Es ist nicht klar, wie groß die Rolle von Antibiotika in den Wettbewerbsbeziehungen zwischen Mikroorganismen unter natürlichen Bedingungen ist. Zelman vaxman glaubte, dass diese Rolle minimal ist, Antibiotika werden nicht anders als in reinen Kulturen auf reichen Umgebungen gebildet. Anschließend wurde jedoch festgestellt, dass bei vielen Produzenten die Aktivität der antibiotikasynthese in Gegenwart anderer Arten oder spezifischer Produkte Ihres Stoffwechsels zunimmt.

Microsoft word - final_responses_to_public_comments_on_lihi_certification.doc

Exelon Power 300 Exelon Way Kennett Square, PA 19348 610-765-5980 Fax
June 23, 2008
Mr. Fred Ayer
Executive Director
Low Impact Hydropower Institute
34 Providence Street
Portland, ME 04103
Re: Exelon Responses to Public Comments on the Conowingo Hydroelectric Project (FERC No. 405)
LIHI Application
Dear Mr. Ayer:
On January 15, 2008, Exelon Generation Company (Exelon) filed an application for certification of its
Conowingo Hydropower Project (Conowingo) by the Low Impact Hydropower Institute (LIHI). Exelon
is seeking a LIHI Certification to gain Tier I status under the Commonwealth of Pennsylvania’s
Renewable Energy Portfolio Standards. The Tier I status would apply only to the 24 MW incremental
hydropower capacity increase at Conowingo, which has resulted from a plant modernization program
consisting of turbine/generator efficiency upgrades. This additional renewable generation capacity is
achieved solely from equipment upgrades, and does not require any alterations by Conowingo to the
current water level and flow management of the Susquehanna River.
As part of the certification process, the Conowingo application was posted on the LIHI webpage and
public comments were solicited for a period of 60 days. On March 22, 2008, the public comment period
for the Conowingo LIHI application closed. Comments were received from: a) Elisabeth Lynch, Clinton
County, Tourism Planner (Clinton County); b) Michael R. Helfrich, Lower Susquehanna Riverkeeper (the
Riverkeeper); c) George Hansell, local citizen; d) the PA Department of Environmental Protection
(PaDEP); e) the PA Fish and Boat Commission (PaFBC); and f) the U.S. Fish and Wildlife Service
Exelon Responses to Public Comments

In general, the public comments received regarding the Conowingo LIHI application relate to either the timing
of the LIHI application, given that the FERC relicensing of Conowingo will start in 2009, or Conowingo’s
perceived deficiencies in meeting certain aspects of the LIHI certification criteria. The following are Exelon
responses, organized by major subject area, to these public comments.
Untimeliness of the LIHI Application: As demonstrated in Exelon’s LIHI application, Conowingo has been
operated to meet stringent measures and conditions requested by federal and state resource agencies over the
term of the current FERC license. A settlement agreement between Exelon and several federal and state
resource agencies was approved by FERC in 1989. The settlement agreement provided for the establishment of a schedule of seasonally adjusted minimum flows, measures to enhance and monitor water quality, the construction of fish passage facilities, as well as other significant environmental protection, mitigation, and enhancement measures. The LIHI does not specify the timing of a project’s FERC relicensing proceeding as one of its eight criteria for granting certification. Certification of a hydropower project by the LIHI of this license “vintage” is not unprecedented, as several projects (e.g., Raystown, Tallassee Shoals, Worumbo, Stagecoach, Island Park, and Winooski One Hydroelectric Projects) with pre-1990 license issuance dates have been previously certified. Exelon believes that Conowingo should be certified based on the LIHI criteria and the project’s performance in meeting the standards set forth in the current FERC license, which were developed in consultation with federal and state resource agencies. Given that the standard term for a LIHI certification is five years, and the current FERC project license expires in 2014, a LIHI certification of Conowingo that is granted in the near term would result in the near simultaneous expiration of both the LIHI certification and the current FERC license in 2014. If, at that time, additional environmental impacts are identified during the upcoming FERC relicensing proceeding, then the resulting mitigation measures included in the new FERC license can be incorporated within any subsequent 5-year LIHI certification application. LIHI Certification Criteria: To receive a LIHI certification, a project must meet specified criteria in eight
different environmental resource areas: 1) river flows, 2) water quality, 3) fish passage and protection, 4)
watershed protection, 5) threatened and endangered species protection, 6) cultural resource protection, 7)
recreation, and 8) facilities recommended for removal. Certification is designed to provide assurances that a
facility has avoided or reduced environmental impacts pursuant to the LIHI’s criteria. The following section
describes the public comments received that relate to these criteria and Exelon’s responses.
River Flows: The PaDEP and the USFWS expressed concerns with fluctuating river flows and water
levels below Conowingo Dam resulting from its operation, and the corresponding impacts on the
aquatic biota that reside downstream of the dam.

