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Water Quality Models and Tools

DEP maintains several water quality models and tools used by the NPDES permitting program. These models and tools are generally used in NPDES permit development and/or utilized by permittees as a part of permit conditions.

Water Quality Models

PENTOXSD and WQM 7.0 are water quality models used to aid in the development water quality-based effluent limits. WQM 7.0 is a Wasteload Allocation Program (WLA) for Dissolved Oxygen and Ammonia-Nitrogen. PENTOXSD is a WLA program for toxics and other substances. Technical Reference Guides and Supplemental Information are available in the Documentation folder of the ZIP file.

PENTOXSD and WQM 7.0 - For download instructions open the ZIP file and review the Read Me file.

NPDES Permit Tools

DEP has developed several tools to aid in NPDES program implementation. These tools are Excel based and do not require installation. Instructions for each tool are available on the first tab of the workbook.

  • Total Residual Chlorine Spreadsheet (Excel) - May be used by DEP to evaluate effluent limitations and monitoring requirements for Total Residual Chlorine (TRC) in NPDES permits.
  • Toxics Screening Analysis Spreadsheet (Macro-Enabled Excel) - May be used by DEP to evaluate water quality parameters of concern for potential effluent limitations and monitoring requirements in NPDES permits.
  • WET Analysis Spreadsheet (Excel) -May be used by DEP to evaluate reasonable potential to exceed water quality standards for Whole Effluent Toxicity (WET) and by NPDES permittees and/or laboratories to evaluate whether WET tests are considered "pass" or "fail". For technical issues or questions, contact the Bureau of Clean Water's Division of Planning and Permitting at 717-787-8184.

For technical issues or questions, contact the Bureau of Clean Water's Division of Planning and Permitting at 717-787-8184.