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Hotel/Motel & Commercial Areas & South Lake Tahoe Airport Industrial Areas & US Highway 50

Status and Trend

Interpretation and Commentary

Hotel/Motel

Status: At or Somewhat Better Than Target
Trend: Little or No Change
Confidence: Moderate

Commercial

Status: At or Somewhat Better Than Target
Trend: Little or No Change
Confidence: Low

South Lake Tahoe Airport

Status: Somewhat Worse Than Target
Trend: Insufficient Data
Confidence: Low

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  • Relevance - This indicator measures 24-hour noise levels in the Hotel/Motel and Commercial land use categories, and the South Lake Tahoe Airport transportation corridor in the Lake Tahoe Basin. Noise by definition, is “unwanted sound,” and is therefore a subjective reaction to acoustical energy or sound levels. Due to the rural nature of the communities and the pristine natural areas in the Lake Tahoe Basin, excessive noise levels may negatively impact community ambiance, one’s recreational experience, and wildlife behavior. In recent years, visitors and residents of the Lake Tahoe Basin have expressed concerns about declining serenity in their community, and their enjoyment of the outdoors due to excessive noise from sources such as on-highway vehicles, off-highway vehicles, over-snow vehicles, watercraft, and aircraft(TRPA 2007c).In addition to existing federal, state, and local noise control regulations, the Tahoe Regional Planning Agency adopted 24-hour noise standards, or Community Noise Equivalent Levels (CNEL), for all land use categories, plan areas, and transportation corridors of the Basin.
  • Adopted Standards  - For the Hotel/Motel and Commercial land use categories and South Lake Tahoe Airport transportation corridors, noise levels shall not exceed a CNEL of 60 dBA.
  • Indicator - A-weighted Decibel (dBA). The A-weighted decibel measurement is used in evaluating the effects of environmental and industrial noise effects on human health.
  • StatusHotel/Motel – The Hotel/Motel land use category has reported “in-attainment” status since 1991 (Engineering Dynamics 1991; TRPA 1996, 2001). In 2011, an annual mean CNEL value of 55 dBA was measured, ranging from 51 to 59 dBA (TRPA 2011d). A status of “at or somewhat better than target” was determined because it was 2% better than the adopted standard.
  • Status Commercial – Since 1991,the Commercial land use category has reported “non-attainment” for one sampling period (1991) (Engineering Dynamics 1991; TRPA 1996, 2001). In 2011, an annual mean CNEL value of 55 dBA (range 51 to 59 dBA) for Commercial areas was measured (TRPA 2011d). A status of “at or somewhat better than target” was determined because it was 2% better than the adopted standard.
  • Status – South Lake Tahoe Airport In 2011, an annual mean CNEL value of 58 dBA (range 51 to 63 dBA) for this category was measured (TRPA 2011d). A status of “somewhat worse than target” was determined because the indicator was 5% worse than the adopted Threshold Standard.

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  • Trend– Hotel/Motel −The change in CNEL for the Hotel/Motel land use category between 1991 and 2011 was +0.16 dBA/year or +0.3% indicating a trend determination of “little or no change.”
  • Trend -  Commercial – Since 1991,the change in CNEL for the Commercial land use category was -0.11% dBA/year or -0.2% indicating a trend determination of “little or no change.”

Confidence

  • Status –Even though 1) noise monitoring equipment was calibrated according to manufacturers’ specifications, 2) sampled land use units and locations within each land use category were randomly selected to improve inferences about the population of these land uses, and 3) additional sampling effort was deployed in 2011, a documented and peer-reviewed protocol for CNEL monitoring does not exist. Consequently, confidence in the status was determined to be “moderate,” because of the spatial and temporal characterization of CNEL across these land use types. 
  • Trend – The confidence in the trend for the Hotel/Motel land use category is “high” for the analysis of 4 data points with a confidence of 97% and a P value of 0.03. The confidence in the trend for the Commercial land use category was determined to be “low” for the analysis of 4 data points with a confidence of 42% and a P value of 0.58. Trend confidence for the South Lake Tahoe Airport transportation corridor was unable to be determined due to the lack of a trend.
  • Overall Confidence - The overall confidence for the Hotel/Motel land use category is “moderate” because there is “moderate” confidence in status and “high” confidence in trend. The overall confidence for the Commercial land use category is “low” because there is “moderate” confidence in status and “low” confidence in trend. Because there is no trend for the South Lake Tahoe Airport transportation corridor, an overall confidence of “low” was designated.
  • Human and Environmental Drivers - Anthropogenic noise levels affecting these land use categories and transportation corridor are primarily generated from vehicles, roadway traffic, aircraft, and recreational activity(TRPA 2011c).Othersecondary anthropogenic noise influences include noise attributed to road construction and ambient Basin noise(TRPA 2011c). Natural events such as thunderstorms and wind influence noise levels as environmental drivers(TRPA 2011c).
  • Monitoring Approach – There is currently no established peer-reviewed monitoring plan or protocol for monitoring and evaluating the CNEL indicator. Historical monitoring consisted of gathering a single 24-hour sample per measured plan area. Threshold Standard attainment status was based on a single sample representing each land use type. In contrast to historic monitoring efforts, a more comprehensive CNEL monitoring effort was implemented in 2011. The 2011 monitoring approach was based on recommendations provided by a noise expert (Brown-Buntin Associates, Inc.), and included a replicated and intensified sampling effort that spanned multiple 24-hour periods to improve the characterization of variation in CNEL. In addition, CNEL values for the South Lake Tahoe Airport transportation corridor were gathered at the “Barton Beach” site (see indicator summary “Single Noise Event-Aircraft” for site specifics) in lieu of an established CNEL monitoring site at Lake Tahoe Airport.
  • Monitoring Partners – Monitoring was conducted by TRPA with land access granted by U.S. Forest Service and the California Tahoe Conservancy.

Links

 
  • Monitoring Plan
  • Conceptual Model

Map

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A map of Hotel/Motel, Commercial, and South Lake Tahoe land use category areas, with monitoring locations (CNEL 60).

Trend Charts

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High and low single day CNEL values (bar endpoints), with annual mean CNEL in land use categories and transportation corridors having a Threshold Standard of CNEL 60 dBA from 1991 to 2011. Source:  TRPA noise monitoring data, Brown and Buntin Associates, Inc., Engineering Dynamics, Inc.

Additional Info

References

Additional Information

Last Updated on Friday, 26 October 2012 15:06