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At least 73 records · Page 4Linked to original sources
USGS2024

Temporal variability in irrigated land and climate influences on salinity loading across the Upper Colorado River Basin, 1986-2017

Freshwater salinization is a growing global concern impacting human and ecosystem needs with impacts to water availability for human and ecological uses. In the Upper Colorado River Basin (UCRB), dissolved solids in streams compound ongoing water supply challenges to further limit water availability and cause economic damages. Much effort has been dedicated to understanding dissolved solid sources, transport, and management in the region, yet temporal variability in loading from key sources such as irrigated lands and the influence of climate on dissolved solids loading remains unknown. Quantifying the contributions and temporal variability of dissolved solids loads from irrigated lands may benefit salinity management efforts. This study applies a time-varying (dynamic) modeling approach to predict annual dissolved solids loads across the UCRB from 1986 through 2017. Between 66% and 82% of the total accumulated dissolved solids load in the basin is from groundwater (storage and baseflow). Our findings link climate, irrigation, and groundwater, and confirm large storage contributions that have declined slightly with time. Dissolved solids loads increase during wet periods and decrease during dry periods, although the relative contributions of different sources vary little with time. Irrigation enhances loading efficiency relative to unirrigated areas through runoff and groundwater, and can locally be a major source of dissolved solids where irrigation occurs. Results indicate that loads from irrigated areas increase when irrigated area and/or water available for runoff increase. Increased regional aridification over the study period may have contributed to decreasing stream salinity through both quicker surface runoff and lagged groundwater storage processes. Study results may be relevant to salinity management in arid environments where water availability is limited and where irrigation influences salinity loading to streams.

Upper Colorado River Basin↗
USGS2015

The Snowmastodon Project: A view of the Last Interglacial Period from high in the Colorado Rockies

In North America, terrestrial records of biodiversity and climate change that span the Last Interglacial Period [or Marine Oxygen Isotope Stage (MIS) 5] are rare. In 2010-11, construction at Ziegler Reservoir near Snowmass Village, Colorado revealed a lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site (ZRFS) also contained thousands of well-preserved bones and teeth of Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals, including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework, shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5.

Conference Paper↗
USGS2016

Using large-scale flow experiments to rehabilitate Colorado River ecosystem function in Grand Canyon: Basis for an adaptive climate-resilient strategy

Adaptive management of Glen Canyon Dam is improving downstream resources of the Colorado River in Glen Canyon National Recreation Area and Grand Canyon National Park. The Glen Canyon Dam Adaptive Management Program (AMP), a federal advisory committee of 25 members with diverse special interests tasked to advise the U.S. Department of the Interior), was established in 1997 in response to the 1992 Grand Canyon Protection Act. Adaptive management assumes that ecosystem responses to management policies are inherently complex and unpredictable, but that understanding and management can be improved through monitoring. Best known for its high-flow experiments intended to benefit physical and biological resources by simulating one aspect of pre-dam conditions—floods, the AMP promotes collaboration among tribal, recreation, hydropower, environmental, water and other natural resource management interests. Monitoring has shown that high flow experiments move limited new tributary sand inputs below the dam from the bottom of the Colorado River to shorelines; rebuilding eroded sandbars that support camping areas and other natural and cultural resources. Spring-timed high flows have also been shown to stimulate aquatic productivity by disturbing the river bed below the dam in Glen Canyon. Understanding about how nonnative tailwater rainbow trout ( Oncorhynchus mykiss ), and downstream endangered humpback chub ( Gila cypha ) respond to dam operations has also increased, but this learning has mostly posed “surprise” adaptation opportunities to managers. Since reoperation of the dam to Modified Low Fluctuating Flows in 1996, rainbow trout now benefit from more stable daily flows and high spring releases, but possibly at a risk to humpback chub and other native fishes downstream. In contrast, humpback chub have so far proven robust to all flows, and native fish have increased under the combination of warmer river temperatures associated with reduced storage in Lake Powell, and a system-wide reduction in trout from 2000-06, possibly due to several years of natural reproduction under limited food supply. Uncertainties about dam operations and ecosystem responses remain, including how native and nonnative fish will interact and respond to possible increased river temperatures under drier basin conditions. Ongoing assessment of operating policies by the AMP’s diverse stakeholders represents a major commitment to the river’s valued resources, while surprise learning opportunities can also help identify a resilient climate-change strategy for co-managing nonnative and endangered native fish, sandbar habitats and other river resources in a region with already complex and ever-increasing water demands.

