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.