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Water Quality Standards Achievement

During the 2013 to 2015 assessment period, an estimated 37 percent of the Chesapeake Bay and its tidal tributaries met water quality standards. This marks an almost 10 percent increase from the previous assessment period, but is far below the 100 percent attainment needed for clean water and a stable aquatic habitat.





September 03, 2013

Scientists from Maryland Department of Natural Resources and University of Maryland’s Chesapeake Biological Laboratory show us key methods for tracking nutrient levels and determining the health of the Chesapeake Bay.
Closed Captions: http://www.youtube.com/watch?v=U1prV3zpeZA

Importance

The Chesapeake Bay and its tidal tributaries can be divided into 92 segments. Each of these segments contains up to five “designated uses,” included deep channel; deep water; open water; shallow water; and migratory fish, spawning and nursery. In all, the Bay and its tidal tributaries contain 291 designated uses. Each of these designated uses—also known as aquatic habitats—has its own set of criteria for dissolved oxygen, water clarity/underwater grasses and chlorophyll a designed to protect those uses. If the Bay and its tidal tributaries are to function as a healthy ecosystem, all water quality standards must be met.

Goal

In 2014, the Chesapeake Bay Program adopted a goal to reduce pollution and achieve the water quality necessary to protect human health and support the region’s underwater resources.

Long-term trend (1985-2015) 

A straight line trend analysis shows a positive trend in the percentage of water quality standards met in the Chesapeake Bay between 1985 and 2014.

Change from previous reporting period (2012-2014 to 2013-2015)

Results of the 2013-2015 assessment period indicate that 37 percent of the water quality standards for the Chesapeake Bay were met during this time. This marks an almost 10 percent increase from those of the previous assessment period, during which 34 percent of water quality standards were met.

Additional Information

Analyzing data

The methodology used to calculate this indicator considers the achievement or non-achievement of water quality standards for dissolved oxygen, water clarity/underwater grasses and chlorophyll a applicable to a designated use within a particular segment. Rather than reporting progress when all designated uses meet standards within a segment, this methodology reports progress when any designated use meets a standard within that segment. This means that instead of reporting on the 92 segments used in the establishment of the Chesapeake Bay’s “pollution diet,” or Total Maximum Daily Load (TMDL), this methodology reports on the 291 designated-use segments contained therein.

This indicator uses a surface area-weighted approach, which multiplies the surface area of a segment by its designated uses and criteria. This approach takes the relative size of each segment into account, ensuring we report the best available measure of water quality standards achievement in the Bay. This approach also gives equal weight to the achievement of the criteria protective of each designated use and segment, preventing any need to weigh differently the importance of restoring dissolved oxygen versus restoring underwater grasses, for example. The indicator combines the assessments of dissolved oxygen, water clarity/underwater grasses and chlorophyll a into a single indicator of water quality, measured against the goal of meeting all three standards across the Bay.

Reporting data

This indicator measures progress toward the achievement of water quality standards for dissolved oxygen, water clarity/underwater grasses and chlorophyll a in three-year assessment periods beginning in 1985. The indicator is consistent with how Delaware, the District of Columbia, Maryland and Virginia list their portions of the Bay’s tidal waters and illustrates Bay-wide improvements over time.

Source of Data

Chesapeake Bay Program

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Annapolis, Maryland 21403
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