Arizona↗
USGS2003

Aspen structure and variability in Rocky Mountain National Park, Colorado, USA

Elk, fire and climate have influenced aspen populations in the Rocky Mountains, but mostly subjective studies have characterized these factors. A broad-scale perspective may shed new light on the status of aspen in the region. We collected field measurements of aspen (Populus tremuloides Michx.) patches encountered within 36 randomly located belt transects in 340 km2 of Rocky Mountain National Park, Colorado, to quantify the aspen population. Aspen covered 5.6% of the area in the transects, much more than expected based on previously collected remotely sensed data. The distribution and structure of aspen patches were highly heterogeneous throughout the study area. Of the 123 aspen patches encountered in the 238 ha surveyed, all but one showed signs of elk browsing or had conifer species mixed with the aspen stems. No significant difference occurred in aspen basal area, density, regeneration, browsing of regeneration and patch size, between areas of concentrated elk use (elk winter range) and areas of dispersed elk use (elk summer range). Two-thirds of the aspen patches were mixed with conifer species. We concluded that the population of aspen in our study area is highly variable in structure and that, at a landscape-scale, evidence of elk browsing is widespread but evidence of aspen decline is not.

Landscape Ecology↗
USGS2015

C 3 and C 4 plant responses to increased temperatures and altered monsoonal precipitation in a cool desert on the Colorado Plateau, USA

Dryland ecosystems represent >40 % of the terrestrial landscape and support over two billion people; consequently, it is vital to understand how drylands will respond to climatic change. However, while arid and semiarid ecosystems commonly experience extremely hot and dry conditions, our understanding of how further temperature increases or altered precipitation will affect dryland plant communities remains poor. To address this question, we assessed plant physiology and growth at a long-term (7-year) climate experiment on the Colorado Plateau , USA, where the community is a mix of shallow-rooted C 3 and C 4 grasses and deep-rooted C 4 shrubs. The experiment maintained elevated-temperature treatments (+2 or +4 °C) in combination with altered summer monsoonal precipitation (+small frequent precipitation events or +large infrequent events). Increased temperature negatively affected photosynthesis and growth of the C 3 and C 4 grasses, but effects varied in their timing: +4 °C treatments negatively affected the C 3 grass early in the growing season of both years, while the negative effects of temperature on the C 4 grass were seen in the +2 and +4 °C treatments, but only during the late growing season of the drier year. Increased summer precipitation did not affect photosynthesis or biomass for any species, either in the year the precipitation was applied or the following year. Although previous research suggests dryland plants, and C 4 grasses in particular, may respond positively to elevated temperature, our findings from a cool desert show marked declines in C 3 and C 4 photosynthesis and growth, with temperature effects dependent on the degree of warming and growing-season precipitation.

Utah↗
USGS2007

Climatic fluctuations and forecasting of streamflow in the lower Colorado River Basin

Water-resource managers need to forecast streamflow in the Lower Colorado River Basin to plan for water-resource projects and to operate reservoirs for water supply. Statistical forecasts of streamflow based on historical records of streamflow can be useful, but statistical assumptions, such as stationarity of flows, need to be evaluated. This study evaluated the relation between climatic fluctuations and stationarity and developed regression equations to forecast streamflow by using climatic fluctuations as explanatory variables. Climatic fluctuations were represented by the Atlantic Multidecadal Oscillation (AMO), Pacific Decadal Oscillation (PDO), and Southern Oscillation Index (SOI). Historical streamflow within the 25- to 30-year positive or negative phases of AMO or PDO was generally stationary. Monotonic trends in annual mean flows were tested at the 21 sites evaluated in this study; 76% of the sites had no significant trends within phases of AMO and 86% of the sites had no significant trends within phases of PDO. As climatic phases shifted in signs, however, many sites had nonstationary flows; 67% of the sites had significant changes in annual mean flow as AMO shifted in signs. The regression equations developed in this study to forecast streamflow incorporate these shifts in climate and streamflow, thus that source of nonstationarity is accounted for. The R 2 value of regression equations that forecast individual years of annual flow for the central part of the study area ranged from 0.28 to 0.49 and averaged 0.39. AMO was the most significant variable, and a combination of indices from both the Atlantic and Pacific Oceans explained much more variation in flows than only the Pacific Ocean indices. The average R2 value for equations with PDO and SOI was 0.15. ?? 2007 American Water Resources Association.

