Indicator
Percent of Land Coverage Within Land Capability Class 1c (allow up to 1% impervious coverage)
2023 Evaluation
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Lands classified as land capability class 1c are among the most sensitive in the Tahoe Region and can support the least amount of land disturbance. The percent of land coverage within land capability class 1c indicator measures the percent of land coverage on class 1c lands in the Tahoe Region. The indicator allows up to one percent impervious coverage within land capability class 1c. Land capability class 1c generally includes mountainous, rocky lands with little or no soil. These environmentally sensitive areas are not generally suitable for development or wildlife, and the lack of soil offers limited opportunities for plant life.

Status
Percent cover in each Bailey land capability class relative to the allowable coverage in class.

Data was created by Tahoe Regional Planning Agency. Access detailed datasets on Tahoe Open Data, including, bailey land capability feature class, remotely sensed impervious coverage feature class, and the permitted coverage summary.

2023 Evaluation
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Status
At or Somewhat Better Than Target
Trend
Little or No Change
Confidence
Moderate
Applicable Standard
SC3: Impervious cover shall comply with the "Land Capability Classification of the Lake Tahoe Basin, California-Nevada, A Guide for Planning", Bailey, 1974. Allowable percent of impervious cover in Land Capability subclass 1c - 1%.
Key Points
  • Impervious coverage within class 1c is estimated to be 495 acres, less than the threshold standard of 537 acres.
  • There was no change in the estimated coverage in class 1c from 2020-2023.
  • The acquisition and restoration of sensitive lands through the Environmental Improvement Program protect watersheds providing valuable habitat for special status species, and enhances recreational opportunities in the Tahoe Region.
  • More than 613 acres of sensitive lands (land capability classes 1-3) were acquired between 2020 and 2023 by Environmental Improvement Program partners.
  • The TRPA Code of Ordinances restricts new land coverage or permanent disturbances in sensitive areas, specifically in classes 1a, 1b, 1c, 2, and 3, with only a few exceptions allowed.
Evaluation Map
Description

Land capability Class 1c lands and impervious surfaces within the Tahoe Region.

 

About the Threshold
This indicator measures the percent of land coverage on different land capability classes as described by Bailey (Bailey, 1974) and updated with the most recent soil survey by the Natural Resources Conservation Service (NRCS) in 2007 (Loftis, 2007; USDA-NRCS, 2007). Impervious cover is a primary indicator of land disturbance. Excessive impervious surface within a watershed contributes to sediment and nutrient inputs to Lake Tahoe and its tributaries impairing water quality, altering surface hydrology and groundwater recharge regimes. The results are often negative impacts on soil health, fisheries, wildlife habitat, and vegetation growth. Impervious surfaces include hard coverage such as roads, buildings, driveways, and parking lots, and soft coverage with soil compaction as a result of use, but where no structure is in place.
Impervious cover is created through use or development on natural lands. This could be for commercial, residential, recreational, and other activities, and encompasses the spectrum of human uses that involve physical modification of the environment. The economy plays a large role in the housing market and the business environment, which are both among the most important drivers of new land coverage in the basin.
Delivering and Measuring Success

EIP Indicators

Rationale Details
At or Somewhat Better Than Target. Land capability Class 1c has 494.5 acres of existing acres of impervious coverage, 42 acres or 8 percent less than what is allowed under the Bailey 1c threshold standard of 537 acres. This makes it "at or somewhat better than target." All permitted projects that add coverage pay a water quality mitigation fee. There were 720 projects that paid water quality mitigation fees between 2000 and 2023, with more than $2.37 million collected during the period for the creation of 1.275 million square feet of added coverage (29 acres) in all classes. During the period, more than 232,000 square feet of coverage (5.3 acres) was removed on 45 parcels as a requirement of permit conditions and from Environmental Improvement Program projects to remove and retire coverage.
Little or No Change. The trends for Impervious cover within class 1c was determined to be "little or no change." Between the 2019 Threshold Evaluation and the 2023 Threshold Evaluation, impervious coverage in class 1c did not change.
Confidence Details
Moderate. For the 2023 analysis, TRPA used the 2019 baseline and added or removed coverage based on the cumulative accounting of acres of cover added in each land capability class based on the rigorous tracking from TRPA permitting data and Environmental Improvement Program tracking. All permitted projects that add coverage pay a water quality mitigation fee; these fee collections were used to assess added coverage. Some inaccuracy is introduced due to unpermitted impervious cover that may have been added or created in the Region, for which no permit was acquired. This reduces the status confidence to moderate. The 2019 Threshold Evaluation for impervious coverage was based on an updated analysis of high-resolution aerial imagery and hand digitizing features from multispectral images collected in 2018 and 2019.
Moderate. Because of the change in source data to using permitting mitigation fees for the 2023 evaluation, comparison of the trend is rated as moderate confidence.
Moderate. There is “moderate” overall confidence based on the accuracy of the impervious surface data and the land capability class results.
Additional Figures and Resources

No photos available.

Coverage Changes 2020-2023
Uploaded On
10/18/2024
File Type
PDF
Description
This table provides the detailed accounting of coverage added by parcel between 2020-2023, based on TRPA permitting actions and the payment of water quality mitigation fees. The table also includes coverage removed and retired through permitting as well as coverage removed by Environmental Improvement Program projects. The coverage changes are reported by year and land capability class.