restoration will improve the circulation of 

 salt water and further reduce chances for 

 brackish marsh expansion. 



Brackish and freshwater marsh habitats 

 can be expanded upstream of the estuary. 

 Suitable sites exist along the Tijuana River 

 and in abandoned agricultural lands. The use 

 of treated wastewater is encouraged for 

 creation and maintenance of artificial 

 marshes. 



Channels and creeks. The channel 

 habitats at Tijuana Estuary are important to 

 nearly all estuarine animals; they are 

 recognized for their value in support of the 

 food chain. All of the endangered birds use 

 channel and creek areas for feeding. In 

 previous years, there have been recreational 

 shellfisheries and commercial bait fisheries. 

 At present, both shellfish gathering and 

 fishing are prohibited in the estuary. 



The problems that affect the channels and 

 creeks ultimately have an impact on the entire 

 estuary, because the estuarine waters move 

 throughout the system. Tidal closure, 

 sedimentation, disturbance from dredging, and 

 reduced water quality (wastewater input, 

 nuisance algal blooms, reduced salinity) all 

 require active management. The impacts of 

 tidal closure are detailed in Chapter 5. 

 Increased sedimentation rates have an impact 

 on benthic organisms, and the associated 

 turbidity affects water-column species. 

 Dredging to remove accumulated sediments and 

 restore tidal flushing in turn creates 

 turbidity and alters the substrate. 



Tidal restoration should make existing 

 channels more suitable for fish and 

 invertebrate use. Excavation of the 

 experimental marsh should have beneficial 

 effects downstream as increased flows erode 

 the fine materials that have accumulated in 

 the Old River Channel. New channels that will 

 be constructed throughout the new tidal 

 marshes should expand this habitat type 

 substantially. 



The monitoring program for channel 

 fishes and invertebrates began in 1986, but 

 was reduced in 1992 due to a 33% cut in 

 funding. Sampling occurred quarterly 



through 1991, but will be done semi- 

 annually in 1992-94. Less frequent 

 sampling will make it difficult to determine 

 how the channel biota respond to the 

 elimination of sewage flows and to improved 

 tidal flushing once the restoration program is 

 underway. 



• Sandflats and mudflats. The intertidal 

 flats are closely associated with tidal channels 

 and creeks, and the impacts of disturbance and 

 considerations for management are similar. 

 The primary values attributed to these sites 

 are their habitat for shorebird resting and 

 foraging and feeding areas for the light-footed 

 clapper rail and Belding's Savannah sparrow. 

 Artificial impoundments can augment these 

 natural shorebird habitats, as was 

 demonstrated by the 70+ wetlands constructed 

 near PERL and used by numerous species of 

 waterfowl and shorebirds. There are 

 numerous opportunities to construct wetlands 

 within the Tijuana River Valley, and treated 

 wastewater should be used for habitat 

 expansion inland of the estuary. Careful 

 management of the hydrology of wastewater 

 wetlands would be needed to insure that the 

 downstream wetlands are not damaged by 

 excessive discharges of fresh water. 



• Beach and dunes. The esthetic quality of 

 beaches makes them the habitat most highly 

 valued by the public. Consequently, human 

 use is extensive throughout the year. 

 Ecologically, the habitats are valued for their 

 support of native animals, including the 

 globose dune beetle, sandy beach tiger beetle, 

 sand dune tiger beetle, wandering skipper, and 

 two nesting birds, the California least tern 

 and snowy plover. Other species, such as 

 Belding's Savannah sparrow, feed on dune and 

 beach insects. The native plants are 

 especially important to the ecosystem, 

 because they stabilize the dunes, which in 

 turn protect the estuary from sea storms. 



The major problem facing the beach and 

 dunes is coastal erosion. Substantial losses of 

 sand occur each winter, but not all is 

 replenished each summer; a continual net loss 

 is obvious from aerial photos from 1928 

 through 1985. The height and location of 

 dunes has changed with recent storm 

 overwashes, and stabilization is needed. In 



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