Streamflow Alteration Active
Flow Modification of the Nation’s Streams and Rivers
Natural flows are critical to healthy ecosystems—learn how flows have changed and why
Humans, just like aquatic organisms, need water. Flood control, urban infrastructure, irrigation of agriculture, and myriad other ways we manage water affect the natural flow of streams and rivers. How do the ways we manage land and water affect the natural patterns of streamflow that ecosystems depend on?
Featured: Projecting future flow in Southwest streams
Streamflow in the Southwestern U.S. is projected to decrease by as much as 36–80% by the end of this century, reports a new study by the U.S. Geological Survey. These decreases could challenge our ability to meet future water demand in this region.
Civilizations sprang up where water was available. In modern times, humans have harnessed freshwater around the world for drinking, agriculture, industry, hydropower, and many other benefits. Human actions that can change streamflow patterns include dam building, stream diversion, pumping of shallow groundwater, and covering the landscape with impervious surfaces such as pavement and roofs.
Changes in climate also can alter flow by altering timing and amount of precipitation. And in most areas, changes in streamflow pattern caused by climate are superimposed on streamflow modifications caused by land and water management.
Human activities and management of water, as well as climate, can affect many aspects of streamflow. How high are the highest high flows, and how low are the lowest low flows? When do those high flows and low flows occur, and how often? Changes to these naturally occurring patterns can have ecological consequences, causing species loss and the diversity of species present to change.
An analysis of streamflow data for 1980–2014 compiled from more than 3,000 streamgaging sites across the U.S. found that low flows now are more frequent but occur for a shorter duration than they would naturally. High flows also are more frequent, but are lower in magnitude and shorter in duration than they would be naturally. Such changes have contributed to the deterioration of stream and river ecosystems. That's because aquatic species have evolved strategies to live with the streamflow regime that has existed for thousands of years. When that streamflow regime changes it can reduce their ability to survive and reproduce.
Climate also has induced changes in streamflow, as assessed at 600 streamgaging sites where influences from land and water management are minimal. Climate factors that affect streamflows include air temperature, whether precipitation falls as rain or snow, and the timing of precipitation and snowmelt. However, human management of land and water resources over the last 3 decades have modified streamflows more than variation in climate has over the same period.
A previous assessment of streamflow at 2,888 sites across the United States found that natural streamflow patterns have been altered at more than 85 percent of the stream sites. There were marked differences in the occurrence, type, and severity of streamflow alteration depending on whether the climate was arid or wet. The more that flow magnitude—how high the highest and lowest flows are—in a stream had diminished, the more likely that the ecological community of the stream was impaired.
Damage to ecosystems from streamflow modification has been successfully mitigated in some cases. Efforts to address streamflow modification can focus on a key streamflow characteristic, such as low-flow magnitude, or can address the entire flow regime—streamflow magnitude, variability, duration, frequency, and timing. The choice depends on specific ecological needs and the flexibility of other goals, such as water supply or energy production. All of these approaches require the scientific analysis and long-term monitoring of ecological and hydrological systems.
The links to the web pages below are a gateway to additional information in the ecology of streams.
SPARROW modeling: Estimating nutrient, sediment, and dissolved solids transport
Water Quality in the Nation’s Streams and Rivers – Current Conditions and Long-Term Trends
Surface-Water Quality and Ecology
Stream Ecology
Access our most recent flow-alteration data. Explore more data releases at ScienceBase.
Natural Monthly Flow Estimates for the Conterminous United States, 1950-2015
U.S. Geological Survey GAGES-II time series data from consistent sources of land use, water use, agriculture, timber activities, dam removals, and other historical anthropogenic influences
Below, you’ll find the latest in peer-reviewed journal articles and USGS reports on flow alteration and its effects. For more publications on this and other water-quality topics, search the USGS Publications Warehouse. Look here for help using the Pubs Warehouse.
