Sequoia Audubon Society
                              San Mateo County, California

SAS Conservation News

Update on SVCW's Popular Bird Watching Impoundment

By Dan Child, Manager, Silicon Valley Clean Water

As many may recall, drainage of Silicon Valley Clean Water's (SVCW)  landscape impoundment, which became a popular bird watching location at the entry of our facilities at 1400 Radio Road in Redwood Shores, was dictated in January of this year after the U.S. Fish & Wildlife Service confirmed the cause of death of more than 200 ducks there as avian cholera.   

The landscape impoundment was created in 1998 on the west side of the treatment plant to eliminate dust from the dry barren dirt in the area and over time became a very popular bird watching destination. The water was kept fresh by a flow of recycled water from the treatment facility to replace water lost by evaporation and by allowing a certain amount to overflow back to the treatment plant. Peak water flow in the hot season reached over 100,000 gallons per day from the recycled water system.

As noted, prior to the avian cholera attack the affected area was a very popular location for the local bird watching community. SVCW plans to reestablish an area in the vicinity of the treatment plant as a landscape impoundment that will again be available for public viewing of birdlife.

In order to assure the avian cholera that infected the area will be eliminated, the water had to be removed and the soils must go through a drying time of more than four consecutive months with unequivocally no precipitation, because any wetting allows the avian cholera bacteria to flourish in the soil.  If the soil is wetted at all, the entire drying cycle must restart. 

Unfortunately, the rains in October and early November substantially moistened the soil, and as a result the drying must be repeated next summer (2015), as this is the most likely period without any precipitation.

The drying process started in January of 2014 with the draining of the standing water in the landscape impoundment.  We determined that the soil did not become completely dry until July.  As a result and based on the information we learned in regard to eliminating avian cholera from the soil, we had to keep the soil completely dry until November 17, 2014.

As described above, that did not happen. 

Depending on the amount of moisture we receive in the coming spring, we hope the soil will be dry earlier than last year and the drying period "end date" will correspondingly be earlier as well.

On top of the drying schedule, SVCW is also working with permitting agencies and our own staff and advisors to develop the best long-term land-use needs and strategy for the area. This is necessitated by our on-going infrastructure improvement/replacement program. 

The redesign and filling of the landscape impoundment area requires completing a permitting process that is complex with multiple agencies involved in review and acceptance of our permit applications.  It is unlikely that any of the landscape impoundment area will have water in it until at least late fall of 2015 and it may be longer than that, depending on the planning and permitting processes.

SVCW anticipates a landscape impoundment in our long-term plans and this area will provide the added benefit of reestablishing an area suitable for avian habitat.

We can all look forward to the return of water bird life along Radio Road in Redwood City, but unfortunately, the exact timing is not currently known.

Egret/heron rookery at the Port of Redwood City

In June 2012 an egret and heron breeding colony was discovered at the Seaport Center and Port property in the tall trees mostly along Chesapeake Drive, with the largest concentration at the intersection of Saginaw Drive and Chesapeake Drive.

August 2, 2014: Last survey report from San Francisco Bay Bird Observatory:

Unofficial numbers/trends:

  • Snowy Egrets – 16 nests, 30 adults, 19 young
  • Great Egrets – 4 nests, 7 adults, 7 young
  • Black-crowned Night Herons – 23 nests, 22 adults, 19 young

These are the same numbers that were reported in late June so the colony seems to be holding pretty steady.

SFBBO will soon be analyzing the data from the entire Colonial Waterbird Program and compiling a final report. Thanks to SAS members who assisted in our efforts to inform the public about the importance of protecting this valuable natural asset.

Contact Sue Cossins susancossins@gmail.com if you have any questions.

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