By Mark Altgelt
Special to the Herald
California’s primary source of water is at risk because sea level is gradually rising and will begin to contaminate the Sacramento-San Joaquin River Delta estuary with ocean water.
Sea level is predicted to rise 3 to 7 feet by 2100, depending on how fast Antarctic and Greenland ice melts. A three foot rise in sea level would inundate the Delta estuary west of Route 5. A larger catastrophe is also looming because any one of several known potential glacier collapses would significantly exceed current sea level rise predictions.
A reference point for rising sea level is Route 37 near Vallejo because it is occasionally being flooded at high tide. That high level of water in the San Pablo Bay feeds into the Delta. Other coastal cities being flooded during high tides include Fort Lauderdale, Fla.; Charleston, S.C.; and Alexandria, Va.
Billions or more dollars will be needed to adapt to rising sea level because cities will need to build barriers to prevent water intrusion and raise and rebuild low lying infrastructure.
The only viable solution for protecting California’s water supply from rising sea level is to build a dam across the Carquinez Strait. That would prevent ocean water from flooding the Delta estuary and would make it possible to stabilize the flow of water through the Delta with the additional water.
A dam would provide a mechanism for containing water in the Delta and maintaining the balance of salinity in the Delta by controlling the flow of water in and out of the Delta.
The amount of Delta water flowing into the ocean during the past two dry and wet years was about 194 to 243 thousand acre-feet per month. If that water was available for use it would meet California’s extensive agriculture, commercial and residential water needs. It would also provide sufficient water for future population growth, increasing temperatures, heat waves and droughts.
Additional water would provide better water quality and more natural water flow to sustain native fish such as endangered Delta smelt, winter-run Chinook salmon and steelhead trout. It would also facilitate restoring watershed and wetland habitats for fish and wildlife species.
Sufficient supplies of water for agriculture would eliminate the need for excessive groundwater extraction which over past decades has depleted groundwater supplies and caused sinking ground, damaged infrastructure and compressed underground water chambers.
A dam would require ship and boat locks and multiple fish ladders to enable ships, boats and fish to enter and exit the Delta. Delta smelt swim with the tide which would bring them to specially designed wide moving escalator like fish ladders that would sweep them in and carry them out of the water and over the dam.
The loss of endangered fish at pumping facilities needs to be prevented with the use of screen material like that used at the Glen-Colusa Irrigation District pumping facility on the Sacramento River.
The federal and state water pumping facilities near Tracy could prevent Delta smelt from entering those pumps by installing enclosed narrow gauge screen, water intake channels in the water leading to each of the pumps. Then pumping would only need to be restricted in spring when juvenile Delta smelt are in the area. Brushes on tracks could mechanically remove debris that would accumulate on the screens.
A dam across the Carquinez Strait will soon be a necessity to protect the Delta from rising sea level. The California Water Code states, “that because of the conditions prevailing in this State the general welfare requires that the water resources of the State be put to beneficial use to the fullest extent of which they are capable.”
The California Department of Water Resources, U.S. Bureau of Reclamation and California Water Commission along with the Contra Costa Water District, Solano County Water Agency and Regional Water Quality Control Boards, should begin developing plans for building a dam across the Carquinez Strait.
Mark Altgelt is a member of Californians for a Carbon Tax.
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Mark I lived in this area for many years. Flooding and the water rising is not true. Look at those railroad tracks along the straits. The are still there and have been for well over a hundred years. The real answer to water is capture it. The Auburn Dam could have been a start. It will happen in the valley sooner than later. No need to panic. Just use common sense and capture the water. Plenty of it.
The mean level of SF Bay, the Carquinez Strait and the water in the Delta have risen about 10 inches since 1900, about 2.3 inches of that since 2000. That is from local tide gages and from precision satellite measurements. It is rising, slowly but steadily, and the satellite measurements show the rate of rise is accelerating. It is hard to see when the average tidal range is +3 to -3 feet per day, but it is there. This is largely due to the increased temperature of ocean water (water expands when heated); much higher rates of increase are predicted when glaciers melt.
Every 10 years or so, someone comes up with a version of the old discredited Reber Plan, and this zombie has risen again. This “proposal” has so many fatal flaws I won’t bother to go through them all. This was studied by the US Corps of Engineers in the 1950’s, and rejected because it causes far more problems than it solves.