Journal of the American Water Resources Associatio↗
USGS2014

Contaminants from Cretaceous black shale: I. Natural weathering processes controlling contaminant cycling in Mancos Shale, southwestern United States, with emphasis on salinity and selenium

Soils derived from black shale can accumulate high concentrations of elements of environmental concern, especially in regions with semiarid to arid climates. One such region is the Colorado River basin in the southwestern United States where contaminants pose a threat to agriculture, municipal water supplies, endangered aquatic species, and water-quality commitments to Mexico. Exposures of Cretaceous Mancos Shale (MS) in the upper basin are a major contributor of salinity and selenium in the Colorado River. Here, we examine the roles of geology, climate, and alluviation on contaminant cycling (emphasis on salinity and Se) during weathering of MS in a Colorado River tributary watershed. Stage I (incipient weathering) began perhaps as long ago as 20 ka when lowering of groundwater resulted in oxidation of pyrite and organic matter. This process formed gypsum and soluble organic matter that persist in the unsaturated, weathered shale today. Enrichment of Se observed in laterally persistent ferric oxide layers likely is due to selenite adsorption onto the oxides that formed during fluctuating redox conditions at the water table. Stage II weathering (pedogenesis) is marked by a significant decrease in bulk density and increase in porosity as shale disaggregates to soil. Rainfall dissolves calcite and thenardite (Na 2 SO 4 ) at the surface, infiltrates to about 1 m, and precipitates gypsum during evaporation. Gypsum formation (estimated 390 kg m −2 ) enriches soil moisture in Na and residual SO 4 . Transpiration of this moisture to the surface or exposure of subsurface soil (slumping) produces more thenardite. Most Se remains in the soil as selenite adsorbed to ferric oxides, however, some oxidizes to selenate and, during wetter conditions is transported with soil moisture to depths below 3 m. Coupled with little rainfall, relatively insoluble gypsum, and the translocation of soluble Se downward, MS landscapes will be a significant nonpoint source of salinity and Se to the Colorado River well into the future. Other trace elements weathering from MS that are often of environmental concern include U and Mo, which mimic Se in their behavior; As, Co, Cr, Cu, Ni, and Pb, which show little redistribution; and Cd, Sb, V, and Zn, which accumulate in Stage I shale, but are lost to varying degrees from upper soil intervals. None of these trace elements have been reported previously as contaminants in the study area.

Colorado↗
USGS1994

Cretaceous pollen in Pliocene rocks: Implications for Pliocene climate in the southwestern United States

Pliocene rocks of the Imperial and Palm Spring Formations in southern California contain reworked Cretaceous pollen that helps determine the timing of erosion of Cretaceous rocks on the Colorado Plateau. The stratigraphic distribution of reworked pollen in the Imperial and Palm Spring Formations suggests that erosion of Cretaceous rocks in the southern part of the Colorado Plateau began by 4.5 Ma. Erosion of Cretaceous rocks in the northern part of the plateau began at 3.9 Ma. This erosional history indicates that rapid and extensive erosion of the Colorado Plateau occurred during the Pliocene and supports the hypothesis that much of the Grand Canyon was cut during the Pliocene, rather than earlier in the Tertiary. Rapid erosion and transport from the Colorado Plateau require the climate in that region during the Pliocene to have been significantly wetter than it is today.

Geology↗
USGS1996

Potential climatic impacts of vegetation change: A regional modeling study

The human species has been modifying the landscape long before the development of modern agrarian techniques. Much of the land area of the conterminous United States is currently used for agricultural production. In certain regions this change in vegetative cover from its natural state may have led to local climatic change. A regional climate version of the Colorado State University Regional Atmospheric Modeling System was used to assess the impact of a natural versus current vegetation distribution on the weather and climate of July 1989. The results indicate that coherent regions of substantial changes, of both positive and negative sign, in screen height temperature, humidity, wind speed, and precipitation are a possible consequence of land use change throughout the United States. The simulated changes in the screen height quantities were closely related to changes in the vegetation parameters of albedo, roughness length, leaf area index, and fractional coverage.

