Wetlands restoration leads the way at Famosa Slough

New pond system will help improve water quality and wildlife habitat and show the way for Mission Bay.

by Jim Peugh


nce slated for filling and paving, the Famosa Slough is continuing to be a place where important lessons are being learned about accommodating and working with nature in an urban setting. Famosa Slough is a 30-acre wetland in the Loma Portal area of San Diego. Originally part of the Mission Bay wetland complex, it was gradually isolated from the bay and filled by development until citizens worked to protect the remaining Slough from further encroachments and establish it as wetland preserve.

This had led to the development of an Enhancement Plan to prevent the degradation of the slough and lead to improved wetlands functioning and to help treat urban storm drain runoff.

April 25 marked the official dedication of an important model project. The San Diego City Park and Recreation Department, in conjunction with the Friends of Famosa Slough, finished the major construction of three shallow ponds at the south end of the Slough. Runoff from the neighborhoods is channelled into an existing concrete pipe that empties into the Slough. The ponds have been constructed at the end of the pipe to help slow and restore a more natural flow into the Slough, which is connected to the San Diego river channel.

The ponds project occupies about two acres of area that had been badly degraded by the accumulated sediments and invasive vegetation from many decades of neglect.

The first of the three new ponds. Pipe provides overflow relief from flooding.

In October and November, volunteers for the Friends helped the Park Department remove much of the nonnative vegetation from the project site. The actual construction work started November 29 and was completed at the end of March.

The three ponds are connected by adjustable pipes and overflow spillways for big storms. The Friends have planted about 1,500 plants, including many that they salvaged and others that were bought or donated. They still have lots of planting and a number of finishing touches to complete.

The project is designed to improve the quality of the urban runoff water that flows into the south end of the Slough. The project will also allow better viewing of the Slough from the south end, will include a nature trail along some of the berms, will improve habitat value, and will facilitate natural expansion of the salt marsh habitat within the Slough.

It will be an important project to watch for results that might be obtained at other candidate restoration sites around Mission Bay: Rose Creek, Tecolote Creek and Cudahy creek. All of these were concreted over, as befitted the engineering approach of that era. Unfortunately, that design only speeds the flow of pollutants into Mission Bay and eliminates most habitat. Byron Wear, San Diego City Council representative from the area, was on hand to congratulate the Friends and others on their efforts. "The City is looking forward to learning how this can be applied elsewhere," Wear commented.


Treatment pond project overview


The three ponds will treat urban runoff from about 100 acres of the Slough's 300-acre watershed. It will intercept sediments, nutrients from fertilizers and pet wastes, and contaminants from a variety of sources. Managed ponds like these can be constructed in many places to reduce or prevent chronic water quality problems.

The ponds are also intended to substantially improve the wildlife value of the project area. They will provide an area of dense riparian vegetation and freshwater marsh, and upland vegetation for a broad range of birds and other wildlife. They will also provide benign and safe access for wildlife viewing and education.

Over the next three years, the plants will grow and the site will gradually look less like a construction site and more and more like a diverse riparian habitat.

Cement blocks in the foreground provide erosion control and a transition between the new ponds.

From August through November, the Friends and the Park Department removed the larger vegetation from the site. Most of it was invasive, such as Brazilian pepper, myoporum, and pampas grass. In November, the contractor, Merkel & Associates, arrived with heavy equipment and dug out the remaining vegetation, mainly Johnson grass, ice plant and cattails. The Park Department removed it from the site using their huge loaders and trucks.

The soft soil of the Slough made construction difficult. Several pieces of equipment got stuck, even though they were designed for tough areas. The original plan was to use large equipment to push large quantities of dirt from one area to another to form the ponds and berms around them. It became clear that the big equipment would just sink in the wet soil. Instead, the soil had to be dug up with an excavator, reaching from a stable area, and carried to its destination by special small bulldozers called Posi-Tracks. The Posi-Track placed the soil to form the permanent berms or, in many cases, temporary berms to support the excavator. Subsequently, the excavator dug up the temporary berms and placed the soil for the Posi-Track to move again. This was a pretty slow process, and took a while to figure out.

