Flooding, Lake Lag, California Water situation

Flooding, Lake Lag, California Water situation - Printable Version

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Flooding, Lake Lag, California Water situation - 81alum - 12-31-2022

Flood warning in effect for San Francisquito Creek, including about half the Stanford campus. NWS warning in effect until 2:45 this afternoon. Rain expected to continue until around 6pm, then should clear for the rest of the day and tomorrow. If coming to the game at Maples tonight, drive carefully and allow time in case of detours.

I am not sure if flooding is currently occurring....I am on Baron Creek in south Palo Alto and it is not a problem yet where we are. The warning does not extend to us but is north on San Francisquito.

I hope this means Lake Lag will be full. That is, after all, its purpose--to divert flood waters.

https://www.mercurynews.com/2022/12/31/authorities-brace-for-flooding-of-pope-chaucer-bridge-in-palo-alto/

The notorious Chaucer bridge is about to flood, apparently.

Folks, watch the news carefully before deciding to leave for the game tonight. Make sure it is safe before doing so. Things are changing rapidly.

https://www.cityofpaloalto.org/Departments/Public-Works/Engineering-Services/Creek-Monitor-Cam

The Creek cam shows the water lapping at the bridge but not quite going over yet. We can hope that is as high as it gets....

RE: Palo Alto Flood Warning until 2:45 - CompSci87 - 12-31-2022

Wow! I live in the area, close enough that I often walk over to the creek.

RE: Palo Alto Flood Warning until 2:45 - M T - 12-31-2022

You can see various creek levels and flow rates here
https://valleywateralert.org/scvwd/sgi.php

RE: Palo Alto Flood Warning until 2:45 - BobK - 12-31-2022

Anyone want my ticket for tonight?
Sec 4 row GG

RE: Palo Alto Flood Warning until 2:45 - PalmTree - 12-31-2022

Jeez - I hope these two are OK....

Palo Alto's newest residents

Otherwise, on a more serious note, a couple of friends got flooded out in 1998 - one house in east Menlo and another in midtown PA. A bunch of us split resources to help them evacuate and clean up afterward - what a mess. Really hoping for the best here.

RE: Palo Alto Flood Warning until 2:45 - Nan3cy - 12-31-2022

https://www.cityofpaloalto.org/Departments/Public-Works/Engineering-Services/Creek-Monitor-Cam

Water heights at all the bridges, and a picture of current conditions at the Bayshore bridge. Don’t quite know what has the Chaucer number bouncing all over the place.

RE: Palo Alto Flood Warning until 2:45 - BostonCard - 12-31-2022

From the link…

Quote: The sensors at Chaucer St and Waverley St on the Creek Monitor are not functioning properly.

RE: Palo Alto Flood Warning until 2:45 - cardcrimson - 12-31-2022

Stay safe. We've had between four and a half and five inches of rain since midnight according to several monitoring sites here in the East Bay. Roads are treacherous. . . .

With a ton more rain on the way next week, could this be another 1861/62?

RE: Palo Alto Flood Warning until 2:45 - 81alum - 12-31-2022

The Merc Article has been updated to indicate that the creek did overtop at the Chaucer Street bridge, forcing the closing of various nearby streets including University. However, the flooding is thus far described as "minor."

https://www.mercurynews.com/2022/12/31/authorities-brace-for-flooding-of-pope-chaucer-bridge-in-palo-alto/

Quote:Creek monitors at Waverly and Chaucer streets failed; police said city staff members were in place to monitor water levels.

So much angst about fixing this problem since 1998, and the political disagreements over how to do it have become legendary. But after all of that, they could not install sensors that worked in a flood? I'm sure they were just fine when the creek was dry....

Meanwhile, 101 has been closed in South San Francisco due to flooding:

https://www.ksbw.com/article/highway-101-closed-indefinitely-due-to-major-flooding-in-south-san-francisco/42373306

The rain is supposed to clear out by 7 or 8, so hopefully by the time the game is over. It could be a mess getting to Maples, however.

Do they allow umbrellas in Maples?

RE: Palo Alto Flood Warning until 2:45 - 81alum - 12-31-2022

Pictures of the flooding and debris. Not nearly as bad as 1998. Next week, however, we have another big storm and the ground is saturated.

https://www.paloaltoonline.com/news/2022/12/31/palo-alto-floods-likely-as-pope-chaucer-bridge-nears-capacity

RE: Palo Alto Flood Warning until 2:45 - jacket3ree - 12-31-2022

This may be the most on topic thread for me in history. I've worked on and around San Francisquito, Matadero, Barron, and Adobe Creeks and the Palo Alto Flood Basin for 36 years now. First, I sincerely wish safety for life, limb, and property and hope the next week of rain on top of wet soils does not result in a repeat of history, although I'm afraid it might.