The flow regime below Conowingo has been studied extensively over the last 20 years, and Exelon has implemented measures to address federal and state resource agency concerns related to river flows during the current FERC license. In particular, the FERC-approved settlement agreement for Conowingo established a schedule of seasonally adjusted minimum flows that have been implemented since 1989, as well as measures to maintain sufficient dissolved oxygen levels in the tailrace. In addition, further study was conducted by the Maryland Department of Natural Resources on benthic macroinvertebrate populations to determine impacts during the winter period (December 1 – February 28). The results of the study were used to determine appropriate minimum flows for the winter period. The winter flow regime was approved by federal and state agencies and recognized by FERC in 2004. Between 1988 and 1991, Exelon installed turbine venting systems in several Conowingo turbines to provide aeration. Test results indicated that turbine venting and intake air injection systems could be used to increase tailrace dissolved oxygen (DO) levels under most conditions. Currently, turbine venting occurs on an as-needed basis. Exelon has an operating procedure that is implemented when DO concentration is less than 6.5 mg/l in the tailrace. In addition to the turbine venting, Exelon contracted with Voith Siemens in 2004 to install aerating turbine runners in two turbines in 2005 (Unit 5) and 2008 (Unit 2) as part of the project modernization program. Since 1989, when the Exelon began turbine venting, DO concentrations have complied with Maryland state water quality standards. Also, in 2002, the Susquehanna River Basin Commission (SRBC) formed the Conowingo Pond Workgroup to develop a management plan for Conowingo Pond. The Workgroup was comprised of representatives from federal and state agencies, hydropower owners, local water utilities, and the SRBC. The Workgroup completed recommendations for its plan in March 2006, and identified the minimum flow requirements at the project as the most critical parameter in managing low flows and enabling the Conowingo Pond to remain viable during droughts. The Conowingo Pond Management Plan established a formal protocol to help balance minimum flow needs and Conowingo Pond levels during low flow conditions. Exelon is currently instituting the measures outlined within the Conowingo Pond Management Plan, and will petition FERC to incorporate these measures into the project license in 2008. The measures implemented by Exelon during the current FERC license term meet the LIHI certification criteria. Moreover, Exelon has actively addressed federal and state resource agency concerns related to flow management over the course of the current FERC license term. If additional environmental impacts related to river flows are identified during the upcoming FERC relicensing proceeding, then the resulting mitigation measures can be considered within any subsequent 5-year LIHI certification application. Water Quality: The PaDEP and the Riverkeeper raised an issue with the lack of mitigation measures
related to the trapping of pollution-bearing sediment behind Conowingo Dam, and the potential effects
on downstream areas (i.e., Chesapeake Bay) should the sediment be remobilized during high river flow