When the soil movement was complete, the major pipes were placed and the contours of the berms and ponds were completed. Later, pipes between ponds and the control structures were added to control the depths in each pond. The erosion control mats were then installed at areas where high levels of erosion could occur.


Revegetation of the treatment pond area


Merkel & Associates drafted a Habitat Mitigation Plan to guide the revegetation process. The plan emphasizes bulrush for the basin bottoms. As a perennial, bulrush will do a better job of containing contaminants than the annual cattails. The plan includes transition plants for the lower portions of the banks, such as willows, mulefat, saltgrass, spiny rush, San Diego marsh elder and California rose.

Looking downstream into Famosa Slough toward the new treatment ponds.

Revegetation efforts actually began as the project started. As the contractors removed bulrush from the site with an excavator, they stacked it nearby. The Friends dug through the stacks and salvaged the roots of the bulrush for eventual replanting. The Friends also salvaged saltgrass from dug-up soil and took cuttings of willows that were removed, rooting them for later replanting.

The upland areas have been revegetated with the same species of plants that the Friends have been placing along Famosa Boulevard, such as lemonade berry, buckwheat, goldenbush and sagebrush. They will also plant several riparian trees, including cottonwood and sycamore, in the wetter upland areas. This great diversity of native plants is selected to support a broad native wildlife community. Watering, weeding and putting in more plants will be a major chore for the next year, and volunteers are welcome.


Wildlife at the treatment ponds

  The new treatment ponds already have had some wildlife use. During construction, willets, yellowlegs, snowy egrets and owls would move in after each day's work, to see what morsels were revealed. Now that the construction is over, the ponds are frequented by blue-winged teal, mallards, willets, and many red-winged blackbirds.


Participants in the treatment pond project

The design and engineering of the treatment ponds was contributed by Project Design Consultants, a San Diego landscape architect firm. The Armorloc blocks and A-Jacks (erosion control materials) are being provided at cost by Erosion Technology, Inc., and Armortec. The primary funding is from a $126,000 Clean Water Act, section 319(h) grant, which the Friends applied for and won. The grant is administered by the San Diego Regional Water Quality Board. The project is also supported by a $40,000 grant to the Friends from the US Fish and Wildlife Service, a major contribution of services from the City, a grant match between the Park Department and the Friends for materials, and labor and funds from the Friends for revegetation and berm stabilization. Merkel and Associates did the construction for the City and is the consultant for the Friends. Some of the plants for revegetation have been contributed by Tree of Life Nursery, Merkel and Associates, and Walter Andersen Nursery; others were purchased or salvaged by the Friends.

Volunteers from the Friends, along with groups from Point Loma Nazarene University, Alpha Phi Omega at UCSD, CHiPS at Scripps Institute of Oceanography/MPL, NCCC, Mesa College, Pt. Loma High School, and Dana School, contributed lots of labor at many phases of the project.

The Friends of Famosa Slough (FFS) is a nonprofit organization established to protect and restore the Slough as a natural wetland preserve and to promote public awareness of the importance of wetlands. The Slough was purchased by the City of San Diego in September 1990 and is managed by the City's Park and Recreation Department.

Volunteers needed!

2nd Saturday of odd-numbered months:
May 13, July 8, September 9, etc.
Meet at 9:00 AM at the intersection of West Point Loma and Famosa Boulevards.

Beginners welcome!

3rd Saturday of every month
April 15, May 20, June 17, July 15, etc.
Meet at 1:00 PM near the kiosk at West Point Loma and Famosa Boulevards

Friends of Famosa Slough, PO Box 87280, San Diego, CA 92138-7280. Email: peughhome.com. For more information, call (619) 224-4591 or see the FFS website: groups.sandiegoinsider.com/ffs