Relevance

Sediment (particularly fine sediment) delivered to Lake Tahoe is known to directly affect the transparency of Lake Tahoe. Suspended sediment concentration is the amount of organic and inorganic particles suspended in water in the stream. Suspended sediments occur naturally in streams and are essential to the ecological function of a stream. Deposition of suspended sediments can create micro-habitats such as pools and sand bars for biota. Excessive amounts of suspended sediment are the leading cause of impairment in streams and lakes of the United States. Too much suspended sediment in the stream can have direct impacts on stream and lake biota. Identified impacts include loss of spawning habitat for fish, reduced amounts of light available for photosynthesis by plants, and shifts to turbidity-tolerant fish communities.

Human and Environmental Drivers

All tributaries within the Tahoe Basin deliver sediment and nutrients to a single downstream waterbody: Lake Tahoe. The Tahoe Basin has 63 individual tributaries and associated watersheds, each with its drainage area, slope, geology, and land-use characteristics resulting in high variability throughout the Region. Variability in the amount, timing, and form of precipitation strongly influences runoff patterns. A substantial rain shadow exists across the basin from west to east; precipitation can be twice as high on the west shore relative to the east shore of Lake Tahoe. Both new and legacy disturbances to the landscape can affect the volume of runoff, erosion rates, and the ability of the watershed to retain sediment and nutrients. Landscape disturbances including, but not limited to, impervious road and parking lot surfaces, residential and commercial development, wildfire, and the degradation of stream environment zones, can contribute to sediment and nutrient inputs to the Lake or its tributaries. Weather variations and their effects on stream hydrology (particularly the extremes of droughts and floods), and long-term climate change are considered among the most important environmental drivers of tributary runoff. Domagalski et al., 2021 suggested that the downward trend for both suspended sediment concentrations and loads were likely attributed to forest growth and recovery. Increases in FSP concentrations observed since the big 2017 water year have been attributed to the ongoing impacts of that water year (Smith 2022).

EIP Action Priorities

• Reduce Stormwater Pollution From: Roads and Highways, Forest Roads, Public and Private Parcels
• Restore Priority Meadows, Wetlands, and Lake Tahoe Tributaries

EIP Indicators

• Acres of SEZ Restored or Enhanced
• Fine Sediment Load Reduction

Example EIP Projects

• Burke Creek/Rabe Meadow Riparian Restoration Project
• High Meadows/Cold Creek Restoration

  This project completed by the USDA Forest Service restored two miles Cold Creek stream channel in the High Meadows area.

Monitoring Programs

• Lake Tahoe Interagency Monitoring Program Stream Monitoring

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