Drawbridge & the Station Island ponds


On Sunday I made my eighth hike out to Drawbridge (permit required!), a deserted town in the middle of South San Francisco Bay where the only firm ground was manmade land. This little town, once home to a couple hundred folks, was situated on Station Island along the first rail line to cross the Bay. It sprouted from the cabin of the bridge tender that looked after the railroad bridges on Coyote Creek and Mud Slough. At its height between construction of the railroad in 1880 and the Depression, surrounded by open marsh and sloughs, Drawbridge must have been a delightfully rustic destination for hunters and fishermen. By 1930 or so the South Bay environment was under considerable stress. Expansion of the salt evaporation pond network reduced tidal flow and scouring and as the marshlands disappeared so did the outdoor life that was Drawbridge’s raison d’être. The injury of marshland loss was followed by the insult of raw sewage from San Jose and by 1960 life in Drawbridge was untenable. The place was abandoned.


Figure 1. Amtrak roaring through Drawbridge

What’s left of Drawbridge is returning to the earth. Most of the buildings have been vandalized or burned to the ground. The survivors are sinking into the mud with missing roofs and collapsed walls. Still, it is a fascinating place to visit. As trains roar through at 80 mph it is easy to imagine the good times that occurred thereabouts. Though as it turns out Drawbridge is not the reason I keep hiking out to Station Island. Instead, it’s the two salt ponds (A20 & A21) that flank Drawbridge and contributed directly to its decline.

In March 2006, the levee separating Salt Ponds A21 and A20 from Coyote Creek was breached to reconnect the former evaporation ponds to the ebb and flow of Bay tidal waters. At the time of the beach, the ponds were desolate, whitish beds of deposited gypsum devoid of flora. Over the ensuing months life has begun to take hold in the form of vegetation. The vegetation is growing quite nicely now – outlining the high ground along historic marsh channels. Each time I visit Station Island there is noticeable change in the breached salt ponds and it is most interesting to watch this progress.

Change at Salt Pond A21

Figure 2: Oblique views of the northeast corner of Salt Pond A21 taken in April 2007 and September 2009. The earlier view shows a relatively desolate plateau surface, although not as desolate as the pond before the levee was breached. The latter view shows a distinct pattern of new vegetation forming around the edges of the historic marsh channels.

Change at Salt Pond A21

Figure 3. Plan views of the same small marsh channel located along the northern borrow ditch. The April 2008 view shows a bare surface with the drier areas mapping higher ground. By September 2009 vegetation has taken root in this higher ground.

I went back through the archives and selected one image from each of seven hikes to represent the surface condition of Salt Pond A21’s plateau (the eighth hike occurred during a high tide). Here is the progression through three years.

Salt Pond A21, Sept 06

Salt Pond A21, April 07

Salt Pond A21, Jan 08

Salt Pond A21, April 08

Salt Pond A21, May 08

Salt Pond A21, April 09

Salt Pond A21, Sept 09

Finally, here is a photo set on Flickr from the most recent September 2009 hike to Drawbridge:

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