Journal of Geophysical Research D: Atmospheres↗
USGS2023

Time, climate, and soil settings set the course for reclamation outcomes following dryland energy development

Soil attributes, climate, and time since reclamation have important implications for oil and gas reclamation success on drylands. It is uncertain if reclaimed well pads, on highly degraded drylands, can successfully regain ecological function or meet indicator benchmarks for reclamation. Here, our goals were to assess patterns in reclamation outcomes relative to (1) soil attributes, climate, and time since reclamation; and (2) plant and soil reference benchmarks. We collected a suite of plant, soil, and landscape characteristics from 134 reclaimed well pads on the Colorado Plateau that spanned climate and soil gradients and ranged from 2 to 20 years post-reclamation, then compared characteristics to those from 583 reference plots. On the reclaimed pads, less saline soils, more mesic climates, and longer time since reclamation were associated with favorable reclamation outcomes based on metrics of plant species richness and diversity, plant structure, and cover of important plant functional groups. However, most pads had major departures in 1/4 indicators, suggesting unsuccessful reclamation. Arid warm locations with shallow soils had the greatest percentage of major departures, and noxious plant richness had the greatest departures across soil and climate settings. Our assessment indicates reclamation is failing in key metrics for most pads, and the results highlight the role of environmental conditions in driving reclamation outcomes. These new insights are valuable for ascertaining possible reclamation outcomes and success rates following energy related disturbance, including orphaned wells and renewable energy development. Importantly, the approach used here has applicability for setting benchmarks and outcome standards.

Land Degradation and Development↗
USGS2019

Climate during the Last Glacial Maximum in the northern Sawatch Range, Colorado, USA

Temperature-index modeling is used to determine the magnitude of temperature depression in the northern Sawatch Range required to maintain steady-state mass balances of six reconstructed glaciers at their extent during the local Last Glacial Maximum (LLGM), dated at ~21 ka. Assuming no significant differences in precipitation compared to modern values, mean annual temperatures in the region were on average 8.8 + 0.5/– 0.8 °C cooler than they are today. Allowing for modest (± 10 cm) increases or decreases in precipitation, required temperature depressions only differ by ±0.2 °C. Temperature depression in the northern Sawatch Range is consistent, although slightly greater, with those determined in other ranges in Colorado using similar approaches. The estimates presented here are, however, substantially less than those suggested by several downscaled simulations of global Last Glacial Maximum (LGM) climate, that might be due to the need for improved calibration of such downscalings, or the models from which they are derived. Our estimates of LGM temperature depression are considerably greater than that previously determined in the study area and those in two other ranges in Colorado derived using different methodologies, the latter being most likely responsible for the discrepancies.

Colorado↗
USGS2011

Effects of climate change and land use on water resources in the Upper Colorado River Basin

The health of the Colorado River watershed is critical to the socioeconomic and ecosystem well-being of the Southwestern United States. Water in springs, streams, and rivers supports a range of aquatic and riparian ecosystems that contain many endangered species. Terrestrial habitats support a wide array of plants and wildlife. In addition, this region is enjoyed by millions of people annually for its recreational and esthetic opportunities. The Colorado River provides water for about 25 million people and is used to irrigate 2.5 million acres of farmland. However, competition for this water is expected to increase as human populations dependent on this water are projected to increase to 38 million by 2020. Climate change is expected to further exacerbate water issues in this region. Drought in the Southwest during 2000-04, caused by both reduced precipitation and a series of the hottest years on record, resulted in streamflows lower than during the 1930s Dust Bowl or the 1950s. Increased temperatures alone are a major factor in reducing surface-water flows in this region. For instance, precipitation received during the winter of 2005 was at the 100-year average. However, low soil moisture and high January-July temperatures resulted in flows that were only 75 percent of average. Climate models predict future warmer temperatures and reduced precipitation in the Upper Colorado River Basin (UCRB), which would reduce water available to humans and ecosystems.

