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San Diego Bay Native Oyster Living Shoreline

Owner: Port of San Diego

Project Location: Chula Vista, California

The San Diego Bay Native Oyster Living Shoreline Project is a shoreline pilot project adjacent to the Chula Vista Wildlife Reserve.  This pilot project involves the placement of reef ball elements for the purpose of conducting a five-year monitoring program to study the success of the pilot project to recruit native oysters to the reef ball elements and to stabilize the adjacent shoreline.

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Project Design

The Project utilized a modular approach under which constructed oyster reef ball elements were placed in a series of six arrays at two tidal elevations along the Project site’s mudflat (three Reef Treatment Areas at each of two elevations). Individual reef ball elements (baycrete reef balls,described below) were organized into reef groups consisting of four reef ball elements placed in a square pattern; the approximate footprint of each reef group is proposed to be 8 feet by 8 feet (including some open space between each element), or 64 square feet. Reef Treatment Areas consist of 15 reef groups arranged in a checkerboard pattern with spacing of 15 feet between the center of each group. Therefore, each Reef Treatment Area consists of 60 reef ball elements. Each oyster Reef Ball Element consists of a baycrete (concrete mixed with local sand and oyster shell aggregate) reef ball with a top diameter of approximately 2 feet, and a wider base which is 4 feet in diameter. The height of each element stands approximately 30 inches above the mudline.

Reef Ball Element Placement & Construction

The project required the placement of 360 Reef Ball Elements, weighing 1,350 pounds each, within six (6) Reef Treatment Areas.  The Project site was constrained by very shallow water with all Reef Ball Elements requiring placement between the 0.00' MLLW and +1' MLLW contours  The site was also constrained by existing eel grass which was required to be protected.  Regulatory permit conditions contained in the Port of San Diego permit, Coastal Commission Permit, National Marine Fisheries Permit and California Fish & Wildlife Permit required full-time biological monitoring to monitor avoidance of eel grass beds and water turbidity that can be caused by construction activities.  With these constraints, construction of the Reef Treatment Areas was required to be completed during tidal conditions which were high enough to allow access with marine construction equipment thereby restricting available work times and limiting installation vessels to small, shallow-draft vessels.  The contract duration was 90 days but, this project was completed 55 calendar days ahead of schedule.

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