Ballona Wetlands
Existing Conditions

From a report dated 4/2/97 by Dr. Michael Josselyn Ph.D.: 

Currently, Ballona Wetlands is essentially a non-tidal wetland and is leveed along its border with Ballona Creek, a tidally influenced channel.  Freshwater from stormwater runoff enters Ballona Wetlands from its eastern and southern boundaries and exits to Ballona Creek in a series of flap gate controlled culverts on channels on the western portion of the wetlands.  However, the flap gates do allow for very little tidal influence within the channels.  Currently, tidal influence in the wetlands is such that water reaches an elevation of +.5 ft msl.  With this being the maximum water elevation, tidal flows remain entirely within the existing channels and tidal exchange is extremely limited.

In a report on the quality of the habitat at Ballona Wetlands, Bol and Zedler (1991) observed the following:

  • Tidal range inside Ballona Wetlands was greatly reduced.

  • Water salinity declined progressively upstream.

  • Macroalgae were abundant and appeared to smother the bethos.

  • Benthic invertebrates were rare and a 62% decline in abundance occurred following the freshwater intrusion in later summer.

  • The fish community was lower in species richness and abundance.

  • Few birds used the channels.

Compared to other open and partially open coastal lagoons, Ballona Wetlands had the lowest benthic invertebrate taxa and abundance, lowest plant diversity, and lower number and abundance of fish (Zedler, 1996).

In a study that compared the fish community of the Ballona Wetlands from 1980-81 to 1996-97, Swift (1997) found that species composition had changed and that few stations have fish.  Swift also noted that the "wetted" habitat is reduced, two species no longer use the marsh as a nursery, and an additional introduced species (sailfin molly - an escaped aquarium fish), has become dominant in much of the marsh.

References:

Boland, J. and J.B. Zelder.  1991.  The functioning of Ballona Wetland in relation to tidal flushing.  Part 1 - Before tidal restoration.  National Audobon Society.

Zedler, J.B.  1996.  Tidal wetland restoration; a scientific perspective and South California focus.  California Sea Grant Publication.

Swift, C.  1997.  The fish fauna of Ballona Marsh, an urban estuary on the western Los Angeles Basin.  Abstract.  California and the World Ocean, '97.

 

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