Discussion pertaining to bats
In order to issue a certificate of public good, the board must find that the project will not have an undue adverse impact on the natural environment which includes assessment of the threats to wildlife habitat and rare and endangered species. In this case, due to the uncertainty from site-specific project studies as well as uncertainty in bat population and estimated bat fatality studies, there is insufficient information for the Board to make the finding that there will not be an undue adverse impact to bat populations resulting from the Georgia Mountain Community Wind Project. In order to make that finding the Board must impose conditions of post-construction monitoring and operational adjustments.
The fatality risk to bats from wind generation facilities is well documented. High levels of bat mortality have been documented at utility scale wind generation facilities similar to the Georgia Mountain Community Wind Project site. Sites that have forested ridgelines consistent with the attributes of this project area show significantly higher mortality rates than sites constructed on flat or agricultural lands. Sites with large turbine heights similar to those proposed at this site also show higher bat fatality rates.
Threats to the health of Vermont's bat populations and other challenges that Vermont bats face make bats particularly vulnerable to fatality risks from wind facilities. Vermont bats are more susceptible to risk because of a low reproductive rate and having to cope with shorter summers and variable weather conditions at Vermont's higher latitude. Also, the more recent threat of White Nose Syndrome on the state's cave dwelling bats have placed these species in a position of unprecedented vulnerability. Because bat populations face these threats, they are more susceptible to detrimental impacts from wind facilities.
Vermont bat's higher risk factors coupled with the uncertainty of GMCW's ability to accurately predict bat fatalities makes it difficult to accurately predict the detrimental impact from the Georgia Mountain wind facility. GMCW was unable to provide bat estimates that factored in scavenger and searcher efficiency rates and conducted a study which involved only 451 detector nights over a three month period. This study falls significantly short of previous studies performed for similar wind projects. Further, the radar study completed by GMCW can not give an accurate estimate of potential bat fatality rates because there is no pool of data suggesting a predictive relationship between pre-construction radar targets and post-construction bat fatality rates. Also, Mr. Gruver used only one comparison site in his model which was located in the state of Maine, a state with a very different and substantially lower residential bat population than the state of Vermont. The shortcomings of these site specific studies limit GMCW's conclusions regarding estimated bat fatalities.
Due to the uncertainty in predicting the project's bat fatality rate, vulnerability of Vermont bat populations and the potential for harm, post construction monitoring is necessary and thresholds must be imposed when assessing the project's impacts on bat fatalities. The Board has previously enforced such post-construction monitoring conditions in the UPC case to study wind facility affects on bat fatalities.
Adverse impacts to bat populations may occur as a result of the new wind facility and should be addressed when estimated bat fatalities for the period July 1 through September 30 at the Green Mountain site exceed 0.0 threatened and endangered bat species/ turbine (Indiana or small footed bat), 3.0 migratory bats/ turbine (combinations of red bat, hoary bat and silver- haired bat) or 5.0 bats/turbine of other species (combinations of little brown bat, big brown bat, northern long-eared bat, and tri-colored bat).
Uncertainty in predicting bat fatality levels at this or any other utility scale wind energy project, requires that adequate measures be taken to either reduce bat fatalities from the start in an effort to avoid undue adverse effects, or to adequately monitor post-construction bat fatalities and, if necessary, initiate operational adjustments to reduce bat fatalities to acceptable levels. If average bat fatality estimates for the post- construction fatality surveys exceed the thresholds, then appropriate mitigation measures should be required to attempt to reduce bat facilities below such thresholds. Adaptive management should be used by the Petitioner to address bat fatality issues.
The petitioner and our experts agree that operational adjustments have proved successful at other sites. Scott Darling has sited several studies that have shown positive on bat populations if significant levels of bat mortality are found. Types of operational adjustments may include date specific shut-down periods, adjustments of cut-in wind speed, or limitations on operation during specific wind and temperature regimes that pose greatest threat of bat fatality events.
Due to the tenuous nature of bat populations in Vermont and the uncertainty of bat fatality studies completed for the Georgia Mountain facility, in order to assure there is no undue adverse impact to bat populations, it is necessary to condition post-construction studies to assess negative impacts of this project on the bat populations and to condition operational adjustments. Post-construction studies will help assure that critical bat fatality thresholds will not be exceeded. If thresholds are exceeded, proper operational adjustments can then be made to lessen the impact on bat fatality rates at the Georgia Mountain Community Wind facility.