TRPA to check on concerns that pier lights hurt lake clarity

RENO - Regional regulators have agreed to look into the possibility that night lights burning on Lake Tahoe's piers could be contributing indirectly to the lake's loss of clarity.

Dr. Paul Guttman, a physician and amateur astronomer, believes the lights are disrupting the natural feeding cycle of tiny aquatic animals in the lake.

Officials for the Tahoe Regional Planning Agency say they don't know if his concerns are valid. But they agree it's worth examining as they explore new regulations that could substantially increase the number of piers allowed at the landmark alpine lake.

"If it could benefit the lake and lake clarity, it would be worth a look," TRPA executive director John Singlaub told a Reno newspaper.

Agency officials have agreed to address the lighting issue in their final environmental report on proposed rules guiding activities along the lake's shoreline.

Guttman is an Incline Village radiologist who also operates the nonprofit Space Science for Schools. He is a member of the International Dark Sky Association, a group formed to fight light pollution they say is dimming the night skies worldwide.

Over the last decade, the growing cities of Reno-Sparks and Carson City are increasingly lighting the night skies, making star-gazing more difficult, Guttman said.

But as Lake Tahoe policy makers debate the possibility of increasing the number of piers, buoys and other shoreline structures, Guttman worries over the possibility that lights could hurt the lake as well.

He bases his concern on the work of scientists who have documented impacts of artificial light on the behavior of zooplankton and other aquatic animals in the northeastern United States.

Guttman said artificial lights on docks and piers could discourage tiny, shrimp-like zooplankton from nighttime feeding on the algae growing in Lake Tahoe, potentially increasing algae growth.

Algae, along with suspended sediments, are responsible for the continuing loss of Lake Tahoe's clarity, which is decreasing at an average rate of more than a foot per year.

"If this biological effect is also in effect here at Lake Tahoe, the algae could build up disproportionately along the shore," Guttman said.

"Night light trespass may have a significant effect," Guttman said.

The effect might be compounded if TRPA lifts a 17-year-old ban on the construction of new piers around much of the lake.