Wind Farm Plan to Protect Rare Bats Is Inadequate, Hearing Officer Finds

posted in: December 2017 | 0

One year ago, the state Board of Land and Natural Resources granted a contested case hearing to the community group Keep the North Shore Country, which opposed a recommendation made a month earlier by the Department of Land and Natural Resources’ Division of Forestry and Wildlife to approve a habitat conservation plan (HCP) and incidental take license (ITL) for a wind farm Na Pua Makani Power Partners, LLC, plans to build in Kahuku, on O‘ahu’s North Shore.

In her proposed decision and order issued on Halloween, hearing officer Yvonne Izu systematically picked apart the the company’s HCP, which is supposed to guide the company’s efforts to protect endangered Hawaiian hoary bats, or ‘ope‘ape‘a, and other protected species from the nine wind turbines that will make up the 27-megawatt facility.

Her decision is yet another attempt by the state in recent months to address more thoroughly the impacts of wind farms in light of new data suggesting that they are killing far more bats than predicted and/ or allowed for by federal and state permits. It comes on the heels of an October 27 decision by the Land Board to require the Auwahi wind farm on Maui to complete a supplemental environmental impact statement for its proposed ten-fold increase in bat takes.

Parties to the contested case must file by December 7 their exceptions to Izu’s recommendation to deny the HCP for the Na Pua Makani wind farm. Responsive briefs are due on the 29th and the Land Board is scheduled to hear oral arguments on January 12.

Whether or not the lack of an approved HCP will derail the project remains to be seen. One facility, the Lalamilo wind farm run by the Hawai‘i County Department of Water Supply, has been operating without a final HCP since last September. State Sen. Gil Riviere, president of Keep the North Shore Country, said there are other such wind farms. “I suppose they chose to run the risk that they would not take any endangered species. Anyway, there is a clear problem in our state with bat take and lack of appropriate mitigation,” he said.

Sole Surrogate

Izu’s main problems with the HCP revolve around its treatment of bat takes and mitigation. To start, she took issue with it estimating the maximum possible number of bat takes from the nine turbines using data from only one wind farm, the Kahuku Wind Project, and assigning a set amount of expected kills to each proposed turbine based on the historic level of take at the Kahuku facility, which has 12 turbines.

“Because the fatality calculation is based on an average per turbine and then multiplied by the number of turbines proposed by NPM [Na Pua Makani], it appears that NPM presumes that the number of WTGs [wind turbines] in a project is irrelevant. If the number of WTGs is irrelevant, NPM fails to explain why its analysis was limited to data from the Kahuku Wind Project and did not consider fatalities per WTG from other wind energy projects in Hawai‘i,” she wrote, adding that the company should have analyzed bat mortality at other wind farms that have been operating longer than the Kahuku project.

Izu also found that the plan failed to assess whether its taller turbines, with longer blades, would kill more bats than the Kahuku facility’s turbines. The turbines there reach a maximum height of 128 meters, while NPM’s turbines would reach 200 meters.

In contending that there is no direct correlation between turbine height and bat take, NPM relied on an article in the Journal of Wildlife Management that found no relationship between bat mortality/turbine and turbine height. However, Izu pointed out, the authors highlighted the fact that they compared turbines that weren’t very different in terms of blade length. Turbine heights in that study ranged between 117 meters and 136 meters, a difference of 19 meters. The difference between the Kahuku project’s turbines and NPM’s is more than 70 meters.

What’s more Izu wrote, a 2016 article titled “Impact of Wind Energy on Bats” concluded that numerous studies support the hypothesis that the taller the turbine, the greater the number of bat fatalities.

“Although this article was published after the final HCP had been drafted, the article cited to studies conducted in 2007, 2008, and 2009 regarding the relation between turbine height and bat mortality,” she wrote.

For example, a 2007 publication, “Variation in bat and bird fatalities at wind energy facilities: assessing the effects of rotor size and tower height,” concluded that replacing older, smaller turbines with fewer larger ones may result in increased numbers of bat fatalities, she wrote.

“In relying on the Kahuku Wind Project as a surrogate for the project, Applicant failed to consider the difference in turbine height in estimating take for the project. For example, although the WTGs at Kawailoa [another O‘ahu wind farm] are taller than Kahuku’s (but still not as tall as the maximum proposed for the Project) Applicant elected to use data solely from Kahuku and not Kawailoa. Contrary to Applicant’s contention, the best scientific data does not support the hypothesis that there is no correlation between turbine height and take,” she wrote.

“Because very little is known about the population status of ‘ope‘ape‘a (estimates range from a few hundred to a few thousand), and given the fact that take of ‘ope‘ape‘a by wind energy facilities may have been underestimated in the past, a robust analysis of potential take is critical,” she continued.

She concluded that NPM’s sole reliance on the Kahuku Wind Project as a surrogate and its failure to consider impacts of turbine height resulted in an estimated take in the HCP that was not reliable enough for the Land Board to determine that the Na Pua Makani turbines would not jeopardize the continued existence of the bat.

Cut-In Speeds

Studies have found that curtailing the turbines during low wind conditions can drastically reduce bat fatalities. Normally, the speed at which wind turbines start to turn — the cut-in speed — is three to four meters per second. To minimize the killing of bats via blade interactions, NPM proposed in its HCP that turbine blades start spinning only when winds are blowing at five meters per second. Otherwise, the blades would be feathered into the wind. This practice is known as low wind speed curtailment (LWSC).

