River System

This report documents the development of quantitative measures (indicators) of ecosystem structure and function for use in a Habitat Needs Assessment (HNA) for the Upper Mississippi River System (UMRS). HNAs are led periodically by the U.S. Army Corps of Engineers’ Upper Mississippi River Restoration (UMRR) Program, which is the primary habitat restoration program on the UMRS. The UMRR Program helps determine how Federal, State and nongovernmental agencies can best address environmental issues on one of the world’s largest and most diverse river systems. Each indicator in this report represents at least one management objective developed for the river system. These objectives were developed in a previous planning effort using an ecosystem management conceptual framework (USACE, 2011). The objectives represent five essential ecosystem characteristics: hydraulics and hydrology, biogeochemistry, geomorphology, habitat, and biota. Subsequent to the 2011 planning effort, the UMRR increased its focus on improving the health and resilience of the UMRS. The indicators presented here are based on the five essential ecosystem characteristics and four aspects of ecosystems thought to support general ecosystem resilience (the ability of an ecosystem to adapt and respond to disturbances): (1) connectivity, (2) diversity and redundancy, (3) controlling variables, and (4) slow processes. Thus, we developed indicators that quantify both essential ecosystem characteristics and characteristics of a resilient river system. The indicators documented in this report focus on important aspects of river floodplain hydrogeomorphology, given the fundamental role hydrogeomorphology plays in determining habitat conditions and ecosystem health and resilience at broad geographic scales. The information contained within this report provides a broader scale (for example, system-wide) context for management decisions made at finer scales (for example, within river reaches or at project sites) and is designed for use in the formal system-wide Habitat Needs Assessment II (HNA–II) led by the UMRR Program.

Upper Mississippi River System↗
USGS2022

Tracking heat in the Willamette River system, Oregon

The Willamette River Basin in northwestern Oregon is home to several cold-water fish species whose habitat has been altered by the Willamette Valley Project, a system of 13 dams and reservoirs operated by the U.S. Army Corps of Engineers. Water-resource managers use a variety of flow- and temperature-management strategies to ameliorate the effects of upstream Willamette Valley Project dams on the habitat and viability of these anadromous and native fish. In this study, new capabilities were added to the CE-QUAL-W2 two-dimensional flow and water-quality model to inform those flow- and temperature-management strategies by tracking the quantities and ages of water and heat from individual upstream sources to downstream locations in the Willamette River system. Specifically, the fraction of water and heat attributable to upstream dam releases or other water inputs, and the fraction of heat sourced from environmental heat fluxes across the water and sediment surfaces, were tracked and quantified in the river at all locations and times simulated by the model. Applying the updated CE-QUAL-W2 models to the Willamette River system for the months of March through October in the years 2011 (cool and wet), 2015 (hot and dry), and 2016 (warm and somewhat dry) demonstrated that the influence of upstream dam releases on downstream water temperature diminished within a few days as water moved downstream. At sites that are roughly two or more days of travel from upstream dams (Albany and downstream), the July–August fraction of riverine heat content that could be tracked back to upstream dam releases typically diminished to less than 20 percent, despite the fact that roughly 50 percent of July–August streamflow could be attributed to upstream dam releases at the same sites. In contrast, the fraction of riverine heat content that could be attributed to environmental energy fluxes continued to increase with downstream distance, from about 59 to 67 percent at Albany during July–August to 62 to 73 percent at Keizer and 68 to 79 percent at Newberg. At locations sufficiently far downstream, upstream dam releases affect water temperature mainly through a decrease in travel time (less time for environmental heat fluxes to warm the river during summer) and an increase in thermal mass (more water to dilute and buffer incoming heat fluxes) rather than through the simple transport of heat content (water temperature) released from the dams. This concept was explored not only for the baseline conditions that occurred in March–October of 2011, 2015, and 2016, but also for a hypothetical high-flow release during August 2016 and an actual high-flow release during August 2017. In these high-flow releases, an extra 2,500 cubic feet per second (roughly) was released from Dexter Dam on the Middle Fork Willamette River, and downstream effects were measured (2017, actual) and simulated (2016, hypothetical). Results of the simulations were consistent with insights gained from the baseline conditions, such that temperature changes caused by flow augmentation were substantial in upstream reaches (measured cooling of about 1.5 °C near Harrisburg [43 miles downstream] and Albany [84 miles downstream] in 2017, and cooling of about 0.5 °C near Albany in 2016) and diminished farther downstream, but still measurable (more than a few tenths of a degree Celsius) even at Newberg, which is about 154 miles downstream. The direct downstream effects of dam releases on the river heat content attributable to those releases were increased by the hypothetical flow augmentation, with increases of 20 percent at Harrisburg and 12 percent at Keizer. Even with a decreased influence of environmental energy fluxes on river heat content, however, the fraction of heat content attributable to such fluxes was still more than 50 percent at and downstream of Albany and more than 70 percent at Newberg, where the river temperature was less affected by upstream dam-release temperatures and instead was affected primarily by a decreased travel time and increased thermal mass.

