Photos: Christopher Campbell
Islais Creek is the second longest creek running through San Francisco. Because of drought, it has recently trickled rather than raced. The creek is also inhibited because along its banks invasive Cape ivy and Himalayan blackberry mitigate its flow.
Consequently, any dash through Glen Canyon Park on the waterway’s journey to its Third Street terminus in the Bayview District is stymied.
Recent rains, however, energized the creek, which once served as an important water source for nineteenth century Gold Rush and Gilded Age San Franciscans and once, when it was not confined to a culvert after leaving Glen Canyon, channeled through meat packing South-of-the-Slot districts where feral feeding dogs dined off offal.
The neighborhood is called Dogpatch these days.
Friends of Glen Canyon Park volunteers have also contributed to the creek’s recent restoration. Supervised by the Recreation and Parks Department’s Natural Resource Department, the Friends, numbering as many as five over the last several months, have labored on the west side of the Canyon boardwalk, immersing themselves in thickets of Arroyo willow and tangles of Himalayan blackberry.
They encountered hidden poison oak, as well. This plant is often found intertwined with blackberry bushes. Poison oak, devoid of glossy leaves this time of year, still generates oils that can cause rashes and itching. Disguised, it is always a challenge to avoid, and several of the volunteers succumbed to its irritants over the last several months.
Throughout December and well into February, volunteers have accessed their work area by stepping from a boardwalk that begins a few yards after leaving Alms Road. The off-trail path to the creek bed is obstructed by widow-maker willow boughs and bulbous blackberry branches.
For each work detail, volunteers wear gloves, a few using sturdy leather ones. The Himalayan blackberry thorns are seriously stout and prickly and can penetrate skin, making it prudent to don protective clothing. The blackberry can be distinguished from the native variety by its thick thorns, very different than the spaghetti-like spines of the California plant.
Both fruits, however, make appetizing eating, but only the Himalayan variation vigorously re-roots, blanketing small trees and shrubs and effectively usurping them. Its abundant bounty is a food source for birds and animals, which helps to spread seeds. This makes the plant ubiquitous enough that little else can grow in the vicinity.
Each Wednesday, rising only after determining they won’t be knocked in the noggin by horizontal willow, which is drawn to a water source such as Isais Creek, volunteers kneel, pulling ivy from the creek side. Intruding blackberry stifled their progress. To fight them back they wielded loppers, pick axes and mattocks, unearthing stems, then prying up ground-deep root crowns. Thankfully the recent rains had saturated the earth, making the task easier.
Once blackberry was removed volunteers turned their full attention to the ivy.
Cape ivy is a perennial, and wildly invasive, vine that can root from every leafy node. Its leaves are shiny green, waxy. Native to South Africa, it has the ability to form a dense ground cover, growing up fences, buildings and trees. It is now rampant throughout California’s coastal riparian areas, thriving in the cool, moist conditions of the coast.
Left to its own devices the vine creates a monoculture, not only stifling the creek’s ability to run, but choking habitat that symbiotically exists side-by-side it. Diversity is endangered; birds cannot gain a foothold on trees, even bugs cannot crawl beneath shrubs because ivy’s detritus smothers the ground.
Being in the same city as the very much human-created Golden Gate Park, it is easy to forget that Glen Canyon Park is a natural area. Not man-made, it boasts few ornamental plants and shrubs, instead home to wildlife, trees, shrubs and plants that one would have to travel a distance to experience outside San Francisco’s 49 square miles.
Like other wilderness areas —Yosemite National Park or Mount Tamalpais State Park —
Glen Canyon Park must be maintained and managed to protective it from marauding invasive species eager to encroach upon plants that never evolved to fight them. Stewardship falls to the City’s Natural Resource Division, staffed with schooled naturalists.
At the moment looking to fill two vacant positions, NRD depends on the volunteer hours it obtains from Friends of Glen Canyon Park. That group’s membership include neighbors from Laidley, Chenery, Sussex, and Stillings Streets, from atop O’Shaughnessy Hollow and Bernal Heights, even from as far away as Plainville, Kansas, the home of a vacationing Sunflower state grandfather visiting his Bemis Street family.
Rec and Parks received 820 hours during the last fiscal year from these caretakers.
On Wednesday, February 13 the Friends did not meet. Rain poured from the sky, showering even more water into the already rapidly running creek, now almost a spillway.
Saturday showed sun, though, meaning next time the Friends would return to its Islais Creek beat.