Arizona, Colorado, New Mexico, Utah, Wyoming↗
USGS2011

Potential climate change effects on water tables and pyrite oxidation in headwater catchments in Colorado

A water, energy, and biogeochemical model (WEBMOD) was constructed to simulate hydrology and pyrite oxidation for the period October 1992 through September 1997. The hydrologic model simulates processes in Loch Vale, a 6.6-km² granitic watershed that drains the east side of the Continental Divide. Parameters describing pyrite oxidation were derived sulfate concentrations measured in pore water and stream water in Handcart Gulch, a naturally acidic watershed in the Colorado Mineral Belt. Average monthly differences in precipitation and temperature between current and future climates, as predicted by using six global circulation models and three carbondioxide emission scenarios, were input into WEBMOD to identify possible shifts in the quantity and quality of the water flowing from the watershed for the period 2005 through 2100. Initial results suggest that increased air temperatures will result in earlier snowmelt compared to current conditions. Average sulfate concentrations and acidity in streams draining hydrothermally altered terrain may decrease as water tables rise in response to greater overall precipitation and earlier snowmelt, although a net increase of sulfate load was simulated as a result of greater overall discharge. Evapotranspiration is expected to increase but not enough to offset the increase in precipitation.

Colorado↗
USGS2017

Forecasted range shifts of arid-land fishes in response to climate change

Climate change is poised to alter the distributional limits, center, and size of many species. Traits may influence different aspects of range shifts, with trophic generality facilitating shifts at the leading edge, and greater thermal tolerance limiting contractions at the trailing edge. The generality of relationships between traits and range shifts remains ambiguous however, especially for imperiled fishes residing in xeric riverscapes. Our objectives were to quantify contemporary fish distributions in the Lower Colorado River Basin, forecast climate change by 2085 using two general circulation models, and quantify shifts in the limits, center, and size of fish elevational ranges according to fish traits. We examined relationships among traits and range shift metrics either singly using univariate linear modeling or combined with multivariate redundancy analysis. We found that trophic and dispersal traits were associated with shifts at the leading and trailing edges, respectively, although projected range shifts were largely unexplained by traits. As expected, piscivores and omnivores with broader diets shifted upslope most at the leading edge while more specialized invertivores exhibited minimal changes. Fishes that were more mobile shifted upslope most at the trailing edge, defying predictions. No traits explained changes in range center or size. Finally, current preference explained multivariate range shifts, as fishes with faster current preferences exhibited smaller multivariate changes. Although range shifts were largely unexplained by traits, more specialized invertivorous fishes with lower dispersal propensity or greater current preference may require the greatest conservation efforts because of their limited capacity to shift ranges under climate change.

Reviews in Fish Biology and Fisheries↗
USGS2025

Effects of climate on temporal variability in streamflow and salinity in the Upper Colorado River Basin

Study Region The Upper Colorado River Basin, a critical water source for more than 40 million people in the western United States. Study Focus Potential decreasing streamflow and elevated salinity concentrations threaten this resource. Climate variability has a large and well-studied effect on streamflow in the basin; however, the effect on salinity loading is less understood. This study investigates how snowpack dynamics, precipitation volume, and air temperature affect both streamflow and salinity at the basin scale from water years 1986–2021. New Hydrological Insights for the Region Climate variables explained 54 % of streamflow variability and 40 % of salinity variability across the basin. Both streamflow and salinity yields have declined in response to climate variability, but their response occurs on different timescales. Streamflow is more sensitive to snowpack, whereas salinity yields respond more strongly to antecedent precipitation. The delayed response of salinity yields may obscure the effects of both climate variability and salinity control measures. Residual analysis identified subbasins where the climate-salinity relation deviated from basin-wide patterns, suggesting that possible anthropogenic or other watershed processes may influence salinity loading in these areas. These novel findings underscore the importance of accounting for climate variability when evaluating long-term trends in streamflow and salinity.

