BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

8.1.8.3 BACKSHORE SETBACKS AND BUFFERSUtilizing the previous criteria results in the delineation of a discernablelandward limit encompassing the backshore area of instability. However, thebackshore boundary and setback are not established as permanently fixedupland limits in order to account for dynamic changes that are present in theshoreline. For example, unstable shoreline bluffs east of Tahoe City have beenexperiencing slope failure and landslides. Because of the landslides, the top edgeof the bluff on some parcels has moved landward over the span of a few years.Therefore, the upland backshore boundary will be adjusted the next time aproject in this locality requires the re-examination of the previously delineatedbackshore of record. The backshore boundary is delineated to be reliable andconstant for most planning and permitting scenarios but it is not permanentlyfixed so that it can be adjusted to account for the dynamic nature of shorezoneadjustment over time.Applying the setback delineation protocols and methods such as those citedabove are considered modest preventative measures against rapid backshoreretreat or bluff failure.Buffers and regulatory setbacks are areas that are delineated around designatedprotected settings in order to reduce potentially adverse impacts to endemicgeomorphic and biogeochemical functions and values. Shorezone, wetland, andSEZ buffers also provide wildlife habitat for use in feeding, roosting, breeding,rearing, seeking cover and mobility, and thermal protection. Finally, buffersreduce the adverse impacts of human disturbance on shorezone habitatsincluding blocking noise and glare; reducing sedimentation and nutrient input;reducing direct human disturbance from dumped debris, cut vegetation, andtrampling; and providing visual separation.Once the unstable backshore lands have been properly identified anddelineated, certain shoreline protective structures may be considered andemployed to both attenuate erosion and thwart the potential loss of property.These structures include various static and dynamic methods as described laterin this chapter.8.1.9 ADDITIONAL TRPA THRESHOLD STANDARDSEnvironmental Threshold Standards Carrying Capacities set environmentalgoals and standards for the Lake Tahoe Region and indirectly define thecapacity of the Region to accommodate additional land development. Landdevelopment may negatively affect attainment of an environmental thresholdstandard. Special efforts, such as mitigation measures, must be taken to reduceimpacts. In particular, shorezone activities can affect all other TRPA ThresholdStandards including Water Quality, Soil Conservation, Air Quality,Vegetation, Wildlife, Fisheries, Scenic Resources, Noise, and Recreation.CHAPTER 8: Shorezone Protective Structures and BMPsTRPA BMP HandbookPage 8-18 2012