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 Climate Change Indicators: Stream
Temperature
This indicator shows changes in stream water temperature
across the Chesapeake Bay region.
Key Points
From 1960 through 2014, water temperature increased at 79
percent of the stream sites measured in the Chesapeake Bay
region (see Figure 1). More than half of these increases
were statistically significant. Only 5 percent of stations
had a significant temperature decrease over the same period.
Since 1960, the Chesapeake Bay region has experienced an
overall increase in stream water temperature. Temperature
has risen by an average of 1.2°F across all sites and 2.2°F
at the sites where trends were statistically significant.
Stream temperatures have risen throughout the Chesapeake Bay
region. The largest increases have occurred in the southern
part of the region. |
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Background
Water temperature is an important physical property of every
river and stream. Many plants, animals, and other organisms
living in streams can flourish only in a specific range of
water temperatures. Temperature can affect certain aspects
of water quality. For example, higher temperatures reduce
levels of dissolved oxygen in the water, which can
negatively affect the growth and productivity of aquatic
life. Persistently warmer temperatures in streams can
accelerate natural chemical reactions and release excess
nutrients into the water. A stream’s water temperature can
also influence the circulation or mixing patterns in the
water it flows into, like bays and estuaries, potentially
affecting nutrient levels and salinity.
Temperatures can vary naturally along the length of a
stream, from cold temperatures near a source of meltwater to
higher temperatures near its outlet to the sea. The
temperature at any given point is a product of many
different factors, including sources of water (for example,
melted snow, a recent rainstorm, or groundwater), the amount
of water in the stream (streamflow), air temperature, plants
along the bank (for example, trees that provide shade), and
the amount of development within the watershed. Over time,
however, an area’s climate has the strongest natural
influence on a stream’s temperature.
The Chesapeake Bay is the largest estuary in the United
States, an important habitat for countless aquatic species,
and a driver of the regional economy. As rising air
temperatures (see the U.S. and Global Temperature indicator)
cause stream temperatures to rise, warmer stream water
coming into the bay can stress plants and animals and worsen
the effects of nutrient pollution that the bay is already
facing. |
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About the Indicator
The U.S. Geological Survey maintains thousands of stream
gauges across the United States. Each gauge measures water
levels several times a day, typically every 15 minutes.
Field technicians visit each gauging station an average of
eight times a year to measure various stream conditions,
including water temperature. This indicator shows how
average water temperatures throughout the year changed
between 1960 and 2014 at 129 stream gauges located across
the Chesapeake Bay region. These stations were selected
because they had high-quality data for this entire time
period.
Indicator Notes
In addition to climate, changes to a stream’s average water
temperature can be influenced by other factors such as
industrial discharges, changes to local hydrology (such as
construction and operation of dams and channels), and
changes to land cover in the watershed. This indicator uses
measurements from all stream gauges with sufficient data.
Thus, it includes some stream sites that are likely more
disturbed by human activities than others. A more detailed
analysis of this data set found that water temperature tends
to increase more quickly than air temperature in
agricultural areas without major dams, but more slowly at
forested sites and in areas influenced by dams. Nonetheless,
a comparison of 35 relatively undisturbed reference stations
with the remaining 94 stations in this indicator showed no
significant difference in trends between the two groups of
stations.
This indicator is based on measurements that are collected
an average of eight times per year, but more in some years
and less in others. The data were analyzed in a way that
accounts for variations in timing and makes it possible to
compare average temperatures across many years.
Data Sources
This indicator is based on an analysis developed by the U.S.
Geological Survey (USGS). Periodic temperature data were
collected by the USGS, and these data are stored in the USGS
National Water Information System.
Technical Documentation
Download related technical information PDF |
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 Figure
1. Changes in Stream Water Temperatures in the
Chesapeake Bay Region, 1960–2014
This map shows the change in water temperature at 129 stream
gauges across the Chesapeake Bay region from 1960 to 2014.
Red circles show locations where temperatures have
increased; blue circles show locations where temperatures
have decreased. Filled circles represent sites where the
change was statistically significant.
Data source: Jastram and Rice, 20153 |
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EPA Page |
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This is the
EPA page for this topic. To see if the Trump
administration has changed the EPA page, simply click the
link and compare the information with this page. If you
notice changes were made to the EPA page, please post a
comment. Thanks. |
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Additional Climate Change Information |
Climate Change and Carbon Dioxide
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change
and carbon dioxide.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice. |
Carbon Dioxide and Climate Change
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of carbon dioxide
and climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice. |
Environmental Group Warns Earth's Health at Risk
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
A report by the World Wildlife Fund looked at thousands of animal populations
and found they have dropped significantly in 40 years. |
Sea Levels Rising at Fastest Rate in 3,000 years
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
A group of scientists say sea levels are rising at record rates. Another group
found that January temperatures in the Arctic reached a record high. |
Capturing CO2 Gas Is Not Easy
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
Most scientists agree that carbon-dioxide gas is partly to blame for climate
change: rising global temperatures. But capturing the CO2 gas released by power
stations is costly and difficult. |
Growth, Climate Change Threaten African Plants and
Animals
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
Researchers believe Africa may lose as much as 30 percent of its animal and
plant species by the end of this century. |
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