Stream Environment Zone

What is an “SEZ,” and why are they important?

Stream environment zone (SEZ) is a term unique to the Lake Tahoe Region. The Tahoe Regional Planning Agency (TRPA) Code of Ordinances defines an SEZ as, “Generally an area that owes its biological and physical characteristics to the presence of surface or ground water.” This definition includes perennial, intermittent, and ephemeral streams; wet meadows, marshes, and other wetlands; riparian areas, beaches, and other areas expressing the presence or influence of surface or ground water. SEZs provide a variety of highly valued services, including water quality maintenance through nutrient cycling and sediment retention, flood attenuation, infiltration and groundwater recharge, open space, scenic and recreational enjoyment, wildlife habitat, and wildfire abatement, among many other functions and values.

Degradation of SEZ in the Lake Tahoe Basin: 

Large-scale SEZ disturbance in the Tahoe Basin began in the 1800s through activities like logging; cattle grazing; stream and river channelization and damming; and fire suppression, with environmental consequences that are still evident in the landscape today. According to the U.S. Forest Service, about 75 percent of wetlands in the urban areas of the Lake Tahoe Basin were lost to development.

What’s being done about it? 

TRPA and partners implement an SEZ program that protects existing SEZ and restores SEZ to its natural function where it has been previously lost. The accomplishments of partners are tracked on the Lake Tahoe Info website at

TRPA was awarded a grant from the U.S. EPA in 2017 to develop a regional plan for monitoring SEZ health, prioritizing SEZ restoration projects, and establishing metrics for measuring the success of restoration projects.

Technical Advisory Committee: 

To implement this project, TRPA convened a Technical Advisory Committee of stakeholders in the Tahoe Basin who work to protect and restore SEZ. The following organizations are part of the advisory committee:

  • Tahoe Regional Planning Agency
  • California Tahoe Conservancy
  • California State Parks
  • Nevada Division of State Lands
  • Lahontan Regional Water Quality Control Board
  • Nevada Division of Environmental Protection
  • U.S. Forest Service – Lake Tahoe Basin Management Unit
  • U.S. Environmental Protection Agency

2017 EPA SEZ Grant Materials:

Meetings materials:

October 26, 2017 – TAC

Reference documents: