APPENDK C 



f SCOPE OF PROJECT REVIEW: PENNSYLVANU DAM PROPOSAL EXAMPLE 



The dam proposed by the City of Harrisburg was to be 3,000 feet long and 17 

 feet high. The dam was to consist of 32 bottom hinged flap gates. The dam would 

 have created an impoundment with a surfoce area of 3,800 acres, a total storage 

 capacity of 35,000 acre feet, and a pool elevation of 306J feet The backwater would 

 have extended approximately eight miles upstream on the Susquehanna River and 

 approximately three miles upstream on the Conodoguinet Creek. 



The project was to be a run-of-the-river facility, using the head difference 

 created by the dam to create electricity. Maximum turbine flow woxild have been 

 10,000 cfs (at a nethead of 12S) and minimum flow would have been 2,000 cfs. Under 

 normal conditions, all flows up to 40,000 cfs would have passed through the turbines. 



The public notice denying 401 certification for this project stated as follows: 



L The construction and operation of the project will result in the significant loss of 

 wetlands and related aquatic habitat and acreage. More specifically: 



a. The destruction of the wetlands will have an adverse impact on the local 

 river ecosystem because of the integral role wetlands play in maintaining 



I that ecosystem. 



b. The destruction of the wetlands will cause the loss of beds of emergent 

 aquatic vegetation that serve as habitat for juvenile fish. Loss of this 

 habitat will adversely affect the relative abundance of juvenile and adult 

 fish (especially smallmouth bass). 



c. The wetlands which wiU be lost are critical habitat for, among other 

 species, the yeUow crowned night heron, black crowned night heron, 

 marsh wren and great egret In addition, the yellow crowned night heron 

 is a proposed State threatened species, and the marsh wren and great 

 egret are candidate species of special concern. 



d. AU affected wetlands areas are important and, to the extent that the loss 

 of these wetlands can be mitigated, the applicant has failed to 

 demonstrate that the mitigation proposed is adequate. To the extent that 

 adequate mitigation is possible, mitigation must include replacement in the 

 river system. 



51 



