January 08, 2008

Sometimes a River Storms Through It

This picture of the San Lorenzo River passing through Santa Cruz was taken in the aftermath of a particularly dramatic storm that battered Northern California last Friday.

The San Lorenzo feeds enough water into the Pacific at Santa Cruz on a yearly basis to earn the name "river," but typically packs all its credentials into a few dramatic episodes each year. In the drier months between late April and late October less water flows in the San Lorenzo than in the average self-respecting creek. In those months its riverbed in Santa Cruz is a protobog of tule and willow and scruffy brush and lounging herons ankledeep in its midriver shallows, through which a narrow course of water meanders in the laziest possible way to exhaust itself against a sandbar that annually blocks the mouth of the river from contact with Monterey Bay.

But commonly in winter storms descend on Santa Cruz from the great weathermaking waters of the the Gulf of Alaska, enormous energetic things gusting with the rain that's the year-round lot of the continent's coast from Juneau to Mendocino, but which in winter pulse vigorously south to engulf as well the coast and inland parts of California during its customary rainy season, whose middle innings reach from November to March.

There's a ridge in the distance in the picture above, and a high point on the ridge from which it drops off to the right. That's the western side of the notch in the mountains through which the San Lorenzo River pours its waters onto the floodplain where Santa Cruz is built. The green berm in the picture on the far side of the river is one of the levees over which the San Lorenzo will manage to flow some day, so prodigious at times is the volume of water transferred from from cloud to watershed north of Santa Cruz in the healthiest of winter storms. Prior to the existence of Santa Cruz the San Lorenzo would just sort of blurt out all the water rushing from that notch in the mountains onto the mile or so of floodplain and let it seek its own sweet way to the ocean, from storm to storm rushing in whatever arbitrary direction it might so incline to reach the beach here or there in any given year.

This is fundamentally uncivil behavior from the point of view of a city which insists on inhabiting the river's floodplain, which is the longstanding and often enough inundated plan of the makers of the city of Santa Cruz.

Fifty years ago a previous version of the plan failed to prevent the San Lorenzo from inundating downtown, much of which, fronting the river, was scraped away and replaced with parking lots and newer buildings in that flood's aftermath. It was determined that what Santa Cruz needed was a storm drain instead of a river running through it, a storm drain of the sort championed by the U.S. Army Corps of Engineers in those days, and so it was built, a modern-made channel for the San Lorenzo. Twenty-five years ago that plan failed and the San Lorenzo flooded Santa Cruz again. The railing in the foreground, the levees on either side of the river, the new bridge connecting Laurel Street downtown to Broadway on the eastern side of the city, all of these are features of the newest plan.

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