Convair Lagoon Eelgrass Mitigation

MBC assisted Teledyne Ryan Aeronautical (now TDY) with design, submittal, and implementation of their Convair Lagoon Eelgrass Mitigation Plan for replacing eelgrass habitat lost due to the capping of PCB contaminated sediments in Convair Lagoon, San Diego Bay. The mitigation plan was originally designed to replace 2.88 acres of impacted habitat. However, due to impacts to least tern foraging areas, unanticipated project delays, and required replacement ratios, the final transplant coverage was 5.65 acres. MBC transplanted a total of 23,374 eelgrass turion bundles to the site and monitored progress of the bed to assess the success of the restoration for five years following the transplant.

Since the site was initially designed to accommodate only about 4 acres of eelgrass, it was necessary to transplant at 1.7 acres of less than optimum habitat to fulfill the mitigation obligation. In this marginal habitat, only about 0.5 acres successfully supported eelgrass after three years. As a result, although eelgrass cover and density was very successful in the 4 acres properly prepared for transplant, overall areal coverage was insufficient to meet mitigation requirements despite the fact that 4.4 acres of eelgrass had become established in the lagoon. At this time, with about 1.25 acres of eelgrass habitat restoration needed to meet the mitigation requirements, other areas were sought to conduct eelgrass habitat restoration.

A search in San Diego and nearby bays proved unsuccessful; therefore other out of kind mitigation options were sought. During negotiations with the U.S. Fish and Wildlife Service (USFWS), MBC developed and implemented a plan to enhance an underutilized nearshore beach to provide a habitat attractive to least terns for nesting in South San Diego Bay. This restoration project was deemed acceptable and reduced TDY's obligation for eelgrass mitigation by 0.5 acres. MBC conducted additional negotiations with the National Marine Fisheries Service (NMFS), the California Department of Fish and Game (CDFG), and USFWS to develop alternative mitigation for TDY's remaining eelgrass mitigation obligation of approximately 1 acre.

As part of the negotiations, MBC published a white paper examining the long term problem of the loss of some giant kelp beds along the Orange County Coast that included a five year plan to restore kelp beds offshore of Laguna Beach. In consultation with NMFS, CDFG and USFWS and with the approval of the U.S. Army Corps of Engineers the kelp restoration plan was approved to restore 10 acres of kelp bed habitat at two sites offshore of Laguna Beach in exchange for TDY's obligation to provide another acre of eelgrass habitat. These sites provided about 40 acres of kelp habitat in the late 1980s.

MBC initiated the kelp restoration program on TDY's behalf in the summer of 2002, which resulted in the establishment of large areas of kelp in the Laguna Beach area. The restoration was determined successful and TDY compliant with its eelgrass mitigation obligation in 2010.