channel edges, high marsh habitats, wetland- 

 upland transitions, inland lagoon, and the 

 adjacent upland. Several roads were present 

 around the periphery of the wetland. 

 However, there was only a path and no houses 

 on the barrier dune adjacent to the salt marsh. 

 Signs of agriculture in the floodplain are 

 evident upstream of the estuary and north of 

 what is now Monument Road. 



depression had been diked to create a sewage 

 pond. Presumably, the dredged channel 

 carried the overflow to the ocean. A bridge 

 had been built over the dredged channel, 

 probably to truck gravel from shallow pits 

 just south of the inland lagoon. The mouth was 



Several physiographic features that 

 changed in later years are noted in the photos 

 of 1928, 1953, 1964, 1970, 1984, and 

 1985. In 1928 (Figure 2.6), the dune had 

 intermittent vegetation extending from what 

 is now Imperial Beach Blvd. south to the 

 estuary mouth. This is consistent with 

 Purer's (1936) description of a rich flora 

 that included shrubs such as lemonadeberry 

 (Rhus integrifolia). Channels had major bare 

 mudflats along their periphery. The inland 

 lagoons clearly contained marsh vegetation 

 throughout. Only a small area of channel is 

 visible, and that was dredged to link the lagoon 

 with the estuary. Two islands were present in 

 the main north-south channel. The mouth 

 (Figure 2.6) had tidal flushing through an 

 opening that angled southwest. A relatively 

 large embayment was located south of the 

 mouth, although it may have been shallower 

 than indicated on the 1904 map (Figure 2.3). 

 What appear to be large salt pannes were 

 present east of the the inland lagoon. 



By 1953 (Figure 2.7), many changes had 

 occurred both in the periphery of the estuary 

 and within the area of tidal influence. 

 Imperial Beach was a well-populated 

 community: a military airport had been built 

 east of the estuary; military activity was 

 evident along the southernmost portion of the 

 beach; and agricultural activities had 

 proceeded to within a few blocks of the beach. 



Within the estuary, several habitats had 

 changed dramatically. The barrier dune had 

 begun to be developed for housing along the 

 northwestern part of the estuary, although 

 dune vegetation was still present farther 

 south. Salt marsh vegetation had established 

 along the edges of the channels. A sewage- 

 treatment plant had been built north of the 

 inland lagoon, and the northernmost 



Figure 2.7. The 1953 aerial photograph of 

 Tijuana Estuary (from U.S. Dept. of 

 Agriculture). Note bridge (B) over the 

 dredged channel, sewage oxidation pond (S), 

 brackish marsh (BM), military installations 

 (Ml), and agricultural uses (A). 



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