The preservation and restoration of watersheds and stream environment zones (SEZs) are important components of the Conservancy's efforts to preserve and enhance the natural environment of the Lake Tahoe Basin.

A SEZ consists of a stream and its drainage, as well as marshes and meadows. Their preservation and restoration is essential to the health of the lake, because they provide natural treatment and conveyance of runoff, which they can reduce by as much as 70% to 90%.

SEZs also provide many other benefits. While they comprise only 5% of the land area within the Tahoe Basin, they are key habitat for wildlife, enhance the scenic values of the basin, and provide dispersed recreation opportunities for hikers.

This program involves a number of direct and grant-funded activities including the removal of fill and improvements such as dams, the revegetation of slopes, and the restoration of stream channels.

To date, the Conservancy has authorized the expenditure of more than $6.1 million for ten SEZ and watershed projects and ongoing restoration of Conservancy lands, which involve the preservation and restoration of 35 acres of land and 1.2 miles of stream.