Guy Wire and Lighting Requirements for Tall Structures
November 9, 2010
In Reply Refer To:
6840, 6510 (CA-930)P
EMS TRANSMISSION: 11/9/10
Instruction Memorandum No. CA-2011-003
Expires: 9/30/2012
To: All CA District and Field Managers
From: Acting State Director
Subject: Guy Wire and Lighting Requirements for Tall Structures
Tall, thin structures, such as meteorological towers, pose a collision risk to wildlife species. These potential impacts are subject to analysis under the National Environmental Policy Act (NEPA) prior to our granting of a Right-Of-Way. In order to use a Categorical Exclusion (CatEx) under NEPA, a project must not adversely affect species of special concern (e.g., species protected under the Endangered Species Act or Bald and Golden Eagle Protection Act). This Instruction Memorandum provides requirements for all structures requiring guy wires and lights (e.g., meteorological towers, cell phone towers) on BLM administered lands. The implementation of these measures reduce the collision risk for avian species sufficiently that a CatEx may be used. If the guidelines below are not implemented, a full NEPA analysis (EA or EIS) must be conducted.
A wide variety of bird species have been documented to collide with guy wires and power lines. It is generally believed that birds collide with lines because the lines are invisible to the birds or because the lines are not seen until it is too late for birds to avoid it. Large, less maneuverable birds are especially vulnerable to collisions with guy wires that are relatively thin and difficult to see from a distance. Poor weather conditions, such as fog, rain or snow, as well as darkness, make the lines even more difficult to see. The following measures increase the visibility of such structures.
1. The use of self-supported structures (i.e., structures that do not require guy wires for support and stability) are preferred whenever feasible. The tower should be painted so that it stands out from the surrounding environment to provide optimum visibility for birds. However, if the use of self-supported structures is not feasible, non self-support structures with guy wires may be used provided that the wires are marked using the following protocols.
2a. If structures are within the range of the golden eagle and/or the historic and current range of the California condor, each and every guy wire should be covered for the entire length of the wire with a series of PVC pipes (minimum of 2 inch diameter) and large orange flight diverter balls (spaced every 5 meters along the wire). PVC that is a highly visible color (other than white) is preferred, or at a minimum alternating between white and another color of PVC pipe to increase the visibility of the wires.
2b. If structures are outside the range of golden eagles and California condors, a variety of methods can be used to reduce bird collisions with guy wires and power lines. In all cases, each and every guy wire (not just external wires) should be clearly marked for the length of the wire. Following APLIC (1994) and USFWS (2000) guidelines, all guy wires should be marked with either spiral vibration dampers (30 spirals per 150 meters of wire) or bird/swan flight diverters (spaced every 5 meters along the wire).
3. Avoid placing lines within wetlands, over canyons, or within important avian movement corridors (i.e., between foraging and nesting sites).
4. Lights are sometimes used to mark guy wires and power lines. Because lights can both attract and confuse migrating birds, use lights only if lighting is needed for aviation safety. Unless otherwise requested by the Federal Aviation Administration, use only the minimum number of strobed, strobe-like, or blinking incandescent lights with a minimum intensity, maximum “off-phased” duel strobe lights. No steady burning lights (e.g., L-810) should be used. All lights should illuminate simultaneously.
5. To ensure and determine the effectiveness of the visual diverters and operational lighting measures employed at a site, regular monitoring (e.g., monthly) for bird fatalities (including scavenger and detectability correction factor studies) is imperatives for all structures with guy wires. If fatalities are observed, they must be reported immediately to the managing Field Office. An annual report on monitoring effort and fatalities must be submitted to the managing Field Office and the State Threatened and Endangered Species Specialist.
Questions on implementing measures for guy wires and lighting to reduce avian collisions may be directed to Amy Fesnock, Endangered Species Coordinator, at (916) 978-4646.
Signed by:
James Wesley Abbott
Acting State Director
Authenticated by:
Richard A. Erickson
Records Management
Literature Cited:
Avian Power Line Interaction Committee. 1994. Suggested practices for avoiding avian collisions on
power lines: state of the art in 1994. Edison Electric Institute and APLIC, Washington DC.
USFWS. 2000. Interim guidelines for recommendations on communication tower siting, construction,
operation and decommissioning. Division of Migratory Birds, Arlington VA.