Oregon↗
USGS2005

Seasonal movement and habitat use by sub-adult bull trout in the upper Flathead River system, Montana

Despite the importance of large-scale habitat connectivity to the threatened bull trout Salvelinus confluentus , little is known about the life history characteristics and processes influencing natural dispersal of migratory populations. We used radiotelemetry to investigate the seasonal movements and habitat use by subadult bull trout (i.e., fish that emigrated from natal streams to the river system) tracked for varying durations from 1999 to 2002 in the upper Flathead River system in northwestern Montana. Telemetry data revealed migratory ( N = 32 fish) and nonmigratory ( N = 35 fish) behavior, indicating variable movement patterns in the subadult phase of bull trout life history. Most migrating subadults (84%) made rapid or incremental downriver movements (mean distance, 33 km; range, 6–129 km) to lower portions of the river system and to Flathead Lake during high spring flows and as temperatures declined in the fall and winter. Bull trout subadults used complex daytime habitat throughout the upper river system, including deep runs that contained unembedded boulder and cobble substrates, pools with large woody debris, and deep lake-influenced areas of the lower river system. Our results elucidate the importance of maintaining natural connections and a diversity of complex habitats over a large spatial scale to conserve the full expression of life history traits and processes influencing the natural dispersal of bull trout populations. Managers should seek to restore and enhance critical river corridor habitat and remove migration barriers, where possible, for recovery and management programs.

Montana↗
USGS2006

Migration of the Pee Dee River system inferred from ancestral paleochannels underlying the South Carolina Grand Strand and Long Bay inner shelf

Several generations of the ancestral Pee Dee River system have been mapped beneath the South Carolina Grand Strand coastline and adjacent Long Bay inner shelf. Deep boreholes onshore and high-resolution seismic-reflection data offshore allow for reconstruction of these paleochannels, which formed during glacial lowstands, when the Pee Dee River system incised subaerially exposed coastal-plain and continental-shelf strata. Paleochannel groups, representing different generations of the system, decrease in age to the southwest, where the modern Pee Dee River merges with several coastal-plain tributaries at Winyah Bay, the southern terminus of Long Bay. Positions of the successive generational groups record a regional, southwestward migration of the river system that may have initiated during the late Pliocene. The migration was primarily driven by barrier-island deposition, resulting from the interaction of fluvial and shoreline processes during eustatic highstands. Structurally driven, subsurface paleotopography associated with the Mid-Carolina Platform High has also indirectly assisted in forcing this migration. These results provide a better understanding of the evolution of the region and help explain the lack of mobile sediment on the Long Bay inner shelf. Migration of the river system caused a profound change in sediment supply during the late Pleistocene. The abundant fluvial source that once fed sand-rich barrier islands was cut off and replaced with a limited source, supplied by erosion and reworking of former coastal deposits exposed at the shore and on the inner shelf.

