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Guest opinion: Searsville proposals muddy San Francisquito Creek flooding questions

 

After an exhaustive multi-entity review of what to do about the Searsville Dam and the mostly silted-up flood plain behind it, Stanford University has proposed a compromise to resolve the longstanding dilemma of what to do about the dam.

There has been a strong push by the group Beyond Searsville Dam to have the dam removed entirely, citing environmental damage to fish and other factors.

And there is an equally long-running concern about downstream flooding every decade or so of San Francisquito Creek, even though it's a bit odd to be discussing floods in flatland Palo Alto, Menlo Park and East Palo Alto during the middle of a major drought.

The dam and the flooding potential of the "volatile" creek are inextricably linked, as the dam's existence has provided some slowdown of the surge of water coming down from steep, short canyons during heavy rains.

The volatility of the creek can sometimes be measured in hours, from a mere trickle to surging whitewater threatening to spill over into residential areas of the three downstream communities. I have personally witnessed the surge a number of times when I resided in The Willows area of Menlo Park and reported on the bitter feelings between the cities when they each were accusing the others of trying to unilaterally raise banks on one side or the other of the creek.

The latest big overflow in 1998 sluiced through north Palo Alto neighborhoods on its way to flood lowlands Palo Alto with several feet of muddy water, causing about $28 million in damage, endless complications with insurance and repairs, and hard feelings all around. In this case, the overflow was at the infamous Pope/Chaucer Street Bridge separating Palo Alto and Menlo Park. Demands to remove the bridge reached a crescendo, along with some lawsuits.

But had the bridge not been there, there might well have been serious flooding into Menlo Park and potentially deadly flooding into some really low areas of East Palo Alto, where water from a levee break could reach a reported 8 to 10 feet deep — drowning depth.

There were a reported 17 "overtoppings" of the creek's banks in addition to the big one at Pope/Chaucer.

Creek anecdotes abound. There was a flood precipitated by heavy rain in the mid-1950s, during which the late Dr. William Clark — en route at night to aid a patient having a heart attack — drove into an icy 3-foot-deep pond in the then-new Oregon underpass at Alma Street. Dr. Clark waded away from his stalled car. The patient died.

Circa 1970 then-City Manager George Morgan was up in the early hours actually helping crews use poles to push tree trunks through the too-small arch opening at Pope/Chaucer Street Bridge.

Along the way, Santa Clara County raised creek banks and built low concrete walls along lower areas of the creek, which helped prevent some floods over the decades. But the patchwork wasn't enough for 1998 and falls far short of protecting against a proverbial "100-year flood" — a misnomer, as it actually means a flood that has a 1 percent chance of occurring in any year. Well, maybe not a drought year.

The 1998 flood was just a "45-year flood," a relative trickle compared to a 100-year flood.

The 1998 flood prompted creation of the Joint Powers Authority for the creek in 1999 by the three downstream cities and San Mateo and Santa Clara counties, resulting in the unpronounceable SFCJPA shorthand.

Its first executive director, Cynthia D'Agosta, helped forge the agency and supplant some of the harder feelings and suspicions between the communities. Her prior experience with the about 100 entities along the Los Angeles River (famous for chase scenes in movies) helped with the thorny challenge, but slogging through federal, state and regional water-related agencies proved tough.

When current director Len Materman took up the challenges, he focused successfully on getting a local funding package put together with contributions from the five agencies represented on the JPA's Board of Directors. The package will pay for major projects — including replacing the Pope/Chaucer Street Bridge! — from Middlefield Road out to the baylands.

He also has pushed hard to move a federal study along relating to the creek's volatility, which would be severely worsened if the surge occurred during a high tide. Results of that study may still be years off, but it's continuing.

But what does all this have to do with Searsville Dam?

A lot. Stanford University is the largest landowner along the creek's watershed, including the Searsville Lake area, now referred increasingly as the Searsville Reservoir — part of Stanford's Jasper Ridge ecological study area.

Yes, the dam and flood plain behind it do play a role in reducing the downstream volatility of the creek, chiefly by creating a slowdown of the surge while water flows away downstream.

Stanford's plan, outlined in a 41-page report, is to stop short of removing the dam through two methods. What to do with the silt is a huge concern, being debated vigorously in online comments on the story.

Stanford officials say their proposed alternatives would not make potential downstream flooding worse. Some add-on alternatives, such as creating large overflow areas upstream, could cost millions of dollars.

But not making things worse may not be enough for the SFCJPA agencies.

Materman said in a telephone interview that some outside funding for upstream improvements would be likely when the federal study is completed and a comprehensive program adopted.

Such funding would not be likely unless there were some real improvement in the flooding risk, he indicated.

Former Weekly Editor Jay Thorwaldson can be emailed at jthorwaldson@paweekly.com and/or jaythor@well.com. He also writes periodic blogs at PaloAltoOnline.com.

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