NPM proposed practicing LWSC from March to November between sunset and sunrise.

“In addition to the intended benefit of reducing bat fatalities, low wind speed curtailment will reduce the risk to Newell’s shearwaters, which could transit the Project at night April – November,” the plan stated.

The Department of Land and Natural Resources’ Division of Forestry and Wildlife recommended in its December 2015 Endangered Species Recovery Committee Hawaiian Hoary Bat Guidance Document that a minimum cut-in speed of five meters per second be employed by wind farms, “increasing to a higher cut-in speed through adaptive management if the rate of bat take is higher than initially expected.”

Izu seemed to think that there was sufficient scientific evidence to support a requirement that the cut-in speed should be even higher. She noted that a study conducted at a wind farm in Indiana demonstrated that bat casualty rates were “significantly different between cut-in speeds raised to 5.0 m/s (50 percent reduction in overall bat mortality) versus turbines with cut-in speeds raised to 6.5 m/s (78 percent reduction in overall bat mortality).”

Even DOFAW biologist Scott Fretz testified during the contested case hearing that curtailing wind production at higher speeds could reduce bat take, she wrote.

She pointed out that under state law, NPM was required to minimize and mitigate the impacts of the take to the maximum extent practicable.

“Although studies to date are inconclusive as to whether there is a significant difference in minimizing bat fatalities when the cut-in speeds are increased from 5 to 6.5 m/s, there is some evidence that it does. Conversely, there is no evidence that cut-in speed of 5 m/s is more effective in minimizing impacts to bats than cut-in speed of 6.5 m/s. Moreover, the inferences are that curtailing wind production at higher speeds could reduce bat take. Therefore, the best scientific knowledge currently available suggests that increasing cut-in speed to 6.5 m/s, rather than 5 m/s, would minimize impacts to the maximum extent,” she wrote, adding that NPM failed to provide evidence that increasing cut-in speed to 6.5 m/s is not practicable.

“By providing for LWSC at 5 m/s, instead of 6.5 m/s, the HCP fails to minimize impacts to ‘ope‘ape‘a to the maximum extent practicable, and, therefore, may not be protecting or maintaining the habitat used by ‘ope‘ape‘a,” she concluded.


Finally, Izu addressed the plan’s failure to come up with adequate mitigation steps as well as measures of success. Under the plan, NPM proposed taking a total 85 bats over 21 years. Mitigation measures (Tier 1) would be implemented if and when total take reached 34 bats. Additional measures (Tier 2) would be taken should another 51 bats be taken.

Tier 1 measures included the provision of funding for bat research and implementation of habitat restoration measures and associated monitoring at a mitigation area at Poamoho Ridge on O‘ahu. Tier 2 measures included the provision of more money for more research and mitigation and monitoring at Poamoho. Mitigation at Poamoho included fencing and removal of feral ungulates and invasive vegetation, among other things.

Izu stated that with bat mitigation measures in general still in their early stages, it was premature to determine whether NPM’s proposals would be a net benefit to the bats.

During the 21-year term of the take permit covering the wind farm, “research efforts may conclude that protecting habitats other than Poamoho Ridge may be more effective in the survival of ‘ope‘ape‘a on O‘ahu, especially as current knowledge indicates that ‘ope‘ape‘a use a variety of different, including disturbed, habitats,” she wrote. Should that become the case, the HCP lacks adaptive management strategies that would enable revisions in NPM’s mitigation plans, she added. What’s more, she stated that the plan is silent as to what happens if pigs, goats and invasive plants are not removed from Poamoho to the extent and in the timeframe provided in the management plan.

Since the HCP lacks an effective adaptive management strategy, as well as any meaningful measures of success, the HCP does not meet state law requirements with respect to the bats, she wrote.


While most of Izu’s concerns about NPM’s habitat conservation plan related to its treatment of bats, she also found fault with its proposed mitigation for threatened and endangered birds. For Hawaiian waterbirds (duck, stilt, coot, and moorhen), NPM proposed to construct fences and erect informational signs at wetland habitats in Kailua, located about an hour southeast of Kahuku. It also proposed to support public education and monitoring through the funding of a part-time biologist. Under the plan, the mitigation would be deemed a success if the fences were constructed in a timely manner and funding were provided for maintenance and the biologist.

“These actions, however, cannot be said, when achieved, to contribute significantly to the protection, maintenance, restoration or enhancement of ecosystems, natural communities, or habitat types,” Izu wrote.

She added that the plan also does not discuss any adaptive management strategy “in the event that fencing, monitoring and public education are not successful in reducing the number of predators entering the marsh, the amount of trash in the parking lot adjacent to the marsh, or increasing the nesting opportunities within the marsh.” In fact, she concluded that most of the measures of success included in the plan were not conducive to adaptive management strategies. “For example, by contributing to a pool of money for ‘a‘o [Newell shearwater] conservation research or projects to be carried out by USFWS, there is no adaptive management strategy under the HCP in the event that the management project that was funded turns out to be ineffective,” she wrote.

(For more background on this issue, see our February 2017 cover story and sidebar, as well as our December 2016 and January and November 2017 “Board Talk” columns.)

— Teresa Dawson

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