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R.Silvestri
Corte Madera del Presidio Creek Capacity Maintenance Now Critical With Winter Rains Coming
El Nino Is Coming
The National Weather Service is now predicting a high probability of an El Nino storm system hitting Northern California this winter. The system now building in the Pacific is the largest recorded in over 40 years. If this prediction is correct, the odds of severe flooding in Mill Valley and particularly in lower Sycamore Park, along the Arroyo Corte Madera del Presidio Creek, are extremely high.
This flooding could easily surpass the disastrous inundations we experienced in the New Year's Eve flood of 2005. In 2005, a flood lasting less than 24 hours caused millions of dollars in damage to property and destroyed hundreds of automobiles.
In spite of this year's winter storm warning forecast and even after losing a major, homeowner's lawsuit in 2006 (due to this same lack of preparedness), the City of Mill Valley has essentially done nothing to maintain the Arroyo Corte Madera del Presidio Creek that runs through the heart of our valley.
Corte Madera del Presidio Creek Is In Urgent Need of Maintenance
An inspection of the creek, as noted in the attached photographs, shows that overgrowth of vegetation, fallen trees, trash, embankment collapse and silting of the stream bed, which reduces flow capacity, has gone unchecked for a decade.
The worst of these problems are found in the portions of the creek running from just south of the bridge at Camino Alto Avenue (near the Safeway shopping center), north to several hundred yards past the bridge a La Goma Avenue (behind the newly constructed office complex).
In a number of instances in this stretch of the creek, as shown on the attached photographic tour, the creek water flow is almost completely blocked. In several places there are even mature trees growing in the channel bed, some of which appear to be at least ten years old.
In addition, the silting up of the creek bed, due to runoff and collapse of the creek embankments, has now significantly reduced the overall flow capacity of the waterway. This essentially ensures that dramatic increases in runoff, as is the case during major rain storms, will force the water to jump the sides of the creek channel and direct the flow onto Sycamore Park streets and through the neighborhood, as it did in 2005.
The Creek is Not Entirely "Natural" and Requires Maintenance
The Corte Madera del Presidio Creek is not entirely a "natural" stream. Sycamore Park was created by the Army Corps of Engineers in the early 1940's by filling in a swamp lands area very similar to what we now find at Bayfront Park. In doing this they filled in many small streams and waterways and confined all the flow into one channel, Corte Madera del Presidio Creek. But the groundwater, running beneath our neighborhoods, continues to travel along its old routes, which has caused portions of some blocks to sink and become more prone to flooding (mid block of Plymouth, Oxford and Sycamore near Valley Circle).
Vigilant maintenance of the creek, removal of overgrowth, excessive vegetation, fallen trees and restoration of creek embankments is critical. Removal of excessive build up of silt and sand bars that have formed as a result, are equally critical in order to maintain adequate drainage to prevent street flooding.
I urge everyone living in proximity to the Corte Madera del Presidio Creek to contact the City of Mill Valley and demand immediate, emergency preparedness action to do all we can to prevent severe flood damage to our homes this coming winter.