The idea of restoring Malibu Lagoon is being sold on two false premises. One is that the lagoon at one time was much larger than it is today; the other is that by dredging a channel leading to a permanent opening in the barrier bar, sea water will enter at higher tides so brackish-water biota might thrive. Neither is valid.
Permanent lagoons exist only at the mouths of low-energy streams. Malibu Creek is a high-energy stream. The UCLA study by Professors Ambrose and Orme upon which restoration proponents rely simply assumes that because lagoonal deposits are found at various depths in borings over much of the Malibu Creek floodplain, there was once a large lagoon. However, historic records show that no such lagoon has existed during the past 200 years.
Malibu Creek produces deltaic deposits at the shoreline where, because of the presence of a barrier bar, very local lagoonal conditions can occur if protected from stream erosion. Such protection is afforded Malibu Lagoon by the highway bridge west abutment. The premise that once there was an extensive, inferentially pristine, lagoon is being used as an emotional crutch to foster support for “restoration” of a lagoon that never existed.
The other invalid premise is that hydrologic conditions in Malibu Creek permit creation of a sort of laboratory lagoon in a new channel. Now proposed is a problematical “naturalized berm” allowing entry of low-flow stream water but not sediment-laden flood water at the channel head and a permanent opening in the bar opposite the channel mouth, about 300 feet east of the Colony. Theoretically, the bar would stay open by flow in a dredged feeder channel from the main lagoon. But at flood cessation, that channel would fill with debris when the stream velocity reduces. All streams do that.
In 50 years living in Malibu, quite a number of them spent surfing, I have seen the bar opening migrate all along the shore in response to stream-load deposition, something no hydrologic model the lagoon proponents tout, can predict. The current restoration plan requires periodic, possibly annual, dredging that the EIR ignores.
Don Michael