Biological relevance of streamflow metrics: Regional and national perspectives
Changing climate drives future streamflow declines and challenges in meeting water demand across the southwestern United States
Effects of urban multi-stressors on three stream biotic assemblages
A database of natural monthly streamflow estimates from 1950 to 2015 for the conterminous United States
The Midwest Stream Quality Assessment—Influences of human activities on streams
Predictability and selection of hydrologic metrics in riverine ecohydrology
Biological relevance of streamflow metrics: Regional and national perspectives
Streamflow alteration and habitat ramifications for a threatened fish species in the Central United States
Classification of California streams using combined deductive and inductive approaches: Setting the foundation for analysis of hydrologic alteration
Estimating natural monthly streamflows in California and the likelihood of anthropogenic modification
Associations of stream health to altered flow and water temperature in the Sierra Nevada, California
An objective and parsimonious approach for classifying natural flow regimes at a continental scale
Macroinvertebrate community change associated with the severity of streamflow alteration
- Overview
Humans, just like aquatic organisms, need water. Flood control, urban infrastructure, irrigation of agriculture, and myriad other ways we manage water affect the natural flow of streams and rivers. How do the ways we manage land and water affect the natural patterns of streamflow that ecosystems depend on?
Featured: Projecting future flow in Southwest streamsStreamflow in the Southwestern U.S. is projected to decrease by as much as 36–80% by the end of this century, reports a new study by the U.S. Geological Survey. These decreases could challenge our ability to meet future water demand in this region.
Civilizations sprang up where water was available. In modern times, humans have harnessed freshwater around the world for drinking, agriculture, industry, hydropower, and many other benefits. Human actions that can change streamflow patterns include dam building, stream diversion, pumping of shallow groundwater, and covering the landscape with impervious surfaces such as pavement and roofs.
Changes in climate also can alter flow by altering timing and amount of precipitation. And in most areas, changes in streamflow pattern caused by climate are superimposed on streamflow modifications caused by land and water management.
Human activities and management of water, as well as climate, can affect many aspects of streamflow. How high are the highest high flows, and how low are the lowest low flows? When do those high flows and low flows occur, and how often? Changes to these naturally occurring patterns can have ecological consequences, causing species loss and the diversity of species present to change.
An analysis of streamflow data for 1980–2014 compiled from more than 3,000 streamgaging sites across the U.S. found that low flows now are more frequent but occur for a shorter duration than they would naturally. High flows also are more frequent, but are lower in magnitude and shorter in duration than they would be naturally. Such changes have contributed to the deterioration of stream and river ecosystems. That's because aquatic species have evolved strategies to live with the streamflow regime that has existed for thousands of years. When that streamflow regime changes it can reduce their ability to survive and reproduce.
Climate also has induced changes in streamflow, as assessed at 600 streamgaging sites where influences from land and water management are minimal. Climate factors that affect streamflows include air temperature, whether precipitation falls as rain or snow, and the timing of precipitation and snowmelt. However, human management of land and water resources over the last 3 decades have modified streamflows more than variation in climate has over the same period.
A previous assessment of streamflow at 2,888 sites across the United States found that natural streamflow patterns have been altered at more than 85 percent of the stream sites. There were marked differences in the occurrence, type, and severity of streamflow alteration depending on whether the climate was arid or wet. The more that flow magnitude—how high the highest and lowest flows are—in a stream had diminished, the more likely that the ecological community of the stream was impaired.
Damage to ecosystems from streamflow modification has been successfully mitigated in some cases. Efforts to address streamflow modification can focus on a key streamflow characteristic, such as low-flow magnitude, or can address the entire flow regime—streamflow magnitude, variability, duration, frequency, and timing. The choice depends on specific ecological needs and the flexibility of other goals, such as water supply or energy production. All of these approaches require the scientific analysis and long-term monitoring of ecological and hydrological systems.
- Science
The links to the web pages below are a gateway to additional information in the ecology of streams.
