Twenty years ago, planners in San Francisco’s Presidio had a once-in-a-generation opportunity: take a former Army Base in the middle of the second most dense urban area in the country and restore its buried-and-forgotten watershed.

Today, the project is nearly complete, with the newest section, Quartermaster Reach, opening to the public in December.

How did they do it? We’ll talk with Presidio Trust ecologist and Associate Director of Natural Resources Lew Stringer about the ideas, challenges, and successes of the restoration of the Tennessee Hollow Watershed in the heart of the city.