Conowingo Pond Management Plan Publication No. 242 June 2006 SUSQUEHANNA RIVER BASIN COMMISSION Paul O. Swartz, Executive Director Denise M. Sheehan, N.Y. Commissioner Kenneth P. Lynch, N.Y. Alternate Scott J. Foti, N.Y. Alternate/Advisor Kathleen A. McGinty, Pa. Commissioner Cathy C. Curran Myers, Pa. Alternate William A. Gast, Pa. Alternate/Advisor Kendl P. Philbrick, Md. Commissioner Dr. Robert M. Summers, Md. Alternate Matthew G. Pajerowski, Md. Alternate/Advisor Major General William T. Grisoli, U.S. Commissioner Colonel Robert J. Davis, Jr., U.S. Alternate Colonel Francis X. Kosich, U.S. Alternate Daniel M. Bierly, U.S. Advisor The Susquehanna River Basin Commission was created as an independent agency by a federal-interstate compact* among the states of Maryland, New York, Commonwealth of Pennsylvania, and the federal government. In creating the Commission, the Congress and state legislatures formally recognized the water resources of the Susquehanna River Basin as a regional asset vested with local, state, and national interests for which all the parties share responsibility. As the single federal-interstate water resources agency with basinwide authority, the Commission’s goal is to coordinate the planning, conservation, management, utilization, development and control of basin water resources among the public and private sectors. *Statutory Citations: Federal - Pub. L. 91-575, 84 Stat. 1509 (December 1970); Maryland - Natural Resources Sec. 8-301 (Michie 1974); New York - ECL Sec. 21-1301 (McKinney 1973); and Pennsylvania - 32 P.S. 820.1 (Supp. 1976). This report is available on our website (www.srbc.net) by selecting Public Information/Technical Reports. For a CD Rom or for a hard copy, contact the Susquehanna River Basin Commission, 1721 N. Front Street, Harrisburg, Pa. 17102-2391, (717) 238-0423, FAX (717) 238-2436, E-mail: [email protected]. ii TABLE OF CONTENTS EXECUTIVE SUMMARY ............................................................................................................ 1 I. INTRODUCTION..................................................................................................................... 7 A. Purpose and Objectives .....................................................................................................7 B. Background of Conowingo Dam and Pond....................................................................... 8 C. Conowingo Pond Workgroup............................................................................................ 9 II. THE RESOURCES AND USES OF THE CONOWINGO POND....................................... 13 A. Fishery Resources ........................................................................................................... 13 B. Hydroelectric Power........................................................................................................ 13 C. Public Water Supply........................................................................................................ 14 D. Thermoelectric Power ..................................................................................................... 15 E. Recreational ..................................................................................................................... 15 F. Future Project................................................................................................................... 16 III. EXISTING PROBLEMS, ISSUES, AND OPPORTUNITIES ............................................ 17 A. Review of Various Interests in Pond’s Resources .......................................................... 17 B. Minimum Releases and the 1988 Settlement Agreement................................................ 20 C. Low Flow Operations...................................................................................................... 21 D. Identification of Existing Problems and Issues ............................................................... 23 E. Opportunities for Improvements...................................................................................... 25 IV. PLANNING PROCESS AND INITIAL SCREENING....................................................... 27 A. Hydrologic Model Development and Verification.......................................................... 27 B. Performance Measures .................................................................................................... 36 C. Baseline Conditions......................................................................................................... 37 D. Operational Alternatives Considered .............................................................................. 38 E. Computer-Aided Negotiations......................................................................................... 40 F. Model Results .................................................................................................................. 42 V. PREFERRED OPERATION ALTERNATIVES .................................................................. 45 A. Description of Preferred Alternatives ............................................................................. 45 B. Evaluation of Preferred Alternatives............................................................................... 47 C. Conclusions and Refinement of Alternatives.................................................................. 49 VI. DISCUSSION OF SELECTED ALTERNATIVE............................................................... 53 VII. CONOWINGO POND MANAGEMENT PLAN............................................................... 57 A. Description of the Conowingo Pond Management Plan ................................................. 57 B. Implementation of the Management Plan........................................................................ 57 C. Operation of the Management Plan................................................................................. 58 D. Related Actions by the Susquehanna River Basin Commission ..................................... 60 E. Long-Term Benefits......................................................................................................... 61 VIII. SUMMARY OF CONCLUSIONS AND ACTIONS........................................................ 63 iii FIGURES Figure I-1. Location of Conowingo Dam and Pond ...................................................................... 9 Figure I-2. Facilities in the Vicinity of the Conowingo Pond...................................................... 10 Figure III-1. Important Operating Elevations (Conowingo Datum) of Conowingo Pond........... 22 Figure IV-1. Locations of Stream Gages Used in Development of Hydrologic Record ............. 29 Figure IV-2. Schematic of Hydrologic Model Coverage............................................................. 30 Figure IV-3. Schematic of Detailed Model Coverage in Lower Susquehanna Basin ................. 31 Figure IV-4. Modeled vs. Historic Marietta Flow in 2002.......................................................... 34 Figure IV-5. Modeled vs. Historic Conowingo Pond Stages in 2002 ......................................... 35 Figure IV-6. Modeled vs. Historic Conowingo Dam Flow Releases in 2002 ............................. 35 TABLES Table IV-1. Stream Gages Used in Development of the Hydrologic Record.............................. 28 Table IV-2. Alternative Operational Plans Evaluated During Computer-Aided Negotiations ... 41 Table V-1. Selected Results of the Final Four Alternatives ........................................................ 50 APPENDICES Appendix 1. Conowingo Pond Workgroup Input.........................................................................65 Appendix 2. Model Development and Verification......................................................................91 Appendix 3. Model Results and Evaluation of Alternatives.......................................................115 Cover Photo (courtesy of Exelon Generation, Inc.): Looking north at Conowingo dam with the pond in the upper portion of the photo. iv ACKNOWLEDGEMENTS The Conowingo Pond Workgroup members were instrumental in the successful development of the selected management plan for the pond and preparation of the Workgroup’s report, which served as the basis for this report by the Susquehanna River Basin Commission. The actively involved members, whose efforts were both important and appreciated, are listed below. Chester Water Authority – Brian MacEwen, Pat Stabler City of Baltimore – Sam Grant, Ed Huff; Frank Donaldson and Tom DiLego (Patton, Harris, Rust & Associates) City of Havre de Grace – Donna Costango Conectiv Mid Merit, LLC – Stu Widom Exelon Generation, Inc. – Al Ryan, Tracy Siglin Harford County – Jackie Ludwig Lancaster County – Mary Frey Maryland Department of the Environment –Mat Pajerowski*, John Smith Maryland Department of Natural Resources – Rich McLean, Steve Schreiner (Versar, Inc.) Pennsylvania Department of Environmental Protection – Bill Gast Pennsylvania Fish and Boat Commission – Mike Hendricks PPL Corporation – Chris Porse Safe Harbor Water Power Corporation – Dick Johnson Susquehanna Electric – Don Baldwin, Ron Smith Susquehanna River Basin Commission – Tom Beauduy, Drew Dehoff, Dave Ladd U.S. Army Corps of Engineers – Bill Haines U.S. Fish and Wildlife Service – Dick St. Pierre York County – John Seitz *Served as chairman of the Workgroup. The Susquehanna River Basin Commission retained the services of HydroLogics, Inc. of Columbia, Maryland, for assistance in the technical, water management,