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State water quality standards assign designated beneficial uses to waters, and the
PaDEP assesses waterways to determine if uses are being attained. A variety of
physical, chemical, and biological water quality and habitat indicators are measured,
and this information is used to decide if water uses are attained. The water quality
indicators used by Pennsylvania for making use attainment decisions are interpreted
within the context of the standards, including designated uses, narrative or numeric
criteria, and anti-degradation policies. Other factors that influence the state’s
selection of indicators include: sampling effort, the cost of collecting and analysing
samples, the variability of the indicator in the environment, the level of precision
desired by decision makers, and the sampling frequency required to meet data
quality objectives. In reality, the bulk of the problems identified for future mitigation
activities are a result of rapid bio-assessment stream surveys.
Aquatic life use data are used to assess the ability of Pennsylvania’s water bodies
to maintain and/or propagate fish species and additional flora and fauna that are
indigenous to state aquatic habitats. Aquatic life use attainment surveys of the
state’s wade able streams and rivers (systems that do not exceed one meter in
depth or one meter/second velocity) are conducted through the DEP’s Statewide
Surface Waters Assessment Program (SSWAP). This SSWAP involves a statewide
assessment of habitat and biological (benthic macroinvertebrate) indicators that are
used to measure the ability of surface waters to support expected aquatic life uses.
Human health use attainment surveys of Pennsylvania’s surface waters are conducted
through the Pennsylvania Fish Tissue Sampling and Fish Advisories Programme. The
purpose of this multi-agency programme is to sample for toxins potentially harmful
to humans. Target species usually consist of water body-specific, recreationally
important species that are commonly taken by anglers for consumption. Fish tissue
samples are generally collected during periods of low flow between August and
October when reproduction is complete and a full summer of exposure to potential
toxins has occurred.
Currently, this programme includes a mixture of risk assessment-based methods
and U.S. Food and Drug Administration (FDA) Action Levels that are used as the
basis for issuing or lifting advisories. Risk assessment methods form the basis for
meal-specific advisories due to PCBs and mercury. Advisories for other compounds
use FDA Action levels to issue ‘Do Not Eat’ advice. Once advisories are issued,
the affected stream segments are put on the State’s ‘impaired water body list’.
Additional Human Health use attainment evaluations, which may result in subsequent
‘listing’, are conducted through the review of raw (intake) water quality as described
through self-monitoring efforts of drinking water facilities. Physical, chemical, or
bacteriological quality over extended periods of time is compared to potable water
supply criteria outlined in Pennsylvania’s Water Quality Standards regulations to
determine use attainment status.
Recreational use attainment decisions for Pennsylvania’s surface waters are made
using bacteriological indicator data collected by government agencies (including the
PaDEP, the Pennsylvania Department of Health, and the United States Geological
Survey) and citizen/volunteer groups. Faecal coliform bacteria are used as indicators
of possible sewage contamination because they are commonly found in human and
animal feces. Although faecal coliforms are generally not harmful themselves, they
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