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indicate the possible presence of pathogenic (disease causing) bacteria, viruses
and protozoa that also live in human and animal digestive systems. Therefore, their
presence in a water body suggests that pathogenic microorganisms may be present
as well, and that water contact recreation such as swimming may be a health risk.
Important recreational areas and aquatic life use impaired water bodies with obvious
potential sources of bacteria (e.g. municipal point sources, combined sewer overflows,
and agricultural sources relating to manure application, livestock grazing, and animal
feeding) are targeted for bacteriological sampling. Sampling is conducted during
the swimming season (May 1 through to September 30) and consists of at least two
sampling groups collected per site per season.
Based on the use of various measures, the water quality status of Pennsylvania’s
waters is summarized using a five-part categorization of waters according to their
use attainment status. Each five-digit water body segment (as shown in Figure 1)
is placed into one of these categories. Different segments of the same stream may
appear on more than one list if the attainment status changes as the water flows
downstream. The listing categories are as follows:
Category 1: Waters attaining all designated uses.
Category 2: Waters where some, but not all, designated uses are met. Attainment
status of the remaining designated uses is unknown because data are insufficient to
categorize a water consistent with the state’s listing methodology.
Category 3: Waters for which there are insufficient or no data and information to
determine, consistent with the State’s listing methodology, if designated uses are
met.
Category 4: Waters impaired for one or more designated uses but not needing
a TMDL because a TMDL has been completed, use attainment is expected to
occur within a short time frame (within 3 years), or the impairment is not due to a
pollutant.
Category 5: Waters impaired for one or more designated uses by any pollutant.
LISTING OF IMPAIRED WATERS
The results of all assessments completed within the state are reported on a publiclyavailable
‘Integrated List’ (www.depweb.state.pa.us/dep/cwp/view.asp?a=3&q=461
149&depNav=|).
On this site, streams can be displayed on top of topographic maps and queried via
the use of an interactive database. Among other things, streams can be queried as
to the reason for their being given an ‘impaired’ (i.e. Category 5) listing. Such reasons
are described in terms of the ‘source’ (e.g. municipal point source, agriculture, urban
run-off, surface mining, etc.) and ‘cause’ (e.g. nutrients, siltation, organic enrichment/
low DO, etc.) assignments given to each impaired stream segment.
Waters included under Category 5 essentially constitute the Section 303(d) list (i.e.
‘impaired waters list’) that the U.S. EPA will approve or disapprove under the Clean
Water Act. Where more than one pollutant is causing the impairment, the water
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