FEDERAL ENERGY REGULATORY COMMISSION Project No. 405 ...

20100204-3055 FERC PDF (Unofficial) 02/04/2010
Project No. 405-087 17
Maryland DNR, SRBC, Pennsylvania DEP, Fish & Boat Commission, and The
Nature Conservancy recommend the following modifications to the revised study plan:
1) study the fish and aquatic community at a reference site and compare it to the project
site below Conowingo dam if the agencies determine an ecologically and physically
similar site has been identified; and 2) collect current aquatic community information via
field surveys because the studies that Exelon cites for the literature review rely too
heavily on fish lift data or data collected prior to the implementation of the current
minimum flow regime. In addition to the above listed modifications, Interior also
recommends that Exelon specifically collect current data on reproductive success, age,
sex, and condition factors of fish, as well as standardized catch-per-unit-effort.
Regarding the agencies’ request to compare the study area with existing or historic
data from a reference site, while possible in some circumstances, staff are not convinced
a suitable reference location can be located. Also, it is not clear how any differences
between the Conowingo site data and the hypothetical reference site data would be
analyzed to discern between potential project effects on the aquatic community and
effects caused by other variables, such as water quality parameters, depth and substrate,
proximity to head of tide, fishing pressure and regulations, and stream order and general
size (mean flow), to name a few. There may be numerous other variables that could
affect aquatic communities. Therefore, staff do not recommend the reference site
modification to the study plan.
Collecting current aquatic community data may be necessary if the literature-based
summary report does not give an accurate and reasonably complete characterization of
the current aquatic community below Conowingo dam. Staff agree that Exelon should
ensure that all studies be included, not just data from the fish lift collections, which do
not include size, age, condition factor, or catch per unit of effort. Staff do not
recommend a modification to the revised study plan at this time, but may recommend onsite
field work in 2011 if the final literature-based study report does not provide enough
information on the aquatic community to evaluate proposed, recommended, or required
operational changes to the project.
3.19 Freshwater Mussel Characterization Study below Conowingo Dam
Exelon proposes to characterize the freshwater mussel community below
Conowingo dam using a combination of a literature search, semi-quantitative field
surveys, a quantitative survey of areas where mussels are found, measurement of habitat
parameters where quantitative surveys are conducted, and reporting of data which will
include GIS-based maps.
Maryland DNR recommends the following modifications to the revised study
plan: 1) review and compare the Conowingo Project study data to existing or historic