Sediment contribution to the Chesapeake Bay is primarily caused by upland erosion associated with different land uses (e.g., agriculture, mining, and construction activities) and stream corridor erosion. Therefore, mitigation measures such as dredging or sluicing of sediment at Conowingo would do little to address the underlying causes of sediment mobilization and deposition. In the past, several groups have studied and attempted to address sediment retention behind Conowingo Dam and nutrient and sediment loading to Chesapeake Bay. The SRBC organized a Sediment Task Force in July 1999 and convened a Sediment Symposium held in Hershey, Pennsylvania in December 2000 to assess the state of current knowledge regarding sediment sources, transport and storage in the basin, implications to Chesapeake Bay of loading from the Susquehanna River and reservoir capacity in the Lower Susquehanna River, and potential management options. The Sediment Task Force found that, regardless of whether a feasible reservoir management option is identified, sediment loading throughout the basin needs to be reduced. It recommended a variety of riverine and upland best management practices (BMPs) to reduce sediment loading. With regard to reservoir management options, the Sediment Task Force considered reservoir dredging, sediment bypassing during non-storm flows, sediment fixing (capping with clean dredged material), and modified dam operations. All but reservoir dredging were dismissed. The Sediment Task Force recommended a feasibility study by the U.S. Army Corps of Engineers (the Corps) to determine whether it is viable to dredge the Lower Susquehanna River reservoirs to maintain sediment retention capacity and minimize sediment loading to Chesapeake Bay. To date, the Corps has not conducted a feasibility study, as funding to conduct the study has not been secured. However, in anticipation of such a study, a cooperative effort was undertaken by the USGS, the Maryland Geological Survey, and the University of Maryland to characterize sediment quality behind the dams for the purpose of identifying dredge disposal options. Studies are also planned by the USGS to conduct bathymetric surveys of Lake Clarke, Lake Aldred, and Conowingo Pond during the summer of 2008. Currently, the presence of Conowingo Dam continues to have a beneficial effect by reducing the detrimental impacts of sediment and nutrient loading to Chesapeake Bay. USGS estimates that Conowingo is currently trapping about 2 percent of the nitrogen, 40 percent of the phosphorus, and 50 to 70 percent of the suspended sediment that would otherwise be transported to the Upper Chesapeake Bay. Exelon’s current operation of Conowingo will continue to have little impact on the amount and timing of sediment and nutrient delivery to Chesapeake Bay From Exelon’s perspective, addressing sediment retention behind the dams on the lower Susquehanna River and nutrient and sediment loading to Chesapeake Bay is a basin-wide issue. Efforts to reduce long-term sediment and nutrient loading from the Susquehanna River to Chesapeake Bay should focus on controllable sources of sediment and nutrient loads (e.g., land-use practices). As such, current efforts by the Corps and USGS to study and potentially address the sediment issue must be continued and supported by both public and private interests throughout the lower Susquehanna River basin. Water Quality (Debris Accumulation): George Hansell, local citizen, commented on the
accumulation of natural and man-made debris that typically occurs behind Conowingo Dam, and the
potential impacts that result from the subsequent downstream movement of the debris during high river
flow events.

The Susquehanna River above Conowingo Dam drains an area of about 27,000 square miles. During high flow events, the water elevation behind the Conowingo Dam has to be kept below elevation 109.5 feet for dam safety purposes, which may necessitate opening of spillway crest gates. During these high flow events, an enormous amount of river-borne debris is scoured from the upper reaches of the watershed and carries into the lower Susquehanna River and Chesapeake Bay. The SRBC has estimated that approximately 90% of river flow debris is transported during high flows. Most of the water-borne debris reaches Conowingo just prior to the peak or crest of the high river flow after crest gates have already been opened. Generally, any debris removal by Exelon takes place during the late spring prior to the recreation and boating season. This is at the end of the high river flow period. At this time Exelon can safely remove material which has accumulated behind the dam. During the summer months, debris is normally not a problem because river flows are typically not high enough to produce significant amounts of debris or spill conditions. Occasionally debris does collect over the summer and it is necessary to remove some debris in the fall. More than 90% of the debris is organic, Exelon’s focus is to remove inorganic material (i.e., tires, plastic drums, and other plastic debris) that cause considerable damage to the turbines. Exelon does not intentionally divert debris over the spillway. As stated previously, approximately 90% of the debris passes over the dam during spill conditions. When the river flow exceeds 80,000 cfs, crest gates must be opened to allow the extra flow to pass downstream. During this time, river-borne debris will flow through the crest gates and continue downstream. Exelon does not remove debris during these high river flow conditions due to safety concerns, because it would be unsafe for personnel or boats to be in the reservoir and in front of the crest gates during spill conditions. Fish Passage and Protection (Upstream): Clinton County, the Riverkeeper, the PaFBC, the PaDEP,
and the USFWS expressed concerns that appropriate facilities are not in place at Conowingo to allow
for the migration of American eel from Chesapeake Bay to areas upstream of the Conowingo Dam.

