The current alignment of Strawberry Creek is well known, and its future location is up to the community. Frank Greenspan’s April 25 letter to the editor suggests that there is some public confusion regarding the current status of the Strawberry Creek and proposals to daylight it. The creek presently enters a five-by-six-foot arched box culvert as it leaves campus at Oxford Street. The culvert jogs diagonally under buildings to Allston Way, runs down Allston Way to near the post office, cuts diagonally under the YMCA to the Center Street side of City Hall, and diagonally crosses the northwest corner of Civic Center Park to Martin Luther King Jr. Way. The culvert runs in perfectly straight segments, whereas the natural channel did not. Thus, the existing culvert is already a “realignment” of the creek.
The currently preferred design concept is to create an open channel reach of Strawberry Creek along Center Street between Oxford and Shattuck that would convey low to medium flows only. The flows would be returned to the existing culvert just above the point where it crosses BART at Allston Way. An existing storm drain culvert along the east side of Shattuck Avenue would need to be enlarged for this purpose. High flows would remain in the existing culvert for the time being, but the new channel would be large enough to convey a 100-year flood flow, the full flow of the creek. Also, its gradient would be aimed to pass over the BART station and continue down Center Street if complete rerouting of the creek becomes desirable at some future date.
The objectives of this concept design are to restore some of the creek’s biological, aesthetic, and flood management functions by creating an open reach. The open channel would not need to be huge to convey the 100-year flood flow. A stepped or V-shaped channel eight feet deep and 25 feet wide would suffice, which is approximately the size of the channel at the lower end of campus. This could easily fit within the 80 feet of total width available for a pedestrian plaza along Center Street, while still allowing for sidewalks and other plaza amenities. Previous studies implied that a wider corridor would be needed for complete “restoration” of the creek. Those studies assumed that the objective was to restore all of the natural functions of the creek, including geomorphic processes such as meandering. While a meandering streambed would be a great option if additional space were available, this is not a requirement for the design discussed above, since it is clear that there are obvious constraints associated with being in a highly developed urban environment. Obviously, meandering streams are not compatible in the context of a highly confined and developed urban setting. The present objectives are to restore some of the creek’s biological, aesthetic and flood management functions by creating this open reach.
There are a range of options for the appearance of the open channel through the plaza. At the “wild” extreme, it could be densely vegetated with native, bank-anchoring shrubs such as willows, and have a natural look featuring spider webs and earth banks blanketed with leaf litter. At the “park” extreme, it could look quite manicured with terraced lawn banks, flagstone walkways and a few high-canopy shade trees. As a whole, the aim would be to maximize the potential ecological services provided by this open space area, while at the same time providing a real amenity to the downtown core. Cities such as San Luis Obispo have done this to great economic and aesthetic benefit, and we see a real opportunity here in Berkeley as well.
Deciding whether to daylight Strawberry Creek through the Center Street plaza and selecting the appearance of the channel are decisions that should be made by the citizens of Berkeley. An upcoming opportunity to participate in that discussion is the public “visioning” event being hosted on June 17 by the Downtown Area Plan Advisory Committee.
Berkeley resident Gus Yates is a professional hydrologist..