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Effort to preserve dark skies in Great Falls moves ahead amidst community split

The roll-top observatory at Turner Farm Park (courtesy Fairfax County Park Authority)

An effort to preserve dark skies in Great Falls recently got a vote of support from the Fairfax County Planning Commission amidst contention within the community.

At a heated Oct. 18 meeting, the commission unanimously recommended approval of regulations to preserve dark skies around Turner Park Farm Observatory Park. Public testimony, however, was divided into two camps.

Proponents called the proposal a necessary step to preserve dark skies, reduce light pollution, and ensure astronomers can continue to get clear views. Opponents said the changes would decrease safety, were being considered without direct community engagement, and did little to result in a meaningful impact on light pollution.

The regulations, which limit outdoor lighting with a half-mile of the observatory, have been in the works for years. The latest version was pared down after several town halls and an online community survey.

Under the proposed zoning ordinance amendment, motion-activated outdoor lights must be 1,500 lumens or less — a drop from the current limit of 4,000 lumens or less. Additionally, all lights need to be fully cut off, which is currently not required.

Still, an exception to the cut-off and shielding requirements will remain for lights at a door or a garage of up to 1,500 lumens per fixture.

The regulations would also set limits on the number of up lights or spotlights allowed. Currently, any number are allowed as long as they are fully cut off or shielded to confine light. The changes would limit each fixture to 300 lumens. Changes would apply to future lights.

But some residents said they were in the dark about the proposal. They also said they were concerned about the safety impacts of reduced lighting.

Laszlo Zsidai, president of Foxvale Farm’s homeowners’ association, said the neighborhood of 115 homes received no direct engagement from the county on the amendment, noting that an online community survey conducted by the county found 50% of respondents were not supportive of the changes. A survey conducted by the HOA of its own community found similar levels of support, he said.

He also questioned if regulating lights near the observatory was effective in the shadow of other high-rise, luminous developments in surrounding areas like Tysons.

“Their light pollution will eat us up,” Zsidai said.

Great Falls has a visibility level of around 6 when judged on a Bortle scale where 1 means excellent viewing and 9 means poor viewing.

Dranesville District Commissioner John Ulfelder emphasized that Great Falls has one of the lowest crime rates compared to other parts of the county.

“Crime in Great Falls is not rampant. It’s not even serious. But it’s important to feel that they have a sense of security,” Ulfelder said.

Others, including the Great Falls Citizens Association and several astronomy organizations, expressed support for the proposal.

Thomas Reinert, president of DarkSky International, described the regulations as a compromise. He noted that students at Thomas Jefferson High School for Science and Technology near Lincolnia can no longer use a telescope on their facility due to the increase in light pollution over the years.

The observatory at Turner Farm is among a handful of facilities in the area where astronomical viewing can continue — for now.

“In no sense are these rules onerous,” Reinert said.

Dr. Peter Plavchan, a professor of physics and astronomy at George Mason University, emphasized that light pollution has doubled in just the last 10 years. He compared the community to a “proverbial frog” sitting in water that is slowly reaching a boiling point.

The proposal heads to the Fairfax County Board of Supervisors for a final vote on Nov. 21.