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EU EN12 - Description of significant impacts of activities, products, and services on biodiversity in protected areas and areas of high biodiversity value outside protected areas.

Impacts of Transmission Facilities
The biodiversity impacts of transmission facility installation are often obvious.  Construction activity, such as clearing vegetation and moving earth to build new facilities, totally removes or drastically decreases onsite biodiversity.  These impacts are typically short-term, lasting only until the vegetation returns to the area, however, siting transmission line corridors can affect biodiversity through habitat fragmentation and alteration.  The transmission corridors themselves may fragment the habitat, possibly preventing the movement of certain animals from one side to the other, due to the cleared vegetation.  Transmission line rights-of-way often require tree removal for construction and maintenance.  A variety of methods are used to maintain transmission corridors, such as mowing, hand cutting, trimming and herbicide use, to keep trees from growing into power lines and causing hazards and service interruptions.  This loss of trees is also a loss of habitat for woodland and forest fauna and the biodiversity within these areas is altered, but in the process, new habitats are created that are favored by a different group of plants and animals.  These areas often become habitat for grass and shrub dependent species that have often lost habitat to other development, e.g., residential, commercial, industrial, agricultural, etc.

Transmission lines and related structures can also create collision hazards for birds.  Avian interactions with transmission lines and structures are species and site specific.  AEP has traditionally responded to animal-related incidences at its transmission and distribution facilities when they became evident.  For example, the company became aware of a line that crossed a breeding colony of black skimmers in coastal Texas.  Fledglings from the colony were being lost for a number of reasons, one of which was collisions with this line.  As a deterrent, spiral marking devices were applied to the line, and according to the Audubon Society members that monitor the colony, the collision rate diminished to a level that no longer endangered the colony.  In 2008, this line was again associated with bird collisions.  Though the black skimmers have moved their colony away from the line, other species intermittently collide with this line.  Plans were being made to mark the entire mile of line when AEP considered a study of collision incidence and the species involved.  To begin this study, the City of Rockport, Audubon Society volunteers, and the AEP crew that services the line, began close and coordinated monitoring of the line in 2008.  A reporting system was devised so that anyone from these groups could report a collision incident to AEP Environmental Services.  Though 2008 may not have been representative, only two birds were found that may have collided with the line.   AEP continues monitoring in this manner, trying to understand which birds are most susceptible to various parts of the line.  Following this evaluation, an additional study will be undertaken, if warranted, to determine the most effective mitigation to reduce bird collisions.   In January 2011, the first collision in over two years occurred.  The three-party monitoring continues and AEP stands ready to act when we have a fair degree of certainty that our actions will reduce collision risk.

The U.S. Fish and Wildlife Service has also required AEP to install marking devices on some spans of newly constructed transmission lines to prevent collisions.  A line in the migratory flyway of the whooping crane was marked with aviation balls along approximately 40 miles of its length for this purpose, as was 6 miles of another line in the Attwater’s prairie chicken historic habitat.  Both bird species are endangered.  Spiral markers have been installed on newly built transmission line spans that cross bays, estuaries, wetlands or other water bodies, at the request of the permitting authorities who thought the new lines could pose a collision potential to birds in general.  At the request of the USFWS’s Whooping Coordinator at the Aransas National Wildlife Refuge, Texas, AEP marked approximately a mile of line that whooping cranes had been observed crossing in their descent to a wildlife feeder.  The whooping crane migration corridor extends from the Northwest Territories in Canada through the U.S. from North Dakota to the Texas Gulf Coast.  AEP is working with other utilities with service area in this corridor and the U.S. Fish and Wildlife Service to consider developing a multi-state, multi-company, corridor-wide habitat conservation plan.  This issue has been prompted by the rapid wind generation development in the corridor and the necessary supporting transmission lines.  The structures add obstacles to crane flight and are taking some of the crane’s stopover habitat.  The USFWS sees the resulting collision risk as a significant threat to the slowly recovering and only natural, self-sustaining population of whooping cranes.

Bird electrocutions occur on utility poles and towers as birds use these structures for perching, roosting and nesting.  AEP applies protective devices to structures when outages have been caused by bird electrocutions and is building a database that will enable us identify high risk structures so preventive measures may be taken.

Thermal Discharges
AEP operates several coal-fired power plants that utilize once-through cooling of heated condenser water formed by waste heat in the steam cycle.  The condenser water is cooled by passive heat transfer as water withdrawn from a river or lake is pumped into the condenser and returned (at a higher temperature) to the source waterbody.  The potential ecological impacts of this heated water are addressed in each plant's Clean Water Act Section 316(a) variance demonstration.  Many of the AEP plants utilizing once-through cooling have an approved 316(a) variance, which signifies that a state regulatory agency has concluded that a balanced, indigenous biological community will be maintained in the source waterbody despite the discharge of cooling water at temperatures in excess of applicable water quality temperature criteria.  Routinely, state agencies require that AEP provide a re-justification of this finding, based on recent water quality and biological studies.  AEP voluntarily conducts ecological assessments at some once-through cooled power plants located on the Ohio River as part of an ongoing Ohio River Ecological Research Program. 

The potential impacts of heated cooling water on biodiversity range from insignificant to temporarily significant, depending on prevailing river flow and ambient temperature conditions.  During extreme drought events, the heated water can cause a temporary displacement of thermally-sensitive fish species in the immediate area where the thermal discharge mixes with the source waterbody.  Typically, the biodiversity "balance" is restored after the extreme river flow and temperature conditions are removed.  At two AEP facilities located on the Muskingum River (Conesville and Muskingum River Plant), the thermal load is regulated such that certain downstream river temperatures will not be exceeded.   It should be noted that a long-term balanced biodiversity condition (despite temporary displacement of some species during rare environmental conditions) is one of the conditions that a discharger must demonstrate to a state agency in order to receive an approved 316(a) variance.

Source Information - FERC hydro relicensing studies; AEP Corp of Engineer 404 compliance programs (wetland mitigations); AEP Avian Protection Program (D. Bouchard). Cooling water intake impacts determined from plant 316(b) studies (Rob Reash).


2012