Progress slow in revising noise standards |

Progress slow in revising noise standards

Patrick McCartney

Editor’s note: This is the seventh installment in the Tahoe Daily Tribune’s examination of the Tahoe Regional Planning Agency’s five-year evaluation of Lake Tahoe’s environment. Today, a look at noise standards.

Forget the sound of babbling brooks.

When it comes to noise, the primary source throughout the Tahoe region is the sound of automobile traffic.

That’s the underlying conclusion in the Tahoe Regional Planning Agency’s 1996 evaluation of noise, one of nine principal environmental standards, or thresholds, first adopted in 1982.

Since the last evaluation, progress has been slow in revising noise standards to better address such sources of noise as personal watercraft, said Rick Angelocci, the agency’s chief of project review.

“The recommendation is to update the single-event noise standard based on newer technology,” Angelocci said. “When we first did the noise threshold, personal watercraft were not an issue. The standard we adopted doesn’t necessarily work well with today’s modern engines, and personal watercraft engines run at higher speeds than they used to.”

Under the existing single-event standard, a boat or automobile must be quieter than 82 decibels when measured from 50 feet away. Trucks, motorcycles and off-road vehicles must be quieter than 86 decibels from the same distance.

But very few engines in operation today would violate that standard, even if they are loud enough to generate complaints. That’s why the TRPA is considering the use of a different noise standard for single-event noises that is based on the interference with human speech.

Monitoring of single-event sounds has been spotty at best, according to the 1996 evaluation. But operations at the Lake Tahoe Airport have been monitored as a requirement of the airport’s master plan.

In 1995, no violation was reported for any of the 2,538 commercial and charter operations, and only one of the 19,019 general-aviation flights violated the noise standard.

The agency employed a consulting firm to monitor community noise levels at 40 locations in 1996, comparing the 24-hour average noise levels with that measured in the same locations five years earlier. The readings, called Community Noise Equivalent Level, give heavier weight to sound levels recorded at night.

Besides determining that automobile traffic is the dominant source of sound in the basin, the monitoring confirmed most of the community noise standards previously adopted by the agency.

But the study suggested that the standards for commercial areas should be lowered, while the standard for wilderness and roadless areas should be raised.

According to the measurements, the average noise in commercial areas never approached the 65-decibel standard; the highest measure was 58 dBA in 1991. And the two rounds of monitoring showed that the 25-decibel standard for wilderness areas was far more quiet than the ambient noise level in an undisturbed area, where monitoring consistently showed noise levels ranging between 40 to 45 decibels.

Despite the modest progress, Angelocci said noise is not an environmental standard that most residents are concerned about.

“Our noise levels are pretty good, on the low end in the terms of standards in other areas,” Angelocci said. “Noise has not been a high-complaint issue compared with others.”

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