By Michael Doyle
Bee Washington Bureau
(Published April 14, 1999)

WASHINGTON -- Soda machines pollute, leaking light into the natural, deep-valley dark of Yosemite National Park.

The light pollution, identified in an internal Yosemite study, isn't unique to the popular Sierra park. At Sequoia, Kings Canyon and dozens of other parks nationwide, rangers consider unwanted light a pervasive trespasser upon the natural experience.

"It's an emerging, and worsening, problem in the parks," Dave Simon of the National Parks and Conservation Association said Tuesday. "Light pollution, like noise pollution, is something that people don't often think about."

Simon recently authored the first survey of light pollution in national parks. An eye-opening one-third of park officials surveyed responded that light pollution was a "moderately serious" or "very serious" problem. Among West Coast park officials, 81 percent termed dark night skies an "important" park resource worthy of protecting.

"One of the really nifty resources, one of the things that people don't think about until they come here, is the night sky," Yosemite spokesman Kendall Thompson said. "We still consider it a pretty important issue."

It's the dark sky that, under elusive ideal conditions, allows people to see up to 45,000 stars and the Milky Way's teeming millions. Yosemite Valley in its natural state is especially dark, because the valley floor is at least 2,000 feet beneath the rim of surrounding granite, and it therefore has high potential for dark-sky aficionados. These are people like the 357 California members of the International Dark-Sky Association, an evocatively named group loaded with professional and amateur astronomers and others who prefer their light to come from other worlds.

Increasingly, the dark-sky advocates also have their feet on the political ground. The new national park study, for one, is meant to spur park service action.

The city of Davis already has adopted what Sacramento astronomy teacher Chris Hulbe called "an exemplary" outdoor lighting ordinance, and the city of Citrus Heights will be considering one. Last week New Mexico became the fourth state to adopt what is dubbed the Dark Sky Protection Act. The law requires shielding of outdoor lights, bans outdoor mercury vapor lights and in other ways restricts so-called "light trespass."

No such standard governs national park lighting, even though a 1988 policy statement cites a desire to minimize intrusive light.

"We consider it significant, but we haven't spent a lot of time on it," National Park Service spokesman David Barna said Tuesday.

Yosemite officials hired a consultant several years ago to study the park's lighting system. Wielding light meters, the consultants found light pollution pouring from soft-drink machines and a gas station that glared all night long. Other Yosemite lights wandered across the spectrum, from purplish mercury vapor to yellowish high-pressure sodium lights. Few Yosemite lights are shielded, and many were termed old and inefficient by the consultant.

"It's gotten so much brighter than when I was a kid," lamented Hulbe, an astronomy teacher at California State University, Sacramento.

Though the Yosemite Valley gas station has since been removed for unrelated reasons, there are still no consistent standards taking account of a national park's need for safety as well as the need to keep unwanted light turned down.

"There's an expectation that we light up the night, but is that appropriate in a national park?" Thompson asked.

Yosemite's January 1997 flooding swamped hopes of putting a new lighting prototype into action, but Thompson said the plan remains potentially valid as Yosemite continues its rebuilding.

"Yosemite has a perfect opportunity to do it right," Simon said.

At Sequoia and Kings Canyon national parks, officials told Simon's survey team that "there is no consistent park policy or program in place to improve night sky visibility." Ninety percent of the Sequoia and Kings Canyon lights still in use are unshielded mercury vapor lights that are "unnecessarily bright and wasteful," park officials said.

But dark-sky fans also complain about light pollution that is outside the national park boundaries and, presumably, outside the ability of park officials to control. Sequoia and Kings Canyon officials, for instance, noted that lights from Fresno, Reedley and Visalia "produce a general sky glow in the west as seen from the parks."

"What we're seeing increasingly is a brighter western horizon," Hulbe said.

The new survey found that 40 percent of parks contacted had taken some steps to limit light pollution, and 21 percent had done nothing.

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