San Elijo Lagoon, one of the few remaining coastal wetlands in San Diego County, provides vital habitats for resident and migratory wildlife and sensitive, threatened, and endangered plants.
The area also offers recreational opportunities to the surrounding community. Unfortunately, 20th century economic development took its toll on the lagoon and its ecosystems. The urbanization of the lagoon’s watershed introduced sediment, nutrients, and bacteria to be introduced into the lagoon; it also demanded the addition of transportation infrastructure, and disposal of sewage sludge. All contributions negatively affected the lagoon. Construction of US Highway 101, Interstate 5, and a railroad line through the lagoon has resulted in constricted tidal and storm flows. Sewage sludge was disposed of in the lagoon contributing high concentrations of nutrients and bacteria. Upstream inputs led to the lagoon being 303D listed by the Water Board for sediment, bacteria, and nutrients. The modification of the original full tidal system, along with direct effects of urbanization upstream has led to degraded habitats and impaired water quality.
Moffatt & Nichol performed all preliminary engineering, led the team for environmental review and permitting, and completed final engineering. We provided lagoon modeling to address hydrodynamics, sedimentation, and water quality. We also providing shoreline modeling and analyzed surfing for impacts of sand placement. Our team monitors the site now during construction and is preparing a five-year post-construction monitoring plan.