factors impacting bay and watershed health
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Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Factors Impacting Bay and Watershed Health
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Pollutants
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Nitrogen Loads and River Flow to the Bay
Billions ofGallons of Flow
0
200
400
600
800
1990 1995 2000 2005 20100
25
50
75
100
Data and Methods: www.chesapeakebay.net/status_nitrogen.aspx. 2008 data are provisional.
Nitrogen Loads and River Flow to Chesapeake BayMillions of Pounds
of Nitrogen
River Flow
Average Load
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Phosphorus Loads and River Flow to the Bay
0
20
40
60
80
1990 1995 2000 2005 20100
25
50
75
100
Billions ofGallons of Flow
Data and Methods: www.chesapeakebay.net/status_phosphorus.aspx. 2008 data are provisional.
Phosphorus Loads and River Flow to Chesapeake BayMillions of Pounds
of Phosphorus
Average Load
River Flow
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Sediment Loads and River Flow to the Bay
• Preliminary estimates indicate that 3.3 million tons of sediment reached the Bay during 2008. This is 700,000 tons more than 2007 and 800,000 tons less than the 4.1 million ton average load from 1990-2008.
• The sediment load estimates do not account for sediment from the coastal plain areas of the watershed.
• Scientists are currently developing methods to quantify the total loads of sediment to the Bay.
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Chemical Contaminant Loads to the Bay • Synthetic organic pesticides and their
degradation products have been widely detected at low levels in the watershed, including emerging contaminants such as pharmaceuticals and hormones.
• Fish (principally male bass) in the Potomac watershed have testicular oocytes - female eggs growing in their testes - a form of intersex. Reproductive abnormalities in fish have been strongly linked with a variety of contaminants that affect the endocrine systems of fish.
• Scientists are currently developing methods to quantify chemical contaminant loads to the Bay.
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Land Use
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Bay Watershed Population and Impervious Surface
0
0.2
0.4
0.6
0.8
1
1.2
1950 1960 1970 1980 1990 2000 2010 2020 20300
5
10
15
20
25
Millions of Acres of Impervious Surface Millions of People
Projection
Data and Methods: www.chesapeakebay.net/status_population.aspx
Bay Watershed Population and Impervious Surface
PopulationImpervious Surface
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Bay Watershed Forest Cover
0
20
40
60
80
100
1650 1700 1750 1800 1850 1900 1950 2000
Percent Forest Cover
Data and Methods: www.chesapeakebay.net/status_watershedforests.aspx
Bay Watershed Forest Cover
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Natural Factors
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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River Flow into Chesapeake Bay
0
10
20
30
40
50
60
70
80
9019
38
1948
1958
1968
1978
1988
1998
2008
Normal Range
Wet Years
DryYears
Data and Methods: www.chesapeakebay.net/status_riverflow.aspx
Water Year Mean River Flow (billions of gallons per day)
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Weather• Rainfall, temperature and winds have a
great impact on water quality, habitats and fish and shellfish populations.
• Climate change and variability have caused water temperatures in the Bay to exhibit greater extremes during the 20th century than the previous 2,000 years.
• Sea-level rise related to climate change is contributing to the loss of vital coastal wetlands.
Chesapeake Bay Health & Restoration Assessment:Executive Summary03/10/09
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Other Pressures
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