FWS letter responds to Lempster Wind (NH) preconstruction studies

Edward Cherian
Iberdrola Renewable Energies USA
20 Warren Street, Suite 8
Concord, NH 03301

Dear Mr. Cherian:

This is in response to your request for our review of the fall 2006 and spring 2007 radar studies at the proposed Lempster, New Hampshire wind project.

As you know, we provided recommendations for radar and other study protocols for the Lempster Project in our July 28, 2006 letter to your predecessor, Mr. Jeff Keeler. Some of these have been incorporated into study protocols and accomplished; others, such as multiple years of radar surveys during migration seasons and the collection of weather data aloft, have not.

The above notwithstanding, several useful studies have been completed by your firm at the project area, which includes Lempster and Bean Mountains and Kennedy Hill. These studies include the radar surveys mentioned above, breeding bird surveys, a bat acoustic survey, and the identification and delineation of wetlands and vernal pools.

As the following paragraphs attest, the radar surveys provide pre-project baseline information that raises a number of important questions concerning bird and bat migration at the project area. These important concerns could not be identified in a pre-project condition without the use of radar technology designed to identify and enumerate flying vertebrates.

The fall 2006 radar report establishes a noteworthy trend in migration traffic that is continued in the spring 2007 report. For currently unknown reasons, the Lempster site appears to be in a migration corridor used by large numbers of flying vertebrates during both of these study periods. The fall 2006 migration rate (602 targets per kilometer per hour) was the second highest among fall radar studies reported in the northeast and the spring 2007 migration rate (542 t/km/hr) was the highest reported among spring radar studies in the northeast, Table 2-1, page 11, both reports.

Fall 2006

Appendix A, Tables 1 (flight volume), and 3 (flight height), fall 2006, indicate a tendency for large numbers of targets, i.e., greater than 10%, to be in or close to rotor-swept elevations during nights when heavy migration traffic (>900 t/km/hr) occurred, e.g., 9/16, 9/26, and 10/10/07. Other than the limited data in Appendix A, Table 3, we do not know how targets were distributed in the airspace on each of these nights during the study period, e.g., no wisker plots with median, 25th and 75th percentiles are provided to display hourly and nightly distribution.

Based on a comparison of some of the tabular data, winds aloft appear to be quite different from winds at ground level. This may affect flight direction, volume and elevation. For instance, a comparison of the nights 9/23-9/26 in Appendix A, Table 4, and Appendix B, Table 1, with Appendix A, flight volume Table 1, flight direction Table 2, and flight elevations Table 3, reveals that these data do not display consistent trends. For example, flight direction may be different from wind direction reported at ground level. Unfortunately, we do not know what the weather parameters are aloft, e.g., l00m, 200m, 300m, etc., for winds (speed, direction, gusts, sheer), temperature, cloud cover and cloud ceiling and ceiling obstruction (i.e., visibility issues) to gain insight into possible causal relationships that may exist.

The fall radar study started on September 6, so it is likely that a substantial segment of the bat and some portion of the bird migration may have been missed.

The flight elevation of the targets tended to be under 500m for most nights and for most hours within nights. Only three nights were reported to have mean flight elevations above 500m (9/6, 9/30, and 10/7). The average flight height for several other radar studies listed in Table 2-1 is above 500m. With an average flight height of 3 87m, the fall 2006 Lempster results are tilted toward the lower end of the range which may increase potential risk. As discussed above, the data would be more informative if provided in the form of wisker plots with median, 25th, and 75th percentiles to identify hourly and nightly distribution.

Based on analysis of first- and second-hour radar data, migration takeoff and stopover activity appears to occur on some nights, e.g., Appendix A, Table 1, on 9/7, 9/11, 9/12, and 10/5, but this is not always supported by flight elevation data. On several nights, perhaps the majority, it appears that nightly migration is well underway prior to the start of radar operation, e.g., Appendix A, Table 1, on 9/6, 9/13, 9/23, 9/27, and 9/28. While the general trend for hours 1 and 2 in Tables 1 and 3 is to be increasing both the number and elevation of targets during this early evening period, finer scale analysis is nearly impossible. By this we mean that estimating the number of targets flying up through or down through the rotor-swept zone during takeoff and landing is fraught with great uncertainty.

Spring 2007

The data in Appendix A, Table 1, spring 2007, indicate that on 14 out of the 30 nights of radar scanning during the spring survey, greater than 20% of the targets were below 125m. Of particular concern, on 5/3 and 5/13, 69% of the targets were below 125m during nights with moderate migration traffic (>300 t/km/hr). Similar disturbing trends exist on 4/20, 5/2, and 5/21, when 45% or more of the targets were below 125m during moderate migration traffic, e.g., 850, 364 and 531 t/km/hr, respectively. There were only five nights out of the 30 nights of radar scanning when less than 10% of the targets were below 125m. Higher numbers of targets in or near the rotor-swept zone indicate a greater risk of collision between nocturnal migrants and turbines or their wind vortices.

Appendix A, Table 4, indicates considerable hour-to-hour variation in flight height within some nights. On 5/17, from hours 4-6, flight elevation went from 1,178m to 363m to 744m. The causal factors for these abrupt changes are unknown, which makes it impossible to predict when targets may suddenly appear in or near the rotor-swept zone. Similar abrupt changes in migration volume appear in Appendix A, Table 2. On 4/23, passage rate drops from 1,521 to 553 targets/km/hr between hours 5 and 6. On 4/26, migration volume changes from 1,229 to 543 targets/km/hr between hours 5 and 6. Whether these are natural pulses stemming from takeoff events earlier in the evening or from some in-route flight event is unknown.

