Thompson Reach, located in the lower Tennessee Hollow Watershed, connects the Main Post to Crissy Field Marsh.
This corner of the Presidio has experienced great changes over time. For millennia a creek ran here, draining the eastern portion of the Presidio and carrying freshwater to an expansive marsh along the northern waterfront (today's Crissy Field). In the 1870s, a vegetable garden was cultivated to the west of the creek bank. In 1883, a firing range was built on the site. Later, as the former Letterman Hospital expanded, the creek was culverted and a dense complex of hospital support buildings was built over it. When those structures were demolished in the 1970s, the resulting building debris further filled this natural depression with its hidden creek.
In 2005, 77,000 tons of Army-era debris was removed and 400 feet of creek was brought above ground (or daylighted).
After remediation was complete, more than 35,000 seedlings from Presidio Nursery were planted to create wildlife habitat. Today, thousands of native plants representing more than 100 species flourish along the re-established streambed.
Nesting birds and many species of butterflies are now spotted here, and stickleback fish are seen swimming in the creek – signs that a vibrant ecosystem is thriving in the lower Tennessee Hollow Watershed.