My PE stamp is on the report/workmap that became the FEMA flood hazard maps that cover Palo Alto, Mountain View, and Los Altos. It is also on the basis of design that became the Matadero and Barron Creek improvements of the late 1990s. The person living near Barron Creek might appreciate that with a series of planned diversions into Matadero Creek, Barron Creek should have 100-year flow capacity. So should Matadero Creek. I know every inch of those systems and have walked the creeks from Foothill Expressway under El Camino in the bypass and on into the flood basin. That leaves San Francisquito Creek.

Without getting into the political reasons it may never be "fixed" completely, San Francisquito remains a problem child. Today's flow provisionally peaked at roughly 4,300 cubic feet per second (cfs) at the USGS gage at Stanford (golf course). That is equivalent to a 10-year return period based on the available record. The Pope-Chaucer Bridge is the first capacity-limiting hydraulic bottleneck and as evidenced by reports of limited overflow today, San Francisquito Creek has about a 10-year capacity. At East Bayshore, water was on the new floodwalls, and it looks like the tide was up. It is of course poor form to say "I told you so" to the people who objected to those floodwalls during their public vetting. Our pump station that sits next to Yeaman Auto Body was cranking away, only needing one of its four large capacity pumps to keep up. This storm is also the first "shake down" for two large storm water pump stations we just finished near Coyote Point, so this has been a busy week. There are some control issues at one of them we need to button down on Tuesday. Fortunately the bat signal didn't go out today. Tomorrow should be a break in the precipitation.

By contrast, February 2-3, 1998 was the flood of record on San Francisquito Creek and essentially a 100-year flow as measured at the gage. Flows leave the alluvial/perched creek channel and flow through Menlo Park, Palo Alto, and East Palo Alto never to return. The most severe flooding in 1998 was south of Colorado Avenue where water is trapped against the Matadero Creek floodwalls. That risk remains.

Every possible solution under the sun has been proposed, but none have met the public, environmental, and financial approval to move forward. Kevin Murray at the SF Creek JPA works tirelessly to get something done, so I'm sure these are anxious days for him. He does have a plan that would improve hydraulics at the Chaucer Bridge and then the next bottlenecks on the system that would then control capacity. The downstream reach is ready to handle the extra flow and additional capacity was recently added at the 101 bridge. The JPA will do what they can, but my understanding is that 100-year protection will simply remain out of reach for a host of reasons.

Stay safe everyone and remember that California is shaped by floods as much as drought.

RE: Palo Alto Flood Warning until 2:45 - newguy - 12-31-2022

(12-31-2022, 08:30 PM)jacket3ree Wrote: This may be the most on topic thread for me in history. I've worked on and around San Francisquito, Matadero, Barron, and Adobe Creeks and the Palo Alto Flood Basin for 36 years now. First, I sincerely wish safety for life, limb, and property and hope the next week of rain on top of wet soils does not result in a repeat of history, although I'm afraid it might.

My PE stamp is on the report/workmap that became the FEMA flood hazard maps that cover Palo Alto, Mountain View, and Los Altos. It is also on the basis of design that became the Matadero and Barron Creek improvements of the late 1990s. The person living near Barron Creek might appreciate that with a series of planned diversions into Matadero Creek, Barron Creek should have 100-year flow capacity. So should Matadero Creek. I know every inch of those systems and have walked the creeks from Foothill Expressway under El Camino in the bypass and on into the flood basin. That leaves San Francisquito Creek.

Without getting into the political reasons it may never be "fixed" completely, San Francisquito remains a problem child. Today's flow provisionally peaked at roughly 4,300 cubic feet per second (cfs) at the USGS gage at Stanford (golf course). That is equivalent to a 10-year return period based on the available record. The Pope-Chaucer Bridge is the first capacity-limiting hydraulic bottleneck and as evidenced by reports of limited overflow today, San Francisquito Creek has about a 10-year capacity. At East Bayshore, water was on the new floodwalls, and it looks like the tide was up. It is of course poor form to say "I told you so" to the people who objected to those floodwalls during their public vetting. Our pump station that sits next to Yeaman Auto Body was cranking away, only needing one of its four large capacity pumps to keep up. This storm is also the first "shake down" for two large storm water pump stations we just finished near Coyote Point, so this has been a busy week. There are some control issues at one of them we need to button down on Tuesday. Fortunately the bat signal didn't go out today. Tomorrow should be a break in the precipitation.

By contrast, February 2-3, 1998 was the flood of record on San Francisquito Creek and essentially a 100-year flow as measured at the gage. Flows leave the alluvial/perched creek channel and flow through Menlo Park, Palo Alto, and East Palo Alto never to return. The most severe flooding in 1998 was south of Colorado Avenue where water is trapped against the Matadero Creek floodwalls. That risk remains.

