Independent Review of Exelon’s LSRRS Model-Enhancements Efforts

As part of an on-going multi-year, multi-investigator program to better understand the impact of storm events on loads of sediments and nutrients from the Lower Susquehanna River Reservoir System (LSRRS) to the Chesapeake Bay (see background page), Exelon Generation Company, LLC (“Exelon”) employed a team of engineers and scientists to undertake a two-phase modeling approach that would enhance and complement the existing Phase 6 HSPF Watershed Model (HSPF) as well as the simulation of inputs to the Bay Water Quality and Sediment Transport Model (WQSTM). The modeling approach included developing both (1) an enhanced one-dimensional HEC-RAS model of Lake Clarke and Lake Aldred, similar in nature to the one developed by the USGS as part of the Lower Susquehanna River Watershed Assessment (LSRWA); and (2) a coupled hydrodynamic, sediment transport, sediment nutrient flux and water quality mass balance model for Conowingo Pond, referred to by its developers as the Conowingo Pond Mass Balance Model (CPMBM). As part of this modeling effort, the Exelon team agreed to work closely with the Chesapeake Bay Program (CBP) Modeling Workgroup and U.S. Army Corps of Engineers modelers throughout the process to ensure that all parties are in agreement on the methods used, and deliverables provided, and implementation of to ensure that the model results will help inform the suite of CBP models (specifically Phase 6 CBP Watershed Model and WQSTM) under development as part of the 2017 Chesapeake Bay Mid Point Assessment.

In addition, Exelon agreed that all modeling efforts and reports would be subject to two independent reviews, including (1) interim review and guidance from an independent modeling evaluation group to be contracted and coordinated by the Chesapeake Research Consortium (CRC) and (2) additional review as part of a larger review of the CBP’s Phase 6 Watershed Model that was already scheduled for 2016 as part of the activities of the CBP’s Scientific and Technical Advisory Committee (STAC). The Evaluation/Review Team comprised four independent evaluators/reviewers. The Scope of Work (which included this same background information as preamble) was agreed upon by all parties at the beginning of the review process. The evaluation group was tasked to review the modeling methods, results, and reports and provide feedback and comments as appropriate. Comments provided by the reviewers were taken under advisement by the Exelon modeling team which then provided responses. Finally, the CRC prepared its Final Report to document the process and results.

The modeling evaluation group comprises four independent reviewers.

The Background section of this site contains some useful background information about the project and the Reviewers section provides links to biographical information about the four independent peer reviewers. The "Documents" tab provides connection to pages with links to the following types of documents:

  • Minutes : Copies of minutes of the five conference calls held between the Exelon Modeling Team, the four independent reviewers, and representatives of the CRC and the Maryland DNR.
  • Scope of Work: The original Scope of Work for this independent review, including schedule updates.
  • Background Technical Documents: The selected technical documents that were submitted to reviewers prior to the review process, all of which are public information.
  • Status Updates: Links to PDFs of Powerpoint presentations given by members of the Exelon Modeling Team to the Chesapeake Bay Program's Modeling Work Group or Modeling Team
  • Final Reports from Exelon Modeling Team: The final reports from the HDR, Inc. and WEST, Inc. consulting Groups
  • Reviewer Comments: Review reports from the four peer reviewers.
  • Exelon Modeling Team Responses to Reviewer Comments
  • Final CRC Publication (Lower Susquehanna River Reservoir System Model Enhancements Peer Review): This official CRC publication summarizes the review and provides most of the information on this web site (all except for the background technical documents and status updates). Its full citation is: Ball, W.P., B.D Michael, D.C. Brady, J.L. Martin, S.H. Scott, and P.R. Wilcock, 2017, Lower Susquehanna River Reservoir System Model Enhancements Peer Review. CRC Publication No. 17-173, Chesapeake Research Consortium, Edgewater, MD. 59 pp.
    Note: This document was first posted on August 31, 2017, but has since been corrected in some minor but important ways on pages i, 40, and 46. The final revised version, now dated "September 2017" is the one posted at this web site.

The above final report has been provided to the Chesapeake Bay Program's (CBP's) Modeling Work Group, which was also kept abreast of the effort throughout the review. The Modeling Work Group, which was also kept informed of review progress over the course of the effort, has used results of this effort to inform modeling revisions undertaken as part of the "Total Maximum Daily Load Mid-Point Assessment" process.


The Conowingo Dam modeling independent review panel is charged with providing an unbiased and independent review of the Lower Susquehanna River Reservoir System model in support of the 2017 Chesapeake Bay Total Maximum Daily Load Mid-Point Assessment.

The information contained on this website is draft, preliminary and does not represent the final views of any individual or the review panel. Comments, presentations and views are to be used for discussion purposes within the panel.

By no means does the website represent the views of the Chesapeake Resource Consortium, Maryland or its agencies and departments, the Chesapeake Bay Program or Exelon and their contractors.