Watershed: a land area where all of the water that falls within drains to a lake, river, or ocean.
For the past decade, revitalization has been underway within the Tennessee Hollow Watershed, and more improvements are on the way. It is rapidly becoming a place where people can hear the trickle of a creek, spot raptors and wildflowers, learn about the Presidio’s earliest residents, and enjoy a walk on a new trail.
The Tennessee Hollow Watershed covers 270 acres – about one-fifth of the park – in the eastern Presidio. It is made up of three streams that flow northward through a valley before merging into one watercourse that meets San Francisco Bay. Its creek system provides the primary freshwater source for the restored Crissy Field Marsh. Tennessee Hollow is important because of its critical plant and wildlife habitat and because some of the Presidio’s most important human history played out here.
A Brief History of the Watershed
For thousands of years, the Tennessee Hollow valley was a patchwork of streams and seasonal wetlands, grasslands, coastal scrub, and shifting sand dunes. The first people to drink its waters were likely the Yelamu Ohlone, whose seasonal camps have been discovered nearby at Crissy Field.
After the Spanish arrived in 1776 and established the fort known as El Presidio, the nearby valley was grazed by cattle. Three decades later, a colonial settlement made up of Spanish, Mexican, and Native American families formed around a spring in the heart of the watershed. Dubbed El Polin Spring, the site was occupied from 1812 through the 1850s. One especially noteworthy inhabitant was Juana Briones. El Polin is considered by some to be San Francisco’s “first suburb” and remains a hot spot for archaeology research and habitat restoration.
In the decades after the U.S. Army took over the Presidio in 1846, it changed the watershed by planting cypress and eucalyptus and by redirecting water via dams and underground channels to make space for a growing military. Tennessee Hollow aquired its name in 1898 in honor of the 1st Tennessee Regiment, a group of volunteer soldiers who camped here before shipping out to the Philippines for the Spanish-American War. The watershed was home to many tent encampments during that period and later served as temporary housing for San Franciscans left homeless by the 1906 earthquake. By the 1930s, several neighborhoods had sprung up and in the 1960s apartment buildings arrived when the Army expanded during the Cold War. As a result, only small pockets of riparian habitat remained.
A Place to Learn and Play
Today, the watershed is being revitalized and new ways for people to learn and play are taking shape. Key efforts include:
- bringing the creek system back above ground
- planting native plants and trees to create habitat
- creating volunteer and learning opportunities
- building new trails
- cleaning up Army-era landfills
- upgrading and reorganizing playing fields
- sharing the history of those who first lived here
El Polin Spring
While habitat restoration is ongoing, the heart of the watershed at El Polin Spring was transformed into an outdoor classroom for nature and history in 2011.
In 2005, 77,000 tons of Army-era landfill debris was removed from this site on the Main Post, and a portion of creek was brought above ground (or "daylighted"). More than 35,000 seedlings from Presidio Nursery were planted to create wildlife habitat. Today, Thompson Reach teems with native plants and nesting birds – signs that a vibrant ecosystem is thriving in the lower Tennessee Hollow Watershed. The number of nesting birds has increased dramatically, and stickleback fish are seen swimming in the creek. View a video about the Thompson Reach restoration >>
In 2008, the surface of the Presidio’s oldest footpath was repaired, the historic brick bridge was cleaned and rehabilitated, and a new boardwalk was added. Plans to improve the lighting fixtures along the trail are in the works.
The area below Inspiration Point Overlook contains one of the few serpentine grasslands within the Golden Gate National Recreation Area, and is home to two federally listed plant species, including the endangered Presidio clarkia. Restoration of native habitats and the historic viewshed has been underway here for a decade. Trees have been gradually removed from the native plant zone, and volunteers and staff have planted thousands of grasses, wildflowers, and shrubs grown at the Presidio Nursery. Poppies, irises, buttercups, blue-eyed grass, yarrow, buckwheat, wild onion, mission bells, sanicles, and an amazing array of native grasses can now be seen.
Fill Site 1 and Landfill 2
In 2010, two large Army-era landfills were excavated south of El Polín Spring. In 2011, several hundred cypress and pine were planted, along with a mix of woodland trees, shrubs, and native plants. A new section of the Mountain Lake Trail. As funding becomes available in coming years, a new practice field will be built near Paul Goode Field.
Landfill E, a large Army-era landfill beneath the former Pop Hicks Field (out of service for more than a decade) was remediated by the Presidio Trust in 2011. In the future the Trust plans to construct a new athletic field at the site, accompanied by parking, restrooms, and a picnic area. Also, the final section of the Ecology Trail will be constructed, providing a direct link for hikers and cyclists between the Arguello Gate and Main Post. As part of the Landfill E project, the western tributary of Tennessee Hollow was brought above ground (or "daylighted"). In the future the riparian zone to the north will be restored.
As part of the effort
to restore the Tennessee Hollow Watershed as a vibrant ecological corridor, 1.5
acres of riparian corridor and seasonal freshwater wetland will be created and
enhanced. To promote freshwater wetland creation, a number of trees will be
removed. Trees along the perimeter of the site will be protected, preserving
the character and stability of the surrounding cultural landscape forest. The
wetland project will be implemented in phases, with the removal of trees taking
place in fall 2013. Construction of the wetland and a pedestrian trail will
begin in summer 2014, following winter rains. Revegetation will follow in
winter 2014-15 and will include freshwater wetland and riparian plant species,
as well as upland coastal scrub and oak woodland species.
The replacement of Doyle Drive with the Presidio Parkway will allow for an 850-foot length of stream currently running through an underground drain to be brought above ground, restoring rare brackish habitat — where fresh water mixes with salt water. This restoration will link Thompson Reach and Crissy Field Marsh. A pedestrian trail will complete the northern end of the Tennessee Hollow Trail, extending from Julius Kahn Playground to Crissy Field.
Tennessee Hollow’s eastern tributary contains the longest stretch of remnant creek and riparian habitat in the watershed today. While some portions of the lower tributary are teeming with wildlife, upstream the Army filled in a large section of creek and directed its flow into underground storm drains. In coming years, this area will be brought back to life by relocating and upgrading Morton Field in order to daylight the underlying creek and create a new creek-side trail.