South Carolina↗
USGS2009

Nonnative Fishes in the Upper Mississippi River System

The introduction, spread, and establishment of nonnative species is widely regarded as a leading threat to aquatic biodiversity and consequently is ranked among the most serious environmental problems facing the United States today. This report presents information on nonnative fish species observed by the Long Term Resource Monitoring Program on the Upper Mississippi River System a nexus of North American freshwater fish diversity for the Nation. The Long Term Resource Monitoring Program, as part of the U.S. Army Corps of Engineers' Environmental Management Plan, is the Nation's largest river monitoring program and stands as the primary source of standardized ecological information on the Upper Mississippi River System. The Long Term Resource Monitoring Program has been monitoring fish communities in six study areas on the Upper Mississippi River System since 1989. During this period, more than 3.5 million individual fish, consisting of 139 species, have been collected. Although fish monitoring activities of the Long Term Resource Monitoring Program focus principally on entire fish communities, data collected by the Program are useful for detecting and monitoring the establishment and spread of nonnative fish species within the Upper Mississippi River System Basin. Sixteen taxa of nonnative fishes, or hybrids thereof, have been observed by the Long Term Resource Monitoring Program since 1989, and several species are presently expanding their distribution and increasing in abundance. For example, in one of the six study areas monitored by the Long Term Resource Monitoring Program, the number of established nonnative species has increased from two to eight species in less than 10 years. Furthermore, contributions of those eight species can account for up to 60 percent of the total annual catch and greater than 80 percent of the observed biomass. These observations are critical because the Upper Mississippi River System stands as a nationally significant pathway for nonnative species expansion between the Mississippi River and the Great Lakes Basin. This report presents a synthesis of data on nonnative fish species observed during Long Term Resource Monitoring Program monitoring activities.

Scientific Investigations Report↗
USGS2025

Adult and hatch-year survival and fidelity of Piping Plovers Charadrius melodus in the lower Platte River system, Nebraska, USA

Knowledge of vital rates informs the conservation and management of threatened and endangered species. In the northern Great Plains, USA, the federally threatened Piping Plover Charadrius melodus uses a variety of nesting habitats including natural river sandbars and human-created sites in the lower Platte River system, Nebraska. In this area, off-river sandpit sites (i.e., active sand and gravel mines, transition sites, and lakeshore housing developments) are not managed to prioritize nesting and are often considered inferior habitat to sandbars. However, most Piping Plovers in the lower Platte River system nest off river, especially in years when sandbar habitat is limited. As the quantity of habitat provided at off-river sites is predicted to decline, evaluating vital rates among different off-river nesting habitats will inform future conservation efforts. We estimated annual survival and fidelity of adult (n = 165) and hatch-year (n = 671) Piping Plovers from 2008 to 2018 and within-season weekly survival of breeding adults (n = 271) from 2011 to 2024. Annual adult survival was 0.771 (95% CI = 0.733–0.804) and hatch-year survival was 0.394 (0.335–0.456). Fidelity to the study area was 0.737 (0.634–0.819) for adults and 0.261 (0.192–0.345) for hatch-years. Within-season apparent weekly survival was higher for Piping Plovers at lakeshore housing developments (0.946 [85% CI = 0.917–0.965]) than sand and gravel mines (0.909 [0.874–0.935]) and transition sites (0.881 [0.834–0.928]). Annual survival of adult and hatch-year birds were comparable to other studies and regions within the Northern Great Plains population, indicating no negative consequence of off-river nesting to survival. Considering that off-river habitats are important for the persistence of Piping Plovers in the lower Platte River system, continued monitoring of survival could help managers evaluate recovery implications under uncertain future habitat availability in the region.

Nebraska↗
USGS2000

National wild and scenic rivers system, January 2000

The National Wild and Scenic Rivers System was created by Congress in 1968 (Public Law 90-542; 16 U.S.C 1271 et seq.) to preserve certain rivers with outstanding natural cultural, or recreational features in a free flowing condition for enjoyment of present and future generations. As of January 2000, the National System has grown from its initial eight components to a 156-river system with representation in 37 states.

Report↗
USGS2024

Hiding in plain sight: Federally protected Ringed Map Turtles (Graptemys oculifera) found in a new river system

Understanding the geographical range of a species is essential to successful conservation and management, but their ranges are not always fully known. Ringed Map Turtles (Graptemys oculifera) have been federally listed as a Threatened species since 1986, and they have long been considered endemic to the Pearl River system of central Mississippi and southeastern Louisiana, USA. Based on a 2021 citizen scientist observation, a new G. oculifera population was discovered in the Bogue Falaya, a river system that is west of and isolated from the Pearl River system. Genetic analyses of 23 individuals from the Bogue Falaya demonstrate their genetic distinctiveness relative to sites in the Pearl River, suggesting it is a natural rather than introduced population. Therefore, G. oculifera should no longer be considered endemic to the Pearl River system, and this Bogue Falaya population of G. oculifera may warrant the designation of a distinct population segment under the U.S. Endangered Species Act. A thorough assessment of the distribution, abundance, and conservation threats to the Bogue Falaya population of G. oculifera as well as surveys of surrounding systems could help to inform future management actions. This discovery of a long-time federally protected species in the city limits of Covington, Louisiana, documents how citizen scientists can advance scientific knowledge.

