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In Sierra Club v. Tahoe Regional Planning Agency, 2014 U.S. Dist. LEXIS 47871, the United States District Court for the Eastern District of California granted the Tahoe Regional Planning Agency’s (TRPA) motion for summary judgment and upheld TRPA’s 2012 Regional Plan Update (RPU).

The Regional Plan, which was adopted in 1987, governs land-use planning and development in the Lake Tahoe basin area. TRPA may not update the plan unless TRPA finds that the amended plan maintains the same environmental standards to protect the lake’s beauty and environment.  Sierra Club and Friends of the West Shore challenged the RPU arguing that the RPU did not maintain the environmental protections in the original Regional Plan for four reasons.

First, Sierra Club contended that the RPU’s switch from a Bailey model to a Total Maximum Daily Load (TMDL) model was arbitrary and capricious. The Bailey model contains strict limits on the impervious surface coverage (such as concrete, asphalt, etc.) on certain soil types. In contrast, the TMDL model takes a broader approach aiming to reduce the total flow of pollutants into the lake. The court emphasized that it should be at its most deferential when considering the scientific judgments of TRPA. The court noted that TRPA had included further analysis of designated areas in response to public comments in the Environmental Impact Statement (EIS) required to be prepared by the TRPA Compact and that the region-wide scale of the TMDL model was consistent with the regional scale of the RPU. As a result, the court deferred to the scientific judgment of TRPA and held that TRPA’s decision to switch to the TMDL model was not arbitrary and capricious.

Second, Sierra Club claimed that the EIS failed to address the cumulative impacts from increased development on soil conservation in certain areas of the lake. However, the court pointed out that while the analysis of soil conservation was minimal compared to the analysis of water-quality impacts, the disparity reflected the significant difference in commentary that TRPA received on the draft EIS. Therefore, the court concluded that the RPU’s findings on soil conservation were sufficiently supported in the record.

Third, Sierra Club contended that the RPU’s reliance on the adoption of new best management practices was arbitrary and capricious. Although best management practices were historically not successful in the region, the RPU included best management practices that would require minimal maintenance such as retaining walls and terracing. Additionally, the RPU incentivized compliance with the best management practices. Thus, the court held it was not arbitrary and capricious for TRPA to conclude that its best management practices would be followed.

Finally, Sierra Club contended that the RPU did not contain substantial evidence that the RPU would maintain the ozone threshold from the original Regional Plan. Sierra Club took issue with TRPA’s reliance on data from a monitoring station in Nevada rather than California. The court again deferred to the judgment of TRPA to determine if the variance in the monitoring stations was permissible or not. As a result, it was not arbitrary and capricious for TRPA to conclude that the RPU sufficiently maintained ozone levels in the Lake Tahoe basin area.


The court was highly deferential to the judgment of TRPA. Although the analysis of some matters in the EIS could have been more robust, TRPA was not required to address “every scientific uncertainty” and its findings were not arbitrary and capricious.

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