Standing with a hoe in his hand, Woodacre resident Melvin Wright surveyed an expanse of land nestled in the San Geronimo Valley. He squinted as the morning light washed over the brim of his hat.

Each Friday, Mr. Wright joins the People’s Watershed Collective, a group of dedicated land stewards who pull weeds, plant natives, and lead educational programming at the San Geronimo Commons. 

Overhead, a resident egret soared past the oaks lining the…