Every possible solution under the sun has been proposed, but none have met the public, environmental, and financial approval to move forward. Kevin Murray at the SF Creek JPA works tirelessly to get something done, so I'm sure these are anxious days for him. He does have a plan that would improve hydraulics at the Chaucer Bridge and then the next bottlenecks on the system that would then control capacity. The downstream reach is ready to handle the extra flow and additional capacity was recently added at the 101 bridge. The JPA will do what they can, but my understanding is that 100-year protection will simply remain out of reach for a host of reasons.

Stay safe everyone and remember that California is shaped by floods as much as drought.

keep up the good work.
dedicated public servants rarely get the thanks they deserve.

RE: Palo Alto Flood Warning until 2:45 - triangle2 - 12-31-2022

Jacket3ree, I spent many years living very close to the Newell St. bridge over San Francisquito. In the 70's, the creek seemed virtually dry as a bone, and as a kid, I spent summer afternoons chasing Swallowtails in the creek and finding the occasional salamander in the few muddy areas one could find. There were other strange things that people had deposited into the creek in the 'dry' era - for a while, there was an old Dodge Dart chassis there, later an abandoned van, plenty of tires, construction debris, and discarded washers/dryers. In later years after the 70's drought had receded, I can remember 2-3 times where we walked over to the bridge and watched the water come basically within a couple of feet from the bottom of the bridge but without much actual flooding. It was pretty frightening to see that much water following through a creek that I had spent so much time walking around in. And, I knew how deep it was as it wasn't exactly easy to get down to the creek bottom.

I had left the area by the time of the '98 flood, but I heard from friends that the water flowed right down Newell and ran through through Edgewater and Hamilton Ave. properties including through a friend's garage. They were intensely gratified to find out that the low point of their property wasn't their living room.

Once, I bumped into someone from the city who had come out to look at the water level at the Newell bridge during a storm when there was some minor flooding. I remember asking him if there was a fix and he shook his head and said that all the properties along that part of the creek were vulnerable and that Newell was so low that there wasn't a great option as far as rebuilding the bridge. He said the fix for the water level needed to happen 'elsewhere.' I didn't ask him what that meant. I bet you have informed opinions on that.

RE: Palo Alto Flood Warning until 2:45 - fishman - 12-31-2022

Jacket3ree - Where do you find the 4,300 cfs figure for the flow of the creek? The USGS site shows much less, and shows the record flows of Feb 2 & 3, 1998 were a bit less than 3,000 cfs. Not doubting your expertise, but where do you get those figures that don't appear on the published current USGS flows for Dec. 31, 2022? In any event, it's a brobdingnagian pulse of water that's causing flooding.

RE: Palo Alto Flooding - jacket3ree - 01-01-2023

Fishman -

I went straight to the USGS site: SAN FRANCISQUITO C A STANFORD UNIVERSITY CA

This is a live link, so I don't know how to copy and paste the hydrograph. There are radio buttons for flow and stage. The data are provisional (vetting will take months), and the number I reported yesterday was from the memory of looking at my phone while standing on the creek bank in the rain, so it appears 4,300 cfs was low on my part - sitting at my desk this morning on a laptop, I read 6,350 cfs at 9:00 on Saturday. This is equivalent to the 40-year event. That's better - it means there is a higher level of protection under existing conditions.

Here is a link to the annual peak streamflow data: Peak Streamflow for the Nation USGS 11164500 SAN FRANCISQUITO C A STANFORD UNIVERSITY CA

02/03/1998 7,200 cfs

Our flood frequency analysis shows the one-percent peak discharge as 8,000 cfs (YMMV)

Make sure you are looking at peak streamflow data, not maximum daily discharge, which would be lower.

Triangle -

Newell Street is one of those "and then" bottlenecks I described earlier, along with University Avenue. From upstream to downstream, historically Middlefield Road, Pope-Chaucer, University, Newell, West Bayshore, 101, and East Bayshore cause problems. If all those bridges were removed, with relatively minor improvement, the creek could pass the flow. Removing, raising or enlarging each of those structures comes with varying degrees of difficulty. That's probably what the City person meant by saying the solution would need to be "elsewhere". One has to be careful in how one removes a bottleneck, or the problem is indeed moved elsewhere. The bridge restrictions between Middlefield and Bayshore needed to be remedied simultaneously if possible, or temporary flow restrictions may be necessary if available funding doesn't allow it all to be done at once.

There are four basic things that can be done on any system like this:

1. Increase flow conveyance (enlarge creek, remove vegetation, and/or improve bridge hydraulics)
2. Reduce the flow by storing water upstream.
3. Reduce the flow by diverting a portion of it (bypass).
4. Nothing. But even then, if the creek is not maintained, flow conveyance will lessen and flooding may increase.