Louisiana↗
USGS2023

Attributes of Upper Mississippi River System contiguous forest areas

Floodplain forests are important features of river systems as they create habitat for a variety of wildlife species as well as influence water quality by sequestering nutrients. The ecological conditions found within forested areas can vary greatly from place to place, contributing to spatial variability in species diversity, animal use of the floodplain, and other ecological functions. For this reason, it is important for managers and researchers to identify and map existing forest conditions for use in restoration practices or research studies. A number of forest attributes have been identified as useful in predicting the local ecological conditions found within forested areas. For example, attributes related to the size, shape and configuration of forest patches have been linked to susceptibility to invasion by exotic species, animal and plant dispersal patterns, population distributions, and species diversity (Zuidema and others, 1996; Laurance and others, 2001; Weathers and others, 2001; Lindenmayer and Franklin 2002; Harper and others, 2005; Ramaharitra 2006). In floodplain forests, patterns of inundation have been shown to influence local soil conditions as well as plant species composition and diversity (De Jager and others, 2012). Knowing the land-use history of forest areas has also been shown to be important in understanding present day ecological conditions of forested areas (Turner and others, 2004). To support floodplain forest research and management actions on the Upper Mississippi River System (UMRS), we identified contiguous forested areas (i.e., areas of forest cover that were separated from each other by other land or water cover types) in the floodplain and calculated a wide range of attributes that define basic ecosystem conditions within such forested areas. The data allows users to query on a set of attributes (e.g., size, shape, inundation characteristics, etc.) to visualize the distribution of various ecological conditions. In addition, the data allows for future data analyses of relationships among different ecological conditions and other data, such as animal and plant population distributions.

Upper Mississippi River system↗
USGS2005

The watershed and river systems management program

The Watershed and River System Management Program (WaRSMP), a joint effort between the U.S. Geological Survey (USGS) and the U.S. Bureau of Reclamation (Reclamation), is focused on research and development of decision support systems and their application to achieve an equitable balance among diverse water resource management demands. Considerations include: (1) legal and political constraints; (2) stake holder and consensus-building; (3) sound technical knowledge; (4) flood control, consumptive use, and hydropower; (5) water transfers; (6) irrigation return flows and water quality; (7) recreation; (8) habitat for endangered species; (9) water supply and proration; (10) near-surface groundwater; and (11) water ownership, accounting, and rights. To address the interdisciplinary and multi-stake holder needs of real-time watershed management, WaRSMP has developed a decision support system toolbox. The USGS Object User Interface facilitates the coupling of Reclamation's RiverWare reservoir operations model with the USGS Modular Modeling and Precipitation Runoff Modeling Systems through a central database. This integration is accomplished through the use of Model and Data Management Interfaces. WaRSMP applications include Colorado River Main stem and Gunnison Basin, the Yakima Basin, the Middle Rio Grande Basin, the Truckee-Carson Basin, and the Umatilla Basin.

Conference Paper↗
USGS2024

How well do existing surveys track fish community performance measures in the St. Clair-Detroit River System?

The St. Clair-Detroit River System (SCDRS) connects Lake Huron to Lake Erie and provides important habitats for many fishes of economic and ecological importance. Portions of the SCDRS are designated as Great Lakes Areas of Concern and fish production and conservation may be compromised. Efforts to address beneficial use impairments have focused on restoring habitat for native fishes and improving aquatic ecosystem health. Considerable site-specific research and long-term, annual fish surveys have examined responses to habitat improvements. However, there is uncertainty surrounding whether individual studies and surveys can assess (1) population-level benefits of habitat enhancements and (2) whether management objectives are being met. To identify monitoring gaps and inform long-term monitoring program development, we compared outputs from SCDRS fish monitoring surveys (based on discussions with regional agencies) with performance measures specified in management plans (obtained through gray literature searches). Performance measures for harvested species aligned well with outputs of existing surveys. In contrast, at-risk fishes often had objectives and performance measures that reflected knowledge gaps and study needs. Although harvested species were well-monitored relative to specified performance measures, at-risk fishes were less reliably collected by existing surveys, except for lake sturgeon Acipenser fulvescens . Effective evaluation of restoration efforts for at-risk fishes may require additional survey efforts that target species-specific habitat use and life history characteristics.

