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Wednesday, June 06, 2012


‘Malibu Lagoon’—
Whence Sustainability?
Lessons in Environmental Error


With the beginning of the Malibu “Lagoon” project and, one assumes, bulldozers now on the way, a final admonition summarizing its more questionable aspects is appropriate. These include the fact that the project does not involve significant restoration and is: unrelated to true lagoonal conditions, hydraulically non-functional, and unfeasible. Therefore, to it, the watchword of all environmental projects—sustainability—cannot be said to apply.
The idea of restoration is closely associated with environmental projects intended to improve the environment.  For example, efforts to protect endangered species are intended to restore them to some previous condition in which they flourished - presumably based on the idea that artificial conditions should not interfere with the natural evolutionary process.  In some instances, however, the concept of restoration seems to be applied simply as a project selling point, regardless of whether or not, in physical terms, it is actually possible.  Such projects commonly fail to specify exactly what past condition they are intended to restore. 
The current proposal to “restore” conditions in the mouth of Malibu Creek, popularly referred to as “Malibu Lagoon,” illustrates the problem. This aspect of it is particularly vexing, because environmental conditions there have been altered so much. The more obvious local events that have introduced distinctive environmental changes affecting conditions at the creek mouth include:  
1. fill placement between the bar on which the Colony is built and Malibu Road;
2. construction of the original highway bridge;
3. initial intense residential development, particularly in the Serra Retreat area, and consequent changes in the natural ground-water regime;
4. installation of the existing bulldozed channels at the western side of the creek;
5. installation of the new highway bridge.
All of these environmental changes have occurred in the context of extensive modification of the Malibu Creek watershed where, since the late 1800s, dams and property development have altered, and continue to alter, the drainage and hence also the environmental conditions at the creek mouth.  In this context, the very idea of restoration, by definition a reversion to some past condition, requires careful examination. In particular, the current idea of lagoonal restoration—which has institutionally gained wide, if ill-informed, acceptance—is simply to replace an existing artificial channel system at the western side of the creek mouth with another of somewhat similar design, the intent of which is to eliminate stagnant conditions there. 
The existing channels were installed in the 1980s—a project which, so far as the record discloses, had no specific ecological purpose. Apparently, the original parking lot and bridges over the channels were simply to provide better public access to the beach—a legitimate purpose of the Department of Parks and Recreation. Unfortunately, the design was left to those with at best a rudimentary knowledge of lagoons, and of stream hydraulics, none at all. It seems clear that the circuitous design of the existing channel system was intended to replicate meanders common to some true lagoons where low-energy stream hydraulics prevail. Such meanders, picturesque though they may be, can never develop a stable, healthy equilibrium in the Malibu Creek floodplain, because the creek is a high-energy stream. Having initially introduced an artificial and entirely bogus stream channel pattern that has harmed the environment, DPR now proposes to replace it with another, with essentially the same defects.
There is no evidence whatsoever that the original artificial channel system somehow improved environmental conditions at the creek mouth. To now describe the proposed project as a “restoration” begs the question of whether the original channel system could have had any advantageous environmental effect. Rather, use of the term by DPR seems nothing more than an appeal to the emotions of those who accept any environmental project as - by definition—desirable, while at the same time attempting to avoid recognition of the environmental ignorance that fostered the problem in the first place. 
To be fair, the original error in design matter is probably not attributive to current DPR representatives. However, the DPR’s continued intransigent defense of the project appears to have two purposes. One is to paper over the original poor planning by those probably no longer with DPR—in the scheme of things understandable if not laudable. The other, however, begs understanding, especially in view of the current State budgetary crisis—not so much because of the environmentally questionable attempt to restore an artificial condition engrafted on the creek mouth some thirty-five years ago, but because—as discussed below—the project simply cannot function as designed as a matter of basic stream hydraulics.
Most of the time, the waters of Malibu Creek are impounded at its mouth behind the sand bar, which is a result of the normal longshore drift, a process in progress for thousands of years. The impoundment is shallow - no more than a few feet deep. It is maintained by a combination of subsurface flow through the bar and creek inflow which is in turn partly from the creek itself and to an un- determined extent by ground-water inflow, since the lowermost reach of the creek—that across its floodplain—is an effluent stream. Depending on these flow rates, and on tidal height and wave action, the creek on occasion, by overtopping or by beach face headward erosion, opens a channel through the bar. As a result, the impounded area is partially drained revealing it to be essentially a mudflat. For thousands of years, such mudflat development at the mouth of Malibu Creek has served as a rookery. The idea that the birds would forsake it for the “avian islands” of the proposed project which—like the “restoration” idea is simply a selling point—nevertheless is blithely accepted by the local goofy greeners, preposterous though it is.  