SPARROW modeling: Estimating nutrient, sediment, and dissolved solids transport
SPARROW (SPAtially Referenced Regression On Watershed attributes) models estimate the amount of a contaminant transported from inland watersheds to larger water bodies by linking monitoring data with information on watershed characteristics and contaminant sources. Interactive, online SPARROW mapping tools allow for easy access to explore relations between human activities, natural processes, and...Water Quality in the Nation’s Streams and Rivers – Current Conditions and Long-Term Trends
The Nation's rivers and streams are a priceless resource, but pollution from urban and agricultural areas pose a threat to our water quality. To understand the value of water quality, and to more effectively manage and protect the Nation's water resources, it's critical that we know the current status of water-quality conditions, and how and why those conditions have been changing over time.Surface-Water Quality and Ecology
Research by the USGS National Water Quality Assessment (NAWQA) Project on water quality of rivers and streams covers a broad range of topics, from nonpoint pollution issues to vulnerability of aquatic ecosystems. Dive in and find out more about current water-quality conditions, how and where water quality is changing, and the latest information on pesticides, nutrients, and other contaminants.Stream Ecology
Who lives in your stream? Rivers and streams, even small ones, are teeming with a vast number of species, including fish, aquatic invertebrates, and algae. Stream ecology is the study of those aquatic species, the way they interrelate, and their interactions with all aspects of these flowing water systems. - Data
Access our most recent flow-alteration data. Explore more data releases at ScienceBase.
Natural Monthly Flow Estimates for the Conterminous United States, 1950-2015
This metadata record describes monthly estimates of natural stream flows for greater than 2.5 million stream reaches, defined by the National Hydrography Dataset (NHD) Version 2.0, in the conterminous United States for the period 1950-2015. A statistical machine learning technique - random forest modeling - was applied to estimate natural flows using 200 potential predictor variables. The datasetU.S. Geological Survey GAGES-II time series data from consistent sources of land use, water use, agriculture, timber activities, dam removals, and other historical anthropogenic influences
This product is a series of ten datasets containing tabular data from historical time series sources for the 9,067 conterminous United States sites in the U.S. Geological Survey (USGS) Geospatial Attributes of Gages for Evaluating Streamflow II (GAGES-II) dataset. The tables contain time-series data derived from consistent sources of agricultural commodities such as crop types, irrigation, and liv - Publications
Below, you’ll find the latest in peer-reviewed journal articles and USGS reports on flow alteration and its effects. For more publications on this and other water-quality topics, search the USGS Publications Warehouse. Look here for help using the Pubs Warehouse.
Biological relevance of streamflow metrics: Regional and national perspectives
Protecting the health of streams and rivers requires identifying ecologically significant attributes of the natural flow regime. Streamflow regimes are routinely quantified using a plethora of hydrologic metrics (HMs), most of which have unknown relevance to biological communities. At regional and national scales, we evaluated which of 509 commonly used HMs were associated with biological indicatoAuthorsDaren Carlisle, Theodore E. Grantham, Ken Eng, David M. WolockFilter Total Items: 22Changing climate drives future streamflow declines and challenges in meeting water demand across the southwestern United States
Society and the environment in the arid southwestern United States depend on reliable water availability, yet current water use outpaces supply. Water demand is projected to grow in the future and climate change is expected to reduce supply. To adapt, water managers need robust estimates of future regional water supply to support management decisions. To address this need, we estimate future streaAuthorsOlivia L. Miller, Annie L. Putman, Jay R. Alder, Matthew P. Miller, Daniel Jones, Daniel WiseEffects of urban multi-stressors on three stream biotic assemblages
During 2014, the U.S. Geological Survey (USGS) National Water-Quality Assessment(NAWQA) project assessed stream quality in 75 streams across an urban disturbance gradient within the Piedmont ecoregion of southeastern United States. Our objectives were to identify primary instream stressors affecting algal, macroinvertebrate and fish assemblages in wadeable streams. Biotic communities were surveyedAuthorsIan R. Waite, Mark D. Munn, Patrick W. Moran, Christopher P. Konrad, Lisa H. Nowell, Michael R. Meador, Peter C. Van Metre, Daren CarlisleA database of natural monthly streamflow estimates from 1950 to 2015 for the conterminous United States