Michigan↗
USGS2019

Movement dynamics of Smallmouth Bass in a large western river system

The Snake River, Idaho, between Swan Falls and Brownlee dams supports a popular fishery for Smallmouth Bass Micropterus dolomieu . Recently, anglers have expressed concern about harvest of Smallmouth Bass associated with seasonal congregations in and near the lower reaches of several major tributaries. Little is known about Smallmouth Bass movement in the system, and a better understanding of movement dynamics will help to guide future management. From March to August 2016, Smallmouth Bass (≥260 mm; n = 1,131) were tagged with T-bar anchor tags to evaluate large-scale movement patterns. Movement was estimated from 63 angler-reported tags for which area descriptions provided sufficient detail to assign a recapture location. Extent of fish movement varied among segments and tributaries from 0 to 128 river kilometers (rkm). From March to May 2017, Smallmouth Bass (≥305 mm; n = 149) in the Snake, Boise, Payette, and Weiser rivers and in Brownlee Reservoir were implanted with radio transmitters. Of the 149 Smallmouth Bass that were released with radio transmitters, 107 were relocated at least once. Additionally, 79.6% of fish with radio transmitters had a maximum extent of movement of 5 rkm or greater and 42.6% had a maximum extent of 30 rkm or greater; one radio-tagged fish moved 167 rkm upstream. Average daily movement of Smallmouth Bass varied among river segments and was greatest in the spring and summer. Fish from the Snake River, tributaries (e.g., Boise River), and Brownlee Reservoir moved all around the study area, indicating an absence of clear population boundaries. As such, Smallmouth Bass in the study area appear to function as one large population as opposed to multiple subpopulations, thereby indicating that management as one population is likely appropriate.

Idaho↗
USGS2002

Dissolved cadmium, zinc, and lead loads from ground-water seepage into the South Fork Coeur d'Alene River system, northern Idaho, 1999

The valley of the South Fork Coeur d’Alene River and some of its tributaries have been heavily impacted by the dispersion of metal-enriched materials from the Coeur d’Alene mining district since 1884. The valley floor, including the unconsolidated valley-fill/flood-plain aquifers, is a major holding area for mine tailings. The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, characterized groundwater and surface-water relations for parts of the South Fork Coeur d’Alene River Basin and quantified the loading of dissolved metals into the South Fork Coeur d’Alene River system from groundwater seepage. This information can be used to determine the effects of dissolved metal from ground-water seepage on the river system and to evaluate the necessity and feasibility of remediation along gaining reaches. This study defines a field approach that can be repeated during and after the implementation of remediation solutions to measure the effectiveness of these efforts in reducing loading to streams. The study area includes three reaches along the South Fork Coeur d’Alene River valley in the Coeur d’Alene mining district in central Shoshone County, northern Idaho: a 3.3-mile reach of Canyon Creek at Woodland Park, a 4.8-mile reach of the South Fork Coeur d’Alene River near Osburn, and a 6.5-mile reach of the South Fork Coeur d’Alene River near Kellogg and Smelterville. Seepage studies were conducted during July 27–29; September 17–19; and October 15–17, 1999. Each seepage study was conducted over a 3-day period, during which each station was measured on a daily basis for streamflow, and waterquality samples were collected. The consecutiveday approach allowed for an evaluation of variability in streamflow gains and losses and metal loading that resulted from changing hydrologic conditions. During the July, September, and October seepage studies, ground-water seepage was the predominant source for gains in dissolved cadmium and zinc loads in the three study reaches, whereas tributary inflow loads were a minor source. The overall average net gain in dissolved zinc load from ground-water seepage into the South Fork Coeur d’Alene River near Kellogg and Smelterville was about 730 pounds per day, compared with the net gains in Canyon Creek at Woodland Park and the South Fork Coeur d’Alene River near Osburn, which were roughly similar at 150 and 218 pounds per day, respectively. The net gain in dissolved cadmium load from ground-water seepage into the three river reaches was about two orders of magnitude less than the gain in dissolved zinc. On the South Fork Coeur d’Alene River study reaches near Osburn and near Kellogg and Smelterville, no pattern associated with an increase or decrease in dissolved lead load along gaining or losing subreaches was recognizable. Canyon Creek at Woodland Park was the only study reach where ground-water seepage contributed appreciably to the dissolved lead load; the average net gain was 1.5 pounds per day. The average dissolved lead loads leaving South Fork Coeur d’Alene River study reaches (corrected for tributary inflow along the study reaches) near Osburn and near Kellogg and Smelterville were 1.4 and 0.8 pounds per day less, respectively, than the loads entering the study reaches. The decrease in dissolved lead could be the result of lead adsorbing onto organic and inorganic sediment surfaces and (or) coprecipitating with iron and manganese oxides. These forms of lead likely will be resuspended into the water column at high flows.

