Stream Environmental Zones (SEZ)

Wetlands play a critical ecological role and provide a wide range of ecosystem services. Foremost among the many functions they provide are maintaining water quality, allowing groundwater infiltration, trapping sediments, serving as hotspots of biological activity and biodiversity, and playing a critical role in the cycling of carbon and nutrients.

The Tahoe Regional Planning Agency (TRPA) defines Stream Environmental Zones (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. The TRPA is tasked with preserving existing SEZ areas and restoring disturbed lands.

This project reviewed TRPA’s current SEZ standards in the context of the latest scientific understanding of wetland ecosystem function. The project report includes: : 1) an updated conceptual model for SEZ function; 2) a description of the  utility of the SEZ model; 3) an assessment of the utility of quantifying SEZ “function” through gross measurements of SEZ area; 4) a review of historic SEZ mapping ; and 5) a review of the potential climate change impacts  to Lake Tahoe Basin SEZs and associated ecosystem services.

Contact for more information: Alison Toy; natoy@ucdavis.edu​