The wrong place to perch

---

Environmental News hand, supports a rule "no lower than 10 ppb [corresponding to the WHO guideline] because of the high costs associated with treating the water down to such low levels," said Alan Roberson, AWWA's director of regulatory affairs. EPA estimates that the proposed 5-ppb standard would affect 12% of community water systems, with 94% of these affected systems serving fewer than 10,000 people. And EPA estimates total compliance costs to range from $379 million to $445 million annually, due to additional treatment equipment, chemicals, and monitoring. AWWA strongly disputes these figures, however, and estimates instead a cost four times EPA's amount Moreover Roberson noted although the senic level EPA is proposing will only affect 12% of water systems "for those 12% the rule will have severe economic impacts " Indeed EPA specified that the regulation will cost an additional $28 per person per vear in affected communities sprvpd hv larep svstems and

Arsenic-tainted groundwater Arsenic concentrations were calculated from roughly 18,850 samples of potable groundwater, although not necessarily current sources of drinking water, drawn from 595 counties nationwide.

Source: U.S. Geological Survey.

t 8 5 n e r nprsnn npr vear in areas sprvpH hv small svstpms

Water systems affected by the rule are situated primarily in western states, parts of the Midwest, and New England where arsenic concentrations in groundwater tend to be higher (see map). Arsenic occurs naturally and can contaminate drinking water through the erosion of

rocks and minerals or through human activities such as fossil fuel burning, paper production, cement manufacturing, and mining. Some 90% of industrial arsenic in the United States is used as a wood preservative, but arsenic is also used in paints, dyes,

metals, drugs, soaps, and semiconductors, according to EPA. The rule was expected to appear in the Federal Register in June. EPA is required under the 1996 Safe Drinking Water Act Amendments to promulgate a final rule by Jan. 1. —KRIS CHRISTEN

The wrong place to perch For all of the pollution-abating promise of wind as a renewable energy technology, wind turbines have a mixed reputation in the environmental community because of their tendency to "Cuisinart"—as one researcher put it— birds that fly too close to their spinning blades. U.S. Scientists are intensively studying this issue in hopes of perfecting a method to avert casualties. As wind power grows in popularity (see feature on page 306A), any damage caused by the technology is likely to fall under increased scrutiny. Extensive stud-

ies of the issue pinpoint only one U.S. site where statistically significant numbers of birds had fatal encounters with turbines: California's Altamont Pass wind farm, according to Karin Sinclair, avian projects manager for the U.S. Department of Energy's National Wind Technology Center. But the issue has commanded attention because those birds were golden eagles. The issue has also been studied in Europe, and the only other area in the world where birds appear to be impacted by wind turbines is in Tarifa, Spain, Sinclair said

2 9 2 A • J U L Y 1 , 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS

The National Renewable Energy Laboratory (NREL) has spent more than $5 million since 1993 to support studies on why birds collide with wind turbines and how such collisions can be avoided. The research being conducted by William Hodos, an avian vision specialist at the University of Maryland-College Park is considered particularly promising. Hodos is working with kestrels, a small bird of prey related to the golden eagle. Although no researcher in the field has actually seen a bird like an eagle be struck down, biologists hypothesize that

they are hit when they attempt to perch atop wind turbines because they cannot see the blades, which typically reach speeds of up to 150-160 mph. In both humans and birds, the retina of the eye "does not have a good ability to keep up with rapidly moving objects," Hodos explained. And the closer a turbine blade is, the harder it is to see because it takes up more space on the retina. Instead, the blade is perceived as a "motion smear " rather than as a solid object, he said. Hodos is attempting to stimulate birds to recognize each of a turbine's two or three blades by painting bars in differing places on them. By giving the eye a place to focus, these patterns render the blades 2-2.5 times more visible, he claims. Hodos hopes to evaluate how the kestrels react to seven different blade patterns over the summer and he may also conduct a demonstration test with painted blades. The goal, he said, is to devise a pattern that be added to both new and existing wind turbines Another strategy is to coat turbine blades with UV paint, but it does not look promising, according to preliminary data presented in May by Dale Strickland, vice president and senior ecologist for Western EcoSystems Technologies, Inc., of Cheyenne, WY. Although birds' eyes allow them to see UV light as a color, the number of fatalities was "much higher" around UV-coated turbines at Foote Creek Rim wind farm in Wyoming, Strickland said. The victims were not birds of prey like eagles, but rather migratory birds, such as Townsend's warbler and rock wrens. The fatalities were most likely to occur at night during the spring when poor weather forced the birds to fly at relatively low altitudes, Strickland explained. Thus far, he and his fellow researchers have not been able to determine why these birds were colliding with the UV-painted turbines. At the Wyoming site as well as two other sites where Strickland has been active researchers have also

The image above illustrates why scientists suspect birds are felled by turbine blades, according to an avian vision specialist. All of the blades on the turbines in this field are moving at the same speed, but the ones closerto the camera—which operates on many of the same principles as the eye—are registered as "motion smears" rather than as solid objects. The closest blades have actually be come transparent (Right) When they are not moving, wind turbine blades provide an optimal place for birds like this kestrel to perch.

found sufficient numbers of dead bats to merit studying the issue in more detail, he said. One of the other sites where Strickland is working is a wind farm in San Gorgonio, CA. The goal there is to gauge whether there are differences in bird fatalities related to turbine size, because newer turbines tend to be much larger than older models. Although he does not expect to be able to report formal results until the end of this summer, Strickland said that his team "was not finding the big advantage [in terms of reduced collisions] for larger turbines that some people hoped ^yg would find " For all the attention these wildlife issues are commanding, wind turbines take a relatively small toll on bird mortality, Sinclair said, noting that NREL expects to have compiled definitive figures on the issue by the end of the year. Flying animals die as the result of collisions with a number of man-made structures and de-

vices, including communication towers, building windows, cars, and high-voltage wires, and a full analysis of the impacts those interactions have on bird populations has never been completed, Sinclair said. In fact, the number of collateral bird casualties is probably lower than that associated with the oil and gas industries, Strickland said, noting that the wind industry is spending quite a bit more on research into its wildlife impacts than those other industries. The issue can be avoided completely at new wind farm sites, Sinclair claimed. A guidance document published last December by the National Wind Coordinating Committee details how to conduct reconnaissance studies to ascertain whether a candidate area is in a migration route or a haven for rare birds. Power planners need to collect at least one year's worth of monitoring data before deciding to site new turbines, Sinclair said. —KELLYN S. BETTS

JULY 1, 2000/ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 2 9 3 A