Some of the public and NGOs like Friends of the Creek favor the fourth option. As crass as this is to say, we need events like this to remind everyone that doing nothing leads to sorrow. Alternative 2 (on stream or off-stream storage) and Alternative 3 (giant concrete underground bypass from Middlefield to the Bay through.....EPA?) have been studied to death and appear to be off the table forever due to ineffectiveness and/or expense. That leaves Alternative 1.

Work should progress from downstream to upstream to avoid induced flooding, and it is. The reach from Bayshore to the Bay is complete, and with some remaining nuance, Bayshore itself is ready to go. That leaves the reach between Middlefield and Bayshore. The JPA has labeled the reach between Pope-Chaucer and Bayshore as "Reach 2". Kevin does a better job of succinctly explaining it than I can:

Kevin Murray Explains

If anyone has further interest, I encourage you to read about it here: The Reach 2 “Upstream Project” When this work is done, the capacity bottleneck moves to Middlefield Road. I haven't heard anything about fixing that, and the downstream capacity is being set to that of Middlefield, which spills in a 100-year event. It appears that a residual 100-year floodplain will remain, but it will less extensive than under current conditions.

Valley Water put together a flyover after the 1998 flood. Full disclosure: They retained my firm to help them reconstruct what happened and we did some modeling. We categorically DID NOT select the background music.

1998 Flood

Remember, a lot of the flooding you see is local - drainage can't get into the perched or leveed creek, so it backs up on the streets.

RE: Palo Alto Flooding - 81alum - 01-01-2023

Thank you so much, Jacket! That is really interesting material. Nice to know a couple of the bottleneck bridges will be replaced soon and that they can continue working their way upstream.

Can you confirm that Lake Lag is part of the flood control scheme? I thought I read that once upon a time....

Second question, I remember an argument about the Baron Creek diversion--that Baron Creek water was going to be diverted in case of a Baron Creek event over to Matadero Creek, but I thought there was a dispute and this plan was halted. Since I live immediately on Baron creek I'd be curious to know if the problems were worked out.

It is sunny today and I biked my way down Edgewood and Woodland and Palo Alto Ave, crossing both at Newell and back at Pope/Chaucer. All streets are open, there are still a few homeowner sandbags in sight and a sump pump or two, but it was surreal to see the stream so far back down after less than 24 hours.

The debris that over topped the bridge at Chaucer was interesting. In addition to a tangle of branches, I counted one basketball, one volleyball, and about a dozen tennis balls. The creek finally agreed to give them all back!

RE: Palo Alto Flooding - jacket3ree - 01-01-2023

81 -

Lake Lag is not part of the flood protection plan. It has to be intentionally filled.

The Barron Creek Diversion and Matadero Creek Bypass Projects were completed in the late '80s / early '90s. They were fully tested during the 1998 event. I have that minute-by-minute record stored on our server somewhere. It was dicey. The diversion worked as intended, but the 1998 event identified capacity problems with Matadero Creek between Alma Street and the flood basin, since it is taking the diverted flow from the Barron Creek watershed. We were retained to sort those out. The subsequent remediation project was completed in the early 'oughts. Matadero and Barron should be OK. There are still problems with San Francisquito Creek and Adobe Creek.

A lot of mud out on the streets of Belmont and San Carlos this morning. Belmont Creek may have overtopped near Harbor.

RE: Palo Alto Flooding - Goose - 01-01-2023

(01-01-2023, 01:01 PM)jacket3ree Wrote: Lake Lag is not part of the flood protection plan. It has to be intentionally filled.

Is this even possible after the removal of the Lagunita Diversion Dam? I know that Lag used to get significant runoff that could at least create a swamp for a few months, but it has been a very long time since I have seen it filled, possibly the early 70s?

RE: Palo Alto Flooding - cardcrimson - 01-01-2023

(01-01-2023, 02:33 PM)Goose Wrote:
(01-01-2023, 01:01 PM)jacket3ree Wrote: Lake Lag is not part of the flood protection plan. It has to be intentionally filled.

Is this even possible after the removal of the Lagunita Diversion Dam? I know that Lag used to get significant runoff that could at least create a swamp for a few months, but it has been a very long time since I have seen it filled, possibly the early 70s?

Had the right letter of the alphabet in the draw in the early 80's, and took both windsurfing and sailing at the boat house. Fantastic times.

RE: Palo Alto Flooding - PAsportsfan - 01-01-2023

(01-01-2023, 02:33 PM)Goose Wrote:
(01-01-2023, 01:01 PM)jacket3ree Wrote: Lake Lag is not part of the flood protection plan. It has to be intentionally filled.

Is this even possible after the removal of the Lagunita Diversion Dam? I know that Lag used to get significant runoff that could at least create a swamp for a few months, but it has been a very long time since I have seen it filled, possibly the early 70s?

2017

https://twitter.com/LombardiHimself/status/838903019643121666