Watersheds & Stream Environment Zones

The Tahoe Regional Planning Agency developed the concept of a Stream Environment Zone (SEZ) to suit unique resources at Lake Tahoe. SEZs include perennial, intermittent, and ephemeral streams and drainages. They also include marshes and meadows. They generally have the following characteristics:

  • streambank (riparian) or wet site (hydric) vegetation;
  • alluvial, hydric soils; and
  • the presence of surface water or near-surface groundwater at least part of the year.

Benefits of Stream Environment Zones

SEZs are a small but important part of the Basin’s landscape. Within the Basin, development has reduced marshes by 75 percent, meadows by 50 percent, and riparian areas by 53 percent. While SEZs may only make up 5 percent of the land area in the Basin, they provide key habitat for 84 percent of the 250 wildlife species in the Basin. SEZs also help to reduce sediment and nutrient runoff concentrations by 70-90 percent. SEZs help buffer floods, including in and around neighborhoods. SEZs often provide scenic recreation opportunities.

Protecting and restoring SEZs is essential given their multiple resource benefits. The Conservancy’s Water Quality and Watershed program restores and enhances important SEZ and watershed areas through projects that include multiple resource benefits, including:

  • water quality improvement,
  • soil erosion control,
  • wildlife and fisheries habitat,
  • greenhouse gas sequestration,
  • vegetation enhancement,
  • scenic resource enhancement,
  • public access, and
  • educational and interpretive opportunities.

Watershed and Stream Environment Zone Projects

The Conservancy implements projects and also provides grants to enable partner agencies to take the lead. Basin partners develop projects using committees including representatives from partner agencies, such as the TRPA and the Lahontan Water Board. The committees assist in evaluating alternatives and restoration strategies. Restoration projects can include:

  • removing fill,
  • restoring natural, historical stream channels,
  • stabilizing and revegetating stream channels,
  • reconnecting floodplains,
  • acquiring SEZ properties, and
  • removing structures and buildings from SEZs.