What we do: Habitat Restoration

San Elijo Lagoon Restoration Feasibility Study

The purpose of the San Elijo Lagoon Restoration Feasibility Study is to provide a sound basis for deciding between different land management alternatives within the San Elijo Lagoon Ecological Reserve and to evaluate alternative actions to restore the habitat functions and values of the lagoon. The Conservancy plays an active role in evaluating and designing the alternatives for the project. This includes channel locations, inlet locations, hydrologic analysis of the different alternatives and costing.
Specific objectives of the Restoration Feasibility Study are to:

Promote multiple uses (shelter, foraging, nesting) of the lagoon by a diversity of species.
Improve habitat quality (sediment stabilization, increased water quality, decreased invasive species).
Increase species diversity.
Support sensitive (especially threatened and endangered) species.
Restore hydrology and soils to a more natural condition.
Enlarge the tidal prism to increase tidal action, circulation, inundation, and mixing.
Manage and reduce the influence of excess freshwater input.
Plan restoration of the whole lagoon at the ecosystem level of organization.
Plan restoration design around implementation of projects that would allow for adaptive management that would enable experimentation into the restoration design, monitor outcomes, and adaptively manage to better achieve the restoration goals.
Account for future changes in sea water inundation and salt marsh distribution via sea level rise.
Account for regional needs in design goals of the restoration of habitats.
Increase habitat heterogeneity.
Decrease habitat fragmentation.
Identify appropriate internal and external reference sites to track effects of project changes.

Examples of the kinds of actions envisioned to help meet the goals and objectives of the Restoration Feasibility Study include:

Dredging of channels.
Increases in tidal circulation.
Reduction in sediment inputs to the lagoon.
Improvement in water quality.
Improvement in habitat quality.
Removal of invasive/exotic plant species.

The objective of the project is to formulate and evaluate an array of feasible alternatives and recommend the one that most effectively improves environmental conditions in the lagoon while complying with local, state, and Federal environmental laws and regulations. The resource agencies are currently working on completing the environmental impact report for this project.

The need for restoration

San Elijo Lagoon provides a mechanism for conveyance and dissipation of floodwater. This leads to a reduction of erosion by slowing of runoff velocities, deposition of flood suspended sediments, shoreline stabilization, recharge of groundwater, and storage of surface water. San Elijo Lagoon also serves to filter suspended sediments, remove organic and inorganic nutrients, remove toxic substances, facilitate nutrient cycling, denitrification, and mineralization. Coastal lagoons, like San Elijo Lagoon are one of the most important coastal ecosystems, because they exhibit very high primary and secondary biological productivity. They are both sources and sinks for nutrients and organic particulates. This productivity supports a very diverse aquatic invertebrate, fish, and benthic communities and they serve as important nursery habitat for a number of marine fish species. They also support diverse populations of resident and migratory bird species, and provide critical habitat for many threatened or endangered plant and avian species.

The biological resources of San Elijo Lagoon have been gradually deteriorating due to the cumulative effects of hydrological and land use changes within the watershed, increased sedimentation, sewage spills, poor water quality, growth of invasive species, and severely limited tidal flushing. In recent years, increased urbanization of the watershed has accelerated the intensity and complexity of environmental impacts on San Elijo Lagoon. Urbanization has accelerated storm water flow rates, sediment transport, and increased input of chemical contaminants and nutrients associated with year-round urban runoff.
Recent management to maintain the inlet open to tidal flushing has substantially improved habitat quality relative to the stagnant conditions that previously developed when the inlet was closed for prolonged periods. Other efforts involving control of invasive species also have resulted in some improvements to habitat quality. Although important, these efforts do not remedy the overarching problems and concerns associated with sedimentation nor address problems to lagoon hydrology associated with urban runoff.

Substantial efforts are now being made to actively manage the San Elijo Lagoon ecosystem. A long-term financial endowment has been established to actively fund maintenance of tidal flushing. Recent efforts over the past ten years to keep the lagoon open to tidal circulation have shown that significant ecological benefits result from increased tidal flushing, as evidenced by increased diversity and abundance of fish, improved water quality, reduced production of mosquitos and midges, enlarged nesting areas for California least terns, Belding's savannah sparrows, and Western snowy plovers, and increased foraging by birds. These ecological improvements have also fostered significant public enjoyment of the lagoon. However, much more work is needed to sustain the productivity and to enhance the carrying capacity of this lagoon.

In addition to increased sedimentation and water quality degradation, animal and plant communities have been affected by the changes in hydrology and land use within the watershed. Fish and bird kills have occurred. Cattails and bulrushes, (fresh/brackish water species) have been encroaching from the East Basin into the Central Basin. These plant species are aggressively reducing circulation throughout the lagoon and are out-competing the salt marsh community. The San Diego Regional Water Quality Control Board (SDRWQCB) determined that 37.1 - 81.5 hectares (150 - 330 acres) of wetlands within San Elijo Lagoon are impaired due to urbanization of the watershed, changes in land uses, eutrophication, sedimentation, construction, agriculture, road building, bacteria, sewage spills, and inability to maintain tidal circulation. Specific impaired beneficial uses in the lagoon include: water contact recreation, wildlife habitat, riparian and marine habitat, and endangered species habitat. These beneficial uses have been impacted by excess nutrients, freshwater, and sediments. Although, degradation of environmental conditions is most evident in San Elijo Lagoon, many of these stressors are derived from perturbations throughout the watershed. All of Escondido Creek (205 square kilometers, 79 square miles) has been listed as impaired, due to degraded drinking water quality from both point and non-point sources of contaminants.