FEDERAL ENERGY REGULATORY COMMISSION Project No. 405 ...

20100204-3055 FERC PDF (Unofficial) 02/04/2010
Project No. 405-087 5
Interior, The Nature Conservancy and SRBC all request modeling to assess the
impacts of the project on water quality (including salinity) in the Susquehanna River and
upper Chesapeake Bay. Interior also recommends collection of water quality data from
the National Oceanic and Atmospheric Administration, Chesapeake Bay Interpretive
Buoy System for the Susquehanna buoy at the mouth of the river for inclusion in the
water quality model. Exelon is not proposing any changes in operation and the proposed
water quality study with staff’s recommended modifications in conjunction with the other
studies should be sufficient for an understanding of the effects of the project on water
quality. If the data supplied in the water quality study report after the first year of study
is insufficient to evaluate project impacts on water quality, modeling could be required
for the second study season.
3.2 Downstream Fish Passage Effectiveness Study
Exelon proposes to estimate entrainment, impingement, and related mortality of
both resident and migratory fish at the project based on a literature review, on-site turbine
mortality testing using balloon tagging methods, and project-specific physical
characteristics such as hydraulic head and turbine specifications.
Maryland DNR, SRBC, Fish & Boat Commission, and Pennsylvania DEP request
several modifications to the turbine mortality part of Exelon’s proposed study as follows:
1) study of all five specific turbine models at the project not just the two general types
(Kaplan and Francis) proposed by Exelon; 2) turbine testing during July and August to
better simulate natural conditions during the most stressful downstream passage period;
3) testing during various operational scenarios, such as “aeration on” versus “aeration
off,” over a range of wicket gate settings, etc.; 4) a better explanation of the statistical
analyses to be used to determine turbine test sample size calculations; 5) mandatory
American eel testing regardless of their seasonal availability; and 6) an increase in the
sample sizes of fish and number of species to be tested. In addition to items (2) and (3)
from the list above, Interior also recommends that Exelon be required to conduct turbine
mortality tests on river herring.
Given the amount of available literature on turbine mortality rates for rivers with
similar species assemblages and dams of similar design to Conowingo, staff do not
believe that on-site turbine mortality testing is necessary to make reasonable estimates of
turbine mortality at the project. While Exelon is certainly free to conduct such studies,
staff believe that a literature review, combined with a review of the compiled studies of
migratory fish already conducted at the project during the current license term, will be
adequate to evaluate proposed, recommended, or required measures.
3.3 Biological and Engineering Studies of American Eel at the Conowingo Project