Forest Management

Home | Forest Management | Urban Lot Management | Protecting the Environment

Urban Lot Management Program

How do urban lots help to protect the Lake Tahoe Basin's environment?

Water Quality

Lake Tahoe watersheds are the natural drainage systems that supply the lake with water. The precipitation that falls within the Lake Tahoe Basin (both rain and snow melt) flows through the ground to creeks and streams, then into the lake. Water that is conveyed by an undisturbed watershed is usually quite pure, because the watershed's soil, plants, and organisms act as a natural water purification system. In fact, in an undisturbed forest, more than ninety-five percent of rain and snowmelt percolates into the ground, where it is filtered on its way to the nearest stream.

In 1968 scientists began testing the clarity of the lake with a device known as a secchi disk.  The secchi disk measures the depth of visibility in the lake.  Throughout the years the readings have shown a decline in water clarity. 

This graphic representation of secchi test results from 1968-2002
shows the declining clarity of the lake.  Data were provided
by the UC Davis Tahoe Research Group and the graphic was
provided by the League to Save Lake Tahoe.

The deterioration in water quality has occurred primarily because the watersheds at Lake Tahoe have been disturbed by the building of roads and urban areas. The pavement, rooftops, and other impervious surfaces commonly found in these urban areas shed over ninety percent of all precipitation. Instead of being filtered by soil, water runs off these impervious surfaces rapidly creating surface runoff. Surface runoff typically concentrates in ditches and gullies, causing soil erosion. When these greater-than-natural flows reach streams, increased stream bank erosion occurs. These increased surface flows help transport sediments such as nitrogen and phosphorus into streams and eventually into Lake Tahoe.

Acquiring undeveloped urban intermix parcels that are environmentally sensitive (meadows, creeks and streams, highly erosive soils, and steep topography) helps to mitigate the negative impacts of development on Lake Tahoe's watersheds. These acquired undeveloped parcels reduce the amount of future impervious surfaces within Lake Tahoe's watersheds and continue to provide the natural hydrologic function of undisturbed forest areas. In addition, these parcels can slow the flow of water from adjoining impervious surfaces and provide opportunities for construction of critical erosion control structures.            

Wildlife Habitat

While the Lake Tahoe Basin remains a significant area for wildlife, its fragile habitat areas have been adversely altered by human activity.  Most of the critical habitats in the Lake Tahoe basin occur in the lower montane forests (below 7000 feet) where the majority of development is concentrated.  Habitat and animal travel routes have been reduced, fragmented, and degraded by urbanization. Even in areas of less intensive development, the natural landscape has been significantly modified by recreational activities, roads and trails.  Acquisition of urban parcels plays a significant role in reducing the effects of habitat loss and fragmentation through preservation of undisturbed, natural forest environments and other natural habitats.

The quality of habitat available to plants and animals is protected and improved through watershed restoration and vegetation management activities on urban intermix parcels.  Watershed restoration activities enhance meadow habitats and restore natural water sources, while noxious weed abatement removes invading species from habitats.  Hazardous fuels reduction projects create healthy forests and improve wildlife habitat by increasing the distribution of forest age classes, promoting species diversity, and reducing tree stand density within the forest landscape.  A healthy forest will be able to support and maintain healthy wildlife populations better than an unhealthy forest.  Fuels reduction projects on urban lots also reduce the risk of habitat loss from catastrophic wildland fire, especially where critical  habitat exists within or adjacent to urban areas.  Additionally, the Forest Service considers the need to protect wildlife habitat when carrying out hazardous fuels reduction projects.  When not a hazard to people or property, logs and snags are purposely retained to provide habitat for wildlife that depend on them for perches, nesting, or cover. 

Urban Biodiversity Study

An ongoing urban biodiversity study, which began in 2002, is being conducted by the University of Nevada-Reno and the University of California-Davis in conjunction with the Forest Service.  The study aims to determine how urban intermix parcels influence plant and animal life in the basin and to what degree, if any, they reduce the effects of habitat fragmentation and degradation.  The results of the study, anticipated to be out in 2006, are expected to provide management agencies in the basin with recommendations and adaptive management tools to achieve biodiversity restoration goals and objectives.

Next Page