First, the Carquinez Dam will cause huge flooding upstream and downstream. On the Bay side of the dam. The tidal flow through the Golden Gate raises and lowers the water elevation +3 to -3 feet on average twice per day. The South Bay, where the tidal wave is a standing wave, has an elevation change of up to +5 and -5 feet (the tide is amplified)! Up here in the North Bay and into the Delta, the wave is progressive, and all that tidal energy goes roaring into the Delta all the way to Sacramento, being dissipated on the way. Put in a dam, and that energy no longer roars up the Delta, and the wave on the Bay side of the Dam changes to a standing wave, and amplifies the tidal range, flooding vast areas that are always dry now.
On the Delta side, all that water coming down the river has to go somewhere. It was over 200,000 cubic feet per second for weeks last winter. That water will pile up behind the dam. How high? Well it will have to be higher than the new high tide on the other side, And that is high enough to flood all the islands in the Delta in a few days, not to mention Antioch, Pittsburg, Brentwood, Martinez, Suisun City etc. In fact, 200,000 cfs will fill up Suisun Bay and all the existing Delta channels tby about 3 or 4 feet in a day if it cannot get out (and the dam prevents that until it is so overtopped that there is a massive flood upstream, all the way to Sacramento). And those “big” pumps can’t handle that kind of flow: the aqueducts have a total capacity of 15,000 cfs, and that doesn’t make a dent in that flow coming at that rate.
Even if the hydrodynamics worked, the Dam creates a water quality disaster with a giant shallow water lake (and no tides to push the water around, helping to turn over the water); there are a lot of treatment plants dumping their wastewater into this system and in the summer (when inflows are low) that will create a huge stinking algal mess like the one that occurred on Jones Tract when it flooded in 2004 (and that did not have the “benefit” of nutrients from wastewater plants..
I could list many more fatal flaws, but simply causing vast flooding is more than enough, and is the reason it never went beyond the preliminary analyses.
The dam would regulate the flow or water in and out of the Delta and the water level in the Bay will be the same whether or not there is a dam. Tide fills and empties the container the same no matter the size of the container. “All that water” flowing into the Delta could be sent to Southern California via the pumps which have the power to reverse the flow of Middle River or released from the Delta when the Delta level is higher than either high or low tide. So as sea level rises, Delta water could be released during low tide. During high tide the dam could be lowered to allow Bay water into the Delta primarily to manage the salinity of the water. Warming temperatures have guaranteed sea level will rise so to protect California’s water source a dam will be needed.
First of all, this was studied by the US COE in 1953 and rejected as totally impractical, It is the reason they built the Bay Model in Sausalito: to study this; it was not considered further for the reasons I stated above..
Typical tidal flow in the Carquinez Strait is +/-700,000 cfs. The Strait is up to 100 feet deep. I would like to see the dam design that can regulate that flow.
Constrict that flow with a dam to “regulate the flow” in the Strait, and water levels on both sides will change, they will go up, That is simple hydrodynamics (you can use the equations of St. Venant and a simple Bay model to show this for yourself),. A recent paper by UC Berkeley researchers http://journals.ametsoc.org/doi/abs/10.1175/JPO-D-13-0214.1 demonstrates this for simply barriers along the Bay coastline in response to sealevel rise. Put those walls in one place and you amplify the tidal levels in other places. A constriction on the Strait would do the same, but with much greater (adverse) effect.
Those “powerful pumps” cannot exceed 15,0000 cfs, the aqueduct capacity. Even in June 2017 there was enough excess flow above the pumping capacity to raise the water level in the Delta a foot per day, and that went on for months.
The reason the pumps “reverse the flow” (actually, te NET flow, they reverse the tidal flow only very close to the pumps themselves, not at the lower end of Old and Middle River where the tidal flow is +/- 30,000 cfs) is because the net flow is usually very small because the flow from the San Joaquin River is a trickle most of the year: it doesn’t take much to reverse the flow . That 15,000 cfs is small compared to the 250,000 cfs inflow on the Sacramento last winter, which already put the Delta in danger of flooding. Put a constriction in the Strait, and it will certainly flood, the Delta all the way to Sacramento.
There are plenty of numerical models around, you might want to try them out and see for yourself.
It’s been a bad idea that has come back periodically for the last 70 years.