Arizona, Colorado, New Mexico, Utah, Wyoming↗
USGS2016

Understanding the past to interpret the future: Comparison of simulated groundwater recharge in the upper Colorado River basin (USA) using observed and general-circulation-model historical climate data

In evaluating potential impacts of climate change on water resources, water managers seek to understand how future conditions may differ from the recent past. Studies of climate impacts on groundwater recharge often compare simulated recharge from future and historical time periods on an average monthly or overall average annual basis, or compare average recharge from future decades to that from a single recent decade. Baseline historical recharge estimates, which are compared with future conditions, are often from simulations using observed historical climate data. Comparison of average monthly results, average annual results, or even averaging over selected historical decades, may mask the true variability in historical results and lead to misinterpretation of future conditions. Comparison of future recharge results simulated using general circulation model (GCM) climate data to recharge results simulated using actual historical climate data may also result in an incomplete understanding of the likelihood of future changes. In this study, groundwater recharge is estimated in the upper Colorado River basin, USA, using a distributed-parameter soil-water balance groundwater recharge model for the period 1951–2010. Recharge simulations are performed using precipitation, maximum temperature, and minimum temperature data from observed climate data and from 97 CMIP5 (Coupled Model Intercomparison Project, phase 5) projections. Results indicate that average monthly and average annual simulated recharge are similar using observed and GCM climate data. However, 10-year moving-average recharge results show substantial differences between observed and simulated climate data, particularly during period 1970–2000, with much greater variability seen for results using observed climate data.

Upper Colorado River basin↗
USGS2015

Phenology and climate relationships in aspen (Populus tremuloides Michx.) forest and woodland communities of southwestern Colorado

Trembling aspen ( Populus tremuloides Michx.) occurs over wide geographical, latitudinal, elevational, and environmental gradients, making it a favorable candidate for a study of phenology and climate relationships. Aspen forests and woodlands provide numerous ecosystem services, such as high primary productivity and biodiversity, retention and storage of environmental variables (precipitation, temperature, snow–water equivalent) that affect the spring and fall phenology of the aspen woodland communities of southwestern Colorado. We assessed the land surface phenology of aspen woodlands using two phenology indices, start of season time (SOST) and end of season time (EOST), from the U.S. Geological Survey (USGS) database of conterminous U.S. phenological indicators over an 11-year time period (2001–2011). These indicators were developed with 250 m resolution remotely sensed data from the Moderate Resolution Imaging Spectroradiometer processed to highlight vegetation response. We compiled data on SOST, EOST, elevation, precipitation, air temperature, and snow water equivalent (SWE) for selected sites having more than 80% cover by aspen woodland communities. In the 11-year time frame of our study, EOST had significant positive correlation with minimum fall temperature and significant negative correlation with fall precipitation. SOST had a significant positive correlation with spring SWE and spring maximum temperature.

Colorado↗
USGS2020

Grazing-induced changes to biological soil crust cover mediate hillslope erosion in a long-term exclosure experiment

Dryland ecosystems are particularly vulnerable to erosion generated by livestock grazing. Quantifying this risk across a variety of landscape settings is essential for successful adaptive management, particularly in light of a changing climate. In the Upper Colorado River Basin, there are nearly 25 000 km 2 of rangelands with underlying soils derived from Mancos Shale, an erodible and saline geologic parent material. Salinity is a major concern within the Colorado River watershed, much of which is attributed to runoff and leaching from Mancos Shale deposits. In a 60-yr paired-watershed experiment in western Colorado, we used silt fences to measure differences in saline hillslope erosion, including both total sediment yield and concentrations of primary saline constituents (Na and Se), in watersheds that were either exposed to grazing or where livestock was excluded. After accounting for the strong effects of soil type, slope, and antecedent precipitation, we found that grazing increased sediment loss by ≈50% across our 8-yr time series (0.1–1.5 tn ha −1 ), consistent with levels reported at the watershed scale in early published work from studies at the same location. Eroded sediment Se levels were low and unaffected by grazing history, but Na concentrations were significantly reduced on grazed hillslopes, likely due to depletion of surface Na in soils exposed to chronic soil disturbance by livestock. Variable selection and path analysis identified that biological soil crust (BSC) cover, more than any other variable, explained the differences in sediment yields between grazed and ungrazed watersheds, partially through the enhancement of soil aggregate stability. Our results suggest that BSC cover should be granted heightened consideration in rangeland decision support tools (e.g., state-and-transition models) and that measures to reduce surface disturbance from livestock such as altering the timing or intensity of grazing may be effective for reducing downstream impacts.

Colorado↗