If you have passed through San Francisco’s Presidio, you probably ran across at least one major construction site. For one, there is the massive undertaking of the Doyle Drive project, an engineering feat that has become a fixture of getting in and out of San Francisco via the Golden gate Bridge for the past couple of years.
On the other side of the park, overlooking the ocean from Lincoln Boulevard, rows of eucalyptus trees are being brought down to enhance the view and restore the hill to a native state.
But there is another project taking place in the Presidio that is not so easily spotted. Below Presidio Parkway, in what looks like a storage yard for heavy machinery next to a gaping hole in the ground, crews are underway in restoring Dragonfly Creek.
If you never knew there was a creek running through that portion of the Presidio, you wouldn’t be alone. There isn’t a creek here, at least not a visible one. In a procedure known as “daylighting”, Dragonfly Creek is being freed from the old pipe it has been running through for nearly a century and brought back to the surface.
“The creek ran through a pipe over 150 feet long, and underneath 15 feet of fill,” says Mark Frey, supervisory ecologist for the Presidio Trust. The weathered old pipes sat in mangled piles off to the side of the site, next to a modest stream of water finally flowing freely above ground.
The military buried the creek in the early 1900s, when the small valley through which Dragonfly Creek ran was filled and used as a storage yard. Once the current Presidio Parkway overpass was built above in the 1930s, the area below became little more than an empty lot underneath a section of road.
With Caltrans bustling above to redo Doyle Drive and the Parkway, the Presidio Trust seized the opportunity to let progress trickle down into the valley below and embark on this creek daylighting project. As a trade-off for the disruption caused by all the road work, Caltrans is footing the bill for a project that Frey says would probably not be happening right now otherwise.
Much of the work is being done by Caltrans employees and contractors from Hanford Applied Restoration and Construction, which is also working large projects at Muir Beach and Point Reyes.
The project began in 2009 with the removal of about 100 eucalyptus trees, which had been such a dominating force in the small valley that a bed of fallen leaves had grown to over a foot deep through out the whole area. Volunteers removed all the leaves by hand, and they were shipped off to the city compost yard.
“We removed the trees in cycles. We would do about 20 at a time,” says Frey. “We were conscious that birds inhabit the trees, and we didn’t want to disrupt them all at once.”
Daylighting in the Presidio first began six years ago at Thompson’s Reach in the lower Tennessee Hollow watershed, home to El Polin Spring. The Presidio Trust removed 77,000 tons of debris, and a 400 foot stretch of creek was brought back to life. Workers and volunteers planted 35,000 native plants of 100 different species. Since then, salamanders, birds, spiders, and butterflies including the Mylitta crescent have all found a new home in the restored waterway.
Once willows and other native plants take hold along the edge of Dragonfly Creek, wildlife numbers could quadruple, Frey estimates.
“I was just at El Polin the other day with a Hanford contractor,” says Frey. “He couldn’t even tell it had been a restoration project. The vegetation is so thick and natural, it looks like it’s always been that way. In five years, you won’t be able to tell this was a restoration site either.”
More daylighting projects are on the horizon for the Presidio. The most expansive one is set to begin as early as 2013. The Quartermaster Reach stretches from Thompson’s Reach to the Crissy Field marsh. What is currently a decaying parking lot will one day be another exposed creek and wetland habitat home to thousands of native plants and animals.
There is still much to be done at Dragonfly Creek. The heavy machinery portion is coming to an end, but contractors will continue to prep the site for planting this coming winter.
Plants for the project will be grown at the Presidio Native Plant nursery, which has open volunteer days every Wednesday and Saturday. For more information on the project and volunteer opportunities at this site and in the Presidio at large, call their main office at 415-561-5300.
Most recent in Habitats: Freshwater, Bay, Marine
Marine ecologists have long been alarmed at the potentially dangerous summertime growth of the single-celled algae Pseudo-nitzschia -- but there are still significant blind spots in our knowledge and research funding has been scarce.
El Nino | Habitats: Freshwater, Bay, Marine
How much sea foam along the shore is normal for this time of year? And how can you tell if it's harmful to marine life? We asked UC Santa Cruz oceanographer Raphael Kudela.
Ask the Naturalist | Climate Change | Habitats: Freshwater, Bay, Marine