The weather and wind data on Appendix A, Table 1, do not reveal consistent trends with passage rate, flight direction, or flight height. In either case, no data were obtained on winds aloft, cloud ceiling height, and other weather data as discussed above. Accordingly, it is not possible to correlate weather data with observed nightly migration events.

Based only on the information in the spring and fall radar reports, we would find the Lempster site to be an unsuitable location for the proposed wind project due to the potential for bird and bat injury and mortality. This conclusion stems from information and data gaps in both reports, as discussed above, but especially from the spring 2007 report which demonstrates a strong tendency for targets to be in or near the rotor-swept zone. The causal factors for this tendency are not explained by the data in these reports, as discussed above. The emphasis has been placed on the enumeration of targets, not underlying mechanisms or factors controlling vertebrate migratory flight through the project area.

In our July 28, 2006 letter, we recommended that three years of radar study be conducted to provide, among other things, information on year-to-year variability on migration events and patterns at the site. In addition, we identified collateral information needs, including cloud ceiling height and other weather data, that should be collected. Thus, we are at a point in time where either we recommend "no project" due to our concern for unauthorized take of migratory birds, or your firm conducts an additional two spring and two fall migration season studies using radar and other remote sensing equipment for target verification. Collateral studies using state-of-the-art equipment to collect information on wind, cloud ceiling, and other weather parameters need to be conducted simultaneously. If you elect to conduct the additional two years of investigations, we highly recommend that the Service be given the opportunity to review the draft scope of services and study plans prior to their being finalized and executed. Be advised that conducting the additional two years of study brings no guarantee. Under the present circumstances, these additional studies could demonstrate 1) whether or not similar fall 2006 and spring 2007 results are repeated in subsequent years, and 2) what combination of events puts birds and bats in or near the rotor-swept zone such that precise, fail-safe shutdown criteria could be developed and implemented in advance of such events occurring in the future. If precise, fail safe shutdown criteria could not be developed, extended shutdown periods (e.g., entire migration season, spring and fall) or "no project" would likely be recommended by the Service.


During our August 16, 2007 meeting, you indicated that you were considering bridging certain wetlands or other waters of the United States to, among other things, avoid Clean Water Act Section 404 jurisdiction. We have not received word on your decision in that matter as of this date. Please advise us and, if you have not done so already, the U.S. Army Corps of Engineers of your decision.

Migratory Bird Treaty Act

Among other things, the Migratory Bird Treaty Act, 16 U.S.C. § 703-7 12, prohibits the taking, killing, injuring, or capture of listed migratory birds. The unauthorized taking of even one bird is legally considered a "take" under the MBTA and is a violation of the law. Bald and golden eagles are afforded additional legal protection under the Bald and Golden Eagle Protection Act. Neither the MBTA nor its implementing regulations, 50 CFR Part 21, provide for permitting of "incidental take" of migratory birds that may be killed or injured by the wind turbines.

The Service carries out its mission to protect migratory birds not only through habitat and species management, regulatory programs, investigations and enforcement, but also through fostering relationships with individuals and industries that proactively seek to eliminate their impacts on migratory birds. It is not possible under the MBTA to absolve individuals, companies, or agencies from liability if unauthorized take occurs. However, depending on the circumstances, the Office of Law Enforcement may exercise enforcement discretion. The Service focuses its attention on those individuals, companies, or agencies that take migratory birds without regard for their actions and the law, especially when conservation measures such as preconstruction surveys have been recommended or developed but are not conducted or properly implemented. In this respect, we note, as discussed above, that inadequate effort has been made to identify the spatial and temporal uses of the airspace by migratory birds at the presently configured project site.

In summary, we believe the Lempster Wind Project fits in a category of activities that constitutes a preventable environmental hazard to migratory birds and bats. The Service recommends that preconstruction surveys for migratory birds and bats as identified above be conducted using a combination of remote sensing technology (radar, acoustic, infrared), state-of-the-art wind and weather instruments, and traditional on-the-ground survey techniques to determine the spatial and temporal uses of these species in the airspace at and adjacent to the Lempster-Bean-Kennedy chain of peaks, ridges and valleys. In the absence of adequate preconstruction data on spatial and temporal uses by avian species, you proceed with this project at your own risk. Any subsequent take of migratory birds may be evaluated in light of this administrative record.

Questions should be directed to Mr. Vernon Lang of this office at 603-223-2541 or email

Sincerely yours,

Michael J. Bartlett
New England Field Office



F. Delgiudice, ACOE
A. Hoar, FWS/ES
A. Manville, FWS/MB/WO
C. Dowd, FWS/LE
D. Pence, FWS/MB/RO
T. Sullivan, NYFO
L. Nordstrom, MEFO
M. Marchand, NHF&G
T. Burack, NHSEC
P. Roth, NHDOJ
Sheridan Brown, Senator Sununu's Office, Manchester, NH
Lisa Levine, Cong. Paul Hodes' Office, Concord, NH
Reading File

ES: VLang:jd: 1-31-08:603-223-2541

Fws Ltr Lempster Wind Nh

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JAN 31 2008
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