New Stream Assessment Methodology Proposed by DEP

October 2013Articles In the Zone

On September 28, 2013, the Pennsylvania Department of Environmental Protection published notice of a new draft Assessment and Listing Methodology for evaluating the water quality of Pennsylvania streams and impaired waters. The methodology and its various protocols form the basis for designating stream segments according to their use attainment status. Such designations can directly influence the economic viability of impacted land development projects. For example, Category 5 waters are impaired by pollutants and require a Total Maximum Daily Load (TMDL) to correct the impairment. When TMDLs are imposed, development along that waterway can be limited, because water discharges must comply with the TMDL.

Sections 303(d) and 305(b) of the Federal Clean Water Act require states to report on the condition of all their waters in the biennial Integrated Report. Stream and lake evaluations presented in the report must be supported by assessment methodologies based on sound science and technical procedures.

DEP’s assessment and listing methodology constitutes the “decision rules” the Department uses when assessing the quality of waters and identifying water bodies that do not meet designated and existing uses. It includes the field collection standards to be utilized when sampling water bodies as well as the scientific data analysis methods to evaluate water quality data.

The draft 2013 methodology would update and expand upon the current 2009 version of its Assessment Methodology by adding new assessment protocols as well as amending some of the exiting protocols.

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