Baltimore and Maryland Watershed Health Assessment, 2010

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Impairments What is Water Quality Impairment? The state of Maryland reports on the status of surface water quality every other year, in the “Integrated Report of Surface Water Quality.” This report identifies whether surface waters are impaired for a number of causes or pollutants including: nutrients, bacteria, sediment, biological community, and toxics. A water body is listed as impaired when it does not meet a water quality standard. When a water body is determined to be impaired, a Total Maximum Daily Load (TMDL) is developed or additional water quality monitoring data are reviewed and a Water Quality Analysis (WQA) report is prepared that will either result in delisting the water body for impairment or the development of a TMDL.

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Causes of Impairments (from 0 to 5) Rationale for Scoring Categories Scoring categories roughly coincided with the number of possible impairments for a watershed.

Note that a drinking water reservoir will have different water quality standards than a harbor. The standards protect for human health and aquatic life. For example, the water quality standards for the Baltimore/Direct Harbor Watershed may allow higher levels of certain pollutants than the Liberty Reservoir Watershed. Why were impairments used as an indicator? A water body is listed as impaired when it does not meet the water quality standards for nutrients, bacteria, sediment, biological community, and/or toxics for its designated use. The impairments within a watershed are measures of the overall water quality within that watershed.

How this map was created The “Integrated Report,” which is developed every two years, places surface waters into different categories, depending on whether they are considered to be meeting a given water quality criterion or whether they are impaired for that criterion. From the “Integrated Report,” it was determined whether or not each of the 14 watersheds was impaired for each of the five possible impairments: nutrients, bacteria, sediment, biological community, and toxics. The score reflected the number of impairments for a given watershed.

Photo courtsey of Baltimore City


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Baltimore and Maryland Watershed Health Assessment, 2010 by Eymund Diegel - Issuu