It is clear that during inundation there can be no tidal intrusion and none while the inundated stream mouth is draining. Subsequently, during periods while the bar channel remains open  and the tide is high enough, there can be some ocean water entry. Even then, however, such entry is limited to channels in the mudflat the axes of which are roughly about three feet above mean sea level. This probably occurs less than about five percent of the time, and the extent into the stream mouth to which brackish conditions develop has never been established. 
It is the brackish condition resulting from the mixing of saline tidal water with terrestrial fresh water that defines the true coastal lagoonal environment. Such brackishness requires frequent periods of extensive mixing, a condition that does not develop in the mouth of Malibu Creek. This is not to say there are no valuable ecological conditions there, but simply that they are not lagoonal and therefore should not be regarded as such. Rather than a lagoon, the mouth of Malibu Creek is actually a kind of wetland with its own special ecology.
Assuming for purposes of discussion that there is some environmental advantage to having some kind of an artificial channel system at the western side of the Malibu Creek mouth, the issue this presents is whether the proposed channel configuration will eliminate the stagnant conditions in the existing artificial channels there. The basic idea is to replace them with a single artificial channel open in its upper reach to the natural creek channel near the highway bridge and open at its lower end near the beach bar. This, it is devoutly believed by its advocates, would improve the channel circulation and hence eliminate present stagnation.
This can happen only if there is some reasonably frequent stream flow. Natural channels are formed by running streams and it is their oxygen-entraining flow that prevents stagnation. However, flow in any channel, natural or artificial, can occur only if there is significant hydraulic gradient. In the mouth of Malibu Creek—i.e., the area the uninformed call a lagoon—there is, most of the time, no significant hydraulic gradient because of damming by the shoreline sand bar. Because there is no hydraulic gradient, there can be no significant flow in the planned bogus channel any more than there is in the existing bogus channels. No grading will change this fact, dismaying though it may be to Malibu’s formidable contingent of starry-eyed environmentalists and painted-in-the-corner DPRers.
Furthermore, even if the proposed less circuitous channel design avoids significant stagnation, it is difficult to see what environmental advantage it would have. In other words, how would conditions in the proposed channel—presumably in hydrologic equilibrium with the inundated area of the creek mouth—differ from that of the inundated area itself? If the answer is that a more lengthy creek mouth shoreline is presented with its own ecology, artificial though it would be, it seems that at the very least, it should be shown it is worth the project cost.
Generally, to be feasible, a project must be capable of being accomplished successfully. The feasibility of the proposed lagoon project is questionable on two levels - one short-term and the other long-term. 
In the short term, the project involves replacing the existing channel system with one of different configuration and depth. This requires a temporary dewatering system in which treated stream water is to be pumped to the shoreline—this to the unmitigated horror of local surfers who, fearing the efficacy of the treatment, are incensed at the idea of having to surf somewhere else for a while. Meanwhile, back at the creek mouth, some sort of dam or berm must be constructed while the excavation is in progress, because Malibu Creek is a perennial stream. Now understand, the excavation is to be done with bulldozers; however, no mention has yet been made, at least publicly, about the problem of ground water in the adjacent stream deposits. The excavation, which will reduce the local mudflat level some six to ten feet, will immediately result in a quick condition—i.e., an upward flow of ground water into the excavation driven by the hydraulic head of ground water in the adjacent in situ mudflat deposits. 
Unlike Sir Arthur Conan Doyle’s Grimpen Mire, in which one could not possibly sink, a bulldozer in creek deposits affected by a quick condition is quite another matter. Many years ago, to my astonishment, some Seabees showed me a rice paddy where they recently had lost a bulldozer in some “quicksand,” and, by George, when the project bulldozing gets underway, I’ll be there with my camera. I’m not going to miss it this time. What will be missed, however, is the original cost for excavation. Switching from the contract cost for bulldozing to an overrun cost for a dragline operation will be significant, but what the hell—it’s just tax money.   
In the long term, it is observed that about every ten to fifteen years, Malibu Creek floods. In this process, the entire shoreline bar, and with it, the ecological species of every kind in the lower creek reach, are washed away. There is little doubt that the channel system now proposed, open—as it would be to the main stream—will either be destroyed or at least partially filled with stream load when the velocity is reduced. How this problem, some $8–15 million later, differs significantly from that of today, no one seems to have considered.

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