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Lands classified as land capability class 6 are considered non-sensitive in the Tahoe Region and can support development. The percent of land coverage within land capability class 6 indicator measures the percent of land coverage on class 6 lands in the Tahoe Region. The indicator allows up to 30 percent impervious coverage within land capability class 6. Land capability class 6 includes gently sloping areas around the northern parts of the Tahoe Region. These non-sensitive areas are well suited for urbanization, active recreation, and other uses.
2019 Evaluation
See how thresholds are evaluated
- Status
- Considerably Better Than Target
- Trend
- Little or No Change
- Confidence
- Moderate
Applicable Standard
SC8: Impervious cover shall comply with the "Land Capability Classification of the Lake Tahoe Basin, California-Nevada, A Guide for Planning", Bailey, 1974.
Key Points
- Impervious coverage within class 6 was estimated to be 2,280 acres, less than the threshold standard of 6,960 acres.
- Class 6 includes about 11 percent of the Tahoe Region.
- Approximately one-third of the regional allowable coverage in class 6 has been utilized.
Evaluation Map
Description
Land capability Class 6 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
No related projects or programs defined for this indicator.
Rationale Details
- Impervious cover within each land capability class was determined by an analysis of LiDAR/multispectral data collected in 2019. Class 6 has fewer existing acres of impervious coverage than is allowed under Bailey, 2,280 acres of existing impervious surfaces with the threshold standard of 6,960 acres. This makes it "considerably better than target."
- The trends for Impervious cover within each land capability class was determined to be "little or no change".
Confidence Details
- Moderate. TRPA has used the best available science and technology over time to assess the Impervious Cover Threshold Standard, different imagery datasets (4-band IKONOS collected in 2002, LiDAR and 8-band multispectral collected in 2010 and 2019). However, because of variation in the methods used to assess impervious surface features and estimate impervious cover, the comparison across evaluations is unsuitable.
- Moderate. There is “moderate” confidence in the current estimates of impervious cover from the LiDAR data and the resulting impervious surface layer.
- Moderate. There is “moderate” overall confidence base on the accuracy assessment of the impervious surface data and the land capability class results.
Additional Figures and Resources
No documents available.