INLET MAINTENANCE PROGRAM   The San Elijo Lagoon Enhancement Plan (County of San Diego 1996) identified several opportunities for enhancement and restoration, mostly by reducing the sedimentation problem and improving tidal exchange and circulation. 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.   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. The ecological effects of increased runoff have been compounded by the obstructions to flow caused by the three major transportation corridors that segment the lagoon. When the lagoon is closed to tidal flushing, all sediment particulates discharged to the lagoon are deposited within the lagoon. Of the 20,000 to 24,000 cubic yards (25,000 to 30,000 tons) per year of sediment that enter the lagoon from the watershed, only about 8,000 cubic yards (10,000 tons) actually transit the lagoon and are discharged to the ocean (Soil Conservation Service 1993). As a result, water quality conditions and many of the habitats within the lagoon have become degraded even though it is still a significant environment for migratory birds; several of which are critically endangered species. When the lagoon is open to tidal flushing, much of this sediment transits the lagoon and is discharged to the ocean.   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 the lagoon.   Generally the inlet becomes intermittently blocked by an accumulation of sand in the tidal channel during the winter storm cycles. The cool weather helps keep oxygen levels in the lagoon in the safe zone. As temperatures rise in the spring and the demand for oxygen increases an inlet operation is conducted before problems arise. A major dredging operation to pull out the sand from the tidal channel and remove the cobbles can cost upwards to $80,000. Timing this procedure in the spring after the winter storm cycle increases the chances of the inlet staying open throughout the warmer summer months. Previous experimental openings showed that a dredging operation in the winter has little chance of keeping the inlet open during the winter storm season.

 

WATERSHED PROTECTION PROGRAM   In 2004 San Elijo Lagoon Conservancy was awarded a $3.9 million Watershed Protection Grant for the benefit of the Carlsbad Watershed Network to control invasive non-native plants in riparian and wetland habitats within the Carlsbad Hydrologic Unit (CHU). The CHU includes watersheds that drain into the following creeks that flow into the Pacific Ocean: Loma Alta, Buena Vista, Agua Hedionda, Encinas, San Marcos, Cottonwood, and Escondido Creeks. Restoration efforts will focus on removing the most threatening invasive plant species which are arundo, tamarisk, pampas grass, and palms.   The Carlsbad Watershed Network is a consortium of nine non-governmental organizations, seven cities in north-coastal San Diego County, the county of San Diego, and over 10 other governmental agencies and academia. The grant program is administered by the State Water Resources Control Board.   The project is expected to significantly improve the conditions, functions, and habitat values of the riparian/wetlands by reducing the detrimental processes associated with invasive plant species, and increasing the ability of the riparian/wetlands to filter contaminants, reduce flooding and bank erosion, and reduce sedimentation. Further, it is expected that these efforts will reduce backwater flooding, the potential for debris jams on bridges and trestles, and the substantial accumulated fire fuel load.   Individual landowners with invasive plant species on their property are contacted and written permission is obtained prior to initiation of any work. There are no costs or fees to the property owner associated with this project.   The main invasive non-native plant species include giant reed (Arundo donax), pampas grass (Cortaderia selloana), tamarisk (Tamarix ramosissima) and palms. These plants do extensive damage to private property and natural resources. They contribute to flood damage, increase the risks associated with fire, and degrade native habitat. They also spread aggressively, potentially onto neighboring properties, making them difficult to control. The targeted plants are treated by applying Rodeo® or Round-up® herbicide to the plant. Both herbicides pose no risk to humans or other animals when used properly. Rodeo¨ is certified by the U.S. Environmental Protection Agency for use in and around wetlands. Fully licensed and insured professionals carry out the applications.   All treated invasive plants are mulched on the site if possible. This reduces the chances of infestation by other non-native plant species. Extra care is taken to avoid impacting native vegetation during the mulching process.   The next phase in the process involves re-vegetation. Native plants will be planted in appropriate areas after invasive plants have been treated, with the goal of restoring habitat function. Re-vegetating the area with native shrubs and trees will greatly improve the riparian habitat that ultimately improves the quality of water entering the lagoons of the CHU, including the San Elijo Lagoon.   Program Updates The initial Watershed Protection grant from the State Water Resources Control Board ends as of March 2007. With that initial funding we treated 279 acres of invasive non-native plants throughout the CHU and identified an additional 290 acres of invasive plants to be treated with other funds. The continuation of the invasive species control program is essential to the health of the CHU.   The initial Watershed Protection grant from the State Water Resources Control Board ended in March 2007. (pdf format 47.2 MB) [ Click here to download the final report ]   Our invasive species data layer is available for interested GIS users ( Inv_2007_03_Parcel.zip - 3.5 MB ) [    Click here to download ]   In 2006, the Wildlife Conservation Board granted an additional $1.5 million to the CWN for the continuation of the invasive species control program throughout the CHU.

 

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