This report card provides a transparent, timely, and geographically detailed assessment of Chesapeake Bay. In 2012, the methods for the report card have changed to include five water quality indicators and two biotic indicators. In 2012, the overall grade for Chesapeake Bay is a 47%, a C. This means the Bay is in moderate health. Fisheries indicators as well as trajectories of reporting region health are also presented. For further details, visit the Report Card website .

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Stream network density exerts a strong influence on ecohydrologic processes in watersheds, yet existing stream maps fail to capture most headwater streams and therefore underestimate stream density. Furthermore, discrepancies between mapped and actual stream length vary between watersheds, confounding efforts to understand the impacts of land use on stream ecosystems.

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This report card provides a transparent, timely, and geographically detailed assessment of Chesapeake Bay. The overall health of Chesapeake Bay, determined using water quality and biotic indicators, declined slightly in 2011. The overall grade of D+ was a decrease for the second year in a row, down from a C- in 2010. Only two reporting regions, the Patapsco and Back Rivers, and the Lower Western Shore (MD), had improved grades in 2011.

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Channel heads are the beginning of river networks and thus knowing their location is important in assessing water resources and health threats to fluvial ecosystems. Despite their importance, most channel heads are unmapped. Remote sensing technologies have not yet proven effective under forested canopies, suggesting that predictive models of channel head locations are the best solution to the impracticality of field-mapping the millions of these features that exist in the U.S. alone.

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This report card provides a transparent, timely, and geographically detailed assessment of 2010 Chesapeake Bay health. The overall health of Chesapeake Bay, assessed using water quality and biotic indicators, declined slightly in 2010. The overall grade decreased from a C in 2009 to C- in 2010. Only two reporting regions (James River and York River) had improved grades in 2010, three were unchanged, and nine declined.

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This report card provides a transparent, timely, and geographically detailed assessment of 2009 Chesapeake Bay habitat health. The overall health of Chesapeake Bay, assessed using water quality and biotic indicators, was the best it has been since 2002. The overall grade improved from C- in 2008 to C in 2009. Eight reporting regions had improved grades in 2009, four were unchanged, and two had slightly worse grades.

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For many studies of urbanization, particularly those covering broad spatial extents and thus requiring the perspective afforded by satellite remote sensing, the longest time series of impervious surface area (ISA) initiate with the availability of Landsat Thematic Mapper (TM) data in the mid 1980s.

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This report card provides a transparent, timely, and geographically detailed annual assessment of 2008 Chesapeake Bay habitat health. This is the third year that the report card has been released. This report card rates 15 reporting regions of the Bay using six indicators that are combined into a single overarching index of habitat health. The overall health of Chesapeake Bay was poor in 2008, obtaining a grade of C-.

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The relevance of the boundary concept to ecological processes has been recently questioned. Humans in the post-industrial era have created novel lateral transport fluxes that have not been sufficiently considered in watershed studies. We describe patterns of land-use change within the Potomac River basin and demonstrate how these changes have blurred traditional ecosystem boundaries by increasing the movement of people, materials, and energy into and within the basin.

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This report card provides a transparent, timely, and geographically detailed annual assessment of 2007 Chesapeake Bay habitat health. This is the second year that the report card has been released. This report card rates 15 reporting regions of the Bay using six indicators that are combined into a single overarching index of habitat health. Habitat health is defined as progress of the six indicators towards established scientifically derived ecological thresholds or goals.

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