Exelon has been a very active participant, along with federal and state resource agencies, in efforts to restore anadromous fish runs to the Susquehanna River. The following is a brief timeline of some of the more significant measures taken to restore anadromous fishes: ¾ 1950’s-State and utility sponsored studies are conducted to assess the possibility of restoring American shad runs to the Susquehanna River. ¾ 1970-Exelon entered into a settlement agreement with resource agencies to build a fish-lift facility (i.e., the West Fish Lift) at Conowingo Dam. ¾ 1972-The West Fish Lift was completed and began operation as part of a trap and transport facility. Per the 1970 agreement, the West Fish Lift was to operate for only 5 years, but Exelon decided to maintain operation of the facility up to the present day to support various restoration activities. ¾ 1979-The Susquehanna River Anadromous Fish Restoration Committee (SRAFRC) adopted a Strategic Plan for Restoration of Migratory Fishes to the Susquehanna River. ¾ 1984-An agreement was reached between the resource agencies and the owners of the Holtwood, Safe Harbor, and York Haven Dams to help fund the existing trap and transport, as well as expand hatchery/stocking operations. ¾ 1989-As part of the most recent FERC License for the Conowingo Project a settlement agreement was reached with resource agencies that resulted in the construction of the East Fish Lift in 1991. ¾ 1993-Owners of the three upstream hydroelectric projects reached a settlement agreement with resource agencies. As a result, permanent upstream fish passage facilities were developed at the Holtwood and Safe Harbor dams in 1997 and at York Haven Dam in 2000. The construction of these upstream facilities was contingent upon Exelon constructing the East Fish Lift in 1991. The major milestone in these efforts was Exelon’s construction of the East Fish Lift, which is currently used to pass American shad and other migratory fishes during the April-June migration season. Although several migratory fishes have been targeted for restoration to the Susquehanna River, specific numerical goals with timelines have only been established by federal and state resource agencies for American shad and river herring. Consequently, virtually all restoration efforts have been directed primarily towards American shad, with secondary efforts toward other species. Recently, there has been much interest in American eel populations throughout the country. On February 2, 2007, the Department of the Interior (DOI) issued a 12-month finding in which it declined to list the American eel as threatened or endangered under the Endangered Species Act of 1973 (ESA). In making this determination, the DOI surveyed and analyzed available information regarding the American eel and concluded, in part, that: 1) eels remain widely distributed over their vast range including most of their historic freshwater habitat, 2) eels are not solely dependent on freshwater habitat, utilizing marine and estuarine habitats as well, 3) the American eel population numbers in the millions, 4) recruitment trends appear variable but stable, and 5) threats acting individually or in combination do not threaten the species at a population level. In terms of the Conowingo Project, American eel caught at the West Fish Lift ranged from 377
(1980) to 91,937 (1974) for the period 1972-1983. By the early 1990s, American eel caught at
the fish lifts had declined, ranging from zero (several years) to 2,741 (1992). From 1997 to 2005,
only 26 American eel were passed or observed at the East Lift, and none have passed the
Holtwood Fish Lift since it began operation in 1997. Exelon worked in cooperation with the
USFWS during the 2007 American eel capture study referred to by the Riverkeeper in his
comments on the LIHI application.
Exelon has actively addressed federal and state resource agency concerns related to fish passage
over the course of the current FERC license term. The measures implemented by Exelon during
the current FERC license term meet the LIHI certification criteria. If additional environmental
impacts related to fish passage are identified during the upcoming FERC relicensing proceeding,
then the resulting mitigation measures can be considered within any subsequent 5-year LIHI
certification application.
Fish Passage and Protection (Downstream): Comments from the PaDEP, the USFWS, Clinton
County, and the Riverkeeper stated that appropriate facilities and/or measures were not in place at
Conowingo to keep downstream migrating American shad and American eel from passing through the
Conowingo turbines, which could result in injury or mortality.