Idaho↗
USGS2018

Population characteristics and management of lentic populations of nonnative Burbot in the Green River system, Wyoming

Fishes introduced outside of their native distributions have the potential to negatively affect their recipient ecosystems. Since their illegal introduction into the Green River, Wyoming, in the 1990s, Burbot Lota lota have been sampled in lotic and lentic environments throughout the Green River system where they pose a threat to native fishes and valuable sport fisheries. In response to this invasion, managers of the Green River have begun to explore the efficacy of a suppression effort targeting Burbot. This study sought to the describe population dynamics of Burbot in the lentic portions of the Green River system and compare with Burbot population dynamics in the Green River. We also sought to evaluate potential management scenarios for a suppression program. Burbot for this study were collected from Fontenelle and Flaming Gorge reservoirs in October and November 2016. Growth rates of Burbot in the lentic portion of the system were higher than for fish in the Green River. Total annual mortality rates of Burbot were approximately 10% lower in reservoirs (33%) than for fish in the Green River. Additionally, lentic Burbot matured earlier than lotic Burbot. An age-structured population model indicated that Burbot populations were growing rapidly (λ = 1.18) in the study reservoirs. Annual exploitation of juvenile Burbot would need to reach 7%. Exploitation of mature Burbot would need to increase to 33% or greater (A ≥ 57%) to effectively suppress Burbot in this system. Sensitivity analysis suggested that mortality of age-1 and age-2 Burbot had the greatest influence on population growth rate. However, due to difficulties in collecting juvenile Burbot in the system, focusing removal effort on mature Burbot may be the most realistic option for suppressing Burbot populations in the Green River system.

Wyoming↗
USGS2023

Dissolved carbon export by large river systems is influenced by source area heterogeneity

Rivers and streams export inorganic and organic carbon derived from contributing landscapes and so downstream carbon fluxes are important quantitative indicators of change in ecosystem function and for the full accounting of terrestrial carbon budgets. Carbon concentration-discharge ( C-Q ) relationships in rivers provide important information about carbon source and behavior in watersheds and are useful for estimating carbon export. However, C-Q relationships are complex in large river systems because of spatial and temporal heterogeneity in carbon dynamics across the watershed and river networks. We quantified dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) fluxes in the Upper Mississippi River basin and investigated their relationships with land cover and hydrology. The magnitude of dissolved carbon yields ranged widely among stations, 0.6–5.7 g DOC m −2 yr −1 and 2.9–11.8 g DIC m −2 yr −1 . Spatial patterns in carbon fluxes were strongly related to land cover, with agricultural sites having high DIC/low DOC exports and forested and wetland areas having the opposite. DIC was always negatively related to discharge ( Q ), while the DOC- Q relationship varied with land cover. Differential behavior of carbon across the basin resulted in Q having a weak relationship with DOC and DIC at the basin outlet. Hence, there is a need to improve understanding of headwater terrestrial-to-aquatic carbon connections in order to improve basin-to-continental-scale carbon export estimates. Our results demonstrate that quantitative understanding of carbon export by large rivers can be improved by incorporating stream network information, such as the timing, location, and source of constituent flux, rather than relying solely upon relationships between constituent behavior and seasonality or discharge at the basin outlet.

Minnesota, Wisconsin↗