To answer that question I studied tidal charts for October 12, 2014, the day I observed and reported the plume of sludge. What I found sent a chill up my spine.
The sludge took 3 1/2 hours (from 2:40 to 6:10) to transit from the south shore lagoon portal to just beyond the Park Street bridge. It had twice that distance to cover before tide changed at 9:21. It took the entire six-hour tidal cycle for the sludge to arrive at the mouth of the Oakand-Alameda Estuary, then the gooey mess would have been drawn right back up the same Estuary by the powerful ship channel current--BACK INTO SAN LEANDRO BAY WHERE SEABIRDS WERE ROOSTING FOR THE NIGHT!
Then the tide reversed again, and the process was repeated! For weeks, the deadly sludge I saw would have been transported back and forth along the Estuary between San Francisco Bay and San Leandro Bay, dousing hundreds of migrating seabirds again and again with layer after layer of toxic goo. (See illustration below, Image 1fx)
(click to enlarge photo)
|Path of Sludge Ploom|
Given the strength of the tide in the Estuary and the distance and speed of the tidewaters, whatever is carried out from San Leandro Bay is most likely to return on the next incoming tide. Then the process is repeated, endlessly.
Like a toilet flushing backward, the "bad stuff" kept returning. Alameda's Tidal Curse was a death trap for marine life.
The sludge's mass gradually diminished over time as some got deposited along the shoreline and bits were carried out into San Francisco Bay. But how long did that take, how many cycles? And how toxic were/are the residues to the seaweed and other marine life (fishes, barnacles, mussels, shrimps, crabs?)
San Leandro Bay's formerly robust marine life is feeding habitat for thousands of seabirds and their entire food chain. As food supply diminishes, so goes the seabird population.
The streaks of foam I saw April 12 (See Continuing Evidence of a Lethal Surfactant), if they are remnants of the initial October 2014 plume, could have returned hundreds of times during the intervening six months.
Migrant seabirds came here to fatten up for their return flight north, only to be drenched daily with a mixture of viscous chemical compounds we now know to be drilling mud (click here for April 19 blog identifying the Goo as drilling mud) and a lethal surfactant that got pushed farther and farther inland with each cycle.
Each successive dousing of surfactant would deposit another layer, to the point where death from hypothermia would result. A surfactant that might normally be considered harmless in a single dose would be lethal. (Click here for a detailed explanation of surfactants.)
Due to this Tidal Curse phenomenon, massive and lasting damage has likely been wreaked on the Estuary and San Leandro Bay as the tides have come and gone and layer after layer of toxic chemicals were deposited on rocks and seaweed and all forms of marine life and habitat, from pilings to bird feathers.
The chemical properties of a surfactant make it the ultimate toxin in a marine environment because surfactant molecules seek always to get between water and on-aqueous matter. Since essentially no marine life or habitat can escape a surfactant, its killing power is incalculable.