A recent review and evaluation of downstream fish passage technologies available for hydroelectric facilities determined that biologically feasible structural options (e.g., angled bar racks, intake diversion screens, and louver systems) and behavioral devices (e.g., strobe lights, sound) are not viable from an engineering perspective and would likely not provide the desired level of protection for outmigrating shad at Conowingo. Passage through the turbine units continues to be the most viable option for transporting juvenile American shad downstream. At present, turbines are considered acceptable passage routes at all the hydroelectric dams on the Lower Susquehanna River. For turbine passage of juvenile shad at Conowingo, maintenance of a 95% survival rate was accepted by the resource agencies. Several studies have been conducted to assess passage survival of juvenile American shad through turbines at hydroelectric stations on the Susquehanna River. A survival rate of approximately 98% was observed for young American shad at the Safe Harbor Hydroelectric Project, which has mixed flow turbines, similar to Conowingo. The Conowingo turbines are large units with relatively low turning speeds, which all other things being equal are more conducive to downstream fish passage. With regard to downstream migration of American eel, there does not appear to be sufficient evidence of outmigration to warrant the imposition of immediate measures to facilitate downstream passage. In addition, there are currently no effective means to pass/protect outmigrating adult eels at individual hydroelectric stations using volitional passage. The measures implemented by Exelon during the current FERC license term meet the LIHI certification criteria. Moreover, Exelon has actively addressed federal and state resource agency concerns related to fish passage over the course of the current FERC license term. If additional environmental impacts related to fish passage are identified during the upcoming FERC relicensing proceeding, then the resulting mitigation measures can be considered within any subsequent 5-year LIHI certification application. Threatened and Endangered Species Protection: Comments from the PaDEP stated that
Conowingo Dam may have impacts on shortnose and Atlantic sturgeon, both of which are endangered
in Pennsylvania. The Atlantic sturgeon is federally endangered.

Shortnose and Atlantic sturgeon have been known to inhabit areas downstream of Conowingo. However, no sturgeons have been captured in the fish lifts since 1972. It is unclear to Exelon whether there is a need for these species to migrate past Conowingo, given their known populations and habitat needs. In addition, no federal and state agencies previously raised concerns or identified impacts related to Conowingo during the term of the current FERC license. If additional environmental impacts related to fish passage are identified during the upcoming FERC relicensing proceeding, then the resulting mitigation measures included in the new FERC license can be incorporated within any subsequent 5-year LIHI certification Recreation: The PaDEP stated that angler and boating access to Conowingo project waters
needed to be further evaluated to ensure that project security measures do not unnecessarily limit
recreation opportunity.

Exelon provides ample opportunity for anglers and boaters to access Conowingo project waters, while at the same time maintaining the security of the facility. Exelon has worked cooperatively with federal and state resource agencies during the current license term to provide alternative angler access below Conowingo, since the closing of the “catwalk”/fisherman’s wharf access area subsequent to the events of September 11, 2001. Specifically, Exelon filed an application to amend its license on July 28, 2006 to provide alternative public access (to the catwalk) including access for those with disabilities. Before filing the application, Exelon held meetings with resource agencies and the general public. On May 1, 2007, FERC issued an Order Amending the Conowingo License, and approved removing the catwalk as a project recreation facility to balance security concerns with the need for public access for recreation. The order also approved alternative recreation facilities at Fisherman's Park on the west side of the Susquehanna River, which will provide anglers, including those with disabilities, with an opportunity to fish along the shoreline. The proposed facility will offer anglers the opportunity to fish along approximately 24 yards of shoreline and will also consist of an upper and lower observation platform. Additionally, the order approved public fishing access along the north and south banks of Octoraro Creek, located on the east side of the Susquehanna River just downstream of Conowingo. This fishing area is completely new and separate from the fishing opportunities that have been traditionally offered on the west side of the Susquehanna River. This new area will be located on the north and south shores of the Octoraro Creek extending from Maryland Route 222 to the point where the stream flows into the Susquehanna River. That point of confluence is approximately 1,600 yards below the Conowingo dam. The measures implemented by Exelon during the current FERC license term meet the LIHI certification criteria. Moreover, Exelon has actively addressed federal and state resource agency concerns related to recreation over the course of the current FERC license term. If additional impacts related to recreation are identified during the upcoming FERC relicensing proceeding, then the resulting mitigation measures can be considered within any subsequent 5-year LIHI certification application. Throughout the current license term, Exelon believes that it has been proactive in addressing federal and state resource agency concerns related to Conowingo. As explained in the LIHI application and in these comments, numerous protection, mitigation, and enhancement measures have been implemented to address Conowingo’s impact on environmental resources and create additional recreation opportunities. Given these circumstances, Exelon believes that Conowingo meets the LIHI criteria and should be granted a 5-year LIHI certification. Thank you for this opportunity to respond to the public comments on the Conowingo LIHI application. If you have any questions or need further clarifications, please feel free to contact me. Sincerely, Colleen E. Hicks Manager, Regulatory & Licensing, Hydro


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