Quantifying and understanding the natural streamflow regime, defined as expected streamflow that would occur in the absence of anthropogenic modification to the hydrologic system, is critically important for the development of management strategies aimed at protecting aquatic ecosystems. Water balance models have been applied frequently to estimate natural flows, but are limited in the number of pAuthorsMatthew P. Miller, Daren Carlisle, David M. Wolock, Michael WieczorekThe Midwest Stream Quality Assessment—Influences of human activities on streams
Healthy streams and the fish and other organisms that live in them contribute to our quality of life. Extensive modification of the landscape in the Midwestern United States, however, has profoundly affected the condition of streams. Row crops and pavement have replaced grasslands and woodlands, streams have been straightened, and wetlands and fields have been drained. Runoff from agricultural andAuthorsPeter C. Van Metre, Barbara Mahler, Daren Carlisle, James F. ColesPredictability and selection of hydrologic metrics in riverine ecohydrology
The natural flow regime is critical to the health of riverine ecosystems. Many hydrologic metrics (HMs) have been developed to describe natural flow regimes, quantify flow alteration, and provide the hydrologic foundation for the development of environmental flow standards. Many applications require the use of models to predict expected natural values of HMs from basin characteristics at sites witAuthorsKen Eng, Theodore E. Grantham, Daren Carlisle, David M. WolockBiological relevance of streamflow metrics: Regional and national perspectives
Protecting the health of streams and rivers requires identifying ecologically significant attributes of the natural flow regime. Streamflow regimes are routinely quantified using a plethora of hydrologic metrics (HMs), most of which have unknown relevance to biological communities. At regional and national scales, we evaluated which of 509 commonly used HMs were associated with biological indicatoAuthorsDaren Carlisle, Theodore E. Grantham, Ken Eng, David M. WolockStreamflow alteration and habitat ramifications for a threatened fish species in the Central United States
In the Central United States, the Arkansas darter (Etheostoma cragini) is listed as a threatened fish species by the State of Kansas. Survival of the darter is threatened by loss of habitat caused by changing streamflow conditions, in particular flow depletion. Future management of darter populations and habitats requires an understanding of streamflow conditions and how those conditions may haveAuthorsKyle E. Juracek, Ken Eng, Daren Carlisle, David M. WolockClassification of California streams using combined deductive and inductive approaches: Setting the foundation for analysis of hydrologic alteration
Regional classification of streams is an early step in the Ecological Limits of Hydrologic Alteration framework. Many stream classifications are based on an inductive approach using hydrologic data from minimally disturbed basins, but this approach may underrepresent streams from heavily disturbed basins or sparsely gaged arid regions. An alternative is a deductive approach, using watershed climatAuthorsMatthew I. Pyne, Daren Carlisle, Christopher P. Konrad, Eric D. SteinEstimating natural monthly streamflows in California and the likelihood of anthropogenic modification
Because natural patterns of streamflow are a fundamental property of the health of streams, there is a critical need to quantify the degree to which human activities have modified natural streamflows. A requirement for assessing streamflow modification in a given stream is a reliable estimate of flows expected in the absence of human influences. Although there are many techniques to predict streamAuthorsDaren Carlisle, David M. Wolock, Jeanette K. Howard, Theodore E. Grantham, Kurt Fesenmyer, Michael WieczorekAssociations of stream health to altered flow and water temperature in the Sierra Nevada, California
Alteration of streamflow and thermal conditions may adversely affect lotic invertebrate communities, but few studies have assessed these phenomena using indicators that control for the potentially confounding influence of natural variability. We designed a study to assess how flow and thermal alteration influence stream health – as indicated by the condition of invertebrate communities. We studiedAuthorsDaren Carlisle, S. Mark Nelson, Jason T. MayAn objective and parsimonious approach for classifying natural flow regimes at a continental scale
Hydro-ecological stream classification-the process of grouping streams by similar hydrologic responses and, by extension, similar aquatic habitat-has been widely accepted and is considered by some to be one of the first steps towards developing ecological flow targets. A new classification of 1543 streamgauges in the contiguous USA is presented by use of a novel and parsimonious approach to undersAuthorsStacey A. Archfield, Jonathan Kennen, Daren Carlisle, David M. WolockMacroinvertebrate community change associated with the severity of streamflow alteration
Natural streamflows play a critical role in stream ecosystems, yet quantitative relations between streamflow alteration and stream health have been elusive. One reason for this difficulty is that neither streamflow alteration nor ecological responses are measured relative to their natural expectations. We assessed macroinvertebrate community condition in 25 mountain streams representing a large grAuthorsDaren Carlisle, Ken Eng, S. M. Nelson